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3401 lines
88 KiB
3401 lines
88 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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* linux/fs/buffer.c |
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* |
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* Copyright (C) 1991, 1992, 2002 Linus Torvalds |
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*/ |
|
|
|
/* |
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* Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 |
|
* |
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* Removed a lot of unnecessary code and simplified things now that |
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* the buffer cache isn't our primary cache - Andrew Tridgell 12/96 |
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* |
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* Speed up hash, lru, and free list operations. Use gfp() for allocating |
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* hash table, use SLAB cache for buffer heads. SMP threading. -DaveM |
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* |
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* Added 32k buffer block sizes - these are required older ARM systems. - RMK |
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* |
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* async buffer flushing, 1999 Andrea Arcangeli <[email protected]> |
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*/ |
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|
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#include <linux/kernel.h> |
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#include <linux/sched/signal.h> |
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#include <linux/syscalls.h> |
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#include <linux/fs.h> |
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#include <linux/iomap.h> |
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#include <linux/mm.h> |
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#include <linux/percpu.h> |
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#include <linux/slab.h> |
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#include <linux/capability.h> |
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#include <linux/blkdev.h> |
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#include <linux/file.h> |
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#include <linux/quotaops.h> |
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#include <linux/highmem.h> |
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#include <linux/export.h> |
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#include <linux/backing-dev.h> |
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#include <linux/writeback.h> |
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#include <linux/hash.h> |
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#include <linux/suspend.h> |
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#include <linux/buffer_head.h> |
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#include <linux/task_io_accounting_ops.h> |
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#include <linux/bio.h> |
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#include <linux/cpu.h> |
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#include <linux/bitops.h> |
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#include <linux/mpage.h> |
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#include <linux/bit_spinlock.h> |
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#include <linux/pagevec.h> |
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#include <linux/sched/mm.h> |
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#include <trace/events/block.h> |
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#include <linux/fscrypt.h> |
|
|
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#include "internal.h" |
|
|
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static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); |
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static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, |
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struct writeback_control *wbc); |
|
|
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#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) |
|
|
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inline void touch_buffer(struct buffer_head *bh) |
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{ |
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trace_block_touch_buffer(bh); |
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mark_page_accessed(bh->b_page); |
|
} |
|
EXPORT_SYMBOL(touch_buffer); |
|
|
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void __lock_buffer(struct buffer_head *bh) |
|
{ |
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wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); |
|
} |
|
EXPORT_SYMBOL(__lock_buffer); |
|
|
|
void unlock_buffer(struct buffer_head *bh) |
|
{ |
|
clear_bit_unlock(BH_Lock, &bh->b_state); |
|
smp_mb__after_atomic(); |
|
wake_up_bit(&bh->b_state, BH_Lock); |
|
} |
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EXPORT_SYMBOL(unlock_buffer); |
|
|
|
/* |
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* Returns if the page has dirty or writeback buffers. If all the buffers |
|
* are unlocked and clean then the PageDirty information is stale. If |
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* any of the pages are locked, it is assumed they are locked for IO. |
|
*/ |
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void buffer_check_dirty_writeback(struct page *page, |
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bool *dirty, bool *writeback) |
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{ |
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struct buffer_head *head, *bh; |
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*dirty = false; |
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*writeback = false; |
|
|
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BUG_ON(!PageLocked(page)); |
|
|
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if (!page_has_buffers(page)) |
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return; |
|
|
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if (PageWriteback(page)) |
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*writeback = true; |
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|
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head = page_buffers(page); |
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bh = head; |
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do { |
|
if (buffer_locked(bh)) |
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*writeback = true; |
|
|
|
if (buffer_dirty(bh)) |
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*dirty = true; |
|
|
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bh = bh->b_this_page; |
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} while (bh != head); |
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} |
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EXPORT_SYMBOL(buffer_check_dirty_writeback); |
|
|
|
/* |
|
* Block until a buffer comes unlocked. This doesn't stop it |
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* from becoming locked again - you have to lock it yourself |
|
* if you want to preserve its state. |
|
*/ |
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void __wait_on_buffer(struct buffer_head * bh) |
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{ |
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wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE); |
|
} |
|
EXPORT_SYMBOL(__wait_on_buffer); |
|
|
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static void buffer_io_error(struct buffer_head *bh, char *msg) |
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{ |
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if (!test_bit(BH_Quiet, &bh->b_state)) |
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printk_ratelimited(KERN_ERR |
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"Buffer I/O error on dev %pg, logical block %llu%s\n", |
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bh->b_bdev, (unsigned long long)bh->b_blocknr, msg); |
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} |
|
|
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/* |
|
* End-of-IO handler helper function which does not touch the bh after |
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* unlocking it. |
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* Note: unlock_buffer() sort-of does touch the bh after unlocking it, but |
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* a race there is benign: unlock_buffer() only use the bh's address for |
|
* hashing after unlocking the buffer, so it doesn't actually touch the bh |
|
* itself. |
|
*/ |
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static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
|
{ |
|
if (uptodate) { |
|
set_buffer_uptodate(bh); |
|
} else { |
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/* This happens, due to failed read-ahead attempts. */ |
|
clear_buffer_uptodate(bh); |
|
} |
|
unlock_buffer(bh); |
|
} |
|
|
|
/* |
|
* Default synchronous end-of-IO handler.. Just mark it up-to-date and |
|
* unlock the buffer. This is what ll_rw_block uses too. |
|
*/ |
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void end_buffer_read_sync(struct buffer_head *bh, int uptodate) |
|
{ |
|
__end_buffer_read_notouch(bh, uptodate); |
|
put_bh(bh); |
|
} |
|
EXPORT_SYMBOL(end_buffer_read_sync); |
|
|
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void end_buffer_write_sync(struct buffer_head *bh, int uptodate) |
|
{ |
|
if (uptodate) { |
|
set_buffer_uptodate(bh); |
|
} else { |
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buffer_io_error(bh, ", lost sync page write"); |
|
mark_buffer_write_io_error(bh); |
|
clear_buffer_uptodate(bh); |
|
} |
|
unlock_buffer(bh); |
|
put_bh(bh); |
|
} |
|
EXPORT_SYMBOL(end_buffer_write_sync); |
|
|
|
/* |
|
* Various filesystems appear to want __find_get_block to be non-blocking. |
|
* But it's the page lock which protects the buffers. To get around this, |
|
* we get exclusion from try_to_free_buffers with the blockdev mapping's |
|
* private_lock. |
|
* |
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* Hack idea: for the blockdev mapping, private_lock contention |
|
* may be quite high. This code could TryLock the page, and if that |
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* succeeds, there is no need to take private_lock. |
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*/ |
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static struct buffer_head * |
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__find_get_block_slow(struct block_device *bdev, sector_t block) |
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{ |
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struct inode *bd_inode = bdev->bd_inode; |
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struct address_space *bd_mapping = bd_inode->i_mapping; |
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struct buffer_head *ret = NULL; |
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pgoff_t index; |
|
struct buffer_head *bh; |
|
struct buffer_head *head; |
|
struct page *page; |
|
int all_mapped = 1; |
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static DEFINE_RATELIMIT_STATE(last_warned, HZ, 1); |
|
|
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index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); |
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page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED); |
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if (!page) |
|
goto out; |
|
|
|
spin_lock(&bd_mapping->private_lock); |
|
if (!page_has_buffers(page)) |
|
goto out_unlock; |
|
head = page_buffers(page); |
|
bh = head; |
|
do { |
|
if (!buffer_mapped(bh)) |
|
all_mapped = 0; |
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else if (bh->b_blocknr == block) { |
|
ret = bh; |
|
get_bh(bh); |
|
goto out_unlock; |
|
} |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
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|
|
/* we might be here because some of the buffers on this page are |
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* not mapped. This is due to various races between |
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* file io on the block device and getblk. It gets dealt with |
|
* elsewhere, don't buffer_error if we had some unmapped buffers |
|
*/ |
|
ratelimit_set_flags(&last_warned, RATELIMIT_MSG_ON_RELEASE); |
|
if (all_mapped && __ratelimit(&last_warned)) { |
|
printk("__find_get_block_slow() failed. block=%llu, " |
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"b_blocknr=%llu, b_state=0x%08lx, b_size=%zu, " |
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"device %pg blocksize: %d\n", |
|
(unsigned long long)block, |
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(unsigned long long)bh->b_blocknr, |
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bh->b_state, bh->b_size, bdev, |
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1 << bd_inode->i_blkbits); |
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} |
|
out_unlock: |
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spin_unlock(&bd_mapping->private_lock); |
