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authorDarrick J. Wong <darrick.wong@oracle.com>2015-02-27 10:44:38 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-04-13 14:03:55 +0200
commitf067d93f11803f587ec2947ba8ac2e4c5f7e3fd9 (patch)
treead60d294715544ddb4c6663178816df1c6b4f9b9
parent72267c2e77226ebfca62d8dbb9bb8fca061bd914 (diff)
downloadlwn-f067d93f11803f587ec2947ba8ac2e4c5f7e3fd9.tar.gz
lwn-f067d93f11803f587ec2947ba8ac2e4c5f7e3fd9.zip
dm io: deal with wandering queue limits when handling REQ_DISCARD and REQ_WRITE_SAME
commit e5db29806b99ce2b2640d2e4d4fcb983cea115c5 upstream. Since it's possible for the discard and write same queue limits to change while the upper level command is being sliced and diced, fix up both of them (a) to reject IO if the special command is unsupported at the start of the function and (b) read the limits once and let the commands error out on their own if the status happens to change. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/md/dm-io.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 37de0173b6d2..74adcd2c967e 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -289,9 +289,16 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
struct request_queue *q = bdev_get_queue(where->bdev);
unsigned short logical_block_size = queue_logical_block_size(q);
sector_t num_sectors;
+ unsigned int uninitialized_var(special_cmd_max_sectors);
- /* Reject unsupported discard requests */
- if ((rw & REQ_DISCARD) && !blk_queue_discard(q)) {
+ /*
+ * Reject unsupported discard and write same requests.
+ */
+ if (rw & REQ_DISCARD)
+ special_cmd_max_sectors = q->limits.max_discard_sectors;
+ else if (rw & REQ_WRITE_SAME)
+ special_cmd_max_sectors = q->limits.max_write_same_sectors;
+ if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) {
dec_count(io, region, -EOPNOTSUPP);
return;
}
@@ -317,7 +324,7 @@ 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) {
- num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
+ num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
remaining -= num_sectors;
} else if (rw & REQ_WRITE_SAME) {
@@ -326,7 +333,7 @@ static void do_region(int rw, unsigned region, struct dm_io_region *where,
*/
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);
+ num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
offset = 0;