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| author | Milan Broz <mbroz@redhat.com> | 2012-03-07 19:09:37 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2012-03-07 19:09:37 +0000 |
| commit | 0c535e0d6f463365c29623350dbd91642363c39b (patch) | |
| tree | 33217f386886b01e5a033ac8c0cf5fb46f5c3464 | |
| parent | 902c6a96a7cb9c50d2a8aed1788efad0a5d8f04c (diff) | |
| download | linux-0c535e0d6f463365c29623350dbd91642363c39b.tar.gz linux-0c535e0d6f463365c29623350dbd91642363c39b.tar.bz2 linux-0c535e0d6f463365c29623350dbd91642363c39b.zip | |
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>
| -rw-r--r-- | drivers/md/dm-io.c | 23 |
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)) |