GFS2: introduce AIL lock
The log lock is currently used to protect the AIL lists and
the movements of buffers into and out of them. The lists
are self contained and no log specific items outside the
lists are accessed when starting or emptying the AIL lists.
Hence the operation of the AIL does not require the protection
of the log lock so split them out into a new AIL specific lock
to reduce the amount of traffic on the log lock. This will
also reduce the amount of serialisation that occurs when
the gfs2_logd pushes on the AIL to move it forward.
This reduces the impact of log pushing on sequential write
throughput.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index eb01f35..4e3c044 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -88,8 +88,8 @@
*/
static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
-__releases(&sdp->sd_log_lock)
-__acquires(&sdp->sd_log_lock)
+__releases(&sdp->sd_ail_lock)
+__acquires(&sdp->sd_ail_lock)
{
struct gfs2_bufdata *bd, *s;
struct buffer_head *bh;
@@ -117,7 +117,7 @@
list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
get_bh(bh);
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
lock_buffer(bh);
if (test_clear_buffer_dirty(bh)) {
bh->b_end_io = end_buffer_write_sync;
@@ -126,7 +126,7 @@
unlock_buffer(bh);
brelse(bh);
}
- gfs2_log_lock(sdp);
+ spin_lock(&sdp->sd_ail_lock);
retry = 1;
break;
@@ -175,10 +175,10 @@
struct gfs2_ail *ai;
int done = 0;
- gfs2_log_lock(sdp);
+ spin_lock(&sdp->sd_ail_lock);
head = &sdp->sd_ail1_list;
if (list_empty(head)) {
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
return;
}
sync_gen = sdp->sd_ail_sync_gen++;
@@ -189,13 +189,13 @@
if (ai->ai_sync_gen >= sync_gen)
continue;
ai->ai_sync_gen = sync_gen;
- gfs2_ail1_start_one(sdp, ai); /* This may drop log lock */
+ gfs2_ail1_start_one(sdp, ai); /* This may drop ail lock */
done = 0;
break;
}
}
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
}
static int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags)
@@ -203,7 +203,7 @@
struct gfs2_ail *ai, *s;
int ret;
- gfs2_log_lock(sdp);
+ spin_lock(&sdp->sd_ail_lock);
list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {
if (gfs2_ail1_empty_one(sdp, ai, flags))
@@ -214,7 +214,7 @@
ret = list_empty(&sdp->sd_ail1_list);
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
return ret;
}
@@ -247,7 +247,7 @@
int wrap = (new_tail < old_tail);
int a, b, rm;
- gfs2_log_lock(sdp);
+ spin_lock(&sdp->sd_ail_lock);
list_for_each_entry_safe(ai, safe, &sdp->sd_ail2_list, ai_list) {
a = (old_tail <= ai->ai_first);
@@ -263,7 +263,7 @@
kfree(ai);
}
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
}
/**
@@ -421,7 +421,7 @@
struct gfs2_ail *ai;
unsigned int tail;
- gfs2_log_lock(sdp);
+ spin_lock(&sdp->sd_ail_lock);
if (list_empty(&sdp->sd_ail1_list)) {
tail = sdp->sd_log_head;
@@ -430,7 +430,7 @@
tail = ai->ai_first;
}
- gfs2_log_unlock(sdp);
+ spin_unlock(&sdp->sd_ail_lock);
return tail;
}
@@ -743,10 +743,12 @@
sdp->sd_log_commited_databuf = 0;
sdp->sd_log_commited_revoke = 0;
+ spin_lock(&sdp->sd_ail_lock);
if (!list_empty(&ai->ai_ail1_list)) {
list_add(&ai->ai_list, &sdp->sd_ail1_list);
ai = NULL;
}
+ spin_unlock(&sdp->sd_ail_lock);
gfs2_log_unlock(sdp);
trace_gfs2_log_flush(sdp, 0);
up_write(&sdp->sd_log_flush_lock);