The patch titled
md: fix innocuous bug in raid6 stripe_to_pdidx
has been added to the -mm tree. Its filename is
md-fix-innocuous-bug-in-raid6-stripe_to_pdidx.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: md: fix innocuous bug in raid6 stripe_to_pdidx
From: NeilBrown <neilb@xxxxxxx>
stripe_to_pdidx finds the index of the parity disk for a given stripe. It
assumes raid5 in that it uses "disks-1" to determine the number of data disks.
This is incorrect for raid6 but fortunately the two usages cancel each other
out. The only way that 'data_disks' affects the calculation of pd_idx in
raid5_compute_sector is when it is divided into the sector number. But as
that sector number is calculated by multiplying in the wrong value of
'data_disks' the division produces the right value.
So it is innocuous but needs to be fixed.
Also change the calculation of raid_disks in compute_blocknr to make it
more obviously correct (it seems at first to always use disks-1 too).
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/md/raid5.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff -puN drivers/md/raid5.c~md-fix-innocuous-bug-in-raid6-stripe_to_pdidx drivers/md/raid5.c
--- a/drivers/md/raid5.c~md-fix-innocuous-bug-in-raid6-stripe_to_pdidx
+++ a/drivers/md/raid5.c
@@ -823,7 +823,8 @@ static sector_t raid5_compute_sector(sec
static sector_t compute_blocknr(struct stripe_head *sh, int i)
{
raid5_conf_t *conf = sh->raid_conf;
- int raid_disks = sh->disks, data_disks = raid_disks - 1;
+ int raid_disks = sh->disks;
+ int data_disks = raid_disks - conf->max_degraded;
sector_t new_sector = sh->sector, check;
int sectors_per_chunk = conf->chunk_size >> 9;
sector_t stripe;
@@ -859,7 +860,6 @@ static sector_t compute_blocknr(struct s
}
break;
case 6:
- data_disks = raid_disks - 2;
if (i == raid6_next_disk(sh->pd_idx, raid_disks))
return 0; /* It is the Q disk */
switch (conf->algorithm) {
@@ -1355,8 +1355,10 @@ static int stripe_to_pdidx(sector_t stri
int pd_idx, dd_idx;
int chunk_offset = sector_div(stripe, sectors_per_chunk);
- raid5_compute_sector(stripe*(disks-1)*sectors_per_chunk
- + chunk_offset, disks, disks-1, &dd_idx, &pd_idx, conf);
+ raid5_compute_sector(stripe * (disks - conf->max_degraded)
+ *sectors_per_chunk + chunk_offset,
+ disks, disks - conf->max_degraded,
+ &dd_idx, &pd_idx, conf);
return pd_idx;
}
_
Patches currently in -mm which might be from neilb@xxxxxxx are
origin.patch
auth_gss-unregister-gss_domain-when-unloading-module-fix.patch
fix-sunrpc-wakeup-execute-race-condition.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets.patch
lockdep-annotate-nfs-nfsd-in-kernel-sockets-tidy.patch
remove-lock_key-approach-to-managing-nested-bd_mutex-locks.patch
simplify-some-aspects-of-bd_mutex-nesting.patch
use-mutex_lock_nested-for-bd_mutex-to-avoid-lockdep-warning.patch
avoid-lockdep-warning-in-md.patch
bdev-fix-bd_part_count-leak.patch
lockdep-annotate-nfsd4-recover-code.patch
md-tidy-up-device-change-notification-when-an-md-array-is-stopped.patch
md-define-raid5_mergeable_bvec.patch
md-handle-bypassing-the-read-cache-assuming-nothing-fails.patch
md-allow-reads-that-have-bypassed-the-cache-to-be-retried-on-failure.patch
md-allow-reads-that-have-bypassed-the-cache-to-be-retried-on-failure-fix.patch
md-allow-reads-that-have-bypassed-the-cache-to-be-retried-on-failure-misc-fixes-for-aligned-read-handling-including-raid6-read-corruption.patch
md-allow-reads-that-have-bypassed-the-cache-to-be-retried-on-failure-misc-fixes-for-error-handling-of-aligned-reads.patch
md-enable-bypassing-cache-for-reads.patch
md-fix-innocuous-bug-in-raid6-stripe_to_pdidx.patch
md-conditionalize-some-code.patch
md-change-lifetime-rules-for-md-devices.patch
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
