xfs: convert log flags to an operational state field

log->l_flags doesn't actually contain "flags" as such, it contains
operational state information that can change at runtime. For the
shutdown state, this at least should be an atomic bit because
it is read without holding locks in many places and so using atomic
bitops for the state field modifications makes sense.

This allows us to use things like test_and_set_bit() on state
changes (e.g. setting XLOG_TAIL_WARN) to avoid races in setting the
state when we aren't holding locks.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 23 insertions, 35 deletions

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 8edfd35317d1..548e823dcd03 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -298,7 +298,7 @@ xlog_grant_head_check(
 	int			free_bytes;
 	int			error = 0;
 
-	ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+	ASSERT(!xlog_in_recovery(log));
 
 	/*
 	 * If there are other waiters on the queue then give them a chance at
@@ -580,6 +580,7 @@ xfs_log_mount(
 	xfs_daddr_t	blk_offset,
 	int		num_bblks)
 {
+	struct xlog	*log;
 	bool		fatal = xfs_sb_version_hascrc(&mp->m_sb);
 	int		error = 0;
 	int		min_logfsbs;
@@ -594,11 +595,12 @@ xfs_log_mount(
 		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
 	}
 
-	mp->m_log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
-	if (IS_ERR(mp->m_log)) {
-		error = PTR_ERR(mp->m_log);
+	log = xlog_alloc_log(mp, log_target, blk_offset, num_bblks);
+	if (IS_ERR(log)) {
+		error = PTR_ERR(log);
 		goto out;
 	}
+	mp->m_log = log;
 
 	/*
 	 * Validate the given log space and drop a critical message via syslog
@@ -663,7 +665,7 @@ xfs_log_mount(
 		xfs_warn(mp, "AIL initialisation failed: error %d", error);
 		goto out_free_log;
 	}
-	mp->m_log->l_ailp = mp->m_ail;
+	log->l_ailp = mp->m_ail;
 
 	/*
 	 * skip log recovery on a norecovery mount.  pretend it all
@@ -675,39 +677,39 @@ xfs_log_mount(
 		if (readonly)
 			mp->m_flags &= ~XFS_MOUNT_RDONLY;
 
-		error = xlog_recover(mp->m_log);
+		error = xlog_recover(log);
 
 		if (readonly)
 			mp->m_flags |= XFS_MOUNT_RDONLY;
 		if (error) {
 			xfs_warn(mp, "log mount/recovery failed: error %d",
 				error);
-			xlog_recover_cancel(mp->m_log);
+			xlog_recover_cancel(log);
 			goto out_destroy_ail;
 		}
 	}
 
-	error = xfs_sysfs_init(&mp->m_log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
+	error = xfs_sysfs_init(&log->l_kobj, &xfs_log_ktype, &mp->m_kobj,
 			       "log");
 	if (error)
 		goto out_destroy_ail;
 
 	/* Normal transactions can now occur */
-	mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
+	clear_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
 
 	/*
 	 * Now the log has been fully initialised and we know were our
 	 * space grant counters are, we can initialise the permanent ticket
 	 * needed for delayed logging to work.
 	 */
-	xlog_cil_init_post_recovery(mp->m_log);
+	xlog_cil_init_post_recovery(log);
 
 	return 0;
 
 out_destroy_ail:
 	xfs_trans_ail_destroy(mp);
 out_free_log:
-	xlog_dealloc_log(mp->m_log);
+	xlog_dealloc_log(log);
 out:
 	return error;
 }
@@ -759,7 +761,7 @@ xfs_log_mount_finish(
 	 * mount failure occurs.
 	 */
 	mp->m_super->s_flags |= SB_ACTIVE;
-	if (log->l_flags & XLOG_RECOVERY_NEEDED)
+	if (xlog_recovery_needed(log))
 		error = xlog_recover_finish(log);
 	if (!error)
 		xfs_log_work_queue(mp);
@@ -775,7 +777,7 @@ xfs_log_mount_finish(
 	 * Don't push in the error case because the AIL may have pending intents
 	 * that aren't removed until recovery is cancelled.
 	 */
-	if (log->l_flags & XLOG_RECOVERY_NEEDED) {
+	if (xlog_recovery_needed(log)) {
 		if (!error) {
 			xfs_log_force(mp, XFS_LOG_SYNC);
 			xfs_ail_push_all_sync(mp->m_ail);
@@ -787,7 +789,7 @@ xfs_log_mount_finish(
 	}
 	xfs_buftarg_drain(mp->m_ddev_targp);
 
