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340 lines
7.8 KiB
340 lines
7.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* linux/fs/9p/vfs_addr.c |
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* |
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* This file contians vfs address (mmap) ops for 9P2000. |
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* |
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* Copyright (C) 2005 by Eric Van Hensbergen <[email protected]> |
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* Copyright (C) 2002 by Ron Minnich <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/errno.h> |
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#include <linux/fs.h> |
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#include <linux/file.h> |
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#include <linux/stat.h> |
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#include <linux/string.h> |
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#include <linux/inet.h> |
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#include <linux/pagemap.h> |
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#include <linux/idr.h> |
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#include <linux/sched.h> |
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#include <linux/uio.h> |
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#include <linux/bvec.h> |
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#include <net/9p/9p.h> |
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#include <net/9p/client.h> |
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#include "v9fs.h" |
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#include "v9fs_vfs.h" |
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#include "cache.h" |
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#include "fid.h" |
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/** |
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* v9fs_fid_readpage - read an entire page in from 9P |
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* @data: Opaque pointer to the fid being read |
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* @page: structure to page |
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* |
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*/ |
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static int v9fs_fid_readpage(void *data, struct page *page) |
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{ |
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struct p9_fid *fid = data; |
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struct inode *inode = page->mapping->host; |
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struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; |
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struct iov_iter to; |
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int retval, err; |
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p9_debug(P9_DEBUG_VFS, "\n"); |
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BUG_ON(!PageLocked(page)); |
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retval = v9fs_readpage_from_fscache(inode, page); |
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if (retval == 0) |
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return retval; |
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iov_iter_bvec(&to, READ, &bvec, 1, PAGE_SIZE); |
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retval = p9_client_read(fid, page_offset(page), &to, &err); |
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if (err) { |
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v9fs_uncache_page(inode, page); |
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retval = err; |
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goto done; |
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} |
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zero_user(page, retval, PAGE_SIZE - retval); |
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flush_dcache_page(page); |
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SetPageUptodate(page); |
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v9fs_readpage_to_fscache(inode, page); |
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retval = 0; |
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done: |
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unlock_page(page); |
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return retval; |
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} |
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/** |
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* v9fs_vfs_readpage - read an entire page in from 9P |
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* |
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* @filp: file being read |
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* @page: structure to page |
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* |
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*/ |
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static int v9fs_vfs_readpage(struct file *filp, struct page *page) |
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{ |
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return v9fs_fid_readpage(filp->private_data, page); |
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} |
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/** |
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* v9fs_vfs_readpages - read a set of pages from 9P |
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* |
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* @filp: file being read |
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* @mapping: the address space |
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* @pages: list of pages to read |
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* @nr_pages: count of pages to read |
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* |
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*/ |
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static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, |
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struct list_head *pages, unsigned nr_pages) |
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{ |
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int ret = 0; |
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struct inode *inode; |
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inode = mapping->host; |
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p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); |
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ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); |
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if (ret == 0) |
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return ret; |
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ret = read_cache_pages(mapping, pages, v9fs_fid_readpage, |
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filp->private_data); |
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p9_debug(P9_DEBUG_VFS, " = %d\n", ret); |
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return ret; |
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} |
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/** |
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* v9fs_release_page - release the private state associated with a page |
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* @page: The page to be released |
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* @gfp: The caller's allocation restrictions |
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* |
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* Returns 1 if the page can be released, false otherwise. |
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*/ |
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static int v9fs_release_page(struct page *page, gfp_t gfp) |
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{ |
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if (PagePrivate(page)) |
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return 0; |
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return v9fs_fscache_release_page(page, gfp); |
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} |
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/** |
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* v9fs_invalidate_page - Invalidate a page completely or partially |
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* @page: The page to be invalidated |
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* @offset: offset of the invalidated region |
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* @length: length of the invalidated region |
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*/ |
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static void v9fs_invalidate_page(struct page *page, unsigned int offset, |
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unsigned int length) |
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{ |
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/* |
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* If called with zero offset, we should release |
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* the private state assocated with the page |
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*/ |
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if (offset == 0 && length == PAGE_SIZE) |
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v9fs_fscache_invalidate_page(page); |
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} |
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static int v9fs_vfs_writepage_locked(struct page *page) |
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{ |
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struct inode *inode = page->mapping->host; |
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struct v9fs_inode *v9inode = V9FS_I(inode); |
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loff_t size = i_size_read(inode); |
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struct iov_iter from; |
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struct bio_vec bvec; |
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int err, len; |
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if (page->index == size >> PAGE_SHIFT) |
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len = size & ~PAGE_MASK; |
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else |
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len = PAGE_SIZE; |
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bvec.bv_page = page; |
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bvec.bv_offset = 0; |
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bvec.bv_len = len; |
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iov_iter_bvec(&from, WRITE, &bvec, 1, len); |
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/* We should have writeback_fid always set */ |
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BUG_ON(!v9inode->writeback_fid); |
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set_page_writeback(page); |
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p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); |