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put_page(page); |
|
out: |
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return ret; |
|
} |
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|
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static void end_buffer_async_read(struct buffer_head *bh, int uptodate) |
|
{ |
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unsigned long flags; |
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struct buffer_head *first; |
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struct buffer_head *tmp; |
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struct page *page; |
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int page_uptodate = 1; |
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|
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BUG_ON(!buffer_async_read(bh)); |
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|
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page = bh->b_page; |
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if (uptodate) { |
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set_buffer_uptodate(bh); |
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} else { |
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clear_buffer_uptodate(bh); |
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buffer_io_error(bh, ", async page read"); |
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SetPageError(page); |
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} |
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|
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/* |
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* Be _very_ careful from here on. Bad things can happen if |
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* two buffer heads end IO at almost the same time and both |
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* decide that the page is now completely done. |
|
*/ |
|
first = page_buffers(page); |
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spin_lock_irqsave(&first->b_uptodate_lock, flags); |
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clear_buffer_async_read(bh); |
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unlock_buffer(bh); |
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tmp = bh; |
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do { |
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if (!buffer_uptodate(tmp)) |
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page_uptodate = 0; |
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if (buffer_async_read(tmp)) { |
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BUG_ON(!buffer_locked(tmp)); |
|
goto still_busy; |
|
} |
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tmp = tmp->b_this_page; |
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} while (tmp != bh); |
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags); |
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|
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/* |
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* If none of the buffers had errors and they are all |
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* uptodate then we can set the page uptodate. |
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*/ |
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if (page_uptodate && !PageError(page)) |
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SetPageUptodate(page); |
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unlock_page(page); |
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return; |
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|
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still_busy: |
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spin_unlock_irqrestore(&first->b_uptodate_lock, flags); |
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return; |
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} |
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|
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struct decrypt_bh_ctx { |
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struct work_struct work; |
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struct buffer_head *bh; |
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}; |
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|
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static void decrypt_bh(struct work_struct *work) |
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{ |
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struct decrypt_bh_ctx *ctx = |
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container_of(work, struct decrypt_bh_ctx, work); |
|
struct buffer_head *bh = ctx->bh; |
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int err; |
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|
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err = fscrypt_decrypt_pagecache_blocks(bh->b_page, bh->b_size, |
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bh_offset(bh)); |
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end_buffer_async_read(bh, err == 0); |
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kfree(ctx); |
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} |
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|
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/* |
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* I/O completion handler for block_read_full_page() - pages |
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* which come unlocked at the end of I/O. |
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*/ |
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static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate) |
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{ |
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/* Decrypt if needed */ |
|
if (uptodate && |
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fscrypt_inode_uses_fs_layer_crypto(bh->b_page->mapping->host)) { |
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struct decrypt_bh_ctx *ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC); |
|
|
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if (ctx) { |
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INIT_WORK(&ctx->work, decrypt_bh); |
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ctx->bh = bh; |
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fscrypt_enqueue_decrypt_work(&ctx->work); |
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return; |
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} |
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uptodate = 0; |
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} |
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end_buffer_async_read(bh, uptodate); |
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} |
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|
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/* |
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* Completion handler for block_write_full_page() - pages which are unlocked |
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* during I/O, and which have PageWriteback cleared upon I/O completion. |
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*/ |
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void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
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{ |
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unsigned long flags; |
|
struct buffer_head *first; |
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struct buffer_head *tmp; |
|
struct page *page; |
|
|
|
BUG_ON(!buffer_async_write(bh)); |
|
|
|
page = bh->b_page; |
|
if (uptodate) { |
|
set_buffer_uptodate(bh); |
|
} else { |
|
buffer_io_error(bh, ", lost async page write"); |
|
mark_buffer_write_io_error(bh); |
|
clear_buffer_uptodate(bh); |
|
SetPageError(page); |
|
} |
|
|
|
first = page_buffers(page); |
|
spin_lock_irqsave(&first->b_uptodate_lock, flags); |
|
|
|
clear_buffer_async_write(bh); |
|
unlock_buffer(bh); |
|
tmp = bh->b_this_page; |
|
while (tmp != bh) { |
|
if (buffer_async_write(tmp)) { |
|
BUG_ON(!buffer_locked(tmp)); |
|
goto still_busy; |
|
} |
|
tmp = tmp->b_this_page; |
|
} |
|
spin_unlock_irqrestore(&first->b_uptodate_lock, flags); |
|
end_page_writeback(page); |
|
return; |
|
|
|
still_busy: |
|
spin_unlock_irqrestore(&first->b_uptodate_lock, flags); |
|
return; |
|
} |
|
EXPORT_SYMBOL(end_buffer_async_write); |
|
|
|
/* |
|
* If a page's buffers are under async readin (end_buffer_async_read |
|
* completion) then there is a possibility that another thread of |
|
* control could lock one of the buffers after it has completed |
|
* but while some of the other buffers have not completed. This |
|
* locked buffer would confuse end_buffer_async_read() into not unlocking |
|
* the page. So the absence of BH_Async_Read tells end_buffer_async_read() |
|
* that this buffer is not under async I/O. |
|
* |
|
* The page comes unlocked when it has no locked buffer_async buffers |
|
* left. |
|
* |
|
* PageLocked prevents anyone starting new async I/O reads any of |
|
* the buffers. |
|
* |
|
* PageWriteback is used to prevent simultaneous writeout of the same |
|
* page. |
|
* |
|
* PageLocked prevents anyone from starting writeback of a page which is |
|
* under read I/O (PageWriteback is only ever set against a locked page). |
|
*/ |
|
static void mark_buffer_async_read(struct buffer_head *bh) |
|
{ |
|
bh->b_end_io = end_buffer_async_read_io; |
|
set_buffer_async_read(bh); |
|
} |
|
|
|
static void mark_buffer_async_write_endio(struct buffer_head *bh, |
|
bh_end_io_t *handler) |
|
{ |
|
bh->b_end_io = handler; |
|
set_buffer_async_write(bh); |
|
} |
|
|
|
void mark_buffer_async_write(struct buffer_head *bh) |
|
{ |
|
mark_buffer_async_write_endio(bh, end_buffer_async_write); |
|
} |
|
EXPORT_SYMBOL(mark_buffer_async_write); |
|
|
|
|
|
/* |
|
* fs/buffer.c contains helper functions for buffer-backed address space's |
|
* fsync functions. A common requirement for buffer-based filesystems is |
|
* that certain data from the backing blockdev needs to be written out for |
|
* a successful fsync(). For example, ext2 indirect blocks need to be |
|
* written back and waited upon before fsync() returns. |
|
* |
|
* The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), |
|
* inode_has_buffers() and invalidate_inode_buffers() are provided for the |
|
* management of a list of dependent buffers at ->i_mapping->private_list. |
|
* |
|
* Locking is a little subtle: try_to_free_buffers() will remove buffers |
|
* from their controlling inode's queue when they are being freed. But |
|
* try_to_free_buffers() will be operating against the *blockdev* mapping |
|
* at the time, not against the S_ISREG file which depends on those buffers. |
|
* So the locking for private_list is via the private_lock in the address_space |
|
* which backs the buffers. Which is different from the address_space |
|
* against which the buffers are listed. So for a particular address_space, |
|
* mapping->private_lock does *not* protect mapping->private_list! In fact, |
|
* mapping->private_list will always be protected by the backing blockdev's |
|
* ->private_lock. |
|
* |
|
* Which introduces a requirement: all buffers on an address_space's |
|
* ->private_list must be from the same address_space: the blockdev's. |
|
* |
|
* address_spaces which do not place buffers at ->private_list via these |
|
* utility functions are free to use private_lock and private_list for |
|
* whatever they want. The only requirement is that list_empty(private_list) |
|
* be true at clear_inode() time. |
|
* |
|
* FIXME: clear_inode should not call invalidate_inode_buffers(). The |
|
* filesystems should do that. invalidate_inode_buffers() should just go |
|
* BUG_ON(!list_empty). |
|
* |
|
* FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should |
|
* take an address_space, not an inode. And it should be called |
|
* mark_buffer_dirty_fsync() to clearly define why those buffers are being |
|
* queued up. |
|
* |
|
* FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the |
|
* list if it is already on a list. Because if the buffer is on a list, |
|
* it *must* already be on the right one. If not, the filesystem is being |
|
* silly. This will save a ton of locking. But first we have to ensure |
|
* that buffers are taken *off* the old inode's list when they are freed |
|
* (presumably in truncate). That requires careful auditing of all |
|
* filesystems (do it inside bforget()). It could also be done by bringing |
|
* b_inode back. |
|
*/ |
|
|
|
/* |
|
* The buffer's backing address_space's private_lock must be held |
|
*/ |
|
static void __remove_assoc_queue(struct buffer_head *bh) |
|
{ |
|
list_del_init(&bh->b_assoc_buffers); |
|
WARN_ON(!bh->b_assoc_map); |
|
bh->b_assoc_map = NULL; |
|
} |
|
|
|
int inode_has_buffers(struct inode *inode) |
|
{ |
|
return !list_empty(&inode->i_data.private_list); |
|
} |
|
|
|
/* |
|
* osync is designed to support O_SYNC io. It waits synchronously for |
|
* all already-submitted IO to complete, but does not queue any new |
|
* writes to the disk. |
|
* |
|
* To do O_SYNC writes, just queue the buffer writes with ll_rw_block as |
|
* you dirty the buffers, and then use osync_inode_buffers to wait for |
|
* completion. Any other dirty buffers which are not yet queued for |
|
* write will not be flushed to disk by the osync. |
|
*/ |
|
static int osync_buffers_list(spinlock_t *lock, struct list_head *list) |
