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author | Mike Snitzer <snitzer@redhat.com> | 2013-05-10 13:37:14 (GMT) |
---|---|---|
committer | Alasdair G Kergon <agk@redhat.com> | 2013-05-10 13:37:14 (GMT) |
commit | d793e684277124d55c5d2444007e224635821346 (patch) | |
tree | e4ce5af71082bdec32105a68c8405405273c1f90 /drivers/md | |
parent | ebb37277796269da36a8bc5d72ed1e8e1fb7d34b (diff) | |
download | linux-d793e684277124d55c5d2444007e224635821346.tar.xz |
dm stripe: fix regression in stripe_width calculation
Fix a regression in the calculation of the stripe_width in the
dm stripe target which led to incorrect processing of device limits.
The stripe_width is the stripe device length divided by the number of
stripes. The group of commits in the range f14fa69 ("dm stripe: fix
size test") to eb850de ("dm stripe: support for non power of 2
chunksize") interfered with each other (a merging error) and led to the
stripe_width being set incorrectly to the 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 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 swap the order of the divisions and to use a temporary
variable for the second one, so that width retains the intended
value.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.6+
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r-- | drivers/md/dm-stripe.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c index ea5e878..d907ca6 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, tmp_len; uint32_t stripes; uint32_t chunk_size; int r; @@ -116,15 +116,16 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv) } width = ti->len; - if (sector_div(width, chunk_size)) { + if (sector_div(width, stripes)) { ti->error = "Target length not divisible by " - "chunk size"; + "number of stripes"; return -EINVAL; } - if (sector_div(width, stripes)) { + tmp_len = width; + if (sector_div(tmp_len, chunk_size)) { ti->error = "Target length not divisible by " - "number of stripes"; + "chunk size"; return -EINVAL; } |