-	log->l_flags &= ~XLOG_RECOVERY_NEEDED;
+	clear_bit(XLOG_RECOVERY_NEEDED, &log->l_opstate);
 	if (readonly)
 		mp->m_flags |= XFS_MOUNT_RDONLY;
 
@@ -1075,7 +1077,7 @@ xfs_log_space_wake(
 		return;
 
 	if (!list_empty_careful(&log->l_write_head.waiters)) {
-		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+		ASSERT(!xlog_in_recovery(log));
 
 		spin_lock(&log->l_write_head.lock);
 		free_bytes = xlog_space_left(log, &log->l_write_head.grant);
@@ -1084,7 +1086,7 @@ xfs_log_space_wake(
 	}
 
 	if (!list_empty_careful(&log->l_reserve_head.waiters)) {
-		ASSERT(!(log->l_flags & XLOG_ACTIVE_RECOVERY));
+		ASSERT(!xlog_in_recovery(log));
 
 		spin_lock(&log->l_reserve_head.lock);
 		free_bytes = xlog_space_left(log, &log->l_reserve_head.grant);
@@ -1466,7 +1468,7 @@ xlog_alloc_log(
 	log->l_logBBstart  = blk_offset;
 	log->l_logBBsize   = num_bblks;
 	log->l_covered_state = XLOG_STATE_COVER_IDLE;
-	log->l_flags	   |= XLOG_ACTIVE_RECOVERY;
+	set_bit(XLOG_ACTIVE_RECOVERY, &log->l_opstate);
 	INIT_DELAYED_WORK(&log->l_work, xfs_log_worker);
 
 	log->l_prev_block  = -1;
@@ -3648,17 +3650,15 @@ xlog_verify_grant_tail(
 	xlog_crack_atomic_lsn(&log->l_tail_lsn, &tail_cycle, &tail_blocks);
 	if (tail_cycle != cycle) {
 		if (cycle - 1 != tail_cycle &&
-		    !(log->l_flags & XLOG_TAIL_WARN)) {
+		    !test_and_set_bit(XLOG_TAIL_WARN, &log->l_opstate)) {
 			xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
 				"%s: cycle - 1 != tail_cycle", __func__);
-			log->l_flags |= XLOG_TAIL_WARN;
 		}
 
 		if (space > BBTOB(tail_blocks) &&
-		    !(log->l_flags & XLOG_TAIL_WARN)) {
+		    !test_and_set_bit(XLOG_TAIL_WARN, &log->l_opstate)) {
 			xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,
 				"%s: space > BBTOB(tail_blocks)", __func__);
-			log->l_flags |= XLOG_TAIL_WARN;
 		}
 	}
 }
@@ -3825,8 +3825,7 @@ xfs_log_force_umount(
 	 * If this happens during log recovery, don't worry about
 	 * locking; the log isn't open for business yet.
 	 */
-	if (!log ||
-	    log->l_flags & XLOG_ACTIVE_RECOVERY) {
+	if (!log || xlog_in_recovery(log)) {
 		mp->m_flags |= XFS_MOUNT_FS_SHUTDOWN;
 		if (mp->m_sb_bp)
 			mp->m_sb_bp->b_flags |= XBF_DONE;
@@ -3863,10 +3862,8 @@ xfs_log_force_umount(
 	 * Mark the log and the iclogs with IO error flags to prevent any
 	 * further log IO from being issued or completed.
 	 */
-	if (!(log->l_flags & XLOG_IO_ERROR)) {
-		log->l_flags |= XLOG_IO_ERROR;
+	if (!test_and_set_bit(XLOG_IO_ERROR, &log->l_opstate))
 		retval = 1;
-	}
 	spin_unlock(&log->l_icloglock);
 
 	/*
@@ -3954,15 +3951,6 @@ xfs_log_check_lsn(
 	return valid;
 }
 
-bool
-xfs_log_in_recovery(
-	struct xfs_mount	*mp)
-{
-	struct xlog		*log = mp->m_log;
-
-	return log->l_flags & XLOG_ACTIVE_RECOVERY;
-}
-
 /*
  * Notify the log that we're about to start using a feature that is protected
  * by a log incompat feature flag.  This will prevent log covering from