| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.8 09/67] fuse: fix fuse_write_end() if zero bytes were copied | Date | Thu, 24 Nov 2016 16:27:03 +0100 |
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4.8-stable review patch. If anyone has any objections, please let me know.
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From: Miklos Szeredi <mszeredi@redhat.com>
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@zeniv.linux.org.uk> Fixes: 6b12c1b37e55 ("fuse: Implement write_begin/write_end callbacks") Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/fuse/file.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1985,6 +1985,10 @@ 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_MASK; @@ -1995,6 +1999,8 @@ static int fuse_write_end(struct file *f fuse_write_update_size(inode, pos + copied); set_page_dirty(page); + +unlock: unlock_page(page); put_page(page);
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