From 04fff6416cb7876091f0b2f413caf43e3618d5ad Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 29 Aug 2016 22:39:56 -0400 Subject: [PATCH] simple_write_end(): don't zero in short copy into uptodate Signed-off-by: Al Viro --- fs/libfs.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 48826d4da189..76048705d922 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -465,6 +465,8 @@ EXPORT_SYMBOL(simple_write_begin); * is not called, so a filesystem that actually does store data in .write_inode * should extend on what's done here with a call to mark_inode_dirty() in the * case that i_size has changed. + * + * Use *ONLY* with simple_readpage() */ int simple_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, @@ -474,14 +476,14 @@ int simple_write_end(struct file *file, struct address_space *mapping, loff_t last_pos = pos + copied; /* zero the stale part of the page if we did a short copy */ - if (copied < len) { - unsigned from = pos & (PAGE_SIZE - 1); - - zero_user(page, from + copied, len - copied); - } + if (!PageUptodate(page)) { + if (copied < len) { + unsigned from = pos & (PAGE_SIZE - 1); - if (!PageUptodate(page)) + zero_user(page, from + copied, len - copied); + } SetPageUptodate(page); + } /* * No need to use i_size_read() here, the i_size * cannot change under us because we hold the i_mutex. -- 2.20.1