This is a note to let you know that I've just added the patch titled
fuse: fix fuse_write_end() if zero bytes were copied
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fuse-fix-fuse_write_end-if-zero-bytes-were-copied.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 59c3b76cc61d1d676f965c192cc7969aa5cb2744 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Thu, 18 Aug 2016 09:10:44 +0200
Subject: fuse: fix fuse_write_end() if zero bytes were copied
From: Miklos Szeredi <mszeredi@xxxxxxxxxx>
commit 59c3b76cc61d1d676f965c192cc7969aa5cb2744 upstream.
If pos is at the beginning of a page and copied is zero then page is not
zeroed but is marked uptodate.
Fix by skipping everything except unlock/put of page if zero bytes were
copied.
Reported-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Fixes: 6b12c1b37e55 ("fuse: Implement write_begin/write_end callbacks")
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/fuse/file.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1997,6 +1997,10 @@ static int fuse_write_end(struct file *f
{
struct inode *inode = page->mapping->host;
+ /* Haven't copied anything? Skip zeroing, size extending, dirtying. */
+ if (!copied)
+ goto unlock;
+
if (!PageUptodate(page)) {
/* Zero any unwritten bytes at the end of the page */
size_t endoff = (pos + copied) & ~PAGE_CACHE_MASK;
@@ -2007,6 +2011,8 @@ static int fuse_write_end(struct file *f
fuse_write_update_size(inode, pos + copied);
set_page_dirty(page);
+
+unlock:
unlock_page(page);
page_cache_release(page);
Patches currently in stable-queue which might be from mszeredi@xxxxxxxxxx are
queue-4.4/fuse-fix-fuse_write_end-if-zero-bytes-were-copied.patch
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