9 files changed, 262 insertions, 47 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index ab6a61db63ce..13956437bc81 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1216,9 +1216,24 @@ error:
         return -EINVAL;
 }
 
+static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+                       struct bio_vec *biovec, int max_size)
+{
+        struct crypt_config *cc = ti->private;
+        struct request_queue *q = bdev_get_queue(cc->dev->bdev);
+
+        if (!q->merge_bvec_fn)
+                return max_size;
+
+        bvm->bi_bdev = cc->dev->bdev;
+        bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin;
+
+        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static struct target_type crypt_target = {
         .name   = "crypt",
-        .version= {1, 5, 0},
+        .version= {1, 6, 0},
         .module = THIS_MODULE,
         .ctr    = crypt_ctr,
         .dtr    = crypt_dtr,
@@ -1228,6 +1243,7 @@ static struct target_type crypt_target = {
         .preresume = crypt_preresume,
         .resume = crypt_resume,
         .message = crypt_message,
+        .merge  = crypt_merge,
 };
 
 static int __init dm_crypt_init(void)
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 17753d80ad22..6449bcdf84ca 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -69,13 +69,25 @@ static void linear_dtr(struct dm_target *ti)
         kfree(lc);
 }
 
-static int linear_map(struct dm_target *ti, struct bio *bio,
-                      union map_info *map_context)
+static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
 {
-        struct linear_c *lc = (struct linear_c *) ti->private;
+        struct linear_c *lc = ti->private;
+
+        return lc->start + (bi_sector - ti->begin);
+}
+
+static void linear_map_bio(struct dm_target *ti, struct bio *bio)
+{
+        struct linear_c *lc = ti->private;
 
         bio->bi_bdev = lc->dev->bdev;
-        bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
+        bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
+}
+
+static int linear_map(struct dm_target *ti, struct bio *bio,
+                      union map_info *map_context)
+{
+        linear_map_bio(ti, bio);
 
         return DM_MAPIO_REMAPPED;
 }
@@ -114,15 +126,31 @@ static int linear_ioctl(struct dm_target *ti, struct inode *inode,
         return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
 }
 
+static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+                        struct bio_vec *biovec, int max_size)
+{
+        struct linear_c *lc = ti->private;
+        struct request_queue *q = bdev_get_queue(lc->dev->bdev);
+
+        if (!q->merge_bvec_fn)
+                return max_size;
+
+        bvm->bi_bdev = lc->dev->bdev;
+        bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
+
+        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static struct target_type linear_target = {
         .name   = "linear",
-        .version= {1, 0, 2},
+        .version= {1, 0, 3},
         .module = THIS_MODULE,
         .ctr    = linear_ctr,
         .dtr    = linear_dtr,
         .map    = linear_map,
         .status = linear_status,
         .ioctl  = linear_ioctl,
+        .merge  = linear_merge,
 };
 
 int __init dm_linear_init(void)
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 67a6f31b7fc3..5b48478c79f5 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -831,7 +831,7 @@ static struct dm_dirty_log_type _disk_type = {
         .status = disk_status,
 };
 
-int __init dm_dirty_log_init(void)
+static int __init dm_dirty_log_init(void)
 {
         int r;
 
@@ -848,7 +848,7 @@ int __init dm_dirty_log_init(void)
         return r;
 }
 
-void __exit dm_dirty_log_exit(void)
+static void __exit dm_dirty_log_exit(void)
 {
         dm_dirty_log_type_unregister(&_disk_type);
         dm_dirty_log_type_unregister(&_core_type);
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 9f7302d4878d..fea966d66f98 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -525,8 +525,10 @@ static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
         }
 
         r = read_param(_params, shift(as), &ps_argc, &ti->error);
-        if (r)
+        if (r) {
+                dm_put_path_selector(pst);
                 return -EINVAL;
+        }
 
         r = pst->create(&pg->ps, ps_argc, as->argv);
         if (r) {
@@ -623,8 +625,10 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
                 struct pgpath *pgpath;
                 struct arg_set path_args;
 
-                if (as->argc < nr_params)
+                if (as->argc < nr_params) {
+                        ti->error = "not enough path parameters";
                         goto bad;
+                }
 
                 path_args.argc = nr_params;
                 path_args.argv = as->argv;
@@ -867,7 +871,7 @@ static int reinstate_path(struct pgpath *pgpath)
         if (pgpath->path.is_active)
                 goto out;
 
-        if (!pgpath->pg->ps.type) {
+        if (!pgpath->pg->ps.type->reinstate_path) {
                 DMWARN("Reinstate path not supported by path selector %s",
                        pgpath->pg->ps.type->name);
                 r = -EINVAL;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1ba8a47d61b1..6e5528aecc98 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -40,6 +40,11 @@
  */
 #define SNAPSHOT_PAGES (((1UL << 20) >> PAGE_SHIFT) ? : 1)
 
