From: Dave Chinner <david@fromorbit.com>
To: Brian Foster <bfoster@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH v2 02/12] libxfs: track largest metadata LSN in use via verifiers
Date: Wed, 23 Sep 2015 13:44:06 +1000 [thread overview]
Message-ID: <20150923034406.GR3902@dastard> (raw)
In-Reply-To: <1441997742-37160-3-git-send-email-bfoster@redhat.com>
On Fri, Sep 11, 2015 at 02:55:32PM -0400, Brian Foster wrote:
> The LSN validation helper is called in the I/O verifier codepath for
> metadata that embed a last-modification LSN. While the codepath exists,
> this is not used in userspace as in the kernel because the former
> doesn't have an active log.
>
> xfs_repair does need to check the validity of the LSN metadata with
> respect to the on-disk log, however. Use the LSN validation mechanism to
> track the largest LSN that has been seen. Export the value so repair can
> use it once it has processed the entire filesystem. Note that the helper
> continues to always return true to preserve existing behavior.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
....
> +xfs_lsn_t libxfs_max_lsn = 0;
> +pthread_mutex_t libxfs_max_lsn_lock = PTHREAD_MUTEX_INITIALIZER;
> +
> void
> xfs_detect_invalid_lsn(
> struct xfs_mount *mp,
> xfs_lsn_t lsn)
> {
> + int cycle = CYCLE_LSN(lsn);
> + int block = BLOCK_LSN(lsn);
> + int max_cycle;
> + int max_block;
> +
> + if (lsn == NULLCOMMITLSN)
> + return;
> +
> + pthread_mutex_lock(&libxfs_max_lsn_lock);
> +
> + max_cycle = CYCLE_LSN(libxfs_max_lsn);
> + max_block = BLOCK_LSN(libxfs_max_lsn);
> +
> + if ((cycle > max_cycle) ||
> + (cycle == max_cycle && block > max_block))
> + libxfs_max_lsn = lsn;
> +
> + pthread_mutex_unlock(&libxfs_max_lsn_lock);
This will have the same lock contention problems that the kernel
code would have had - my repair scalablity tests regularly reach
over 1GB/s of metadata being prefetched through tens of threads, so
this is going have a significant impact on performance in those
tests....
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2015-09-23 3:44 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-11 18:55 [PATCH v2 00/12] xfsprogs: format the log correctly on v5 supers Brian Foster
2015-09-11 18:55 ` [PATCH v2 01/12] libxfs: validate metadata LSNs against log on v5 superblocks Brian Foster
2015-09-11 18:55 ` [PATCH v2 02/12] libxfs: track largest metadata LSN in use via verifiers Brian Foster
2015-09-23 3:44 ` Dave Chinner [this message]
2015-09-23 13:18 ` Brian Foster
2015-09-23 22:36 ` Dave Chinner
2015-10-01 20:38 ` Brian Foster
2015-10-02 2:16 ` Dave Chinner
2015-10-02 11:33 ` Brian Foster
2015-09-11 18:55 ` [PATCH v2 03/12] libxfs: don't hardcode cycle 1 into unmount op header Brian Foster
2015-09-23 3:48 ` Dave Chinner
2015-09-23 13:22 ` Brian Foster
2015-09-24 0:37 ` Dave Chinner
2015-09-24 13:00 ` Brian Foster
2015-09-11 18:55 ` [PATCH v2 04/12] libxfs: pass lsn param to log clear and record header logging helpers Brian Foster
2015-09-11 18:55 ` [PATCH v2 05/12] libxfs: add ability to clear log to arbitrary log cycle Brian Foster
2015-09-11 18:55 ` [PATCH v2 06/12] libxlog: pull struct xlog out of xlog_is_dirty() Brian Foster
2015-09-11 18:55 ` [PATCH v2 07/12] xfs_repair: track log state throughout all recovery phases Brian Foster
2015-09-11 18:55 ` [PATCH v2 08/12] xfs_repair: process the log in no_modify mode Brian Foster
2015-09-11 18:55 ` [PATCH v2 09/12] xfs_repair: format the log with forward cycle number on v5 supers Brian Foster
2015-09-11 18:55 ` [PATCH v2 10/12] xfs_repair: don't clear the log by default Brian Foster
2015-09-11 18:55 ` [PATCH v2 11/12] xfs_db: do not reset current lsn from uuid command on v5 supers Brian Foster
2015-09-11 18:55 ` [PATCH v2 12/12] db/metadump: bump lsn when log is cleared " Brian Foster
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