From: David Sterba <dsterba@suse.cz>
To: Josef Bacik <josef@toxicpanda.com>
Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 4/8] btrfs: remove the recursion handling code in locking.c
Date: Wed, 11 Nov 2020 15:59:01 +0100 [thread overview]
Message-ID: <20201111145901.GR6756@twin.jikos.cz> (raw)
In-Reply-To: <007a92c9-7af3-9aec-ba65-fc9ff3cda132@toxicpanda.com>
On Wed, Nov 11, 2020 at 09:43:50AM -0500, Josef Bacik wrote:
> > 185
> > 186 /*
> > 187 * Helper to output refs and locking status of extent buffer. Useful to debug
> > 188 * race condition related problems.
> > 189 */
> > 190 static void print_eb_refs_lock(struct extent_buffer *eb)
> > 191 {
> > 192 #ifdef CONFIG_BTRFS_DEBUG
> > 193 btrfs_info(eb->fs_info, "refs %u lock_owner %u current %u",
> > 194 atomic_read(&eb->refs), eb->lock_owner, current->pid);
> > 195 #endif
> > 196 }
> >
> > The safety check added in b72c3aba09a53fc7c18 ("btrfs: locking: Add
> > extra check in btrfs_init_new_buffer() to avoid deadlock") and it seems
> > to be useful but I think it builds on the assumptions of the previous
> > tree locks. The mentioned warning uses the recursive locking which is
> > being removed.
>
> Sorry I should have explained why I was leaving this in my cover letter. The
> safety check is for the case that the free space cache is corrupted and we try
> to allocate a block that we are currently using and have locked in the path. I
> would have preferred to move it under CONFIG_BTRFS_DEBUG, but it does actually
> help in the case of a bad free space cache, so I think we have to keep it. Thanks,
Yeah that's a valid reason to keep it, I'll update the changelog.
next prev parent reply other threads:[~2020-11-11 15:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 21:27 [PATCH 0/8] Locking cleanups and lockdep fix Josef Bacik
2020-11-06 21:27 ` [PATCH 1/8] btrfs: cleanup the locking in btrfs_next_old_leaf Josef Bacik
2020-11-09 10:06 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 2/8] btrfs: unlock to current level " Josef Bacik
2020-11-09 10:12 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 3/8] btrfs: kill path->recurse Josef Bacik
2020-11-09 10:19 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 4/8] btrfs: remove the recursion handling code in locking.c Josef Bacik
2020-11-09 10:20 ` Filipe Manana
2020-11-11 14:14 ` David Sterba
2020-11-11 14:29 ` David Sterba
2020-11-11 14:43 ` Josef Bacik
2020-11-11 14:59 ` David Sterba [this message]
2020-11-06 21:27 ` [PATCH 5/8] btrfs: remove __btrfs_read_lock_root_node Josef Bacik
2020-11-09 10:20 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 6/8] btrfs: use btrfs_tree_read_lock in btrfs_search_slot Josef Bacik
2020-11-09 10:21 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 7/8] btrfs: remove the recurse parameter from __btrfs_tree_read_lock Josef Bacik
2020-11-09 10:22 ` Filipe Manana
2020-11-06 21:27 ` [PATCH 8/8] btrfs: remove ->recursed from extent_buffer Josef Bacik
2020-11-09 10:23 ` Filipe Manana
2020-11-12 18:18 ` [PATCH 0/8] Locking cleanups and lockdep fix David Sterba
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