From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yb0-f198.google.com (mail-yb0-f198.google.com [209.85.213.198]) by kanga.kvack.org (Postfix) with ESMTP id C89756B04E7 for ; Fri, 5 Jan 2018 10:40:54 -0500 (EST) Received: by mail-yb0-f198.google.com with SMTP id b93so2100782ybi.13 for ; Fri, 05 Jan 2018 07:40:54 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id q65sor1730322ywh.32.2018.01.05.07.40.53 for (Google Transport Security); Fri, 05 Jan 2018 07:40:53 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1510555438-28996-1-git-send-email-amir73il@gmail.com> References: <1510555438-28996-1-git-send-email-amir73il@gmail.com> From: Amir Goldstein Date: Fri, 5 Jan 2018 17:40:53 +0200 Message-ID: Subject: Re: [PATCH v2] tmpfs: allow decoding a file handle of an unlinked file Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Hugh Dickins Cc: Jeff Layton , "J . Bruce Fields" , James Bottomley , overlayfs , linux-fsdevel , Al Viro , Miklos Szeredi , linux-mm@kvack.org On Mon, Nov 13, 2017 at 8:43 AM, Amir Goldstein wrote: > 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); > } > > -- Hugh, Did you get a chance to look at this patch? The test for decoding a file handle of an unlinked file has already been merged to xfstest generic/467 and the test is failing on tmpfs without this change. Can you please take or ACK this patch? Thanks, Amir. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org