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end_page_writeback(page); |
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return err; |
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} |
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static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) |
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{ |
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int retval; |
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p9_debug(P9_DEBUG_VFS, "page %p\n", page); |
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retval = v9fs_vfs_writepage_locked(page); |
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if (retval < 0) { |
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if (retval == -EAGAIN) { |
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redirty_page_for_writepage(wbc, page); |
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retval = 0; |
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} else { |
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SetPageError(page); |
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mapping_set_error(page->mapping, retval); |
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} |
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} else |
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retval = 0; |
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unlock_page(page); |
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return retval; |
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} |
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/** |
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* v9fs_launder_page - Writeback a dirty page |
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* @page: The page to be cleaned up |
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* |
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* Returns 0 on success. |
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*/ |
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static int v9fs_launder_page(struct page *page) |
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{ |
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int retval; |
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struct inode *inode = page->mapping->host; |
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v9fs_fscache_wait_on_page_write(inode, page); |
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if (clear_page_dirty_for_io(page)) { |
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retval = v9fs_vfs_writepage_locked(page); |
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if (retval) |
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return retval; |
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} |
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return 0; |
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} |
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/** |
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* v9fs_direct_IO - 9P address space operation for direct I/O |
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* @iocb: target I/O control block |
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* @iter: The data/buffer to use |
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* |
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* The presence of v9fs_direct_IO() in the address space ops vector |
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* allowes open() O_DIRECT flags which would have failed otherwise. |
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* |
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* In the non-cached mode, we shunt off direct read and write requests before |
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* the VFS gets them, so this method should never be called. |
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* |
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* Direct IO is not 'yet' supported in the cached mode. Hence when |
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* this routine is called through generic_file_aio_read(), the read/write fails |
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* with an error. |
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* |
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*/ |
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static ssize_t |
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v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) |
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{ |
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struct file *file = iocb->ki_filp; |
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loff_t pos = iocb->ki_pos; |
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ssize_t n; |
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int err = 0; |
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if (iov_iter_rw(iter) == WRITE) { |
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n = p9_client_write(file->private_data, pos, iter, &err); |
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if (n) { |
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struct inode *inode = file_inode(file); |
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loff_t i_size = i_size_read(inode); |
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if (pos + n > i_size) |
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inode_add_bytes(inode, pos + n - i_size); |
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} |
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} else { |
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n = p9_client_read(file->private_data, pos, iter, &err); |
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} |
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return n ? n : err; |
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} |
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static int v9fs_write_begin(struct file *filp, 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 retval = 0; |
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struct page *page; |
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struct v9fs_inode *v9inode; |
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pgoff_t index = pos >> PAGE_SHIFT; |
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struct inode *inode = mapping->host; |
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p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); |
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v9inode = V9FS_I(inode); |
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start: |
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page = grab_cache_page_write_begin(mapping, index, flags); |
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if (!page) { |
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retval = -ENOMEM; |
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goto out; |
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} |
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BUG_ON(!v9inode->writeback_fid); |
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if (PageUptodate(page)) |
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goto out; |
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if (len == PAGE_SIZE) |
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goto out; |
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retval = v9fs_fid_readpage(v9inode->writeback_fid, page); |
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put_page(page); |
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if (!retval) |
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goto start; |
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out: |
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*pagep = page; |
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return retval; |
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} |
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static int v9fs_write_end(struct file *filp, struct address_space *mapping, |
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loff_t pos, unsigned len, unsigned copied, |
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struct page *page, void *fsdata) |
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{ |
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loff_t last_pos = pos + copied; |
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struct inode *inode = page->mapping->host; |
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p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); |
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if (!PageUptodate(page)) { |
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if (unlikely(copied < len)) { |
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copied = 0; |
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goto out; |
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} else if (len == PAGE_SIZE) { |
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SetPageUptodate(page); |
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} |
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} |
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/* |
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* No need to use i_size_read() here, the i_size |
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* cannot change under us because we hold the i_mutex. |
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*/ |
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if (last_pos > inode->i_size) { |
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inode_add_bytes(inode, last_pos - inode->i_size); |
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i_size_write(inode, last_pos); |
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} |
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set_page_dirty(page); |
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out: |
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unlock_page(page); |
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put_page(page); |
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return copied; |
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} |
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const struct address_space_operations v9fs_addr_operations = { |
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.readpage = v9fs_vfs_readpage, |
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.readpages = v9fs_vfs_readpages, |
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.set_page_dirty = __set_page_dirty_nobuffers, |
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.writepage = v9fs_vfs_writepage, |
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.write_begin = v9fs_write_begin, |
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.write_end = v9fs_write_end, |
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.releasepage = v9fs_release_page, |
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.invalidatepage = v9fs_invalidate_page, |
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.launder_page = v9fs_launder_page, |
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.direct_IO = v9fs_direct_IO, |
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};
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