+/*
+ * The size of the mempool used to track chunks in use.
+ */
+#define MIN_IOS 256
+
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);
 
@@ -91,7 +96,63 @@ struct dm_snap_pending_exception {
  */
 static struct kmem_cache *exception_cache;
 static struct kmem_cache *pending_cache;
-static mempool_t *pending_pool;
+
+struct dm_snap_tracked_chunk {
+        struct hlist_node node;
+        chunk_t chunk;
+};
+
+static struct kmem_cache *tracked_chunk_cache;
+
+static struct dm_snap_tracked_chunk *track_chunk(struct dm_snapshot *s,
+                                                 chunk_t chunk)
+{
+        struct dm_snap_tracked_chunk *c = mempool_alloc(s->tracked_chunk_pool,
+                                                        GFP_NOIO);
+        unsigned long flags;
+
+        c->chunk = chunk;
+
+        spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+        hlist_add_head(&c->node,
+                       &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)]);
+        spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+        return c;
+}
+
+static void stop_tracking_chunk(struct dm_snapshot *s,
+                                struct dm_snap_tracked_chunk *c)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&s->tracked_chunk_lock, flags);
+        hlist_del(&c->node);
+        spin_unlock_irqrestore(&s->tracked_chunk_lock, flags);
+
+        mempool_free(c, s->tracked_chunk_pool);
+}
+
+static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk)
+{
+        struct dm_snap_tracked_chunk *c;
+        struct hlist_node *hn;
+        int found = 0;
+
+        spin_lock_irq(&s->tracked_chunk_lock);
+
+        hlist_for_each_entry(c, hn,
+            &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) {
+                if (c->chunk == chunk) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        spin_unlock_irq(&s->tracked_chunk_lock);
+
+        return found;
+}
 
 /*
  * One of these per registered origin, held in the snapshot_origins hash
@@ -302,14 +363,19 @@ static void free_exception(struct dm_snap_exception *e)
         kmem_cache_free(exception_cache, e);
 }
 
-static struct dm_snap_pending_exception *alloc_pending_exception(void)
+static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snapshot *s)
 {
-        return mempool_alloc(pending_pool, GFP_NOIO);
+        struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
+                                                             GFP_NOIO);
+
+        pe->snap = s;
+
+        return pe;
 }
 
 static void free_pending_exception(struct dm_snap_pending_exception *pe)
 {
-        mempool_free(pe, pending_pool);
+        mempool_free(pe, pe->snap->pending_pool);
 }
 
 static void insert_completed_exception(struct dm_snapshot *s,
@@ -482,6 +548,7 @@ static int set_chunk_size(struct dm_snapshot *s, const char *chunk_size_arg,
 static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
         struct dm_snapshot *s;
+        int i;
         int r = -EINVAL;
         char persistent;
         char *origin_path;
@@ -564,11 +631,30 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto bad5;
         }
 
+        s->pending_pool = mempool_create_slab_pool(MIN_IOS, pending_cache);
+        if (!s->pending_pool) {
+                ti->error = "Could not allocate mempool for pending exceptions";
+                goto bad6;
+        }
+
+        s->tracked_chunk_pool = mempool_create_slab_pool(MIN_IOS,
+                                                         tracked_chunk_cache);
+        if (!s->tracked_chunk_pool) {
+                ti->error = "Could not allocate tracked_chunk mempool for "
+                            "tracking reads";
+                goto bad_tracked_chunk_pool;
+        }
+
+        for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+                INIT_HLIST_HEAD(&s->tracked_chunk_hash[i]);
+
+        spin_lock_init(&s->tracked_chunk_lock);
+
         /* Metadata must only be loaded into one table at once */
         r = s->store.read_metadata(&s->store);
         if (r < 0) {
                 ti->error = "Failed to read snapshot metadata";
-                goto bad6;
+                goto bad_load_and_register;
         } else if (r > 0) {
                 s->valid = 0;
                 DMWARN("Snapshot is marked invalid.");
@@ -582,7 +668,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         if (register_snapshot(s)) {
                 r = -EINVAL;
                 ti->error = "Cannot register snapshot origin";
-                goto bad6;
+                goto bad_load_and_register;
         }
 
         ti->private = s;
@@ -590,6 +676,12 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
         return 0;
 
+ bad_load_and_register:
+        mempool_destroy(s->tracked_chunk_pool);
+
+ bad_tracked_chunk_pool:
+        mempool_destroy(s->pending_pool);
+
  bad6:
         dm_kcopyd_client_destroy(s->kcopyd_client);
 