|
{ |
|
struct buffer_head *bh; |
|
struct list_head *p; |
|
int err = 0; |
|
|
|
spin_lock(lock); |
|
repeat: |
|
list_for_each_prev(p, list) { |
|
bh = BH_ENTRY(p); |
|
if (buffer_locked(bh)) { |
|
get_bh(bh); |
|
spin_unlock(lock); |
|
wait_on_buffer(bh); |
|
if (!buffer_uptodate(bh)) |
|
err = -EIO; |
|
brelse(bh); |
|
spin_lock(lock); |
|
goto repeat; |
|
} |
|
} |
|
spin_unlock(lock); |
|
return err; |
|
} |
|
|
|
void emergency_thaw_bdev(struct super_block *sb) |
|
{ |
|
while (sb->s_bdev && !thaw_bdev(sb->s_bdev)) |
|
printk(KERN_WARNING "Emergency Thaw on %pg\n", sb->s_bdev); |
|
} |
|
|
|
/** |
|
* sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
|
* @mapping: the mapping which wants those buffers written |
|
* |
|
* Starts I/O against the buffers at mapping->private_list, and waits upon |
|
* that I/O. |
|
* |
|
* Basically, this is a convenience function for fsync(). |
|
* @mapping is a file or directory which needs those buffers to be written for |
|
* a successful fsync(). |
|
*/ |
|
int sync_mapping_buffers(struct address_space *mapping) |
|
{ |
|
struct address_space *buffer_mapping = mapping->private_data; |
|
|
|
if (buffer_mapping == NULL || list_empty(&mapping->private_list)) |
|
return 0; |
|
|
|
return fsync_buffers_list(&buffer_mapping->private_lock, |
|
&mapping->private_list); |
|
} |
|
EXPORT_SYMBOL(sync_mapping_buffers); |
|
|
|
/* |
|
* Called when we've recently written block `bblock', and it is known that |
|
* `bblock' was for a buffer_boundary() buffer. This means that the block at |
|
* `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's |
|
* dirty, schedule it for IO. So that indirects merge nicely with their data. |
|
*/ |
|
void write_boundary_block(struct block_device *bdev, |
|
sector_t bblock, unsigned blocksize) |
|
{ |
|
struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); |
|
if (bh) { |
|
if (buffer_dirty(bh)) |
|
ll_rw_block(REQ_OP_WRITE, 0, 1, &bh); |
|
put_bh(bh); |
|
} |
|
} |
|
|
|
void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) |
|
{ |
|
struct address_space *mapping = inode->i_mapping; |
|
struct address_space *buffer_mapping = bh->b_page->mapping; |
|
|
|
mark_buffer_dirty(bh); |
|
if (!mapping->private_data) { |
|
mapping->private_data = buffer_mapping; |
|
} else { |
|
BUG_ON(mapping->private_data != buffer_mapping); |
|
} |
|
if (!bh->b_assoc_map) { |
|
spin_lock(&buffer_mapping->private_lock); |
|
list_move_tail(&bh->b_assoc_buffers, |
|
&mapping->private_list); |
|
bh->b_assoc_map = mapping; |
|
spin_unlock(&buffer_mapping->private_lock); |
|
} |
|
} |
|
EXPORT_SYMBOL(mark_buffer_dirty_inode); |
|
|
|
/* |
|
* Add a page to the dirty page list. |
|
* |
|
* It is a sad fact of life that this function is called from several places |
|
* deeply under spinlocking. It may not sleep. |
|
* |
|
* If the page has buffers, the uptodate buffers are set dirty, to preserve |
|
* dirty-state coherency between the page and the buffers. It the page does |
|
* not have buffers then when they are later attached they will all be set |
|
* dirty. |
|
* |
|
* The buffers are dirtied before the page is dirtied. There's a small race |
|
* window in which a writepage caller may see the page cleanness but not the |
|
* buffer dirtiness. That's fine. If this code were to set the page dirty |
|
* before the buffers, a concurrent writepage caller could clear the page dirty |
|
* bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean |
|
* page on the dirty page list. |
|
* |
|
* We use private_lock to lock against try_to_free_buffers while using the |
|
* page's buffer list. Also use this to protect against clean buffers being |
|
* added to the page after it was set dirty. |
|
* |
|
* FIXME: may need to call ->reservepage here as well. That's rather up to the |
|
* address_space though. |
|
*/ |
|
bool block_dirty_folio(struct address_space *mapping, struct folio *folio) |
|
{ |
|
struct buffer_head *head; |
|
bool newly_dirty; |
|
|
|
spin_lock(&mapping->private_lock); |
|
head = folio_buffers(folio); |
|
if (head) { |
|
struct buffer_head *bh = head; |
|
|
|
do { |
|
set_buffer_dirty(bh); |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
} |
|
/* |
|
* Lock out page's memcg migration to keep PageDirty |
|
* synchronized with per-memcg dirty page counters. |
|
*/ |
|
folio_memcg_lock(folio); |
|
newly_dirty = !folio_test_set_dirty(folio); |
|
spin_unlock(&mapping->private_lock); |
|
|
|
if (newly_dirty) |
|
__folio_mark_dirty(folio, mapping, 1); |
|
|
|
folio_memcg_unlock(folio); |
|
|
|
if (newly_dirty) |
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
|
|
|
return newly_dirty; |
|
} |
|
EXPORT_SYMBOL(block_dirty_folio); |
|
|
|
/* |
|
* Write out and wait upon a list of buffers. |
|
* |
|
* We have conflicting pressures: we want to make sure that all |
|
* initially dirty buffers get waited on, but that any subsequently |
|
* dirtied buffers don't. After all, we don't want fsync to last |
|
* forever if somebody is actively writing to the file. |
|
* |
|
* Do this in two main stages: first we copy dirty buffers to a |
|
* temporary inode list, queueing the writes as we go. Then we clean |
|
* up, waiting for those writes to complete. |
|
* |
|
* During this second stage, any subsequent updates to the file may end |
|
* up refiling the buffer on the original inode's dirty list again, so |
|
* there is a chance we will end up with a buffer queued for write but |
|
* not yet completed on that list. So, as a final cleanup we go through |
|
* the osync code to catch these locked, dirty buffers without requeuing |
|
* any newly dirty buffers for write. |
|
*/ |
|
static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) |
|
{ |
|
struct buffer_head *bh; |
|
struct list_head tmp; |
|
struct address_space *mapping; |
|
int err = 0, err2; |
|
struct blk_plug plug; |
|
|
|
INIT_LIST_HEAD(&tmp); |
|
blk_start_plug(&plug); |
|
|
|
spin_lock(lock); |
|
while (!list_empty(list)) { |
|
bh = BH_ENTRY(list->next); |
|
mapping = bh->b_assoc_map; |
|
__remove_assoc_queue(bh); |
|
/* Avoid race with mark_buffer_dirty_inode() which does |
|
* a lockless check and we rely on seeing the dirty bit */ |
|
smp_mb(); |
|
if (buffer_dirty(bh) || buffer_locked(bh)) { |
|
list_add(&bh->b_assoc_buffers, &tmp); |
|
bh->b_assoc_map = mapping; |
|
if (buffer_dirty(bh)) { |
|
get_bh(bh); |
|
spin_unlock(lock); |
|
/* |
|
* Ensure any pending I/O completes so that |
|
* write_dirty_buffer() actually writes the |
|
* current contents - it is a noop if I/O is |
|
* still in flight on potentially older |
|
* contents. |
|
*/ |
|
write_dirty_buffer(bh, REQ_SYNC); |
|
|
|
/* |
|
* Kick off IO for the previous mapping. Note |
|
* that we will not run the very last mapping, |
|
* wait_on_buffer() will do that for us |
|
* through sync_buffer(). |
|
*/ |
|
brelse(bh); |
|
spin_lock(lock); |
|
} |
|
} |
|
} |
|
|
|
spin_unlock(lock); |
|
blk_finish_plug(&plug); |
|
spin_lock(lock); |
|
|
|
while (!list_empty(&tmp)) { |
|
bh = BH_ENTRY(tmp.prev); |
|
get_bh(bh); |
|
mapping = bh->b_assoc_map; |
|
__remove_assoc_queue(bh); |
|
/* Avoid race with mark_buffer_dirty_inode() which does |
|
* a lockless check and we rely on seeing the dirty bit */ |
|
smp_mb(); |
|
if (buffer_dirty(bh)) { |
|
list_add(&bh->b_assoc_buffers, |
|
&mapping->private_list); |
|
bh->b_assoc_map = mapping; |
|
} |
|
spin_unlock(lock); |
|
wait_on_buffer(bh); |
|
if (!buffer_uptodate(bh)) |
|
err = -EIO; |
|
brelse(bh); |
|
spin_lock(lock); |
|
} |
|
|
|
spin_unlock(lock); |
|
err2 = osync_buffers_list(lock, list); |
|
if (err) |
|
return err; |
|
else |
|
return err2; |
|
} |
|
|
|
/* |
|
* Invalidate any and all dirty buffers on a given inode. We are |
|
* probably unmounting the fs, but that doesn't mean we have already |
|
* done a sync(). Just drop the buffers from the inode list. |
|
* |
|
* NOTE: we take the inode's blockdev's mapping's private_lock. Which |
|
* assumes that all the buffers are against the blockdev. Not true |
|
* for reiserfs. |
|
*/ |
|
void invalidate_inode_buffers(struct inode *inode) |
|
{ |
|
if (inode_has_buffers(inode)) { |
|
struct address_space *mapping = &inode->i_data; |
|
struct list_head *list = &mapping->private_list; |
|
struct address_space *buffer_mapping = mapping->private_data; |
|
|
|
spin_lock(&buffer_mapping->private_lock); |
|
while (!list_empty(list)) |
|
__remove_assoc_queue(BH_ENTRY(list->next)); |
|
spin_unlock(&buffer_mapping->private_lock); |
|
} |
|
} |
|
EXPORT_SYMBOL(invalidate_inode_buffers); |
|
|
|
/* |
|
* Remove any clean buffers from the inode's buffer list. This is called |
|
* when we're trying to free the inode itself. Those buffers can pin it. |
|
* |
|
* Returns true if all buffers were removed. |
|
*/ |
|
int remove_inode_buffers(struct inode *inode) |
|
{ |
|
int ret = 1; |
|
|
|
if (inode_has_buffers(inode)) { |
|
struct address_space *mapping = &inode->i_data; |
|
struct list_head *list = &mapping->private_list; |
|
struct address_space *buffer_mapping = mapping->private_data; |
|
|
|
spin_lock(&buffer_mapping->private_lock); |
|
while (!list_empty(list)) { |
|
struct buffer_head *bh = BH_ENTRY(list->next); |
|
if (buffer_dirty(bh)) { |
|
ret = 0; |
|
break; |
|
} |
|
__remove_assoc_queue(bh); |
|
} |
|
spin_unlock(&buffer_mapping->private_lock); |
|
} |
|
return ret; |
|
} |
|
|
|
/* |
|
* Create the appropriate buffers when given a page for data area and |
|
* the size of each buffer.. Use the bh->b_this_page linked list to |
|
* follow the buffers created. Return NULL if unable to create more |
|
* buffers. |
|
* |
|
* The retry flag is used to differentiate async IO (paging, swapping) |
|
* which may not fail from ordinary buffer allocations. |
|
*/ |
|
struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, |
|
bool retry) |
|
{ |
|
struct buffer_head *bh, *head; |
|
gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT; |
|
long offset; |
|
struct mem_cgroup *memcg, *old_memcg; |
|
|
|
if (retry) |
|
gfp |= __GFP_NOFAIL; |
|
|
|
/* The page lock pins the memcg */ |
|
memcg = page_memcg(page); |
|
old_memcg = set_active_memcg(memcg); |
|
|
|
head = NULL; |
|
offset = PAGE_SIZE; |
|
while ((offset -= size) >= 0) { |
|
bh = alloc_buffer_head(gfp); |
|
if (!bh) |
|
goto no_grow; |
|
|
|
bh->b_this_page = head; |
|
bh->b_blocknr = -1; |
|
head = bh; |
|
|
|
bh->b_size = size; |
|
|
|
/* Link the buffer to its page */ |
|
set_bh_page(bh, page, offset); |
|
} |
|
out: |
|
set_active_memcg(old_memcg); |
|
return head; |
|
/* |
|
* In case anything failed, we just free everything we got. |
|
*/ |
|
no_grow: |
|
if (head) { |
|
do { |
|
bh = head; |
|
head = head->b_this_page; |
|
free_buffer_head(bh); |
|
} while (head); |
|
} |
|
|
|
goto out; |
|
} |
|
EXPORT_SYMBOL_GPL(alloc_page_buffers); |
|
|
|
static inline void |
|
link_dev_buffers(struct page *page, struct buffer_head *head) |
|
{ |
|
struct buffer_head *bh, *tail; |
|
|
|
bh = head; |
|
do { |
|
tail = bh; |
|
bh = bh->b_this_page; |
|
} while (bh); |
|
tail->b_this_page = head; |
|
attach_page_private(page, head); |
|
} |
|
|
|
static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size) |
|
{ |
|
sector_t retval = ~((sector_t)0); |
|
loff_t sz = bdev_nr_bytes(bdev); |
|
|
|
if (sz) { |
|
unsigned int sizebits = blksize_bits(size); |
|
retval = (sz >> sizebits); |
|
} |
|
return retval; |
|
} |
|
|
|
/* |
|
* Initialise the state of a blockdev page's buffers. |
|
*/ |
|
static sector_t |
|
init_page_buffers(struct page *page, struct block_device *bdev, |
|
sector_t block, int size) |
|
{ |
|
struct buffer_head *head = page_buffers(page); |
|
struct buffer_head *bh = head; |
|
int uptodate = PageUptodate(page); |
|
sector_t end_block = blkdev_max_block(bdev, size); |
|
|
|
do { |
|
if (!buffer_mapped(bh)) { |
|
bh->b_end_io = NULL; |
|
bh->b_private = NULL; |
|
bh->b_bdev = bdev; |
|
bh->b_blocknr = block; |
|
if (uptodate) |
|
set_buffer_uptodate(bh); |
|
if (block < end_block) |
|
set_buffer_mapped(bh); |
|
} |
|
block++; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
|
|
/* |
|
* Caller needs to validate requested block against end of device. |
|
*/ |
|
return end_block; |
|
} |
|
|
|
/* |
|
* Create the page-cache page that contains the requested block. |
|
* |
|
* This is used purely for blockdev mappings. |
|
*/ |
|
static int |
|
grow_dev_page(struct block_device *bdev, sector_t block, |
|
pgoff_t index, int size, int sizebits, gfp_t gfp) |
|
{ |
|
struct inode *inode = bdev->bd_inode; |
|
struct page *page; |
|
struct buffer_head *bh; |
|
sector_t end_block; |
|
int ret = 0; |
|
gfp_t gfp_mask; |
|
|
|
gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp; |
|
|
|
/* |
|
* XXX: __getblk_slow() can not really deal with failure and |
|
* will endlessly loop on improvised global reclaim. Prefer |
|
* looping in the allocator rather than here, at least that |
|
* code knows what it's doing. |
|
*/ |
|
gfp_mask |= __GFP_NOFAIL; |
|
|
|
page = find_or_create_page(inode->i_mapping, index, gfp_mask); |
|
|
|
BUG_ON(!PageLocked(page)); |
|
|
|
if (page_has_buffers(page)) { |
|
bh = page_buffers(page); |
|
if (bh->b_size == size) { |
|
end_block = init_page_buffers(page, bdev, |
|
(sector_t)index << sizebits, |
|
size); |
|
goto done; |
|
} |
|
if (!try_to_free_buffers(page)) |
|
goto failed; |
|
} |
|
|
|
/* |
|
* Allocate some buffers for this page |
|
*/ |
|
bh = alloc_page_buffers(page, size, true); |
|
|
|
/* |
|
* Link the page to the buffers and initialise them. Take the |
|
* lock to be atomic wrt __find_get_block(), which does not |
|
* run under the page lock. |
|
*/ |
|
spin_lock(&inode->i_mapping->private_lock); |
|
link_dev_buffers(page, bh); |
|
