dm thin: fix discard corruption

[pandora-kernel.git] / drivers / md / dm-io.c

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ad2eba4..ea5dd28 100644 (file)
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -296,6 +296,8 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
        unsigned offset;
        unsigned num_bvecs;
        sector_t remaining = where->count;
+       struct request_queue *q = bdev_get_queue(where->bdev);
+       sector_t discard_sectors;
 
        /*
         * where->count may be zero if rw holds a flush and we need to
@@ -305,9 +307,12 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
                /*
                 * Allocate a suitably sized-bio.
                 */
-               num_bvecs = dm_sector_div_up(remaining,
-                                            (PAGE_SIZE >> SECTOR_SHIFT));
-               num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), num_bvecs);
+               if (rw & REQ_DISCARD)
+                       num_bvecs = 1;
+               else
+                       num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
+                                         dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
+
                bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
                bio->bi_sector = where->sector + (where->count - remaining);
                bio->bi_bdev = where->bdev;
@@ -315,10 +320,14 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
                bio->bi_destructor = dm_bio_destructor;
                store_io_and_region_in_bio(bio, io, region);
 
-               /*
-                * Try and add as many pages as possible.
-                */
-               while (remaining) {
+               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;
+               } else while (remaining) {
+                       /*
+                        * Try and add as many pages as possible.
+                        */
                        dp->get_page(dp, &page, &len, &offset);
                        len = min(len, to_bytes(remaining));
                        if (!bio_add_page(bio, page, len, offset))