[PATCH] dm: mirror sector offset fix

The device-mapper core does not perform any remapping of bios before passing
them to the targets.  If a particular mapping begins part-way into a device,
targets obtain the sector relative to the start of the mapping by subtracting
ti->begin.

The dm-raid1 target didn't do this everywhere: this patch fixes it, taking
care to subtract ti->begin exactly once for each bio.

[akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled]

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 4ad269e66525ede34e94f2f0e5509f4661d5f752..346f3a59e7764250adadbb0284c82e391ce0b13f 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -106,12 +106,42 @@ struct region {
        struct bio_list delayed_bios;
 };
 
+
+/*-----------------------------------------------------------------
+ * Mirror set structures.
+ *---------------------------------------------------------------*/
+struct mirror {
+       atomic_t error_count;
+       struct dm_dev *dev;
+       sector_t offset;
+};
+
+struct mirror_set {
+       struct dm_target *ti;
+       struct list_head list;
+       struct region_hash rh;
+       struct kcopyd_client *kcopyd_client;
+
+       spinlock_t lock;        /* protects the next two lists */
+       struct bio_list reads;
+       struct bio_list writes;
+
+       /* recovery */
+       region_t nr_regions;
+       int in_sync;
+
+       struct mirror *default_mirror;  /* Default mirror */
+
+       unsigned int nr_mirrors;
+       struct mirror mirror[0];
+};
+
 /*
  * Conversion fns
  */
 static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
 {
-       return bio->bi_sector >> rh->region_shift;
+       return (bio->bi_sector - rh->ms->ti->begin) >> rh->region_shift;
 }
 
 static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
@@ -539,35 +569,6 @@ static void rh_start_recovery(struct region_hash *rh)
        wake();
 }
 
-/*-----------------------------------------------------------------
- * Mirror set structures.
- *---------------------------------------------------------------*/
-struct mirror {
-       atomic_t error_count;
-       struct dm_dev *dev;
-       sector_t offset;
-};
-
-struct mirror_set {
-       struct dm_target *ti;
-       struct list_head list;
-       struct region_hash rh;
-       struct kcopyd_client *kcopyd_client;
-
-       spinlock_t lock;        /* protects the next two lists */
-       struct bio_list reads;
-       struct bio_list writes;
-
-       /* recovery */
-       region_t nr_regions;
-       int in_sync;
-
-       struct mirror *default_mirror;  /* Default mirror */
-
-       unsigned int nr_mirrors;
-       struct mirror mirror[0];
-};
-
 /*
  * Every mirror should look like this one.
  */
@@ -1113,7 +1114,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio,
        struct mirror *m;
        struct mirror_set *ms = ti->private;
 
-       map_context->ll = bio->bi_sector >> ms->rh.region_shift;
+       map_context->ll = bio_to_region(&ms->rh, bio);
 
        if (rw == WRITE) {
                queue_bio(ms, bio, rw);