end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits, |
|
size); |
|
spin_unlock(&inode->i_mapping->private_lock); |
|
done: |
|
ret = (block < end_block) ? 1 : -ENXIO; |
|
failed: |
|
unlock_page(page); |
|
put_page(page); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Create buffers for the specified block device block's page. If |
|
* that page was dirty, the buffers are set dirty also. |
|
*/ |
|
static int |
|
grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp) |
|
{ |
|
pgoff_t index; |
|
int sizebits; |
|
|
|
sizebits = PAGE_SHIFT - __ffs(size); |
|
index = block >> sizebits; |
|
|
|
/* |
|
* Check for a block which wants to lie outside our maximum possible |
|
* pagecache index. (this comparison is done using sector_t types). |
|
*/ |
|
if (unlikely(index != block >> sizebits)) { |
|
printk(KERN_ERR "%s: requested out-of-range block %llu for " |
|
"device %pg\n", |
|
__func__, (unsigned long long)block, |
|
bdev); |
|
return -EIO; |
|
} |
|
|
|
/* Create a page with the proper size buffers.. */ |
|
return grow_dev_page(bdev, block, index, size, sizebits, gfp); |
|
} |
|
|
|
static struct buffer_head * |
|
__getblk_slow(struct block_device *bdev, sector_t block, |
|
unsigned size, gfp_t gfp) |
|
{ |
|
/* Size must be multiple of hard sectorsize */ |
|
if (unlikely(size & (bdev_logical_block_size(bdev)-1) || |
|
(size < 512 || size > PAGE_SIZE))) { |
|
printk(KERN_ERR "getblk(): invalid block size %d requested\n", |
|
size); |
|
printk(KERN_ERR "logical block size: %d\n", |
|
bdev_logical_block_size(bdev)); |
|
|
|
dump_stack(); |
|
return NULL; |
|
} |
|
|
|
for (;;) { |
|
struct buffer_head *bh; |
|
int ret; |
|
|
|
bh = __find_get_block(bdev, block, size); |
|
if (bh) |
|
return bh; |
|
|
|
ret = grow_buffers(bdev, block, size, gfp); |
|
if (ret < 0) |
|
return NULL; |
|
} |
|
} |
|
|
|
/* |
|
* The relationship between dirty buffers and dirty pages: |
|
* |
|
* Whenever a page has any dirty buffers, the page's dirty bit is set, and |
|
* the page is tagged dirty in the page cache. |
|
* |
|
* At all times, the dirtiness of the buffers represents the dirtiness of |
|
* subsections of the page. If the page has buffers, the page dirty bit is |
|
* merely a hint about the true dirty state. |
|
* |
|
* When a page is set dirty in its entirety, all its buffers are marked dirty |
|
* (if the page has buffers). |
|
* |
|
* When a buffer is marked dirty, its page is dirtied, but the page's other |
|
* buffers are not. |
|
* |
|
* Also. When blockdev buffers are explicitly read with bread(), they |
|
* individually become uptodate. But their backing page remains not |
|
* uptodate - even if all of its buffers are uptodate. A subsequent |
|
* block_read_full_page() against that page will discover all the uptodate |
|
* buffers, will set the page uptodate and will perform no I/O. |
|
*/ |
|
|
|
/** |
|
* mark_buffer_dirty - mark a buffer_head as needing writeout |
|
* @bh: the buffer_head to mark dirty |
|
* |
|
* mark_buffer_dirty() will set the dirty bit against the buffer, then set |
|
* its backing page dirty, then tag the page as dirty in the page cache |
|
* and then attach the address_space's inode to its superblock's dirty |
|
* inode list. |
|
* |
|
* mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, |
|
* i_pages lock and mapping->host->i_lock. |
|
*/ |
|
void mark_buffer_dirty(struct buffer_head *bh) |
|
{ |
|
WARN_ON_ONCE(!buffer_uptodate(bh)); |
|
|
|
trace_block_dirty_buffer(bh); |
|
|
|
/* |
|
* Very *carefully* optimize the it-is-already-dirty case. |
|
* |
|
* Don't let the final "is it dirty" escape to before we |
|
* perhaps modified the buffer. |
|
*/ |
|
if (buffer_dirty(bh)) { |
|
smp_mb(); |
|
if (buffer_dirty(bh)) |
|
return; |
|
} |
|
|
|
if (!test_set_buffer_dirty(bh)) { |
|
struct page *page = bh->b_page; |
|
struct address_space *mapping = NULL; |
|
|
|
lock_page_memcg(page); |
|
if (!TestSetPageDirty(page)) { |
|
mapping = page_mapping(page); |
|
if (mapping) |
|
__set_page_dirty(page, mapping, 0); |
|
} |
|
unlock_page_memcg(page); |
|
if (mapping) |
|
__mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
|
} |
|
} |
|
EXPORT_SYMBOL(mark_buffer_dirty); |
|
|
|
void mark_buffer_write_io_error(struct buffer_head *bh) |
|
{ |
|
struct super_block *sb; |
|
|
|
set_buffer_write_io_error(bh); |
|
/* FIXME: do we need to set this in both places? */ |
|
if (bh->b_page && bh->b_page->mapping) |
|
mapping_set_error(bh->b_page->mapping, -EIO); |
|
if (bh->b_assoc_map) |
|
mapping_set_error(bh->b_assoc_map, -EIO); |
|
rcu_read_lock(); |
|
sb = READ_ONCE(bh->b_bdev->bd_super); |
|
if (sb) |
|
errseq_set(&sb->s_wb_err, -EIO); |
|
rcu_read_unlock(); |
|
} |
|
EXPORT_SYMBOL(mark_buffer_write_io_error); |
|
|
|
/* |
|
* Decrement a buffer_head's reference count. If all buffers against a page |
|
* have zero reference count, are clean and unlocked, and if the page is clean |
|
* and unlocked then try_to_free_buffers() may strip the buffers from the page |
|
* in preparation for freeing it (sometimes, rarely, buffers are removed from |
|
* a page but it ends up not being freed, and buffers may later be reattached). |
|
*/ |
|
void __brelse(struct buffer_head * buf) |
|
{ |
|
if (atomic_read(&buf->b_count)) { |
|
put_bh(buf); |
|
return; |
|
} |
|
WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
|
} |
|
EXPORT_SYMBOL(__brelse); |
|
|
|
/* |
|
* bforget() is like brelse(), except it discards any |
|
* potentially dirty data. |
|
*/ |
|
void __bforget(struct buffer_head *bh) |
|
{ |
|
clear_buffer_dirty(bh); |
|
if (bh->b_assoc_map) { |
|
struct address_space *buffer_mapping = bh->b_page->mapping; |
|
|
|
spin_lock(&buffer_mapping->private_lock); |
|
list_del_init(&bh->b_assoc_buffers); |
|
bh->b_assoc_map = NULL; |
|
spin_unlock(&buffer_mapping->private_lock); |
|
} |
|
__brelse(bh); |
|
} |
|
EXPORT_SYMBOL(__bforget); |
|
|
|
static struct buffer_head *__bread_slow(struct buffer_head *bh) |
|
{ |
|
lock_buffer(bh); |
|
if (buffer_uptodate(bh)) { |
|
unlock_buffer(bh); |
|
return bh; |
|
} else { |
|
get_bh(bh); |
|
bh->b_end_io = end_buffer_read_sync; |
|
submit_bh(REQ_OP_READ, 0, bh); |
|
wait_on_buffer(bh); |
|
if (buffer_uptodate(bh)) |
|
return bh; |
|
} |
|
brelse(bh); |
|
return NULL; |
|
} |
|
|
|
/* |
|
* Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). |
|
* The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their |
|
* refcount elevated by one when they're in an LRU. A buffer can only appear |
|
* once in a particular CPU's LRU. A single buffer can be present in multiple |
|
* CPU's LRUs at the same time. |
|
* |
|
* This is a transparent caching front-end to sb_bread(), sb_getblk() and |
|
* sb_find_get_block(). |
|
* |
|
* The LRUs themselves only need locking against invalidate_bh_lrus. We use |
|
* a local interrupt disable for that. |
|
*/ |
|
|
|
#define BH_LRU_SIZE 16 |
|
|
|
struct bh_lru { |
|
struct buffer_head *bhs[BH_LRU_SIZE]; |
|
}; |
|
|
|
static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; |
|
|
|
#ifdef CONFIG_SMP |
|
#define bh_lru_lock() local_irq_disable() |
|
#define bh_lru_unlock() local_irq_enable() |
|
#else |
|
#define bh_lru_lock() preempt_disable() |
|
#define bh_lru_unlock() preempt_enable() |
|
#endif |
|
|
|
static inline void check_irqs_on(void) |
|
{ |
|
#ifdef irqs_disabled |
|
BUG_ON(irqs_disabled()); |
|
#endif |
|
} |
|
|
|
/* |
|
* Install a buffer_head into this cpu's LRU. If not already in the LRU, it is |
|
* inserted at the front, and the buffer_head at the back if any is evicted. |
|
* Or, if already in the LRU it is moved to the front. |
|
*/ |
|
static void bh_lru_install(struct buffer_head *bh) |
|
{ |
|
struct buffer_head *evictee = bh; |
|
struct bh_lru *b; |
|
int i; |
|
|
|
check_irqs_on(); |
|
bh_lru_lock(); |
|
|
|
/* |
|
* the refcount of buffer_head in bh_lru prevents dropping the |
|
* attached page(i.e., try_to_free_buffers) so it could cause |
|
* failing page migration. |
|
* Skip putting upcoming bh into bh_lru until migration is done. |
|
*/ |
|
if (lru_cache_disabled()) { |
|
bh_lru_unlock(); |
|
return; |
|
} |
|
|
|
b = this_cpu_ptr(&bh_lrus); |
|
for (i = 0; i < BH_LRU_SIZE; i++) { |
|
swap(evictee, b->bhs[i]); |
|
if (evictee == bh) { |
|
bh_lru_unlock(); |
|
return; |
|
} |
|
} |
|
|
|
get_bh(bh); |
|
bh_lru_unlock(); |
|
brelse(evictee); |
|
} |
|
|
|
/* |
|
* Look up the bh in this cpu's LRU. If it's there, move it to the head. |
|
*/ |
|
static struct buffer_head * |
|
lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
|
{ |
|
struct buffer_head *ret = NULL; |
|
unsigned int i; |
|
|
|
check_irqs_on(); |
|
bh_lru_lock(); |
|
for (i = 0; i < BH_LRU_SIZE; i++) { |
|
struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); |
|
|
|
if (bh && bh->b_blocknr == block && bh->b_bdev == bdev && |
|
bh->b_size == size) { |
|
if (i) { |
|
while (i) { |
|
__this_cpu_write(bh_lrus.bhs[i], |
|
__this_cpu_read(bh_lrus.bhs[i - 1])); |
|
i--; |
|
} |
|
__this_cpu_write(bh_lrus.bhs[0], bh); |
|
} |
|
get_bh(bh); |
|
ret = bh; |
|
break; |
|
} |
|
} |
|
bh_lru_unlock(); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Perform a pagecache lookup for the matching buffer. If it's there, refresh |
|
* it in the LRU and mark it as accessed. If it is not present then return |
|
* NULL |
|
*/ |
|
struct buffer_head * |
|
__find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
|
{ |
|
struct buffer_head *bh = lookup_bh_lru(bdev, block, size); |
|
|
|
if (bh == NULL) { |
|
/* __find_get_block_slow will mark the page accessed */ |
|
bh = __find_get_block_slow(bdev, block); |
|
if (bh) |
|
bh_lru_install(bh); |
|
} else |
|
touch_buffer(bh); |
|
|
|
return bh; |
|
} |
|
EXPORT_SYMBOL(__find_get_block); |
|
|
|
/* |
|
* __getblk_gfp() will locate (and, if necessary, create) the buffer_head |
|
* which corresponds to the passed block_device, block and size. The |
|
* returned buffer has its reference count incremented. |
|
* |
|
* __getblk_gfp() will lock up the machine if grow_dev_page's |
|
* try_to_free_buffers() attempt is failing. FIXME, perhaps? |
|
*/ |
|
struct buffer_head * |
|
__getblk_gfp(struct block_device *bdev, sector_t block, |
|
unsigned size, gfp_t gfp) |
|
{ |
|
struct buffer_head *bh = __find_get_block(bdev, block, size); |
|
|
|
might_sleep(); |
|
if (bh == NULL) |
|
bh = __getblk_slow(bdev, block, size, gfp); |
|
return bh; |
|
} |
|
EXPORT_SYMBOL(__getblk_gfp); |
|
|
|
/* |
|
* Do async read-ahead on a buffer.. |
|
*/ |
|
void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
|
{ |
|
struct buffer_head *bh = __getblk(bdev, block, size); |
|
if (likely(bh)) { |
|
ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); |
|
brelse(bh); |
|
} |
|
} |
|
EXPORT_SYMBOL(__breadahead); |
|
|
|
void __breadahead_gfp(struct block_device *bdev, sector_t block, unsigned size, |
|
gfp_t gfp) |
|
{ |
|
struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); |
|
if (likely(bh)) { |
|
ll_rw_block(REQ_OP_READ, REQ_RAHEAD, 1, &bh); |
|
brelse(bh); |
|
} |
|
} |
|
EXPORT_SYMBOL(__breadahead_gfp); |
|
|
|
/** |
|
* __bread_gfp() - reads a specified block and returns the bh |
|
* @bdev: the block_device to read from |
|
* @block: number of block |
|
* @size: size (in bytes) to read |
|
* @gfp: page allocation flag |
|
* |
|
* Reads a specified block, and returns buffer head that contains it. |
|
* The page cache can be allocated from non-movable area |
|
* not to prevent page migration if you set gfp to zero. |
|
* It returns NULL if the block was unreadable. |
|
*/ |
|
struct buffer_head * |
|
__bread_gfp(struct block_device *bdev, sector_t block, |
|
unsigned size, gfp_t gfp) |
|
{ |
|
struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp); |
|
|
|
if (likely(bh) && !buffer_uptodate(bh)) |
|
bh = __bread_slow(bh); |
|
return bh; |
|
} |
|
EXPORT_SYMBOL(__bread_gfp); |
|
|
|
static void __invalidate_bh_lrus(struct bh_lru *b) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) { |
|
brelse(b->bhs[i]); |
|
b->bhs[i] = NULL; |
|
} |
|
} |
|
/* |
|
* invalidate_bh_lrus() is called rarely - but not only at unmount. |
|
* This doesn't race because it runs in each cpu either in irq |
|
* or with preempt disabled. |
|
*/ |
|
static void invalidate_bh_lru(void *arg) |
|
{ |
|
struct bh_lru *b = &get_cpu_var(bh_lrus); |
|
|
|
__invalidate_bh_lrus(b); |
|
put_cpu_var(bh_lrus); |
|
} |
|
|
|
bool has_bh_in_lru(int cpu, void *dummy) |
|
{ |
|
struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); |
|
int i; |
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) { |
|
if (b->bhs[i]) |
|
return true; |
|
} |
|
|
|
return false; |
|
} |
|
|
|
void invalidate_bh_lrus(void) |
|
{ |
|
on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1); |
|
} |
|
EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
|
|
|
/* |
|
* It's called from workqueue context so we need a bh_lru_lock to close |
|
* the race with preemption/irq. |
|
*/ |
|
void invalidate_bh_lrus_cpu(void) |
|
{ |
|
struct bh_lru *b; |
|
|
|
bh_lru_lock(); |
|
b = this_cpu_ptr(&bh_lrus); |
|
__invalidate_bh_lrus(b); |
|
bh_lru_unlock(); |
|
} |
|
|
|
void set_bh_page(struct buffer_head *bh, |
|
struct page *page, unsigned long offset) |
|
{ |
|
bh->b_page = page; |
|
BUG_ON(offset >= PAGE_SIZE); |
|
if (PageHighMem(page)) |
|
/* |
|
* This catches illegal uses and preserves the offset: |
|
*/ |
|
bh->b_data = (char *)(0 + offset); |
|
else |
|
bh->b_data = page_address(page) + offset; |
|
} |
|
EXPORT_SYMBOL(set_bh_page); |
|
|
|
/* |
|
* Called when truncating a buffer on a page completely. |
|
*/ |
|
|
|
/* Bits that are cleared during an invalidate */ |
|
#define BUFFER_FLAGS_DISCARD \ |
|
(1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \ |
|
1 << BH_Delay | 1 << BH_Unwritten) |
