The stripe_width is the stripe device length divided by the number of
stripes. Unfortunately, commit eb850de ("dm stripe: support for non
power of 2 chunksize") introduced a regression that resulted in the
stripe_width being set to stripe device length divided by chunk_size *
stripe_count.
For example, a stripe device's table with: 0 33553920 striped 3 512 ...
should result in a stripe_width of 11184640 (33553920 / 3), but due to
the bug it was being getting set to 21845 (33553920 / (512 * 3)).
The impact of this bug is that device topologies that previously worked
fine with the stripe target are no longer considered valid. In
particular, there is a higher risk of seeing this issue if one of the
stripe devices has a 4K logical block size. Resulting in an error
message like this:
"device-mapper: table: 253:4: len=21845 not aligned to h/w logical block size 4096 of dm-1"
The fix is to not use the 'width' variable as a temporary variable that
is modified as a side-effect of the sector_div() as part of an earlier
negative check before the stripe_width calculation (which also uses the
'width' variable).
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 3.6+
---
drivers/md/dm-stripe.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index ea5e878..9e1ec9b 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -94,7 +94,7 @@ static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
struct stripe_c *sc;
- sector_t width;
+ sector_t width, temp;
uint32_t stripes;
uint32_t chunk_size;
int r;
@@ -115,13 +115,14 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
return -EINVAL;
}
- width = ti->len;
- if (sector_div(width, chunk_size)) {
+ temp = ti->len;
+ if (sector_div(temp, chunk_size)) {
ti->error = "Target length not divisible by "
"chunk size";
return -EINVAL;
}
+ width = ti->len;
if (sector_div(width, stripes)) {
ti->error = "Target length not divisible by "
"number of stripes";
--
1.7.1
--
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