@@ -624,6 +716,9 @@ static void __free_exceptions(struct dm_snapshot *s)
 
 static void snapshot_dtr(struct dm_target *ti)
 {
+#ifdef CONFIG_DM_DEBUG
+        int i;
+#endif
         struct dm_snapshot *s = ti->private;
 
         flush_workqueue(ksnapd);
@@ -632,8 +727,17 @@ static void snapshot_dtr(struct dm_target *ti)
         /* After this returns there can be no new kcopyd jobs. */
         unregister_snapshot(s);
 
+#ifdef CONFIG_DM_DEBUG
+        for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
+                BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));
+#endif
+
+        mempool_destroy(s->tracked_chunk_pool);
+
         __free_exceptions(s);
 
+        mempool_destroy(s->pending_pool);
+
         dm_put_device(ti, s->origin);
         dm_put_device(ti, s->cow);
 
@@ -772,6 +876,13 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
         }
 
         /*
+         * Check for conflicting reads. This is extremely improbable,
+         * so yield() is sufficient and there is no need for a wait queue.
+         */
+        while (__chunk_is_tracked(s, pe->e.old_chunk))
+                yield();
+
+        /*
          * Add a proper exception, and remove the
          * in-flight exception from the list.
          */
@@ -873,7 +984,7 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
          * to hold the lock while we do this.
          */
         up_write(&s->lock);
-        pe = alloc_pending_exception();
+        pe = alloc_pending_exception(s);
         down_write(&s->lock);
 
         if (!s->valid) {
@@ -893,7 +1004,6 @@ __find_pending_exception(struct dm_snapshot *s, struct bio *bio)
         bio_list_init(&pe->snapshot_bios);
         pe->primary_pe = NULL;
         atomic_set(&pe->ref_count, 0);
-        pe->snap = s;
         pe->started = 0;
 
         if (s->store.prepare_exception(&s->store, &pe->e)) {
@@ -974,14 +1084,10 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
                         start_copy(pe);
                         goto out;
                 }
-        } else
-                /*
-                 * FIXME: this read path scares me because we
-                 * always use the origin when we have a pending
-                 * exception.  However I can't think of a
-                 * situation where this is wrong - ejt.
-                 */
+        } else {
                 bio->bi_bdev = s->origin->bdev;
+                map_context->ptr = track_chunk(s, chunk);
+        }
 
  out_unlock:
         up_write(&s->lock);
@@ -989,6 +1095,18 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
         return r;
 }
 
+static int snapshot_end_io(struct dm_target *ti, struct bio *bio,
+                           int error, union map_info *map_context)
+{
+        struct dm_snapshot *s = ti->private;
+        struct dm_snap_tracked_chunk *c = map_context->ptr;
+
+        if (c)
+                stop_tracking_chunk(s, c);
+
+        return 0;
+}
+
 static void snapshot_resume(struct dm_target *ti)
 {
         struct dm_snapshot *s = ti->private;
@@ -1266,6 +1384,7 @@ static struct target_type snapshot_target = {
         .ctr     = snapshot_ctr,
         .dtr     = snapshot_dtr,
         .map     = snapshot_map,
+        .end_io  = snapshot_end_io,
         .resume  = snapshot_resume,
         .status  = snapshot_status,
 };
@@ -1306,9 +1425,9 @@ static int __init dm_snapshot_init(void)
                 goto bad4;
         }
 
-        pending_pool = mempool_create_slab_pool(128, pending_cache);
-        if (!pending_pool) {
-                DMERR("Couldn't create pending pool.");
+        tracked_chunk_cache = KMEM_CACHE(dm_snap_tracked_chunk, 0);
+        if (!tracked_chunk_cache) {
+                DMERR("Couldn't create cache to track chunks in use.");
                 r = -ENOMEM;
                 goto bad5;
         }
@@ -1317,13 +1436,13 @@ static int __init dm_snapshot_init(void)
         if (!ksnapd) {
                 DMERR("Failed to create ksnapd workqueue.");
                 r = -ENOMEM;
-                goto bad6;
+                goto bad_pending_pool;
         }
 
         return 0;
 
-      bad6:
-        mempool_destroy(pending_pool);
+      bad_pending_pool:
+        kmem_cache_destroy(tracked_chunk_cache);
       bad5:
         kmem_cache_destroy(pending_cache);
       bad4:
@@ -1352,9 +1471,9 @@ static void __exit dm_snapshot_exit(void)
                 DMERR("origin unregister failed %d", r);
 
         exit_origin_hash();
-        mempool_destroy(pending_pool);
         kmem_cache_destroy(pending_cache);
         kmem_cache_destroy(exception_cache);
+        kmem_cache_destroy(tracked_chunk_cache);
 }
 
