diff options
| -rw-r--r-- | drivers/md/dm-table.c | 3 | ||||
| -rw-r--r-- | drivers/md/dm.c | 61 | ||||
| -rw-r--r-- | drivers/md/dm.h | 2 |
3 files changed, 64 insertions, 2 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index d58b200a353..03516c7f5be 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -540,8 +540,7 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, * If not we'll force DM to use PAGE_SIZE or * smaller I/O, just to be safe. */ - - if (q->merge_bvec_fn && !ti->type->merge) + if (dm_queue_merge_is_compulsory(q) && !ti->type->merge) blk_limits_max_hw_sectors(limits, (unsigned int) (PAGE_SIZE >> 9)); return 0; diff --git a/drivers/md/dm.c b/drivers/md/dm.c index aeb0fa1ccfe..1000eaf984e 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -111,6 +111,7 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo); #define DMF_FREEING 3 #define DMF_DELETING 4 #define DMF_NOFLUSH_SUSPENDING 5 +#define DMF_MERGE_IS_OPTIONAL 6 /* * Work processed by per-device workqueue. @@ -1993,6 +1994,59 @@ static void __set_size(struct mapped_device *md, sector_t size) } /* + * Return 1 if the queue has a compulsory merge_bvec_fn function. + * + * If this function returns 0, then the device is either a non-dm + * device without a merge_bvec_fn, or it is a dm device that is + * able to split any bios it receives that are too big. + */ +int dm_queue_merge_is_compulsory(struct request_queue *q) +{ + struct mapped_device *dev_md; + + if (!q->merge_bvec_fn) + return 0; + + if (q->make_request_fn == dm_request) { + dev_md = q->queuedata; + if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags)) + return 0; + } + + return 1; +} + +static int dm_device_merge_is_compulsory(struct dm_target *ti, + struct dm_dev *dev, sector_t start, + sector_t len, void *data) +{ + struct block_device *bdev = dev->bdev; + struct request_queue *q = bdev_get_queue(bdev); + + return dm_queue_merge_is_compulsory(q); +} + +/* + * Return 1 if it is acceptable to ignore merge_bvec_fn based + * on the properties of the underlying devices. + */ +static int dm_table_merge_is_optional(struct dm_table *table) +{ + unsigned i = 0; + struct dm_target *ti; + + while (i < dm_table_get_num_targets(table)) { + ti = dm_table_get_target(table, i++); + + if (ti->type->iterate_devices && + ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL)) + return 0; + } + + return 1; +} + +/* * Returns old map, which caller must destroy. */ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, @@ -2002,6 +2056,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, struct request_queue *q = md->queue; sector_t size; unsigned long flags; + int merge_is_optional; size = dm_table_get_size(t); @@ -2027,10 +2082,16 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t, __bind_mempools(md, t); + merge_is_optional = dm_table_merge_is_optional(t); + write_lock_irqsave(&md->map_lock, flags); old_map = md->map; md->map = t; dm_table_set_restrictions(t, q, limits); + if (merge_is_optional) + set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); + else + clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags); write_unlock_irqrestore(&md->map_lock, flags); return old_map; diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 1aaf16746da..6745dbd278a 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -66,6 +66,8 @@ int dm_table_alloc_md_mempools(struct dm_table *t); void dm_table_free_md_mempools(struct dm_table *t); struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t); +int dm_queue_merge_is_compulsory(struct request_queue *q); + void dm_lock_md_type(struct mapped_device *md); void dm_unlock_md_type(struct mapped_device *md); void dm_set_md_type(struct mapped_device *md, unsigned type); |