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authorMike Snitzer <snitzer@redhat.com>2012-05-19 01:01:01 +0100
committerAlasdair G Kergon <agk@redhat.com>2012-05-19 01:01:01 +0100
commitf402693d06f32e746c6153e459c5fb064fa02741 (patch)
treec4cfcf2702b3e5a1e94e3c3b923b52c413e4325a
parent36be50515fe2aef61533b516fa2576a2c7fe7664 (diff)
downloadlinux-stericsson-f402693d06f32e746c6153e459c5fb064fa02741.tar.gz
dm thin: fix table output when pool target disables discard passdown internally
When the thin pool target clears the discard_passdown parameter internally, it incorrectly changes the table line reported to userspace. This breaks dumb string comparisons on these table lines in generic userspace device-mapper library code and leads to tables being reloaded repeatedly when nothing is actually meant to be changing. This patch corrects this by no longer changing the table line when discard passdown was disabled. We can still tell when discard passdown is overridden by looking for the message "Discard unsupported by data device (sdX): Disabling discard passdown." This automatic detection is also moved from the 'load' to the 'resume' so that it is re-evaluated should the properties of underlying devices change. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm-thin.c32
1 files changed, 17 insertions, 15 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 2fd87b544a93..eb3d138ff55a 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1632,6 +1632,21 @@ static int bind_control_target(struct pool *pool, struct dm_target *ti)
pool->low_water_blocks = pt->low_water_blocks;
pool->pf = pt->pf;
+ /*
+ * If discard_passdown was enabled verify that the data device
+ * supports discards. Disable discard_passdown if not; otherwise
+ * -EOPNOTSUPP will be returned.
+ */
+ if (pt->pf.discard_passdown) {
+ struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
+ if (!q || !blk_queue_discard(q)) {
+ char buf[BDEVNAME_SIZE];
+ DMWARN("Discard unsupported by data device (%s): Disabling discard passdown.",
+ bdevname(pt->data_dev->bdev, buf));
+ pool->pf.discard_passdown = 0;
+ }
+ }
+
return 0;
}
@@ -1988,19 +2003,6 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
goto out_flags_changed;
}
- /*
- * If discard_passdown was enabled verify that the data device
- * supports discards. Disable discard_passdown if not; otherwise
- * -EOPNOTSUPP will be returned.
- */
- if (pf.discard_passdown) {
- struct request_queue *q = bdev_get_queue(data_dev->bdev);
- if (!q || !blk_queue_discard(q)) {
- DMWARN("Discard unsupported by data device: Disabling discard passdown.");
- pf.discard_passdown = 0;
- }
- }
-
pt->pool = pool;
pt->ti = ti;
pt->metadata_dev = metadata_dev;
@@ -2385,7 +2387,7 @@ static int pool_status(struct dm_target *ti, status_type_t type,
(unsigned long long)pt->low_water_blocks);
count = !pool->pf.zero_new_blocks + !pool->pf.discard_enabled +
- !pool->pf.discard_passdown;
+ !pt->pf.discard_passdown;
DMEMIT("%u ", count);
if (!pool->pf.zero_new_blocks)
@@ -2394,7 +2396,7 @@ static int pool_status(struct dm_target *ti, status_type_t type,
if (!pool->pf.discard_enabled)
DMEMIT("ignore_discard ");
- if (!pool->pf.discard_passdown)
+ if (!pt->pf.discard_passdown)
DMEMIT("no_discard_passdown ");
break;