|
|
|
static void discard_buffer(struct buffer_head * bh) |
|
{ |
|
unsigned long b_state, b_state_old; |
|
|
|
lock_buffer(bh); |
|
clear_buffer_dirty(bh); |
|
bh->b_bdev = NULL; |
|
b_state = bh->b_state; |
|
for (;;) { |
|
b_state_old = cmpxchg(&bh->b_state, b_state, |
|
(b_state & ~BUFFER_FLAGS_DISCARD)); |
|
if (b_state_old == b_state) |
|
break; |
|
b_state = b_state_old; |
|
} |
|
unlock_buffer(bh); |
|
} |
|
|
|
/** |
|
* block_invalidate_folio - Invalidate part or all of a buffer-backed folio. |
|
* @folio: The folio which is affected. |
|
* @offset: start of the range to invalidate |
|
* @length: length of the range to invalidate |
|
* |
|
* block_invalidate_folio() is called when all or part of the folio has been |
|
* invalidated by a truncate operation. |
|
* |
|
* block_invalidate_folio() does not have to release all buffers, but it must |
|
* ensure that no dirty buffer is left outside @offset and that no I/O |
|
* is underway against any of the blocks which are outside the truncation |
|
* point. Because the caller is about to free (and possibly reuse) those |
|
* blocks on-disk. |
|
*/ |
|
void block_invalidate_folio(struct folio *folio, size_t offset, size_t length) |
|
{ |
|
struct buffer_head *head, *bh, *next; |
|
size_t curr_off = 0; |
|
size_t stop = length + offset; |
|
|
|
BUG_ON(!folio_test_locked(folio)); |
|
|
|
/* |
|
* Check for overflow |
|
*/ |
|
BUG_ON(stop > folio_size(folio) || stop < length); |
|
|
|
head = folio_buffers(folio); |
|
if (!head) |
|
return; |
|
|
|
bh = head; |
|
do { |
|
size_t next_off = curr_off + bh->b_size; |
|
next = bh->b_this_page; |
|
|
|
/* |
|
* Are we still fully in range ? |
|
*/ |
|
if (next_off > stop) |
|
goto out; |
|
|
|
/* |
|
* is this block fully invalidated? |
|
*/ |
|
if (offset <= curr_off) |
|
discard_buffer(bh); |
|
curr_off = next_off; |
|
bh = next; |
|
} while (bh != head); |
|
|
|
/* |
|
* We release buffers only if the entire folio is being invalidated. |
|
* The get_block cached value has been unconditionally invalidated, |
|
* so real IO is not possible anymore. |
|
*/ |
|
if (length == folio_size(folio)) |
|
filemap_release_folio(folio, 0); |
|
out: |
|
return; |
|
} |
|
EXPORT_SYMBOL(block_invalidate_folio); |
|
|
|
|
|
/* |
|
* We attach and possibly dirty the buffers atomically wrt |
|
* block_dirty_folio() via private_lock. try_to_free_buffers |
|
* is already excluded via the page lock. |
|
*/ |
|
void create_empty_buffers(struct page *page, |
|
unsigned long blocksize, unsigned long b_state) |
|
{ |
|
struct buffer_head *bh, *head, *tail; |
|
|
|
head = alloc_page_buffers(page, blocksize, true); |
|
bh = head; |
|
do { |
|
bh->b_state |= b_state; |
|
tail = bh; |
|
bh = bh->b_this_page; |
|
} while (bh); |
|
tail->b_this_page = head; |
|
|
|
spin_lock(&page->mapping->private_lock); |
|
if (PageUptodate(page) || PageDirty(page)) { |
|
bh = head; |
|
do { |
|
if (PageDirty(page)) |
|
set_buffer_dirty(bh); |
|
if (PageUptodate(page)) |
|
set_buffer_uptodate(bh); |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
} |
|
attach_page_private(page, head); |
|
spin_unlock(&page->mapping->private_lock); |
|
} |
|
EXPORT_SYMBOL(create_empty_buffers); |
|
|
|
/** |
|
* clean_bdev_aliases: clean a range of buffers in block device |
|
* @bdev: Block device to clean buffers in |
|
* @block: Start of a range of blocks to clean |
|
* @len: Number of blocks to clean |
|
* |
|
* We are taking a range of blocks for data and we don't want writeback of any |
|
* buffer-cache aliases starting from return from this function and until the |
|
* moment when something will explicitly mark the buffer dirty (hopefully that |
|
* will not happen until we will free that block ;-) We don't even need to mark |
|
* it not-uptodate - nobody can expect anything from a newly allocated buffer |
|
* anyway. We used to use unmap_buffer() for such invalidation, but that was |
|
* wrong. We definitely don't want to mark the alias unmapped, for example - it |
|
* would confuse anyone who might pick it with bread() afterwards... |
|
* |
|
* Also.. Note that bforget() doesn't lock the buffer. So there can be |
|
* writeout I/O going on against recently-freed buffers. We don't wait on that |
|
* I/O in bforget() - it's more efficient to wait on the I/O only if we really |
|
* need to. That happens here. |
|
*/ |
|
void clean_bdev_aliases(struct block_device *bdev, sector_t block, sector_t len) |
|
{ |
|
struct inode *bd_inode = bdev->bd_inode; |
|
struct address_space *bd_mapping = bd_inode->i_mapping; |
|
struct pagevec pvec; |
|
pgoff_t index = block >> (PAGE_SHIFT - bd_inode->i_blkbits); |
|
pgoff_t end; |
|
int i, count; |
|
struct buffer_head *bh; |
|
struct buffer_head *head; |
|
|
|
end = (block + len - 1) >> (PAGE_SHIFT - bd_inode->i_blkbits); |
|
pagevec_init(&pvec); |
|
while (pagevec_lookup_range(&pvec, bd_mapping, &index, end)) { |
|
count = pagevec_count(&pvec); |
|
for (i = 0; i < count; i++) { |
|
struct page *page = pvec.pages[i]; |
|
|
|
if (!page_has_buffers(page)) |
|
continue; |
|
/* |
|
* We use page lock instead of bd_mapping->private_lock |
|
* to pin buffers here since we can afford to sleep and |
|
* it scales better than a global spinlock lock. |
|
*/ |
|
lock_page(page); |
|
/* Recheck when the page is locked which pins bhs */ |
|
if (!page_has_buffers(page)) |
|
goto unlock_page; |
|
head = page_buffers(page); |
|
bh = head; |
|
do { |
|
if (!buffer_mapped(bh) || (bh->b_blocknr < block)) |
|
goto next; |
|
if (bh->b_blocknr >= block + len) |
|
break; |
|
clear_buffer_dirty(bh); |
|
wait_on_buffer(bh); |
|
clear_buffer_req(bh); |
|
next: |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
unlock_page: |
|
unlock_page(page); |
|
} |
|
pagevec_release(&pvec); |
|
cond_resched(); |
|
/* End of range already reached? */ |
|
if (index > end || !index) |
|
break; |
|
} |
|
} |
|
EXPORT_SYMBOL(clean_bdev_aliases); |
|
|
|
/* |
|
* Size is a power-of-two in the range 512..PAGE_SIZE, |
|
* and the case we care about most is PAGE_SIZE. |
|
* |
|
* So this *could* possibly be written with those |
|
* constraints in mind (relevant mostly if some |
|
* architecture has a slow bit-scan instruction) |
|
*/ |
|
static inline int block_size_bits(unsigned int blocksize) |
|
{ |
|
return ilog2(blocksize); |
|
} |
|
|
|
static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state) |
|
{ |
|
BUG_ON(!PageLocked(page)); |
|
|
|
if (!page_has_buffers(page)) |
|
create_empty_buffers(page, 1 << READ_ONCE(inode->i_blkbits), |
|
b_state); |
|
return page_buffers(page); |
|
} |
|
|
|
/* |
|
* NOTE! All mapped/uptodate combinations are valid: |
|
* |
|
* Mapped Uptodate Meaning |
|
* |
|
* No No "unknown" - must do get_block() |
|
* No Yes "hole" - zero-filled |
|
* Yes No "allocated" - allocated on disk, not read in |
|
* Yes Yes "valid" - allocated and up-to-date in memory. |
|
* |
|
* "Dirty" is valid only with the last case (mapped+uptodate). |
|
*/ |
|
|
|
/* |
|
* While block_write_full_page is writing back the dirty buffers under |
|
* the page lock, whoever dirtied the buffers may decide to clean them |
|
* again at any time. We handle that by only looking at the buffer |
|
* state inside lock_buffer(). |
|
* |
|
* If block_write_full_page() is called for regular writeback |
|
* (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a |
|
* locked buffer. This only can happen if someone has written the buffer |
|
* directly, with submit_bh(). At the address_space level PageWriteback |
|
* prevents this contention from occurring. |
|
* |
|
* If block_write_full_page() is called with wbc->sync_mode == |
|
* WB_SYNC_ALL, the writes are posted using REQ_SYNC; this |
|
* causes the writes to be flagged as synchronous writes. |
|
*/ |
|
int __block_write_full_page(struct inode *inode, struct page *page, |
|
get_block_t *get_block, struct writeback_control *wbc, |
|
bh_end_io_t *handler) |
|
{ |
|
int err; |
|
sector_t block; |
|
sector_t last_block; |
|
struct buffer_head *bh, *head; |
|
unsigned int blocksize, bbits; |
|
int nr_underway = 0; |
|
int write_flags = wbc_to_write_flags(wbc); |
|
|
|
head = create_page_buffers(page, inode, |
|
(1 << BH_Dirty)|(1 << BH_Uptodate)); |
|
|
|
/* |
|
* Be very careful. We have no exclusion from block_dirty_folio |
|
* here, and the (potentially unmapped) buffers may become dirty at |
|
* any time. If a buffer becomes dirty here after we've inspected it |
|
* then we just miss that fact, and the page stays dirty. |
|
* |
|
* Buffers outside i_size may be dirtied by block_dirty_folio; |
|
* handle that here by just cleaning them. |
|
*/ |
|
|
|
bh = head; |
|
blocksize = bh->b_size; |
|
bbits = block_size_bits(blocksize); |
|
|
|
block = (sector_t)page->index << (PAGE_SHIFT - bbits); |
|
last_block = (i_size_read(inode) - 1) >> bbits; |
|
|
|
/* |
|
* Get all the dirty buffers mapped to disk addresses and |
|
* handle any aliases from the underlying blockdev's mapping. |
|
*/ |
|
do { |
|
if (block > last_block) { |
|
/* |
|
* mapped buffers outside i_size will occur, because |
|
* this page can be outside i_size when there is a |
|
* truncate in progress. |
|
*/ |
|
/* |
|
* The buffer was zeroed by block_write_full_page() |
|
*/ |
|
clear_buffer_dirty(bh); |
|
set_buffer_uptodate(bh); |
|
} else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
|
buffer_dirty(bh)) { |
|
WARN_ON(bh->b_size != blocksize); |
|
err = get_block(inode, block, bh, 1); |
|
if (err) |
|
goto recover; |
|
clear_buffer_delay(bh); |
|
if (buffer_new(bh)) { |
|
/* blockdev mappings never come here */ |
|
clear_buffer_new(bh); |
|
clean_bdev_bh_alias(bh); |
|
} |
|
} |
|
bh = bh->b_this_page; |
|
block++; |
|
} while (bh != head); |
|
|
|
do { |
|
if (!buffer_mapped(bh)) |
|
continue; |
|
/* |
|
* If it's a fully non-blocking write attempt and we cannot |
|
* lock the buffer then redirty the page. Note that this can |
|
* potentially cause a busy-wait loop from writeback threads |
|
* and kswapd activity, but those code paths have their own |
|
* higher-level throttling. |
|
*/ |
|
if (wbc->sync_mode != WB_SYNC_NONE) { |
|
lock_buffer(bh); |
|
} else if (!trylock_buffer(bh)) { |
|
redirty_page_for_writepage(wbc, page); |
|
continue; |
|
} |
|
if (test_clear_buffer_dirty(bh)) { |
|
mark_buffer_async_write_endio(bh, handler); |
|
} else { |
|
unlock_buffer(bh); |
|
} |
|
} while ((bh = bh->b_this_page) != head); |
|
|
|
/* |
|
* The page and its buffers are protected by PageWriteback(), so we can |
|
* drop the bh refcounts early. |
|
*/ |
|
BUG_ON(PageWriteback(page)); |
|
set_page_writeback(page); |
|
|
|
do { |
|
struct buffer_head *next = bh->b_this_page; |
|
if (buffer_async_write(bh)) { |
|
submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, wbc); |
|
nr_underway++; |
|
} |
|
bh = next; |
|
} while (bh != head); |
|
unlock_page(page); |
|
|
|
err = 0; |
|
done: |
|
if (nr_underway == 0) { |
|
/* |
|
* The page was marked dirty, but the buffers were |
|
* clean. Someone wrote them back by hand with |
|
* ll_rw_block/submit_bh. A rare case. |
|
*/ |
|
end_page_writeback(page); |
|
|
|
/* |
|
* The page and buffer_heads can be released at any time from |
|
* here on. |
|
*/ |
|
} |
|
return err; |
|
|
|
recover: |
|
/* |
|
* ENOSPC, or some other error. We may already have added some |
|
* blocks to the file, so we need to write these out to avoid |
|
* exposing stale data. |
|
* The page is currently locked and not marked for writeback |
|
*/ |
|
bh = head; |
|
/* Recovery: lock and submit the mapped buffers */ |
|
do { |
|
if (buffer_mapped(bh) && buffer_dirty(bh) && |
|
!buffer_delay(bh)) { |
|
lock_buffer(bh); |
|
mark_buffer_async_write_endio(bh, handler); |
|
} else { |
|
/* |
|
* The buffer may have been set dirty during |
|
* attachment to a dirty page. |
|
*/ |
|
clear_buffer_dirty(bh); |
|
} |
|
} while ((bh = bh->b_this_page) != head); |
|
SetPageError(page); |
|
BUG_ON(PageWriteback(page)); |
|
mapping_set_error(page->mapping, err); |
|
set_page_writeback(page); |
|
do { |
|
struct buffer_head *next = bh->b_this_page; |
|
if (buffer_async_write(bh)) { |
|
clear_buffer_dirty(bh); |
|
submit_bh_wbc(REQ_OP_WRITE, write_flags, bh, wbc); |
|
nr_underway++; |
|
} |
|
bh = next; |
|
} while (bh != head); |
|
unlock_page(page); |
|
goto done; |
|
} |
|
EXPORT_SYMBOL(__block_write_full_page); |
|
|
|
/* |
|
* If a page has any new buffers, zero them out here, and mark them uptodate |
|
* and dirty so they'll be written out (in order to prevent uninitialised |
|
* block data from leaking). And clear the new bit. |
|
*/ |
|
void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) |
|
{ |
|
unsigned int block_start, block_end; |
|
struct buffer_head *head, *bh; |
|
|
|
BUG_ON(!PageLocked(page)); |
|
if (!page_has_buffers(page)) |
|
return; |
|
|
|
bh = head = page_buffers(page); |
|
block_start = 0; |
|
do { |
|
block_end = block_start + bh->b_size; |
|
|
|
if (buffer_new(bh)) { |
|
if (block_end > from && block_start < to) { |
|
if (!PageUptodate(page)) { |
|
unsigned start, size; |
|
|
|
start = max(from, block_start); |
|
size = min(to, block_end) - start; |
|
|
|
zero_user(page, start, size); |
|
set_buffer_uptodate(bh); |
|
} |
|
|
|
clear_buffer_new(bh); |
|
mark_buffer_dirty(bh); |
|
} |
|
} |
|
|
|
block_start = block_end; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
} |
|
EXPORT_SYMBOL(page_zero_new_buffers); |
|
|
|
static void |
|
iomap_to_bh(struct inode *inode, sector_t block, struct buffer_head *bh, |
|
const struct iomap *iomap) |
|
{ |
|
loff_t offset = block << inode->i_blkbits; |
|
|
|
bh->b_bdev = iomap->bdev; |
|
|
|
/* |
|
* Block points to offset in file we need to map, iomap contains |
|
* the offset at which the map starts. If the map ends before the |
