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authorMilan Broz <mbroz@redhat.com>2012-03-07 19:09:37 +0000
committerAlasdair G Kergon <agk@redhat.com>2012-03-07 19:09:37 +0000
commit0c535e0d6f463365c29623350dbd91642363c39b (patch)
tree33217f386886b01e5a033ac8c0cf5fb46f5c3464 /drivers/md/dm-io.c
parent902c6a96a7cb9c50d2a8aed1788efad0a5d8f04c (diff)
downloadlinux-0c535e0d6f463365c29623350dbd91642363c39b.tar.bz2
dm io: fix discard support
This patch fixes a crash by recognising discards in dm_io. Currently dm_mirror can send REQ_DISCARD bios if running over a discard-enabled device and without support in dm_io the system crashes badly. BUG: unable to handle kernel paging request at 00800000 IP: __bio_add_page.part.17+0xf5/0x1e0 ... bio_add_page+0x56/0x70 dispatch_io+0x1cf/0x240 [dm_mod] ? km_get_page+0x50/0x50 [dm_mod] ? vm_next_page+0x20/0x20 [dm_mod] ? mirror_flush+0x130/0x130 [dm_mirror] dm_io+0xdc/0x2b0 [dm_mod] ... Introduced in 2.6.38-rc1 by commit 5fc2ffeabb9ee0fc0e71ff16b49f34f0ed3d05b4 (dm raid1: support discard). Signed-off-by: Milan Broz <mbroz@redhat.com> Cc: stable@kernel.org Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-io.c')
-rw-r--r--drivers/md/dm-io.c23
1 files changed, 16 insertions, 7 deletions
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index ad2eba40e319..ea5dd289fe2a 100644
--- 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))