Re: [PATCH 09/11] xfs: merge unmount record write iclog cleanup.

Brian Foster
2020-03-05T18:08:15Z

On Wed, Mar 04, 2020 at 06:53:59PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> The unmount iclog handling is duplicated in both
> xfs_log_unmount_write() and xfs_log_write_unmount_record(). We only
> need one copy of it in xfs_log_unmount_write() because that is the
> only function that calls xfs_log_write_unmount_record().
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---

Any reason for the period at the end of the patch subject? I just
noticed it now, but the previous patch has one as well.

> fs/xfs/xfs_log.c | 130 +++++++++++++++++------------------------------
> 1 file changed, 48 insertions(+), 82 deletions(-)
>
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index bdf604d31d8c..a687c20dd77d 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
...
> @@ -931,61 +926,41 @@ xlog_unmount_write(
> }
>
> error = xlog_write_unmount_record(log, tic, &lsn, flags);
> - /*
> - * At this point, we're umounting anyway, so there's no point in
> - * transitioning log state to IOERROR. Just continue...
> - */
> -out_err:
> - if (error)
> - xfs_alert(mp, "%s: unmount record failed", __func__);
> -
> - spin_lock(&log->l_icloglock);
> - iclog = log->l_iclog;
> - atomic_inc(&iclog->ic_refcnt);
> - xlog_state_want_sync(log, iclog);
> - error = xlog_state_release_iclog(log, iclog);
> - switch (iclog->ic_state) {
> - default:
> - if (!XLOG_FORCED_SHUTDOWN(log)) {
> - xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
> - break;
> - }
> - /* fall through */
> - case XLOG_STATE_ACTIVE:
> - case XLOG_STATE_DIRTY:
> + if (error) {
> + /* A full shutdown is unnecessary at this point of unmount */
> + spin_lock(&log->l_icloglock);
> + log->l_flags |= XLOG_IO_ERROR;

A previous patch added this to xlog_state_ioerror(). Nits aside, the
rest looks fine to me:

Reviewed-by: Brian Foster <bfoster@redhat.com>

> + xlog_state_ioerror(log);
> spin_unlock(&log->l_icloglock);
> - break;
> }
>
> - if (tic) {
> - trace_xfs_log_umount_write(log, tic);
> - xlog_ungrant_log_space(log, tic);
> - xfs_log_ticket_put(tic);
> - }
> + trace_xfs_log_umount_write(log, tic);
> + xlog_ungrant_log_space(log, tic);
> + xfs_log_ticket_put(tic);
> +out_err:
> + if (error)
> + xfs_alert(mp, "%s: unmount record failed", __func__);
> + return error;
> }
>
> /*
> - * Unmount record used to have a string "Unmount filesystem--" in the
> - * data section where the "Un" was really a magic number (XLOG_UNMOUNT_TYPE).
> - * We just write the magic number now since that particular field isn't
> - * currently architecture converted and "Unmount" is a bit foo.
> - * As far as I know, there weren't any dependencies on the old behaviour.
> + * Finalise the unmount by writing the unmount record to the log. This is the
> + * mark that the filesystem was cleanly unmounted.
> + *
> + * Avoid writing the unmount record on no-recovery mounts, ro-devices, or when
> + * the log has already been shut down.
> */
> -
> static int
> -xfs_log_unmount_write(xfs_mount_t *mp)
> +xfs_log_unmount_write(
> + struct xfs_mount *mp)
> {
> - struct xlog *log = mp->m_log;
> - xlog_in_core_t *iclog;
> + struct xlog *log = mp->m_log;
> + struct xlog_in_core *iclog;
> #ifdef DEBUG
> - xlog_in_core_t *first_iclog;
> + struct xlog_in_core *first_iclog;
> #endif
> - int error;
> + int error;
>
> - /*
> - * Don't write out unmount record on norecovery mounts or ro devices.
> - * Or, if we are doing a forced umount (typically because of IO errors).
> - */
> if (mp->m_flags & XFS_MOUNT_NORECOVERY ||
> xfs_readonly_buftarg(log->l_targ)) {
> ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
> @@ -1005,41 +980,32 @@ xfs_log_unmount_write(xfs_mount_t *mp)
> iclog = iclog->ic_next;
> } while (iclog != first_iclog);
> #endif
> - if (! (XLOG_FORCED_SHUTDOWN(log))) {
> - xlog_unmount_write(log);
> - } else {
> - /*
> - * We're already in forced_shutdown mode, couldn't
> - * even attempt to write out the unmount transaction.
> - *
> - * Go through the motions of sync'ing and releasing
> - * the iclog, even though no I/O will actually happen,
> - * we need to wait for other log I/Os that may already
> - * be in progress. Do this as a separate section of
> - * code so we'll know if we ever get stuck here that
> - * we're in this odd situation of trying to unmount
> - * a file system that went into forced_shutdown as
> - * the result of an unmount..
> - */
> - spin_lock(&log->l_icloglock);
> - iclog = log->l_iclog;
> - atomic_inc(&iclog->ic_refcnt);
> - xlog_state_want_sync(log, iclog);
> - error = xlog_state_release_iclog(log, iclog);
> - switch (iclog->ic_state) {
> - case XLOG_STATE_ACTIVE:
> - case XLOG_STATE_DIRTY:
> - case XLOG_STATE_IOERROR:
> - spin_unlock(&log->l_icloglock);
> - break;
> - default:
> - xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
> - break;
> - }
> - }
>
> + if (!XLOG_FORCED_SHUTDOWN(log))
> + error = xlog_unmount_write(log);
> +
> + /*
> + * Sync and release the current iclog so the unmount record gets to
> + * disk. If we are in a shutdown state, no IO will be done, but we still
> + * we need to wait for other log I/Os that may already be in progress.
> + */
> + spin_lock(&log->l_icloglock);
> + iclog = log->l_iclog;
> + atomic_inc(&iclog->ic_refcnt);
> + xlog_state_want_sync(log, iclog);
> + error = xlog_state_release_iclog(log, iclog);
> + switch (iclog->ic_state) {
> + case XLOG_STATE_ACTIVE:
> + case XLOG_STATE_DIRTY:
> + case XLOG_STATE_IOERROR:
> + spin_unlock(&log->l_icloglock);
> + break;
> + default:
> + xlog_wait(&iclog->ic_force_wait, &log->l_icloglock);
> + break;
> + }
> return error;
> -} /* xfs_log_unmount_write */
> +}
>
> /*
> * Empty the log for unmount/freeze.
> --
> 2.24.0.rc0
>