lkml.org 
[lkml]   [2012]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[ 65/68] dm io: fix discard support
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Milan Broz <mbroz@redhat.com>

commit 0c535e0d6f463365c29623350dbd91642363c39b upstream.

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>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-io.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)

--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -296,6 +296,8 @@ static void do_region(int rw, unsigned r
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 r
/*
* 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 r
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))



\
 
 \ /
  Last update: 2012-03-09 21:07    [W:0.266 / U:5.924 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site