Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752638Ab0HBREB (ORCPT ); Mon, 2 Aug 2010 13:04:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36973 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751646Ab0HBRD7 (ORCPT ); Mon, 2 Aug 2010 13:03:59 -0400 Message-ID: <4C56FA35.7060607@redhat.com> Date: Mon, 02 Aug 2010 12:02:45 -0500 From: Eric Sandeen User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100301 Fedora/3.0.3-1.fc11 Lightning/1.0b2pre Thunderbird/3.0.3 MIME-Version: 1.0 To: Stefan Bader CC: Greg KH , linux-kernel@vger.kernel.org, stable@kernel.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, stable-review@kernel.org, alan@lxorguk.ukuu.org.uk Subject: Re: [Stable-review] [116/165] ext4: dont return to userspace after freezing the fs with a mutex held References: <20100730171510.105264205@clark.site> <4C56B45E.9010601@canonical.com> In-Reply-To: <4C56B45E.9010601@canonical.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5360 Lines: 159 On 08/02/2010 07:04 AM, Stefan Bader wrote: > We have reports about this patch breaking lvm snapshhots. Eric, there is a patch > mentioned which is supposed to fix things but its not upstream, yet. > Do you know what happened to that? right, patch below is needed to fix things. Ted just acked it on the list recently; Greg, I'd either drop 116/165 for now, or include the patch below which should be upstream soon... -Eric > -Stefan > > PATCH] ext4: fix freeze deadlock under IO > > Commit 6b0310fbf087ad6 caused a regression resulting in deadlocks > when freezing a filesystem which had active IO; the vfs_check_frozen > level (SB_FREEZE_WRITE) did not let the freeze-related IO syncing > through. Duh. > > Changing the test to FREEZE_TRANS should let the normal freeze > syncing get through the fs, but still block any transactions from > starting once the fs is completely frozen. > > I tested this by running fsstress in the background while periodically > snapshotting the fs and running fsck on the result. I ran into > occasional deadlocks, but different ones. I think this is a > fine fix for the problem at hand, and the other deadlocky things > will need more investigation. > > Reported-by: Phillip Susi > Signed-off-by: Eric Sandeen > --- > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 4e8983a..a45ced9 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -241,7 +241,7 @@ handle_t *ext4_journal_start_sb(struct super_block *sb, int > nblocks) > if (sb->s_flags & MS_RDONLY) > return ERR_PTR(-EROFS); > > - vfs_check_frozen(sb, SB_FREEZE_WRITE); > + vfs_check_frozen(sb, SB_FREEZE_TRANS); > /* Special case here: if the journal has aborted behind our > * backs (eg. EIO in the commit thread), then we still need to > * take the FS itself readonly cleanly. */ > @@ -3491,7 +3491,7 @@ int ext4_force_commit(struct super_block *sb) > > journal = EXT4_SB(sb)->s_journal; > if (journal) { > - vfs_check_frozen(sb, SB_FREEZE_WRITE); > + vfs_check_frozen(sb, SB_FREEZE_TRANS); > ret = ext4_journal_force_commit(journal); > } > > > > On 07/30/2010 07:15 PM, Greg KH wrote: >> 2.6.32-stable review patch. If anyone has any objections, please let us know. >> >> ------------------ >> >> commit 6b0310fbf087ad6e9e3b8392adca97cd77184084 upstream (as of v2.6.34-git13) >> >> ext4_freeze() used jbd2_journal_lock_updates() which takes >> the j_barrier mutex, and then returns to userspace. The >> kernel does not like this: >> >> ================================================ >> [ BUG: lock held when returning to user space! ] >> ------------------------------------------------ >> lvcreate/1075 is leaving the kernel with locks still held! >> 1 lock held by lvcreate/1075: >> #0: (&journal->j_barrier){+.+...}, at: [] >> jbd2_journal_lock_updates+0xe1/0xf0 >> >> Use vfs_check_frozen() added to ext4_journal_start_sb() and >> ext4_force_commit() instead. >> >> Addresses-Red-Hat-Bugzilla: #568503 >> >> Signed-off-by: Eric Sandeen >> Signed-off-by: "Theodore Ts'o" >> Signed-off-by: Greg Kroah-Hartman >> --- >> fs/ext4/super.c | 20 ++++++++++---------- >> 1 file changed, 10 insertions(+), 10 deletions(-) >> >> --- a/fs/ext4/super.c >> +++ b/fs/ext4/super.c >> @@ -227,6 +227,7 @@ handle_t *ext4_journal_start_sb(struct s >> if (sb->s_flags & MS_RDONLY) >> return ERR_PTR(-EROFS); >> >> + vfs_check_frozen(sb, SB_FREEZE_WRITE); >> /* Special case here: if the journal has aborted behind our >> * backs (eg. EIO in the commit thread), then we still need to >> * take the FS itself readonly cleanly. */ >> @@ -3391,8 +3392,10 @@ int ext4_force_commit(struct super_block >> return 0; >> >> journal = EXT4_SB(sb)->s_journal; >> - if (journal) >> + if (journal) { >> + vfs_check_frozen(sb, SB_FREEZE_WRITE); >> ret = ext4_journal_force_commit(journal); >> + } >> >> return ret; >> } >> @@ -3441,18 +3444,16 @@ static int ext4_freeze(struct super_bloc >> * the journal. >> */ >> error = jbd2_journal_flush(journal); >> - if (error < 0) { >> - out: >> - jbd2_journal_unlock_updates(journal); >> - return error; >> - } >> + if (error < 0) >> + goto out; >> >> /* Journal blocked and flushed, clear needs_recovery flag. */ >> EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); >> error = ext4_commit_super(sb, 1); >> - if (error) >> - goto out; >> - return 0; >> +out: >> + /* we rely on s_frozen to stop further updates */ >> + jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); >> + return error; >> } >> >> /* >> @@ -3469,7 +3470,6 @@ static int ext4_unfreeze(struct super_bl >> EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); >> ext4_commit_super(sb, 1); >> unlock_super(sb); >> - jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); >> return 0; >> } >> >> >> >> _______________________________________________ >> Stable-review mailing list >> Stable-review@linux.kernel.org >> http://linux.kernel.org/mailman/listinfo/stable-review > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/