From: David Sterba <dsterba@suse.cz>
To: Nikolay Borisov <nborisov@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] btrfs: Remove unnecessary check from join_running_log_trans
Date: Thu, 1 Aug 2019 15:03:43 +0200 [thread overview]
Message-ID: <20190801130343.GS28208@twin.jikos.cz> (raw)
In-Reply-To: <20190523115126.10532-1-nborisov@suse.com>
On Thu, May 23, 2019 at 02:51:26PM +0300, Nikolay Borisov wrote:
> join_running_log_trans checks btrfs_root::log_root outside of
> btrfs_root::log_mutex to avoid contention on the mutex. Turns out this
> check is not necessary because the two callers of join_running_log_trans
> (both of which deal with removing entries from the tree-log during
> unlink) explicitly check whether the respective inode has been logged in
> the current transaction. If it hasn't then it won't have any items in
> the tree-log and call path will return before calling
> join_running_log_trans. If the check passes, however, then it's
> guaranteed that btrfs_root::log_root is set because the inode is logged.
>
> Those guarantees allows us to remove the speculative as well as the
> implicity and tricky memory barrier. No functionl changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
Added to misc-next, thanks.
prev parent reply other threads:[~2019-08-01 13:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-23 11:51 [PATCH] btrfs: Remove unnecessary check from join_running_log_trans Nikolay Borisov
2019-07-12 11:24 ` Filipe Manana
2019-08-01 13:03 ` David Sterba [this message]
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