linux-kernel - [PATCH 4.4 07/20] fuse: fix READDIRPLUS skipping an entry

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Date:   Tue, 31 Oct 2017 10:55:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jakob Unterwurzacher <jakobunt@...il.com>,
        Marios Titas <redneb@....com>,
        Miklos Szeredi <mszeredi@...hat.com>
Subject: [PATCH 4.4 07/20] fuse: fix READDIRPLUS skipping an entry

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@...hat.com>

commit c6cdd51404b7ac12dd95173ddfc548c59ecf037f upstream.

Marios Titas running a Haskell program noticed a problem with fuse's
readdirplus: when it is interrupted by a signal, it skips one directory
entry.

The reason is that fuse erronously updates ctx->pos after a failed
dir_emit().

The issue originates from the patch adding readdirplus support.

Reported-by: Jakob Unterwurzacher <jakobunt@...il.com>
Tested-by: Marios Titas <redneb@....com>
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Fixes: 0b05b18381ee ("fuse: implement NFS-like readdirplus support")
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/fuse/dir.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1295,7 +1295,8 @@ static int parse_dirplusfile(char *buf,
 			*/
 			over = !dir_emit(ctx, dirent->name, dirent->namelen,
 				       dirent->ino, dirent->type);
-			ctx->pos = dirent->off;
+			if (!over)
+				ctx->pos = dirent->off;
 		}
 
 		buf += reclen;