linux-kernel - [PATCH 3.16 140/204] fuse: fix READDIRPLUS skipping an entry

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Message-ID: <lsq.1514480744.703265510@decadent.org.uk>
Date:   Thu, 28 Dec 2017 17:05:44 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Marios Titas" <redneb@....com>,
        "Jakob Unterwurzacher" <jakobunt@...il.com>,
        "Miklos Szeredi" <mszeredi@...hat.com>
Subject: [PATCH 3.16 140/204] fuse: fix READDIRPLUS skipping an entry

3.16.52-rc1 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: Ben Hutchings <ben@...adent.org.uk>
---
 fs/fuse/dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1382,7 +1382,8 @@ 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;