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199 lines
4.9 KiB
199 lines
4.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* fs/bfs/file.c |
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* BFS file operations. |
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* Copyright (C) 1999-2018 Tigran Aivazian <[email protected]> |
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* |
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* Make the file block allocation algorithm understand the size |
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* of the underlying block device. |
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* Copyright (C) 2007 Dmitri Vorobiev <[email protected]> |
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* |
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*/ |
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#include <linux/fs.h> |
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#include <linux/buffer_head.h> |
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#include "bfs.h" |
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#undef DEBUG |
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#ifdef DEBUG |
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#define dprintf(x...) printf(x) |
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#else |
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#define dprintf(x...) |
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#endif |
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const struct file_operations bfs_file_operations = { |
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.llseek = generic_file_llseek, |
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.read_iter = generic_file_read_iter, |
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.write_iter = generic_file_write_iter, |
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.mmap = generic_file_mmap, |
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.splice_read = generic_file_splice_read, |
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}; |
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static int bfs_move_block(unsigned long from, unsigned long to, |
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struct super_block *sb) |
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{ |
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struct buffer_head *bh, *new; |
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bh = sb_bread(sb, from); |
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if (!bh) |
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return -EIO; |
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new = sb_getblk(sb, to); |
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memcpy(new->b_data, bh->b_data, bh->b_size); |
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mark_buffer_dirty(new); |
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bforget(bh); |
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brelse(new); |
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return 0; |
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} |
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static int bfs_move_blocks(struct super_block *sb, unsigned long start, |
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unsigned long end, unsigned long where) |
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{ |
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unsigned long i; |
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dprintf("%08lx-%08lx->%08lx\n", start, end, where); |
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for (i = start; i <= end; i++) |
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if(bfs_move_block(i, where + i, sb)) { |
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dprintf("failed to move block %08lx -> %08lx\n", i, |
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where + i); |
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return -EIO; |
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} |
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return 0; |
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} |
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static int bfs_get_block(struct inode *inode, sector_t block, |
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struct buffer_head *bh_result, int create) |
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{ |
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unsigned long phys; |
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int err; |
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struct super_block *sb = inode->i_sb; |
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struct bfs_sb_info *info = BFS_SB(sb); |
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struct bfs_inode_info *bi = BFS_I(inode); |
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phys = bi->i_sblock + block; |
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if (!create) { |
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if (phys <= bi->i_eblock) { |
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dprintf("c=%d, b=%08lx, phys=%09lx (granted)\n", |
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create, (unsigned long)block, phys); |
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map_bh(bh_result, sb, phys); |
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} |
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return 0; |
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} |
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/* |
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* If the file is not empty and the requested block is within the |
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* range of blocks allocated for this file, we can grant it. |
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*/ |
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if (bi->i_sblock && (phys <= bi->i_eblock)) { |
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dprintf("c=%d, b=%08lx, phys=%08lx (interim block granted)\n", |
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create, (unsigned long)block, phys); |
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map_bh(bh_result, sb, phys); |
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return 0; |
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} |
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/* The file will be extended, so let's see if there is enough space. */ |
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if (phys >= info->si_blocks) |
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return -ENOSPC; |
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/* The rest has to be protected against itself. */ |
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mutex_lock(&info->bfs_lock); |
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/* |
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* If the last data block for this file is the last allocated |
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* block, we can extend the file trivially, without moving it |
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* anywhere. |
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*/ |
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if (bi->i_eblock == info->si_lf_eblk) { |
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dprintf("c=%d, b=%08lx, phys=%08lx (simple extension)\n", |
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create, (unsigned long)block, phys); |
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map_bh(bh_result, sb, phys); |
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info->si_freeb -= phys - bi->i_eblock; |
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info->si_lf_eblk = bi->i_eblock = phys; |
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mark_inode_dirty(inode); |
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err = 0; |
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goto out; |
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} |
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/* Ok, we have to move this entire file to the next free block. */ |
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phys = info->si_lf_eblk + 1; |
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if (phys + block >= info->si_blocks) { |
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err = -ENOSPC; |
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goto out; |
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} |
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if (bi->i_sblock) { |
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err = bfs_move_blocks(inode->i_sb, bi->i_sblock, |
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bi->i_eblock, phys); |
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if (err) { |
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dprintf("failed to move ino=%08lx -> fs corruption\n", |
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inode->i_ino); |
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goto out; |
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} |
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} else |
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err = 0; |
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dprintf("c=%d, b=%08lx, phys=%08lx (moved)\n", |
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create, (unsigned long)block, phys); |
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bi->i_sblock = phys; |
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phys += block; |
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info->si_lf_eblk = bi->i_eblock = phys; |
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/* |
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* This assumes nothing can write the inode back while we are here |
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* and thus update inode->i_blocks! (XXX) |
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*/ |
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info->si_freeb -= bi->i_eblock - bi->i_sblock + 1 - inode->i_blocks; |
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mark_inode_dirty(inode); |
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map_bh(bh_result, sb, phys); |
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out: |
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mutex_unlock(&info->bfs_lock); |
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return err; |
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} |
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static int bfs_writepage(struct page *page, struct writeback_control *wbc) |
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{ |
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return block_write_full_page(page, bfs_get_block, wbc); |
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} |
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static int bfs_readpage(struct file *file, struct page *page) |
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{ |
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return block_read_full_page(page, bfs_get_block); |
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} |
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static void bfs_write_failed(struct address_space *mapping, loff_t to) |
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{ |
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struct inode *inode = mapping->host; |
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if (to > inode->i_size) |
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truncate_pagecache(inode, inode->i_size); |
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} |
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static int bfs_write_begin(struct file *file, struct address_space *mapping, |
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loff_t pos, unsigned len, unsigned flags, |
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struct page **pagep, void **fsdata) |
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{ |
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int ret; |
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ret = block_write_begin(mapping, pos, len, flags, pagep, |
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bfs_get_block); |
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if (unlikely(ret)) |
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bfs_write_failed(mapping, pos + len); |
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return ret; |
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} |
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static sector_t bfs_bmap(struct address_space *mapping, sector_t block) |
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{ |
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return generic_block_bmap(mapping, block, bfs_get_block); |
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} |
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const struct address_space_operations bfs_aops = { |
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.set_page_dirty = __set_page_dirty_buffers, |
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.readpage = bfs_readpage, |
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.writepage = bfs_writepage, |
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.write_begin = bfs_write_begin, |
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.write_end = generic_write_end, |
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.bmap = bfs_bmap, |
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}; |
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const struct inode_operations bfs_file_inops;
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