|
* current block, then do not map the buffer and let the caller |
|
* handle it. |
|
*/ |
|
BUG_ON(offset >= iomap->offset + iomap->length); |
|
|
|
switch (iomap->type) { |
|
case IOMAP_HOLE: |
|
/* |
|
* If the buffer is not up to date or beyond the current EOF, |
|
* we need to mark it as new to ensure sub-block zeroing is |
|
* executed if necessary. |
|
*/ |
|
if (!buffer_uptodate(bh) || |
|
(offset >= i_size_read(inode))) |
|
set_buffer_new(bh); |
|
break; |
|
case IOMAP_DELALLOC: |
|
if (!buffer_uptodate(bh) || |
|
(offset >= i_size_read(inode))) |
|
set_buffer_new(bh); |
|
set_buffer_uptodate(bh); |
|
set_buffer_mapped(bh); |
|
set_buffer_delay(bh); |
|
break; |
|
case IOMAP_UNWRITTEN: |
|
/* |
|
* For unwritten regions, we always need to ensure that regions |
|
* in the block we are not writing to are zeroed. Mark the |
|
* buffer as new to ensure this. |
|
*/ |
|
set_buffer_new(bh); |
|
set_buffer_unwritten(bh); |
|
fallthrough; |
|
case IOMAP_MAPPED: |
|
if ((iomap->flags & IOMAP_F_NEW) || |
|
offset >= i_size_read(inode)) |
|
set_buffer_new(bh); |
|
bh->b_blocknr = (iomap->addr + offset - iomap->offset) >> |
|
inode->i_blkbits; |
|
set_buffer_mapped(bh); |
|
break; |
|
} |
|
} |
|
|
|
int __block_write_begin_int(struct folio *folio, loff_t pos, unsigned len, |
|
get_block_t *get_block, const struct iomap *iomap) |
|
{ |
|
unsigned from = pos & (PAGE_SIZE - 1); |
|
unsigned to = from + len; |
|
struct inode *inode = folio->mapping->host; |
|
unsigned block_start, block_end; |
|
sector_t block; |
|
int err = 0; |
|
unsigned blocksize, bbits; |
|
struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; |
|
|
|
BUG_ON(!folio_test_locked(folio)); |
|
BUG_ON(from > PAGE_SIZE); |
|
BUG_ON(to > PAGE_SIZE); |
|
BUG_ON(from > to); |
|
|
|
head = create_page_buffers(&folio->page, inode, 0); |
|
blocksize = head->b_size; |
|
bbits = block_size_bits(blocksize); |
|
|
|
block = (sector_t)folio->index << (PAGE_SHIFT - bbits); |
|
|
|
for(bh = head, block_start = 0; bh != head || !block_start; |
|
block++, block_start=block_end, bh = bh->b_this_page) { |
|
block_end = block_start + blocksize; |
|
if (block_end <= from || block_start >= to) { |
|
if (folio_test_uptodate(folio)) { |
|
if (!buffer_uptodate(bh)) |
|
set_buffer_uptodate(bh); |
|
} |
|
continue; |
|
} |
|
if (buffer_new(bh)) |
|
clear_buffer_new(bh); |
|
if (!buffer_mapped(bh)) { |
|
WARN_ON(bh->b_size != blocksize); |
|
if (get_block) { |
|
err = get_block(inode, block, bh, 1); |
|
if (err) |
|
break; |
|
} else { |
|
iomap_to_bh(inode, block, bh, iomap); |
|
} |
|
|
|
if (buffer_new(bh)) { |
|
clean_bdev_bh_alias(bh); |
|
if (folio_test_uptodate(folio)) { |
|
clear_buffer_new(bh); |
|
set_buffer_uptodate(bh); |
|
mark_buffer_dirty(bh); |
|
continue; |
|
} |
|
if (block_end > to || block_start < from) |
|
folio_zero_segments(folio, |
|
to, block_end, |
|
block_start, from); |
|
continue; |
|
} |
|
} |
|
if (folio_test_uptodate(folio)) { |
|
if (!buffer_uptodate(bh)) |
|
set_buffer_uptodate(bh); |
|
continue; |
|
} |
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) && |
|
!buffer_unwritten(bh) && |
|
(block_start < from || block_end > to)) { |
|
ll_rw_block(REQ_OP_READ, 0, 1, &bh); |
|
*wait_bh++=bh; |
|
} |
|
} |
|
/* |
|
* If we issued read requests - let them complete. |
|
*/ |
|
while(wait_bh > wait) { |
|
wait_on_buffer(*--wait_bh); |
|
if (!buffer_uptodate(*wait_bh)) |
|
err = -EIO; |
|
} |
|
if (unlikely(err)) |
|
page_zero_new_buffers(&folio->page, from, to); |
|
return err; |
|
} |
|
|
|
int __block_write_begin(struct page *page, loff_t pos, unsigned len, |
|
get_block_t *get_block) |
|
{ |
|
return __block_write_begin_int(page_folio(page), pos, len, get_block, |
|
NULL); |
|
} |
|
EXPORT_SYMBOL(__block_write_begin); |
|
|
|
static int __block_commit_write(struct inode *inode, struct page *page, |
|
unsigned from, unsigned to) |
|
{ |
|
unsigned block_start, block_end; |
|
int partial = 0; |
|
unsigned blocksize; |
|
struct buffer_head *bh, *head; |
|
|
|
bh = head = page_buffers(page); |
|
blocksize = bh->b_size; |
|
|
|
block_start = 0; |
|
do { |
|
block_end = block_start + blocksize; |
|
if (block_end <= from || block_start >= to) { |
|
if (!buffer_uptodate(bh)) |
|
partial = 1; |
|
} else { |
|
set_buffer_uptodate(bh); |
|
mark_buffer_dirty(bh); |
|
} |
|
if (buffer_new(bh)) |
|
clear_buffer_new(bh); |
|
|
|
block_start = block_end; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
|
|
/* |
|
* If this is a partial write which happened to make all buffers |
|
* uptodate then we can optimize away a bogus readpage() for |
|
* the next read(). Here we 'discover' whether the page went |
|
* uptodate as a result of this (potentially partial) write. |
|
*/ |
|
if (!partial) |
|
SetPageUptodate(page); |
|
return 0; |
|
} |
|
|
|
/* |
|
* block_write_begin takes care of the basic task of block allocation and |
|
* bringing partial write blocks uptodate first. |
|
* |
|
* The filesystem needs to handle block truncation upon failure. |
|
*/ |
|
int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len, |
|
unsigned flags, struct page **pagep, get_block_t *get_block) |
|
{ |
|
pgoff_t index = pos >> PAGE_SHIFT; |
|
struct page *page; |
|
int status; |
|
|
|
page = grab_cache_page_write_begin(mapping, index, flags); |
|
if (!page) |
|
return -ENOMEM; |
|
|
|
status = __block_write_begin(page, pos, len, get_block); |
|
if (unlikely(status)) { |
|
unlock_page(page); |
|
put_page(page); |
|
page = NULL; |
|
} |
|
|
|
*pagep = page; |
|
return status; |
|
} |
|
EXPORT_SYMBOL(block_write_begin); |
|
|
|
int block_write_end(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned copied, |
|
struct page *page, void *fsdata) |
|
{ |
|
struct inode *inode = mapping->host; |
|
unsigned start; |
|
|
|
start = pos & (PAGE_SIZE - 1); |
|
|
|
if (unlikely(copied < len)) { |
|
/* |
|
* The buffers that were written will now be uptodate, so we |
|
* don't have to worry about a readpage reading them and |
|
* overwriting a partial write. However if we have encountered |
|
* a short write and only partially written into a buffer, it |
|
* will not be marked uptodate, so a readpage might come in and |
|
* destroy our partial write. |
|
* |
|
* Do the simplest thing, and just treat any short write to a |
|
* non uptodate page as a zero-length write, and force the |
|
* caller to redo the whole thing. |
|
*/ |
|
if (!PageUptodate(page)) |
|
copied = 0; |
|
|
|
page_zero_new_buffers(page, start+copied, start+len); |
|
} |
|
flush_dcache_page(page); |
|
|
|
/* This could be a short (even 0-length) commit */ |
|
__block_commit_write(inode, page, start, start+copied); |
|
|
|
return copied; |
|
} |
|
EXPORT_SYMBOL(block_write_end); |
|
|
|
int generic_write_end(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned copied, |
|
struct page *page, void *fsdata) |
|
{ |
|
struct inode *inode = mapping->host; |
|
loff_t old_size = inode->i_size; |
|
bool i_size_changed = false; |
|
|
|
copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); |
|
|
|
/* |
|
* No need to use i_size_read() here, the i_size cannot change under us |
|
* because we hold i_rwsem. |
|
* |
|
* But it's important to update i_size while still holding page lock: |
|
* page writeout could otherwise come in and zero beyond i_size. |
|
*/ |
|
if (pos + copied > inode->i_size) { |
|
i_size_write(inode, pos + copied); |
|
i_size_changed = true; |
|
} |
|
|
|
unlock_page(page); |
|
put_page(page); |
|
|
|
if (old_size < pos) |
|
pagecache_isize_extended(inode, old_size, pos); |
|
/* |
|
* Don't mark the inode dirty under page lock. First, it unnecessarily |
|
* makes the holding time of page lock longer. Second, it forces lock |
|
* ordering of page lock and transaction start for journaling |
|
* filesystems. |
|
*/ |
|
if (i_size_changed) |
|
mark_inode_dirty(inode); |
|
return copied; |
|
} |
|
EXPORT_SYMBOL(generic_write_end); |
|
|
|
/* |
|
* block_is_partially_uptodate checks whether buffers within a folio are |
|
* uptodate or not. |
|
* |
|
* Returns true if all buffers which correspond to the specified part |
|
* of the folio are uptodate. |
|
*/ |
|
bool block_is_partially_uptodate(struct folio *folio, size_t from, size_t count) |
|
{ |
|
unsigned block_start, block_end, blocksize; |
|
unsigned to; |
|
struct buffer_head *bh, *head; |
|
bool ret = true; |
|
|
|
head = folio_buffers(folio); |
|
if (!head) |
|
return false; |
|
blocksize = head->b_size; |
|
to = min_t(unsigned, folio_size(folio) - from, count); |
|
to = from + to; |
|
if (from < blocksize && to > folio_size(folio) - blocksize) |
|
return false; |
|
|
|
bh = head; |
|
block_start = 0; |
|
do { |
|
block_end = block_start + blocksize; |
|
if (block_end > from && block_start < to) { |
|
if (!buffer_uptodate(bh)) { |
|
ret = false; |
|
break; |
|
} |
|
if (block_end >= to) |
|
break; |
|
} |
|
block_start = block_end; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(block_is_partially_uptodate); |
|
|
|
/* |
|
* Generic "read page" function for block devices that have the normal |
|
* get_block functionality. This is most of the block device filesystems. |
|
* Reads the page asynchronously --- the unlock_buffer() and |
|
* set/clear_buffer_uptodate() functions propagate buffer state into the |
|
* page struct once IO has completed. |
|
*/ |
|
int block_read_full_page(struct page *page, get_block_t *get_block) |
|
{ |
|
struct inode *inode = page->mapping->host; |
|
sector_t iblock, lblock; |
|
struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; |
|
unsigned int blocksize, bbits; |
|
int nr, i; |
|
int fully_mapped = 1; |
|
|
|
head = create_page_buffers(page, inode, 0); |
|
blocksize = head->b_size; |
|
bbits = block_size_bits(blocksize); |
|
|
|
iblock = (sector_t)page->index << (PAGE_SHIFT - bbits); |
|
lblock = (i_size_read(inode)+blocksize-1) >> bbits; |
|
bh = head; |
|
nr = 0; |
|
i = 0; |
|
|
|
do { |
|
if (buffer_uptodate(bh)) |
|
continue; |
|
|
|
if (!buffer_mapped(bh)) { |
|
int err = 0; |
|
|
|
fully_mapped = 0; |
|
if (iblock < lblock) { |
|
WARN_ON(bh->b_size != blocksize); |
|
err = get_block(inode, iblock, bh, 0); |
|
if (err) |
|
SetPageError(page); |
|
} |
|
if (!buffer_mapped(bh)) { |
|
zero_user(page, i * blocksize, blocksize); |
|
if (!err) |
|
set_buffer_uptodate(bh); |
|
continue; |
|
} |
|
/* |
|
* get_block() might have updated the buffer |
|
* synchronously |
|
*/ |
|
if (buffer_uptodate(bh)) |
|
continue; |
|
} |
|
arr[nr++] = bh; |
|
} while (i++, iblock++, (bh = bh->b_this_page) != head); |
|
|
|
if (fully_mapped) |
|
SetPageMappedToDisk(page); |
|
|
|
if (!nr) { |
|
/* |
|
* All buffers are uptodate - we can set the page uptodate |
|
* as well. But not if get_block() returned an error. |
|
*/ |
|
if (!PageError(page)) |
|
SetPageUptodate(page); |
|
unlock_page(page); |
|
return 0; |
|
} |
|
|
|
/* Stage two: lock the buffers */ |
|
for (i = 0; i < nr; i++) { |
|
bh = arr[i]; |
|
lock_buffer(bh); |
|
mark_buffer_async_read(bh); |
|
} |
|
|
|
/* |
|
* Stage 3: start the IO. Check for uptodateness |
|
* inside the buffer lock in case another process reading |
|
* the underlying blockdev brought it uptodate (the sct fix). |
|
*/ |
|
for (i = 0; i < nr; i++) { |
|
bh = arr[i]; |
|
if (buffer_uptodate(bh)) |
|
end_buffer_async_read(bh, 1); |
|
else |
|
submit_bh(REQ_OP_READ, 0, bh); |
|
} |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(block_read_full_page); |
|
|
|
/* utility function for filesystems that need to do work on expanding |
|
* truncates. Uses filesystem pagecache writes to allow the filesystem to |
|
* deal with the hole. |
|
*/ |
|
int generic_cont_expand_simple(struct inode *inode, loff_t size) |
|
{ |
|
struct address_space *mapping = inode->i_mapping; |
|
struct page *page; |
|
void *fsdata; |
|
int err; |
|
|
|
err = inode_newsize_ok(inode, size); |
|
if (err) |
|
goto out; |
|
|
|
err = pagecache_write_begin(NULL, mapping, size, 0, 0, &page, &fsdata); |
|
if (err) |
|
goto out; |
|
|
|
err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
|
BUG_ON(err > 0); |
|
|
|
out: |
|
return err; |
|
} |
|
EXPORT_SYMBOL(generic_cont_expand_simple); |
|
|
|
static int cont_expand_zero(struct file *file, struct address_space *mapping, |
|
loff_t pos, loff_t *bytes) |
|
{ |
|
struct inode *inode = mapping->host; |
|
unsigned int blocksize = i_blocksize(inode); |
|
struct page *page; |
|
void *fsdata; |
|
pgoff_t index, curidx; |
|
loff_t curpos; |
|
unsigned zerofrom, offset, len; |
|
int err = 0; |
|
|
|
index = pos >> PAGE_SHIFT; |
|
offset = pos & ~PAGE_MASK; |
|
|
|
while (index > (curidx = (curpos = *bytes)>>PAGE_SHIFT)) { |
|
zerofrom = curpos & ~PAGE_MASK; |
|
if (zerofrom & (blocksize-1)) { |
|
*bytes |= (blocksize-1); |
|
(*bytes)++; |
|
} |
|
len = PAGE_SIZE - zerofrom; |
|
|
|
err = pagecache_write_begin(file, mapping, curpos, len, 0, |
|
&page, &fsdata); |
|
if (err) |
|
goto out; |
|
zero_user(page, zerofrom, len); |
|
err = pagecache_write_end(file, mapping, curpos, len, len, |
|
page, fsdata); |
|
if (err < 0) |
|
goto out; |
|
BUG_ON(err != len); |
|
err = 0; |
|
|
|
balance_dirty_pages_ratelimited(mapping); |
|
|
|
if (fatal_signal_pending(current)) { |
|
err = -EINTR; |
|
goto out; |
|
} |
|
} |
|
|
|
/* page covers the boundary, find the boundary offset */ |
|
if (index == curidx) { |
|
zerofrom = curpos & ~PAGE_MASK; |
|
/* if we will expand the thing last block will be filled */ |
|
if (offset <= zerofrom) { |
|
goto out; |
|
} |
|
if (zerofrom & (blocksize-1)) { |
|
*bytes |= (blocksize-1); |
|
(*bytes)++; |
|
} |
|
len = offset - zerofrom; |
|
|
|
err = pagecache_write_begin(file, mapping, curpos, len, 0, |
|
&page, &fsdata); |
|
if (err) |
|
goto out; |
|
zero_user(page, zerofrom, len); |
