Change mapped device to implement direct_access function, dm_blk_direct_access(), which calls a target direct_access function. 'struct target_type' is extended to have target direct_access interface. This function limits direct accessible size to the dm_target's limit with max_io_len().
Signed-off-by: Toshi Kani <[email protected]> Cc: Alasdair Kergon <[email protected]> Cc: Mike Snitzer <[email protected]> Cc: Dan Williams <[email protected]> Cc: Ross Zwisler <[email protected]> --- drivers/md/dm.c | 29 +++++++++++++++++++++++++++++ include/linux/device-mapper.h | 10 ++++++++++ 2 files changed, 39 insertions(+) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 1b2f962..6e9f958 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1473,6 +1473,34 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len) } EXPORT_SYMBOL_GPL(dm_set_target_max_io_len); +static long dm_blk_direct_access(struct block_device *bdev, sector_t sector, + void __pmem **kaddr, pfn_t *pfn, long size) +{ + struct mapped_device *md = bdev->bd_disk->private_data; + struct dm_table *map; + struct dm_target *ti; + int srcu_idx; + long len, ret = -EIO; + + map = dm_get_live_table(md, &srcu_idx); + if (!map) + return ret; + + ti = dm_table_find_target(map, sector); + if (!dm_target_is_valid(ti)) + goto out; + + len = max_io_len(sector, ti) << SECTOR_SHIFT; + size = min(len, size); + + if (ti->type->direct_access) + ret = ti->type->direct_access(ti, sector, kaddr, pfn, size); + +out: + dm_put_live_table(md, srcu_idx); + return min(ret, size); +} + /* * A target may call dm_accept_partial_bio only from the map routine. It is * allowed for all bio types except REQ_FLUSH. @@ -3721,6 +3749,7 @@ static const struct block_device_operations dm_blk_dops = { .open = dm_blk_open, .release = dm_blk_close, .ioctl = dm_blk_ioctl, + .direct_access = dm_blk_direct_access, .getgeo = dm_blk_getgeo, .pr_ops = &dm_pr_ops, .owner = THIS_MODULE diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 0830c9e..16e6c8c 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -116,6 +116,15 @@ typedef void (*dm_io_hints_fn) (struct dm_target *ti, */ typedef int (*dm_busy_fn) (struct dm_target *ti); +/* + * Returns: + * < 0 : error + * >= 0 : the number of bytes accessible at the address + */ +typedef long (*dm_direct_access_fn) (struct dm_target *ti, sector_t sector, + void __pmem **kaddr, pfn_t *pfn, + long size); + void dm_error(const char *message); struct dm_dev { @@ -162,6 +171,7 @@ struct target_type { dm_busy_fn busy; dm_iterate_devices_fn iterate_devices; dm_io_hints_fn io_hints; + dm_direct_access_fn direct_access; /* For internal device-mapper use. */ struct list_head list;
