From 77469c3f570e329acb631c5c03780eacdca2a534 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 29 Aug 2016 20:56:35 -0400 Subject: [PATCH] 9p: saner ->write_end() on failing copy into non-uptodate page If we had a short copy into an uptodate page, there's no reason whatsoever to zero anything; OTOH, if that page had _not_ been uptodate, we must have been trying to overwrite it completely and got a short copy. In that case, overwriting the end with zeroes, marking uptodate and sending to server is just plain wrong. Just unlock, keep it non-uptodate and return 0. Signed-off-by: Al Viro --- fs/9p/vfs_addr.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c index 6181ad79e1a5..ff8ece89fb99 100644 --- a/fs/9p/vfs_addr.c +++ b/fs/9p/vfs_addr.c @@ -309,18 +309,10 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping, p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); - if (unlikely(copied < len)) { - /* - * zero out the rest of the area - */ - unsigned from = pos & (PAGE_SIZE - 1); - - zero_user(page, from + copied, len - copied); - flush_dcache_page(page); + if (unlikely(copied < len && !PageUptodate(page))) { + copied = 0; + goto out; } - - if (!PageUptodate(page)) - SetPageUptodate(page); /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_mutex. @@ -330,6 +322,7 @@ static int v9fs_write_end(struct file *filp, struct address_space *mapping, i_size_write(inode, last_pos); } set_page_dirty(page); +out: unlock_page(page); put_page(page); -- 2.20.1