|
err = pagecache_write_end(file, mapping, curpos, len, len, |
|
page, fsdata); |
|
if (err < 0) |
|
goto out; |
|
BUG_ON(err != len); |
|
err = 0; |
|
} |
|
out: |
|
return err; |
|
} |
|
|
|
/* |
|
* For moronic filesystems that do not allow holes in file. |
|
* We may have to extend the file. |
|
*/ |
|
int cont_write_begin(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned flags, |
|
struct page **pagep, void **fsdata, |
|
get_block_t *get_block, loff_t *bytes) |
|
{ |
|
struct inode *inode = mapping->host; |
|
unsigned int blocksize = i_blocksize(inode); |
|
unsigned int zerofrom; |
|
int err; |
|
|
|
err = cont_expand_zero(file, mapping, pos, bytes); |
|
if (err) |
|
return err; |
|
|
|
zerofrom = *bytes & ~PAGE_MASK; |
|
if (pos+len > *bytes && zerofrom & (blocksize-1)) { |
|
*bytes |= (blocksize-1); |
|
(*bytes)++; |
|
} |
|
|
|
return block_write_begin(mapping, pos, len, flags, pagep, get_block); |
|
} |
|
EXPORT_SYMBOL(cont_write_begin); |
|
|
|
int block_commit_write(struct page *page, unsigned from, unsigned to) |
|
{ |
|
struct inode *inode = page->mapping->host; |
|
__block_commit_write(inode,page,from,to); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(block_commit_write); |
|
|
|
/* |
|
* block_page_mkwrite() is not allowed to change the file size as it gets |
|
* called from a page fault handler when a page is first dirtied. Hence we must |
|
* be careful to check for EOF conditions here. We set the page up correctly |
|
* for a written page which means we get ENOSPC checking when writing into |
|
* holes and correct delalloc and unwritten extent mapping on filesystems that |
|
* support these features. |
|
* |
|
* We are not allowed to take the i_mutex here so we have to play games to |
|
* protect against truncate races as the page could now be beyond EOF. Because |
|
* truncate writes the inode size before removing pages, once we have the |
|
* page lock we can determine safely if the page is beyond EOF. If it is not |
|
* beyond EOF, then the page is guaranteed safe against truncation until we |
|
* unlock the page. |
|
* |
|
* Direct callers of this function should protect against filesystem freezing |
|
* using sb_start_pagefault() - sb_end_pagefault() functions. |
|
*/ |
|
int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
|
get_block_t get_block) |
|
{ |
|
struct page *page = vmf->page; |
|
struct inode *inode = file_inode(vma->vm_file); |
|
unsigned long end; |
|
loff_t size; |
|
int ret; |
|
|
|
lock_page(page); |
|
size = i_size_read(inode); |
|
if ((page->mapping != inode->i_mapping) || |
|
(page_offset(page) > size)) { |
|
/* We overload EFAULT to mean page got truncated */ |
|
ret = -EFAULT; |
|
goto out_unlock; |
|
} |
|
|
|
/* page is wholly or partially inside EOF */ |
|
if (((page->index + 1) << PAGE_SHIFT) > size) |
|
end = size & ~PAGE_MASK; |
|
else |
|
end = PAGE_SIZE; |
|
|
|
ret = __block_write_begin(page, 0, end, get_block); |
|
if (!ret) |
|
ret = block_commit_write(page, 0, end); |
|
|
|
if (unlikely(ret < 0)) |
|
goto out_unlock; |
|
set_page_dirty(page); |
|
wait_for_stable_page(page); |
|
return 0; |
|
out_unlock: |
|
unlock_page(page); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(block_page_mkwrite); |
|
|
|
/* |
|
* nobh_write_begin()'s prereads are special: the buffer_heads are freed |
|
* immediately, while under the page lock. So it needs a special end_io |
|
* handler which does not touch the bh after unlocking it. |
|
*/ |
|
static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) |
|
{ |
|
__end_buffer_read_notouch(bh, uptodate); |
|
} |
|
|
|
/* |
|
* Attach the singly-linked list of buffers created by nobh_write_begin, to |
|
* the page (converting it to circular linked list and taking care of page |
|
* dirty races). |
|
*/ |
|
static void attach_nobh_buffers(struct page *page, struct buffer_head *head) |
|
{ |
|
struct buffer_head *bh; |
|
|
|
BUG_ON(!PageLocked(page)); |
|
|
|
spin_lock(&page->mapping->private_lock); |
|
bh = head; |
|
do { |
|
if (PageDirty(page)) |
|
set_buffer_dirty(bh); |
|
if (!bh->b_this_page) |
|
bh->b_this_page = head; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
attach_page_private(page, head); |
|
spin_unlock(&page->mapping->private_lock); |
|
} |
|
|
|
/* |
|
* On entry, the page is fully not uptodate. |
|
* On exit the page is fully uptodate in the areas outside (from,to) |
|
* The filesystem needs to handle block truncation upon failure. |
|
*/ |
|
int nobh_write_begin(struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned flags, |
|
struct page **pagep, void **fsdata, |
|
get_block_t *get_block) |
|
{ |
|
struct inode *inode = mapping->host; |
|
const unsigned blkbits = inode->i_blkbits; |
|
const unsigned blocksize = 1 << blkbits; |
|
struct buffer_head *head, *bh; |
|
struct page *page; |
|
pgoff_t index; |
|
unsigned from, to; |
|
unsigned block_in_page; |
|
unsigned block_start, block_end; |
|
sector_t block_in_file; |
|
int nr_reads = 0; |
|
int ret = 0; |
|
int is_mapped_to_disk = 1; |
|
|
|
index = pos >> PAGE_SHIFT; |
|
from = pos & (PAGE_SIZE - 1); |
|
to = from + len; |
|
|
|
page = grab_cache_page_write_begin(mapping, index, flags); |
|
if (!page) |
|
return -ENOMEM; |
|
*pagep = page; |
|
*fsdata = NULL; |
|
|
|
if (page_has_buffers(page)) { |
|
ret = __block_write_begin(page, pos, len, get_block); |
|
if (unlikely(ret)) |
|
goto out_release; |
|
return ret; |
|
} |
|
|
|
if (PageMappedToDisk(page)) |
|
return 0; |
|
|
|
/* |
|
* Allocate buffers so that we can keep track of state, and potentially |
|
* attach them to the page if an error occurs. In the common case of |
|
* no error, they will just be freed again without ever being attached |
|
* to the page (which is all OK, because we're under the page lock). |
|
* |
|
* Be careful: the buffer linked list is a NULL terminated one, rather |
|
* than the circular one we're used to. |
|
*/ |
|
head = alloc_page_buffers(page, blocksize, false); |
|
if (!head) { |
|
ret = -ENOMEM; |
|
goto out_release; |
|
} |
|
|
|
block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); |
|
|
|
/* |
|
* We loop across all blocks in the page, whether or not they are |
|
* part of the affected region. This is so we can discover if the |
|
* page is fully mapped-to-disk. |
|
*/ |
|
for (block_start = 0, block_in_page = 0, bh = head; |
|
block_start < PAGE_SIZE; |
|
block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
|
int create; |
|
|
|
block_end = block_start + blocksize; |
|
bh->b_state = 0; |
|
create = 1; |
|
if (block_start >= to) |
|
create = 0; |
|
ret = get_block(inode, block_in_file + block_in_page, |
|
bh, create); |
|
if (ret) |
|
goto failed; |
|
if (!buffer_mapped(bh)) |
|
is_mapped_to_disk = 0; |
|
if (buffer_new(bh)) |
|
clean_bdev_bh_alias(bh); |
|
if (PageUptodate(page)) { |
|
set_buffer_uptodate(bh); |
|
continue; |
|
} |
|
if (buffer_new(bh) || !buffer_mapped(bh)) { |
|
zero_user_segments(page, block_start, from, |
|
to, block_end); |
|
continue; |
|
} |
|
if (buffer_uptodate(bh)) |
|
continue; /* reiserfs does this */ |
|
if (block_start < from || block_end > to) { |
|
lock_buffer(bh); |
|
bh->b_end_io = end_buffer_read_nobh; |
|
submit_bh(REQ_OP_READ, 0, bh); |
|
nr_reads++; |
|
} |
|
} |
|
|
|
if (nr_reads) { |
|
/* |
|
* The page is locked, so these buffers are protected from |
|
* any VM or truncate activity. Hence we don't need to care |
|
* for the buffer_head refcounts. |
|
*/ |
|
for (bh = head; bh; bh = bh->b_this_page) { |
|
wait_on_buffer(bh); |
|
if (!buffer_uptodate(bh)) |
|
ret = -EIO; |
|
} |
|
if (ret) |
|
goto failed; |
|
} |
|
|
|
if (is_mapped_to_disk) |
|
SetPageMappedToDisk(page); |
|
|
|
*fsdata = head; /* to be released by nobh_write_end */ |
|
|
|
return 0; |
|
|
|
failed: |
|
BUG_ON(!ret); |
|
/* |
|
* Error recovery is a bit difficult. We need to zero out blocks that |
|
* were newly allocated, and dirty them to ensure they get written out. |
|
* Buffers need to be attached to the page at this point, otherwise |
|
* the handling of potential IO errors during writeout would be hard |
|
* (could try doing synchronous writeout, but what if that fails too?) |
|
*/ |
|
attach_nobh_buffers(page, head); |
|
page_zero_new_buffers(page, from, to); |
|
|
|
out_release: |
|
unlock_page(page); |
|
put_page(page); |
|
*pagep = NULL; |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(nobh_write_begin); |
|
|
|
int nobh_write_end(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned copied, |
|
struct page *page, void *fsdata) |
|
{ |
|
struct inode *inode = page->mapping->host; |
|
struct buffer_head *head = fsdata; |
|
struct buffer_head *bh; |
|
BUG_ON(fsdata != NULL && page_has_buffers(page)); |
|
|
|
if (unlikely(copied < len) && head) |
|
attach_nobh_buffers(page, head); |
|
if (page_has_buffers(page)) |
|
return generic_write_end(file, mapping, pos, len, |
|
copied, page, fsdata); |
|
|
|
SetPageUptodate(page); |
|
set_page_dirty(page); |
|
if (pos+copied > inode->i_size) { |
|
i_size_write(inode, pos+copied); |
|
mark_inode_dirty(inode); |
|
} |
|
|
|
unlock_page(page); |
|
put_page(page); |
|
|
|
while (head) { |
|
bh = head; |
|
head = head->b_this_page; |
|
free_buffer_head(bh); |
|
} |
|
|
|
return copied; |
|
} |
|
EXPORT_SYMBOL(nobh_write_end); |
|
|
|
/* |
|
* nobh_writepage() - based on block_full_write_page() except |
|
* that it tries to operate without attaching bufferheads to |
|
* the page. |
|
*/ |
|
int nobh_writepage(struct page *page, get_block_t *get_block, |
|
struct writeback_control *wbc) |
|
{ |
|
struct inode * const inode = page->mapping->host; |
|
loff_t i_size = i_size_read(inode); |
|
const pgoff_t end_index = i_size >> PAGE_SHIFT; |
|
unsigned offset; |
|
int ret; |
|
|
|
/* Is the page fully inside i_size? */ |
|
if (page->index < end_index) |
|
goto out; |
|
|
|
/* Is the page fully outside i_size? (truncate in progress) */ |
|
offset = i_size & (PAGE_SIZE-1); |
|
if (page->index >= end_index+1 || !offset) { |
|
unlock_page(page); |
|
return 0; /* don't care */ |
|
} |
|
|
|
/* |
|
* The page straddles i_size. It must be zeroed out on each and every |
|
* writepage invocation because it may be mmapped. "A file is mapped |
|
* in multiples of the page size. For a file that is not a multiple of |
|
* the page size, the remaining memory is zeroed when mapped, and |
|
* writes to that region are not written out to the file." |
|
*/ |
|
zero_user_segment(page, offset, PAGE_SIZE); |
|
out: |
|
ret = mpage_writepage(page, get_block, wbc); |
|
if (ret == -EAGAIN) |
|
ret = __block_write_full_page(inode, page, get_block, wbc, |
|
end_buffer_async_write); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(nobh_writepage); |
|
|
|
int nobh_truncate_page(struct address_space *mapping, |
|
loff_t from, get_block_t *get_block) |
|
{ |
|
pgoff_t index = from >> PAGE_SHIFT; |
|
unsigned offset = from & (PAGE_SIZE-1); |
|
unsigned blocksize; |
|
sector_t iblock; |
|
unsigned length, pos; |
|
struct inode *inode = mapping->host; |
|
struct page *page; |
|
struct buffer_head map_bh; |
|
int err; |
|
|
|
blocksize = i_blocksize(inode); |
|
length = offset & (blocksize - 1); |
|
|
|
/* Block boundary? Nothing to do */ |
|
if (!length) |
|
return 0; |
|
|
|
length = blocksize - length; |
|
iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); |
|
|
|
page = grab_cache_page(mapping, index); |
|
err = -ENOMEM; |
|
if (!page) |
|
goto out; |
|
|
|
if (page_has_buffers(page)) { |
|
has_buffers: |
|
unlock_page(page); |
|
put_page(page); |
|
return block_truncate_page(mapping, from, get_block); |
|
} |
|
|
|
/* Find the buffer that contains "offset" */ |
|
pos = blocksize; |
|
while (offset >= pos) { |
|
iblock++; |
|
pos += blocksize; |
|
} |
|
|
|
map_bh.b_size = blocksize; |
|
map_bh.b_state = 0; |
|
err = get_block(inode, iblock, &map_bh, 0); |
|
if (err) |
|
goto unlock; |
|
/* unmapped? It's a hole - nothing to do */ |
|
if (!buffer_mapped(&map_bh)) |
|
goto unlock; |
|
|
|
/* Ok, it's mapped. Make sure it's up-to-date */ |
|
if (!PageUptodate(page)) { |
|
err = mapping->a_ops->readpage(NULL, page); |
|
if (err) { |
|
put_page(page); |
|
goto out; |
|
} |
|
lock_page(page); |
|
if (!PageUptodate(page)) { |
|
err = -EIO; |
|
goto unlock; |
|
} |
|
if (page_has_buffers(page)) |
|
goto has_buffers; |
|
} |
|
zero_user(page, offset, length); |
|
set_page_dirty(page); |
|
err = 0; |
|
|
|
unlock: |
|
unlock_page(page); |
|
put_page(page); |
|
out: |
|
return err; |
|
} |
|
EXPORT_SYMBOL(nobh_truncate_page); |
|
|
|
int block_truncate_page(struct address_space *mapping, |
|
loff_t from, get_block_t *get_block) |
|
{ |
|
pgoff_t index = from >> PAGE_SHIFT; |
|
unsigned offset = from & (PAGE_SIZE-1); |
|
unsigned blocksize; |
|
sector_t iblock; |
|
unsigned length, pos; |
|
struct inode *inode = mapping->host; |
|
struct page *page; |
|
struct buffer_head *bh; |
|
int err; |
|
|
|
blocksize = i_blocksize(inode); |
|
length = offset & (blocksize - 1); |
|
|
|
/* Block boundary? Nothing to do */ |
|
if (!length) |
|
return 0; |
|
|
|
length = blocksize - length; |
|
iblock = (sector_t)index << (PAGE_SHIFT - inode->i_blkbits); |
|
|
|
page = grab_cache_page(mapping, index); |
|
err = -ENOMEM; |
|
if (!page) |
|
goto out; |
|
|
|
if (!page_has_buffers(page)) |
|
create_empty_buffers(page, blocksize, 0); |
|
|
|
/* Find the buffer that contains "offset" */ |
|
bh = page_buffers(page); |
|
pos = blocksize; |
|
while (offset >= pos) { |
|
bh = bh->b_this_page; |
|
iblock++; |
|
pos += blocksize; |
|
} |
|
|
|
err = 0; |
|
if (!buffer_mapped(bh)) { |
|
WARN_ON(bh->b_size != blocksize); |
|
err = get_block(inode, iblock, bh, 0); |
|
if (err) |
|
goto unlock; |
|
/* unmapped? It's a hole - nothing to do */ |
|
