Merge tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull dm update from Alasdair G Kergon:
 "Miscellaneous device-mapper fixes, cleanups and performance
  improvements.

  Of particular note:
   - Disable broken WRITE SAME support in all targets except linear and
     striped.  Use it when kcopyd is zeroing blocks.
   - Remove several mempools from targets by moving the data into the
     bio's new front_pad area(which dm calls 'per_bio_data').
   - Fix a race in thin provisioning if discards are misused.
   - Prevent userspace from interfering with the ioctl parameters and
     use kmalloc for the data buffer if it's small instead of vmalloc.
   - Throttle some annoying error messages when I/O fails."

* tag 'dm-3.8-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm: (36 commits)
  dm stripe: add WRITE SAME support
  dm: remove map_info
  dm snapshot: do not use map_context
  dm thin: dont use map_context
  dm raid1: dont use map_context
  dm flakey: dont use map_context
  dm raid1: rename read_record to bio_record
  dm: move target request nr to dm_target_io
  dm snapshot: use per_bio_data
  dm verity: use per_bio_data
  dm raid1: use per_bio_data
  dm: introduce per_bio_data
  dm kcopyd: add WRITE SAME support to dm_kcopyd_zero
  dm linear: add WRITE SAME support
  dm: add WRITE SAME support
  dm: prepare to support WRITE SAME
  dm ioctl: use kmalloc if possible
  dm ioctl: remove PF_MEMALLOC
  dm persistent data: improve improve space map block alloc failure message
  dm thin: use DMERR_LIMIT for errors
  ...

1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 1c46f97d6664..ea49834377c8 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -287,7 +287,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
         unsigned num_bvecs;
         sector_t remaining = where->count;
         struct request_queue *q = bdev_get_queue(where->bdev);
-        sector_t discard_sectors;
+        unsigned short logical_block_size = queue_logical_block_size(q);
+        sector_t num_sectors;
 
         /*
          * where->count may be zero if rw holds a flush and we need to
@@ -297,7 +298,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
                 /*
                  * Allocate a suitably sized-bio.
                  */
-                if (rw & REQ_DISCARD)
+                if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
                         num_bvecs = 1;
                 else
                         num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
@@ -310,9 +311,21 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
                 store_io_and_region_in_bio(bio, io, region);
 
                 if (rw & REQ_DISCARD) {
-                        discard_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
-                        bio->bi_size = discard_sectors << SECTOR_SHIFT;
-                        remaining -= discard_sectors;
+                        num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
+                        bio->bi_size = num_sectors << SECTOR_SHIFT;
+                        remaining -= num_sectors;
+                } else if (rw & REQ_WRITE_SAME) {
+                        /*
+                         * WRITE SAME only uses a single page.
+                         */
+                        dp->get_page(dp, &page, &len, &offset);
+                        bio_add_page(bio, page, logical_block_size, offset);
+                        num_sectors = min_t(sector_t, q->limits.max_write_same_sectors, remaining);
+                        bio->bi_size = num_sectors << SECTOR_SHIFT;
+
+                        offset = 0;
+                        remaining -= num_sectors;
+                        dp->next_page(dp);
                 } else while (remaining) {
                         /*
                          * Try and add as many pages as possible.