From 59c3b76cc61d1d676f965c192cc7969aa5cb2744 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 18 Aug 2016 09:10:44 +0200 Subject: [PATCH] fuse: fix fuse_write_end() if zero bytes were copied 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 Fixes: 6b12c1b37e55 ("fuse: Implement write_begin/write_end callbacks") Cc: # v3.15+ Signed-off-by: Miklos Szeredi --- fs/fuse/file.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index abc66a6237fd..2401c5dabb2a 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1985,6 +1985,10 @@ static int fuse_write_end(struct file *file, struct address_space *mapping, { 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 *file, struct address_space *mapping, fuse_write_update_size(inode, pos + copied); set_page_dirty(page); + +unlock: unlock_page(page); put_page(page); -- 2.30.2