if (!buffer_mapped(bh)) |
|
goto unlock; |
|
} |
|
|
|
/* Ok, it's mapped. Make sure it's up-to-date */ |
|
if (PageUptodate(page)) |
|
set_buffer_uptodate(bh); |
|
|
|
if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
|
err = -EIO; |
|
ll_rw_block(REQ_OP_READ, 0, 1, &bh); |
|
wait_on_buffer(bh); |
|
/* Uhhuh. Read error. Complain and punt. */ |
|
if (!buffer_uptodate(bh)) |
|
goto unlock; |
|
} |
|
|
|
zero_user(page, offset, length); |
|
mark_buffer_dirty(bh); |
|
err = 0; |
|
|
|
unlock: |
|
unlock_page(page); |
|
put_page(page); |
|
out: |
|
return err; |
|
} |
|
EXPORT_SYMBOL(block_truncate_page); |
|
|
|
/* |
|
* The generic ->writepage function for buffer-backed address_spaces |
|
*/ |
|
int block_write_full_page(struct page *page, get_block_t *get_block, |
|
struct writeback_control *wbc) |
|
{ |
|
struct inode * const inode = page->mapping->host; |
|
loff_t i_size = i_size_read(inode); |
|
const pgoff_t end_index = i_size >> PAGE_SHIFT; |
|
unsigned offset; |
|
|
|
/* Is the page fully inside i_size? */ |
|
if (page->index < end_index) |
|
return __block_write_full_page(inode, page, get_block, wbc, |
|
end_buffer_async_write); |
|
|
|
/* Is the page fully outside i_size? (truncate in progress) */ |
|
offset = i_size & (PAGE_SIZE-1); |
|
if (page->index >= end_index+1 || !offset) { |
|
unlock_page(page); |
|
return 0; /* don't care */ |
|
} |
|
|
|
/* |
|
* The page straddles i_size. It must be zeroed out on each and every |
|
* writepage invocation because it may be mmapped. "A file is mapped |
|
* in multiples of the page size. For a file that is not a multiple of |
|
* the page size, the remaining memory is zeroed when mapped, and |
|
* writes to that region are not written out to the file." |
|
*/ |
|
zero_user_segment(page, offset, PAGE_SIZE); |
|
return __block_write_full_page(inode, page, get_block, wbc, |
|
end_buffer_async_write); |
|
} |
|
EXPORT_SYMBOL(block_write_full_page); |
|
|
|
sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
|
get_block_t *get_block) |
|
{ |
|
struct inode *inode = mapping->host; |
|
struct buffer_head tmp = { |
|
.b_size = i_blocksize(inode), |
|
}; |
|
|
|
get_block(inode, block, &tmp, 0); |
|
return tmp.b_blocknr; |
|
} |
|
EXPORT_SYMBOL(generic_block_bmap); |
|
|
|
static void end_bio_bh_io_sync(struct bio *bio) |
|
{ |
|
struct buffer_head *bh = bio->bi_private; |
|
|
|
if (unlikely(bio_flagged(bio, BIO_QUIET))) |
|
set_bit(BH_Quiet, &bh->b_state); |
|
|
|
bh->b_end_io(bh, !bio->bi_status); |
|
bio_put(bio); |
|
} |
|
|
|
static int submit_bh_wbc(int op, int op_flags, struct buffer_head *bh, |
|
struct writeback_control *wbc) |
|
{ |
|
struct bio *bio; |
|
|
|
BUG_ON(!buffer_locked(bh)); |
|
BUG_ON(!buffer_mapped(bh)); |
|
BUG_ON(!bh->b_end_io); |
|
BUG_ON(buffer_delay(bh)); |
|
BUG_ON(buffer_unwritten(bh)); |
|
|
|
/* |
|
* Only clear out a write error when rewriting |
|
*/ |
|
if (test_set_buffer_req(bh) && (op == REQ_OP_WRITE)) |
|
clear_buffer_write_io_error(bh); |
|
|
|
if (buffer_meta(bh)) |
|
op_flags |= REQ_META; |
|
if (buffer_prio(bh)) |
|
op_flags |= REQ_PRIO; |
|
|
|
bio = bio_alloc(bh->b_bdev, 1, op | op_flags, GFP_NOIO); |
|
|
|
fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO); |
|
|
|
bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9); |
|
|
|
bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh)); |
|
BUG_ON(bio->bi_iter.bi_size != bh->b_size); |
|
|
|
bio->bi_end_io = end_bio_bh_io_sync; |
|
bio->bi_private = bh; |
|
|
|
/* Take care of bh's that straddle the end of the device */ |
|
guard_bio_eod(bio); |
|
|
|
if (wbc) { |
|
wbc_init_bio(wbc, bio); |
|
wbc_account_cgroup_owner(wbc, bh->b_page, bh->b_size); |
|
} |
|
|
|
submit_bio(bio); |
|
return 0; |
|
} |
|
|
|
int submit_bh(int op, int op_flags, struct buffer_head *bh) |
|
{ |
|
return submit_bh_wbc(op, op_flags, bh, NULL); |
|
} |
|
EXPORT_SYMBOL(submit_bh); |
|
|
|
/** |
|
* ll_rw_block: low-level access to block devices (DEPRECATED) |
|
* @op: whether to %READ or %WRITE |
|
* @op_flags: req_flag_bits |
|
* @nr: number of &struct buffer_heads in the array |
|
* @bhs: array of pointers to &struct buffer_head |
|
* |
|
* ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
|
* requests an I/O operation on them, either a %REQ_OP_READ or a %REQ_OP_WRITE. |
|
* @op_flags contains flags modifying the detailed I/O behavior, most notably |
|
* %REQ_RAHEAD. |
|
* |
|
* This function drops any buffer that it cannot get a lock on (with the |
|
* BH_Lock state bit), any buffer that appears to be clean when doing a write |
|
* request, and any buffer that appears to be up-to-date when doing read |
|
* request. Further it marks as clean buffers that are processed for |
|
* writing (the buffer cache won't assume that they are actually clean |
|
* until the buffer gets unlocked). |
|
* |
|
* ll_rw_block sets b_end_io to simple completion handler that marks |
|
* the buffer up-to-date (if appropriate), unlocks the buffer and wakes |
|
* any waiters. |
|
* |
|
* All of the buffers must be for the same device, and must also be a |
|
* multiple of the current approved size for the device. |
|
*/ |
|
void ll_rw_block(int op, int op_flags, int nr, struct buffer_head *bhs[]) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < nr; i++) { |
|
struct buffer_head *bh = bhs[i]; |
|
|
|
if (!trylock_buffer(bh)) |
|
continue; |
|
if (op == WRITE) { |
|
if (test_clear_buffer_dirty(bh)) { |
|
bh->b_end_io = end_buffer_write_sync; |
|
get_bh(bh); |
|
submit_bh(op, op_flags, bh); |
|
continue; |
|
} |
|
} else { |
|
if (!buffer_uptodate(bh)) { |
|
bh->b_end_io = end_buffer_read_sync; |
|
get_bh(bh); |
|
submit_bh(op, op_flags, bh); |
|
continue; |
|
} |
|
} |
|
unlock_buffer(bh); |
|
} |
|
} |
|
EXPORT_SYMBOL(ll_rw_block); |
|
|
|
void write_dirty_buffer(struct buffer_head *bh, int op_flags) |
|
{ |
|
lock_buffer(bh); |
|
if (!test_clear_buffer_dirty(bh)) { |
|
unlock_buffer(bh); |
|
return; |
|
} |
|
bh->b_end_io = end_buffer_write_sync; |
|
get_bh(bh); |
|
submit_bh(REQ_OP_WRITE, op_flags, bh); |
|
} |
|
EXPORT_SYMBOL(write_dirty_buffer); |
|
|
|
/* |
|
* For a data-integrity writeout, we need to wait upon any in-progress I/O |
|
* and then start new I/O and then wait upon it. The caller must have a ref on |
|
* the buffer_head. |
|
*/ |
|
int __sync_dirty_buffer(struct buffer_head *bh, int op_flags) |
|
{ |
|
int ret = 0; |
|
|
|
WARN_ON(atomic_read(&bh->b_count) < 1); |
|
lock_buffer(bh); |
|
if (test_clear_buffer_dirty(bh)) { |
|
/* |
|
* The bh should be mapped, but it might not be if the |
|
* device was hot-removed. Not much we can do but fail the I/O. |
|
*/ |
|
if (!buffer_mapped(bh)) { |
|
unlock_buffer(bh); |
|
return -EIO; |
|
} |
|
|
|
get_bh(bh); |
|
bh->b_end_io = end_buffer_write_sync; |
|
ret = submit_bh(REQ_OP_WRITE, op_flags, bh); |
|
wait_on_buffer(bh); |
|
if (!ret && !buffer_uptodate(bh)) |
|
ret = -EIO; |
|
} else { |
|
unlock_buffer(bh); |
|
} |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(__sync_dirty_buffer); |
|
|
|
int sync_dirty_buffer(struct buffer_head *bh) |
|
{ |
|
return __sync_dirty_buffer(bh, REQ_SYNC); |
|
} |
|
EXPORT_SYMBOL(sync_dirty_buffer); |
|
|
|
/* |
|
* try_to_free_buffers() checks if all the buffers on this particular page |
|
* are unused, and releases them if so. |
|
* |
|
* Exclusion against try_to_free_buffers may be obtained by either |
|
* locking the page or by holding its mapping's private_lock. |
|
* |
|
* If the page is dirty but all the buffers are clean then we need to |
|
* be sure to mark the page clean as well. This is because the page |
|
* may be against a block device, and a later reattachment of buffers |
|
* to a dirty page will set *all* buffers dirty. Which would corrupt |
|
* filesystem data on the same device. |
|
* |
|
* The same applies to regular filesystem pages: if all the buffers are |
|
* clean then we set the page clean and proceed. To do that, we require |
|
* total exclusion from block_dirty_folio(). That is obtained with |
|
* private_lock. |
|
* |
|
* try_to_free_buffers() is non-blocking. |
|
*/ |
|
static inline int buffer_busy(struct buffer_head *bh) |
|
{ |
|
return atomic_read(&bh->b_count) | |
|
(bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); |
|
} |
|
|
|
static int |
|
drop_buffers(struct page *page, struct buffer_head **buffers_to_free) |
|
{ |
|
struct buffer_head *head = page_buffers(page); |
|
struct buffer_head *bh; |
|
|
|
bh = head; |
|
do { |
|
if (buffer_busy(bh)) |
|
goto failed; |
|
bh = bh->b_this_page; |
|
} while (bh != head); |
|
|
|
do { |
|
struct buffer_head *next = bh->b_this_page; |
|
|
|
if (bh->b_assoc_map) |
|
__remove_assoc_queue(bh); |
|
bh = next; |
|
} while (bh != head); |
|
*buffers_to_free = head; |
|
detach_page_private(page); |
|
return 1; |
|
failed: |
|
return 0; |
|
} |
|
|
|
int try_to_free_buffers(struct page *page) |
|
{ |
|
struct address_space * const mapping = page->mapping; |
|
struct buffer_head *buffers_to_free = NULL; |
|
int ret = 0; |
|
|
|
BUG_ON(!PageLocked(page)); |
|
if (PageWriteback(page)) |
|
return 0; |
|
|
|
if (mapping == NULL) { /* can this still happen? */ |
|
ret = drop_buffers(page, &buffers_to_free); |
|
goto out; |
|
} |
|
|
|
spin_lock(&mapping->private_lock); |
|
ret = drop_buffers(page, &buffers_to_free); |
|
|
|
/* |
|
* If the filesystem writes its buffers by hand (eg ext3) |
|
* then we can have clean buffers against a dirty page. We |
|
* clean the page here; otherwise the VM will never notice |
|
* that the filesystem did any IO at all. |
|
* |
|
* Also, during truncate, discard_buffer will have marked all |
|
* the page's buffers clean. We discover that here and clean |
|
* the page also. |
|
* |
|
* private_lock must be held over this entire operation in order |
|
* to synchronise against block_dirty_folio and prevent the |
|
* dirty bit from being lost. |
|
*/ |
|
if (ret) |
|
cancel_dirty_page(page); |
|
spin_unlock(&mapping->private_lock); |
|
out: |
|
if (buffers_to_free) { |
|
struct buffer_head *bh = buffers_to_free; |
|
|
|
do { |
|
struct buffer_head *next = bh->b_this_page; |
|
free_buffer_head(bh); |
|
bh = next; |
|
} while (bh != buffers_to_free); |
|
} |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(try_to_free_buffers); |
|
|
|
/* |
|
* Buffer-head allocation |
|
*/ |
|
static struct kmem_cache *bh_cachep __read_mostly; |
|
|
|
/* |
|
* Once the number of bh's in the machine exceeds this level, we start |
|
* stripping them in writeback. |
|
*/ |
|
static unsigned long max_buffer_heads; |
|
|
|
int buffer_heads_over_limit; |
|
|
|
struct bh_accounting { |
|
int nr; /* Number of live bh's */ |
|
int ratelimit; /* Limit cacheline bouncing */ |
|
}; |
|
|
|
static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; |
|
|
|
static void recalc_bh_state(void) |
|
{ |
|
int i; |
|
int tot = 0; |
|
|
|
if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096) |
|
return; |
|
__this_cpu_write(bh_accounting.ratelimit, 0); |
|
for_each_online_cpu(i) |
|
tot += per_cpu(bh_accounting, i).nr; |
|
buffer_heads_over_limit = (tot > max_buffer_heads); |
|
} |
|
|
|
struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
|
{ |
|
struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); |
|
if (ret) { |
|
INIT_LIST_HEAD(&ret->b_assoc_buffers); |
|
spin_lock_init(&ret->b_uptodate_lock); |
|
preempt_disable(); |
|
__this_cpu_inc(bh_accounting.nr); |
|
recalc_bh_state(); |
|
preempt_enable(); |
|
} |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(alloc_buffer_head); |
|
|
|
void free_buffer_head(struct buffer_head *bh) |
|
{ |
|
BUG_ON(!list_empty(&bh->b_assoc_buffers)); |
|
kmem_cache_free(bh_cachep, bh); |
|
preempt_disable(); |
|
__this_cpu_dec(bh_accounting.nr); |
|
recalc_bh_state(); |
|
preempt_enable(); |
|
} |
|
EXPORT_SYMBOL(free_buffer_head); |
|
|
|
static int buffer_exit_cpu_dead(unsigned int cpu) |
|
{ |
|
int i; |
|
struct bh_lru *b = &per_cpu(bh_lrus, cpu); |
|
|
|
for (i = 0; i < BH_LRU_SIZE; i++) { |
|
brelse(b->bhs[i]); |
|
b->bhs[i] = NULL; |
|
} |
|
this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); |
|
per_cpu(bh_accounting, cpu).nr = 0; |
|
return 0; |
|
} |
|
|
|
/** |
|
* bh_uptodate_or_lock - Test whether the buffer is uptodate |
|
* @bh: struct buffer_head |
|
* |
|
* Return true if the buffer is up-to-date and false, |
|
* with the buffer locked, if not. |
|
*/ |
|
int bh_uptodate_or_lock(struct buffer_head *bh) |
|
{ |
|
if (!buffer_uptodate(bh)) { |
|
lock_buffer(bh); |
|
if (!buffer_uptodate(bh)) |
|
return 0; |
|
unlock_buffer(bh); |
|
} |
|
return 1; |
|
} |
|
EXPORT_SYMBOL(bh_uptodate_or_lock); |
|
|
|
/** |
|
* bh_submit_read - Submit a locked buffer for reading |
|
* @bh: struct buffer_head |
|
* |
|
* Returns zero on success and -EIO on error. |
|
*/ |
|
int bh_submit_read(struct buffer_head *bh) |
|
{ |
|
BUG_ON(!buffer_locked(bh)); |
|
|
|
if (buffer_uptodate(bh)) { |
|
unlock_buffer(bh); |
|
return 0; |
|
} |
|
|
|
get_bh(bh); |
|
bh->b_end_io = end_buffer_read_sync; |
|
submit_bh(REQ_OP_READ, 0, bh); |
|
wait_on_buffer(bh); |
|
if (buffer_uptodate(bh)) |
|
return 0; |
|
return -EIO; |
|
} |
|
EXPORT_SYMBOL(bh_submit_read); |
|
|
|
void __init buffer_init(void) |
|
{ |
|
unsigned long nrpages; |
|
int ret; |
|
|
|
bh_cachep = kmem_cache_create("buffer_head", |
|
sizeof(struct buffer_head), 0, |
|
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| |
|
SLAB_MEM_SPREAD), |
|
NULL); |
|
|
|
/* |
|
* Limit the bh occupancy to 10% of ZONE_NORMAL |
|
*/ |
|
nrpages = (nr_free_buffer_pages() * 10) / 100; |
|
max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); |
|
ret = cpuhp_setup_state_nocalls(CPUHP_FS_BUFF_DEAD, "fs/buffer:dead", |
|
NULL, buffer_exit_cpu_dead); |
|
WARN_ON(ret < 0); |
|
}
|
|
|