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authorAlasdair G Kergon <agk@redhat.com>2006-10-03 04:15:30 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-03 11:04:14 -0400
commitca3a931fd33b841cbcc5932f8eac7c43e0909242 (patch)
treebc8aa7ace1a5e528cbfabc01b17a2016c55bc448 /drivers
parent9d493fa8c943ed4ec6e42b7ebfd8f0b7657d54f8 (diff)
[PATCH] dm snapshot: add workqueue
Add a workqueue so that I/O can be queued up to be flushed from a separate thread (e.g. if local interrupts are disabled). A new per-snapshot spinlock pe_lock is introduced to protect queued_bios. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-snap.c33
-rw-r--r--drivers/md/dm-snap.h12
2 files changed, 45 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index d92980177b5c..1c6485404db4 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -39,6 +39,9 @@
39 */ 39 */
40#define SNAPSHOT_PAGES 256 40#define SNAPSHOT_PAGES 256
41 41
42struct workqueue_struct *ksnapd;
43static void flush_queued_bios(void *data);
44
42struct pending_exception { 45struct pending_exception {
43 struct exception e; 46 struct exception e;
44 47
@@ -488,6 +491,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
488 s->active = 0; 491 s->active = 0;
489 s->last_percent = 0; 492 s->last_percent = 0;
490 init_rwsem(&s->lock); 493 init_rwsem(&s->lock);
494 spin_lock_init(&s->pe_lock);
491 s->table = ti->table; 495 s->table = ti->table;
492 496
493 /* Allocate hash table for COW data */ 497 /* Allocate hash table for COW data */
@@ -523,6 +527,9 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
523 goto bad6; 527 goto bad6;
524 } 528 }
525 529
530 bio_list_init(&s->queued_bios);
531 INIT_WORK(&s->queued_bios_work, flush_queued_bios, s);
532
526 /* Add snapshot to the list of snapshots for this origin */ 533 /* Add snapshot to the list of snapshots for this origin */
527 /* Exceptions aren't triggered till snapshot_resume() is called */ 534 /* Exceptions aren't triggered till snapshot_resume() is called */
528 if (register_snapshot(s)) { 535 if (register_snapshot(s)) {
@@ -561,6 +568,8 @@ static void snapshot_dtr(struct dm_target *ti)
561{ 568{
562 struct dm_snapshot *s = (struct dm_snapshot *) ti->private; 569 struct dm_snapshot *s = (struct dm_snapshot *) ti->private;
563 570
571 flush_workqueue(ksnapd);
572
564 /* Prevent further origin writes from using this snapshot. */ 573 /* Prevent further origin writes from using this snapshot. */
565 /* After this returns there can be no new kcopyd jobs. */ 574 /* After this returns there can be no new kcopyd jobs. */
566 unregister_snapshot(s); 575 unregister_snapshot(s);
@@ -594,6 +603,19 @@ static void flush_bios(struct bio *bio)
594 } 603 }
595} 604}
596 605
606static void flush_queued_bios(void *data)
607{
608 struct dm_snapshot *s = (struct dm_snapshot *) data;
609 struct bio *queued_bios;
610 unsigned long flags;
611
612 spin_lock_irqsave(&s->pe_lock, flags);
613 queued_bios = bio_list_get(&s->queued_bios);
614 spin_unlock_irqrestore(&s->pe_lock, flags);
615
616 flush_bios(queued_bios);
617}
618
597/* 619/*
598 * Error a list of buffers. 620 * Error a list of buffers.
599 */ 621 */
@@ -1240,8 +1262,17 @@ static int __init dm_snapshot_init(void)
1240 goto bad5; 1262 goto bad5;
1241 } 1263 }
1242 1264
1265 ksnapd = create_singlethread_workqueue("ksnapd");
1266 if (!ksnapd) {
1267 DMERR("Failed to create ksnapd workqueue.");
1268 r = -ENOMEM;
1269 goto bad6;
1270 }
1271
1243 return 0; 1272 return 0;
1244 1273
1274 bad6:
1275 mempool_destroy(pending_pool);
1245 bad5: 1276 bad5:
1246 kmem_cache_destroy(pending_cache); 1277 kmem_cache_destroy(pending_cache);
1247 bad4: 1278 bad4:
@@ -1259,6 +1290,8 @@ static void __exit dm_snapshot_exit(void)
1259{ 1290{
1260 int r; 1291 int r;
1261 1292
1293 destroy_workqueue(ksnapd);
1294
1262 r = dm_unregister_target(&snapshot_target); 1295 r = dm_unregister_target(&snapshot_target);
1263 if (r) 1296 if (r)
1264 DMERR("snapshot unregister failed %d", r); 1297 DMERR("snapshot unregister failed %d", r);
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 221eb8880c80..15fa2ae6cdc2 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -10,7 +10,9 @@
10#define DM_SNAPSHOT_H 10#define DM_SNAPSHOT_H
11 11
12#include "dm.h" 12#include "dm.h"
13#include "dm-bio-list.h"
13#include <linux/blkdev.h> 14#include <linux/blkdev.h>
15#include <linux/workqueue.h>
14 16
15struct exception_table { 17struct exception_table {
16 uint32_t hash_mask; 18 uint32_t hash_mask;
@@ -112,10 +114,20 @@ struct dm_snapshot {
112 struct exception_table pending; 114 struct exception_table pending;
113 struct exception_table complete; 115 struct exception_table complete;
114 116
117 /*
118 * pe_lock protects all pending_exception operations and access
119 * as well as the snapshot_bios list.
120 */
121 spinlock_t pe_lock;
122
115 /* The on disk metadata handler */ 123 /* The on disk metadata handler */
116 struct exception_store store; 124 struct exception_store store;
117 125
118 struct kcopyd_client *kcopyd_client; 126 struct kcopyd_client *kcopyd_client;
127
128 /* Queue of snapshot writes for ksnapd to flush */
129 struct bio_list queued_bios;
130 struct work_struct queued_bios_work;
119}; 131};
120 132
121/* 133/*