[GFS2] Update locking in log.c
Replace the lock_for_trans()/lock_for_flush() functions with an rwsem.
In fact the sd_log_flush_lock becomes an rwsem (the write part of it)
and is extended slightly to cover everything that the lock_for_flush()
used to cover. The read part of the lock is instead of lock_for_trans().
This corrects the races in the original code and reduces the code size.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h
index be307185..35163b5 100644
--- a/fs/gfs2/incore.h
+++ b/fs/gfs2/incore.h
@@ -611,10 +611,6 @@
/* Log stuff */
spinlock_t sd_log_lock;
- atomic_t sd_log_trans_count;
- wait_queue_head_t sd_log_trans_wq;
- atomic_t sd_log_flush_count;
- wait_queue_head_t sd_log_flush_wq;
unsigned int sd_log_blks_reserved;
unsigned int sd_log_commited_buf;
@@ -643,7 +639,7 @@
int sd_log_idle;
unsigned long sd_log_flush_time;
- struct mutex sd_log_flush_lock;
+ struct rw_semaphore sd_log_flush_lock;
struct list_head sd_log_flush_list;
unsigned int sd_log_flush_head;
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 16c1444..b103d9a 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -29,32 +29,6 @@
#define PULL 1
-static void lock_for_trans(struct gfs2_sbd *sdp)
-{
- wait_event(sdp->sd_log_trans_wq, atomic_read(&sdp->sd_log_flush_count) ? 0 : 1);
- atomic_inc(&sdp->sd_log_trans_count);
-}
-
-static void unlock_from_trans(struct gfs2_sbd *sdp)
-{
- gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_trans_count));
- if (atomic_dec_and_test(&sdp->sd_log_trans_count))
- wake_up(&sdp->sd_log_flush_wq);
-}
-
-static void gfs2_lock_for_flush(struct gfs2_sbd *sdp)
-{
- atomic_inc(&sdp->sd_log_flush_count);
- wait_event(sdp->sd_log_flush_wq, atomic_read(&sdp->sd_log_trans_count) ? 0 : 1);
-}
-
-static void gfs2_unlock_from_flush(struct gfs2_sbd *sdp)
-{
- gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_flush_count));
- if (atomic_dec_and_test(&sdp->sd_log_flush_count))
- wake_up(&sdp->sd_log_trans_wq);
-}
-
/**
* gfs2_struct2blk - compute stuff
* @sdp: the filesystem
@@ -109,9 +83,8 @@
first = NULL;
for (;;) {
- if (first &&
- (head->prev != first ||
- gfs2_ail1_empty_one(sdp, first_ai, 0)))
+ if (first && (head->prev != first ||
+ gfs2_ail1_empty_one(sdp, first_ai, 0)))
break;
for (tmp = head->prev; tmp != head; tmp = tmp->prev) {
@@ -194,23 +167,21 @@
return -EINVAL;
mutex_lock(&sdp->sd_log_reserve_mutex);
- for (;;) {
- gfs2_log_lock(sdp);
- if (sdp->sd_log_blks_free > blks) {
- sdp->sd_log_blks_free -= blks;
- gfs2_log_unlock(sdp);
- mutex_unlock(&sdp->sd_log_reserve_mutex);
- break;
- }
-
+ gfs2_log_lock(sdp);
+ while(sdp->sd_log_blks_free <= blks) {
gfs2_log_unlock(sdp);
gfs2_ail1_empty(sdp, 0);
gfs2_log_flush(sdp);
if (try++)
gfs2_ail1_start(sdp, 0);
+ gfs2_log_lock(sdp);
}
- lock_for_trans(sdp);
+ sdp->sd_log_blks_free -= blks;
+ gfs2_log_unlock(sdp);
+ mutex_unlock(&sdp->sd_log_reserve_mutex);
+
+ down_read(&sdp->sd_log_flush_lock);
return 0;
}
@@ -224,7 +195,7 @@
void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
{
- unlock_from_trans(sdp);
+ up_read(&sdp->sd_log_flush_lock);
gfs2_log_lock(sdp);
sdp->sd_log_blks_free += blks;
@@ -474,20 +445,20 @@
ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);
INIT_LIST_HEAD(&ai->ai_ail1_list);
INIT_LIST_HEAD(&ai->ai_ail2_list);
- gfs2_lock_for_flush(sdp);
+
+ down_write(&sdp->sd_log_flush_lock);
if (gl) {
gfs2_log_lock(sdp);
if (list_empty(&gl->gl_le.le_list)) {
gfs2_log_unlock(sdp);
- gfs2_unlock_from_flush(sdp);
+ up_write(&sdp->sd_log_flush_lock);
kfree(ai);
return;
}
gfs2_log_unlock(sdp);
}
- mutex_lock(&sdp->sd_log_flush_lock);
gfs2_assert_withdraw(sdp,
sdp->sd_log_num_buf == sdp->sd_log_commited_buf);
@@ -519,9 +490,8 @@
}
gfs2_log_unlock(sdp);
- mutex_unlock(&sdp->sd_log_flush_lock);
sdp->sd_vfs->s_dirt = 0;
- gfs2_unlock_from_flush(sdp);
+ up_write(&sdp->sd_log_flush_lock);
kfree(ai);
}
@@ -573,7 +543,7 @@
lops_incore_commit(sdp, tr);
sdp->sd_vfs->s_dirt = 1;
- unlock_from_trans(sdp);
+ up_read(&sdp->sd_log_flush_lock);
gfs2_log_lock(sdp);
if (sdp->sd_log_num_buf > gfs2_tune_get(sdp, gt_incore_log_blocks)) {
@@ -591,9 +561,8 @@
void gfs2_log_shutdown(struct gfs2_sbd *sdp)
{
- mutex_lock(&sdp->sd_log_flush_lock);
+ down_write(&sdp->sd_log_flush_lock);
- gfs2_assert_withdraw(sdp, !atomic_read(&sdp->sd_log_trans_count));
gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
gfs2_assert_withdraw(sdp, !sdp->sd_log_num_gl);
gfs2_assert_withdraw(sdp, !sdp->sd_log_num_buf);
@@ -618,6 +587,6 @@
sdp->sd_log_wraps++;
sdp->sd_log_tail = sdp->sd_log_head;
- mutex_unlock(&sdp->sd_log_flush_lock);
+ up_write(&sdp->sd_log_flush_lock);
}
diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 2628bf3..5166455 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -88,8 +88,6 @@
mutex_init(&sdp->sd_quota_mutex);
spin_lock_init(&sdp->sd_log_lock);
- init_waitqueue_head(&sdp->sd_log_trans_wq);
- init_waitqueue_head(&sdp->sd_log_flush_wq);
INIT_LIST_HEAD(&sdp->sd_log_le_gl);
INIT_LIST_HEAD(&sdp->sd_log_le_buf);
@@ -101,7 +99,7 @@
INIT_LIST_HEAD(&sdp->sd_ail1_list);
INIT_LIST_HEAD(&sdp->sd_ail2_list);
- mutex_init(&sdp->sd_log_flush_lock);
+ init_rwsem(&sdp->sd_log_flush_lock);
INIT_LIST_HEAD(&sdp->sd_log_flush_list);
INIT_LIST_HEAD(&sdp->sd_revoke_list);
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 63e7fed..aa1a619 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -74,10 +74,10 @@
return 0;
- fail_gunlock:
+fail_gunlock:
gfs2_glock_dq(&tr->tr_t_gh);
- fail_holder_uninit:
+fail_holder_uninit:
gfs2_holder_uninit(&tr->tr_t_gh);
kfree(tr);
