From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f195.google.com ([209.85.128.195]:50612 "EHLO mail-wr0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751377AbdKMGnO (ORCPT ); Mon, 13 Nov 2017 01:43:14 -0500 From: Amir Goldstein To: Miklos Szeredi , Al Viro Cc: Jeff Layton , "J . Bruce Fields" , James Bottomley , linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Hugh Dickins Subject: [PATCH v2] tmpfs: allow decoding a file handle of an unlinked file Date: Mon, 13 Nov 2017 08:43:58 +0200 Message-Id: <1510555438-28996-1-git-send-email-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: tmpfs uses the helper d_find_alias() to find a dentry from a decoded inode, but d_find_alias() skips unhashed dentries, so unlinked files cannot be decoded from a file handle. This can be reproduced using xfstests test program open_by_handle: $ open_by handle -c /tmp/testdir $ open_by_handle -dk /tmp/testdir open_by_handle(/tmp/testdir/file000000) returned 116 incorrectly on an unlinked open file! To fix this, if d_find_alias() can't find a hashed alias, call d_find_any_alias() to return an unhashed one. Cc: Hugh Dickins Cc: Al Viro Signed-off-by: Amir Goldstein --- Al, Miklos, Can either of you take this patch through your tree? Thanks, Amir. Changes since v1: - Prefer a hashed alias (James) - Use existing d_find_any_alias() helper mm/shmem.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/shmem.c b/mm/shmem.c index 07a1d22807be..5d3fa4099f54 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3404,6 +3404,15 @@ static int shmem_match(struct inode *ino, void *vfh) return ino->i_ino == inum && fh[0] == ino->i_generation; } +/* Find any alias of inode, but prefer a hashed alias */ +static struct dentry *shmem_find_alias(struct inode *inode) +{ + struct dentry *alias = d_find_alias(inode); + + return alias ?: d_find_any_alias(inode); +} + + static struct dentry *shmem_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len, int fh_type) { @@ -3420,7 +3429,7 @@ static struct dentry *shmem_fh_to_dentry(struct super_block *sb, inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), shmem_match, fid->raw); if (inode) { - dentry = d_find_alias(inode); + dentry = shmem_find_alias(inode); iput(inode); } -- 2.7.4