From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f199.google.com (mail-yw0-f199.google.com [209.85.161.199]) by kanga.kvack.org (Postfix) with ESMTP id 09CEF6B0005 for ; Sat, 27 Jan 2018 17:02:56 -0500 (EST) Received: by mail-yw0-f199.google.com with SMTP id y197so2953950ywg.15 for ; Sat, 27 Jan 2018 14:02:56 -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 g9sor6828931ybi.21.2018.01.27.14.02.54 for (Google Transport Security); Sat, 27 Jan 2018 14:02:54 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1510555438-28996-1-git-send-email-amir73il@gmail.com> From: Amir Goldstein Date: Sun, 28 Jan 2018 00:02:53 +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 , Al Viro Cc: Jeff Layton , "J . Bruce Fields" , James Bottomley , overlayfs , linux-fsdevel , Miklos Szeredi , Linux MM On Fri, Jan 5, 2018 at 5:40 PM, Amir Goldstein wrote: > 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? > Ping. Real problem. Trivial fix. Al, Can you take 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