From 5e7f23373bf9a853e9256e81e86724cdd0a33c29 Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Mon, 13 Jun 2011 22:31:12 +0100 Subject: [PATCH] afs: afs_fill_page reads too much, or wrong data afs_fill_page should read the page that is about to be written but the current implementation has a number of issues. If we aren't extending the file we always read PAGE_CACHE_SIZE at offset 0. If we are extending the file we try to read the entire file. Change afs_fill_page to read PAGE_CACHE_SIZE at the right offset, clamped to i_size. While here, avoid calling afs_fill_page when we are doing a PAGE_CACHE_SIZE write. Signed-off-by: Anton Blanchard Signed-off-by: David Howells Signed-off-by: Al Viro --- fs/afs/write.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/fs/afs/write.c b/fs/afs/write.c index 789b3afb3423..b806285ff853 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -84,23 +84,21 @@ void afs_put_writeback(struct afs_writeback *wb) * partly or wholly fill a page that's under preparation for writing */ static int afs_fill_page(struct afs_vnode *vnode, struct key *key, - loff_t pos, unsigned len, struct page *page) + loff_t pos, struct page *page) { loff_t i_size; - unsigned eof; int ret; + int len; - _enter(",,%llu,%u", (unsigned long long)pos, len); - - ASSERTCMP(len, <=, PAGE_CACHE_SIZE); + _enter(",,%llu", (unsigned long long)pos); i_size = i_size_read(&vnode->vfs_inode); - if (pos + len > i_size) - eof = i_size; + if (pos + PAGE_CACHE_SIZE > i_size) + len = i_size - pos; else - eof = PAGE_CACHE_SIZE; + len = PAGE_CACHE_SIZE; - ret = afs_vnode_fetch_data(vnode, key, 0, eof, page); + ret = afs_vnode_fetch_data(vnode, key, pos, len, page); if (ret < 0) { if (ret == -ENOENT) { _debug("got NOENT from server" @@ -153,9 +151,8 @@ int afs_write_begin(struct file *file, struct address_space *mapping, *pagep = page; /* page won't leak in error case: it eventually gets cleaned off LRU */ - if (!PageUptodate(page)) { - _debug("not up to date"); - ret = afs_fill_page(vnode, key, pos, len, page); + if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) { + ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page); if (ret < 0) { kfree(candidate); _leave(" = %d [prep]", ret); -- 2.20.1