xfs: allow assigning the tail lsn with the AIL lock held
Provide a variant of xlog_assign_tail_lsn that has the AIL lock already
held. By doing so we do an additional atomic_read + atomic_set under
the lock, which comes down to two instructions.
Switch xfs_trans_ail_update_bulk and xfs_trans_ail_delete_bulk to the
new version to reduce the number of lock roundtrips, and prepare for
a new addition that would require a third lock roundtrip in
xfs_trans_ail_delete_bulk. This addition is also the reason for
slightly rearranging the conditionals and relying on xfs_log_space_wake
for checking that the filesystem has been shut down internally.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 1dead07..77acc53 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -79,7 +79,7 @@
* Return a pointer to the first item in the AIL. If the AIL is empty, then
* return NULL.
*/
-static xfs_log_item_t *
+xfs_log_item_t *
xfs_ail_min(
struct xfs_ail *ailp)
{
@@ -667,11 +667,15 @@
if (!list_empty(&tmp))
xfs_ail_splice(ailp, cur, &tmp, lsn);
- spin_unlock(&ailp->xa_lock);
- if (mlip_changed && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
- xlog_assign_tail_lsn(ailp->xa_mount);
+ if (mlip_changed) {
+ if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount))
+ xlog_assign_tail_lsn_locked(ailp->xa_mount);
+ spin_unlock(&ailp->xa_lock);
+
xfs_log_space_wake(ailp->xa_mount);
+ } else {
+ spin_unlock(&ailp->xa_lock);
}
}
@@ -729,11 +733,15 @@
if (mlip == lip)
mlip_changed = 1;
}
- spin_unlock(&ailp->xa_lock);
- if (mlip_changed && !XFS_FORCED_SHUTDOWN(ailp->xa_mount)) {
- xlog_assign_tail_lsn(ailp->xa_mount);
+ if (mlip_changed) {
+ if (!XFS_FORCED_SHUTDOWN(ailp->xa_mount))
+ xlog_assign_tail_lsn_locked(ailp->xa_mount);
+ spin_unlock(&ailp->xa_lock);
+
xfs_log_space_wake(ailp->xa_mount);
+ } else {
+ spin_unlock(&ailp->xa_lock);
}
}