[dm-devel] [RFC][PATCH] A bunch of small dm-snap.c changes

[Christophe Saout]

Hi,

going through dm-snap.c I made some small modifications.

o Minumum hash size of 64 instead of setting hash size to 64 if the
  calculated size would be smaller than 1.

o Only use list_entry if we are working on a list.

o Check for drop_snapshot function before calling it (transient
  snapshots don't have one).

o Use correct size prefix in status sprintf for chunk size.

o Use C99 initializers.


--- linux.orig/drivers/md/dm-snap.c	2004-01-10 18:07:10.000000000 +0100
+++ linux/drivers/md/dm-snap.c	2004-01-10 18:33:22.000000000 +0100
@@ -373,7 +373,7 @@
 	 * Make this smaller than the real hash table
 	 */
 	hash_size >>= 3;
-	if (!hash_size)
+	if (hash_size < 64)
 		hash_size = 64;
 
 	if (init_exception_table(&s->pending, hash_size)) {
@@ -675,7 +675,7 @@
 		remove_exception(&pe->e);
 		flush = __flush_bios(pe);
 
-		/* Submit any pending write BHs */
+		/* Submit any pending write bios */
 		up_write(&s->lock);
 
 		flush_bios(bio_list_get(&pe->snapshot_bios));
@@ -779,7 +779,7 @@
 	e = lookup_exception(&s->pending, chunk);
 	if (e) {
 		/* cast the exception to a pending exception */
-		pe = list_entry(e, struct pending_exception, e);
+		pe = container_of(e, struct pending_exception, e);
 
 	} else {
 		/*
@@ -793,7 +793,7 @@
 		e = lookup_exception(&s->pending, chunk);
 		if (e) {
 			free_pending_exception(pe);
-			pe = list_entry(e, struct pending_exception, e);
+			pe = container_of(e, struct pending_exception, e);
 		} else {
 			pe->e.old_chunk = chunk;
 			bio_list_init(&pe->origin_bios);
@@ -859,7 +859,8 @@
 			pe = __find_pending_exception(s, bio);
 
 			if (!pe) {
-				s->store.drop_snapshot(&s->store);
+				if (s->store.drop_snapshot)
+					s->store.drop_snapshot(&s->store);
 				s->valid = 0;
 				r = -EIO;
 				up_write(&s->lock);
@@ -952,7 +953,7 @@
 		 */
 		format_dev_t(cow, snap->cow->bdev->bd_dev);
 		format_dev_t(org, snap->origin->bdev->bd_dev);
-		snprintf(result, maxlen, "%s %s %c %lld", org, cow,
+		snprintf(result, maxlen, "%s %s %c " SECTOR_FORMAT, org, cow,
 			 snap->type, snap->chunk_size);
 		break;
 	}
@@ -1165,25 +1166,25 @@
 }
 
 static struct target_type origin_target = {
-	name:	"snapshot-origin",
-	version: {1, 0, 1},
-	module:	THIS_MODULE,
-	ctr:	origin_ctr,
-	dtr:	origin_dtr,
-	map:	origin_map,
-	resume:	origin_resume,
-	status:	origin_status,
+	.name    = "snapshot-origin",
+	.version = {1, 0, 1},
+	.module  = THIS_MODULE,
+	.ctr     = origin_ctr,
+	.dtr     = origin_dtr,
+	.map     = origin_map,
+	.resume  = origin_resume,
+	.status  = origin_status,
 };
 
 static struct target_type snapshot_target = {
-	name:	"snapshot",
-	version: {1, 0, 1},
-	module:	THIS_MODULE,
-	ctr:	snapshot_ctr,
-	dtr:	snapshot_dtr,
-	map:	snapshot_map,
-	resume: snapshot_resume,
-	status:	snapshot_status,
+	.name    = "snapshot",
+	.version = {1, 0, 1},
+	.module  = THIS_MODULE,
+	.ctr     = snapshot_ctr,
+	.dtr     = snapshot_dtr,
+	.map     = snapshot_map,
+	.resume  = snapshot_resume,
+	.status  = snapshot_status,
 };
 
 static int __init dm_snapshot_init(void)