 /* Module hooks */
diff --git a/drivers/md/dm-snap.h b/drivers/md/dm-snap.h
index 24f9fb73b982..292c15609ae3 100644
--- a/drivers/md/dm-snap.h
+++ b/drivers/md/dm-snap.h
@@ -130,6 +130,10 @@ struct exception_store {
         void *context;
 };
 
+#define DM_TRACKED_CHUNK_HASH_SIZE      16
+#define DM_TRACKED_CHUNK_HASH(x)        ((unsigned long)(x) & \
+                                         (DM_TRACKED_CHUNK_HASH_SIZE - 1))
+
 struct dm_snapshot {
         struct rw_semaphore lock;
         struct dm_target *ti;
@@ -157,6 +161,8 @@ struct dm_snapshot {
         /* The last percentage we notified */
         int last_percent;
 
+        mempool_t *pending_pool;
+
         struct exception_table pending;
         struct exception_table complete;
 
@@ -174,6 +180,11 @@ struct dm_snapshot {
         /* Queue of snapshot writes for ksnapd to flush */
         struct bio_list queued_bios;
         struct work_struct queued_bios_work;
+
+        /* Chunks with outstanding reads */
+        mempool_t *tracked_chunk_pool;
+        spinlock_t tracked_chunk_lock;
+        struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
 };
 
 /*
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 94116eaf4709..798e468103b8 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -506,14 +506,13 @@ void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev)
         rs->max_sectors =
                 min_not_zero(rs->max_sectors, q->max_sectors);
 
-        /* FIXME: Device-Mapper on top of RAID-0 breaks because DM
-         *        currently doesn't honor MD's merge_bvec_fn routine.
-         *        In this case, we'll force DM to use PAGE_SIZE or
-         *        smaller I/O, just to be safe. A better fix is in the
-         *        works, but add this for the time being so it will at
-         *        least operate correctly.
+        /*
+         * Check if merge fn is supported.
+         * If not we'll force DM to use PAGE_SIZE or
+         * smaller I/O, just to be safe.
          */
-        if (q->merge_bvec_fn)
+
+        if (q->merge_bvec_fn && !ti->type->merge)
                 rs->max_sectors =
                         min_not_zero(rs->max_sectors,
                                      (unsigned int) (PAGE_SIZE >> 9));
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 372369b1cc20..bca448e11878 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -37,8 +37,8 @@ static DEFINE_SPINLOCK(_minor_lock);
 struct dm_io {
         struct mapped_device *md;
         int error;
-        struct bio *bio;
         atomic_t io_count;
+        struct bio *bio;
         unsigned long start_time;
 };
 
@@ -829,6 +829,49 @@ static int __split_bio(struct mapped_device *md, struct bio *bio)
  * CRUD END
  *---------------------------------------------------------------*/
 
+static int dm_merge_bvec(struct request_queue *q,
+                         struct bvec_merge_data *bvm,
+                         struct bio_vec *biovec)
+{
+        struct mapped_device *md = q->queuedata;
+        struct dm_table *map = dm_get_table(md);
+        struct dm_target *ti;
+        sector_t max_sectors;
+        int max_size;
+
+        if (unlikely(!map))
+                return 0;
+
+        ti = dm_table_find_target(map, bvm->bi_sector);
+
+        /*
+         * Find maximum amount of I/O that won't need splitting
+         */
+        max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
+                          (sector_t) BIO_MAX_SECTORS);
+        max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
+        if (max_size < 0)
+                max_size = 0;
+
+        /*
+         * merge_bvec_fn() returns number of bytes
+         * it can accept at this offset
+         * max is precomputed maximal io size
+         */
+        if (max_size && ti->type->merge)
+                max_size = ti->type->merge(ti, bvm, biovec, max_size);
+
+        /*
+         * Always allow an entire first page
+         */
+        if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
+                max_size = biovec->bv_len;
+
+        dm_table_put(map);
+
+        return max_size;
+}
+
 /*
  * The request function that just remaps the bio built up by
  * dm_merge_bvec.
@@ -1032,6 +1075,7 @@ static struct mapped_device *alloc_dev(int minor)
         blk_queue_make_request(md->queue, dm_request);
         blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
         md->queue->unplug_fn = dm_unplug_all;
+        blk_queue_merge_bvec(md->queue, dm_merge_bvec);
 
         md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
         if (!md->io_pool)
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 8c03b634e62e..1e59a0b0a78a 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -100,12 +100,6 @@ int dm_lock_for_deletion(struct mapped_device *md);
 
 void dm_kobject_uevent(struct mapped_device *md);
 
-/*
- * Dirty log
- */
-int dm_dirty_log_init(void);
-void dm_dirty_log_exit(void);
-
 int dm_kcopyd_init(void);
 void dm_kcopyd_exit(void);