diff options
| author |   NeilBrown <neilb@suse.de> | 2006-12-10 02:20:49 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-10 09:57:21 -0800 |
| commit | b875e531fc82db592d6093594593d5cafde0a1cd (patch) | |
| tree | 4bf23fcee1a1d1675339ea7e5d671dde6dd8641f /drivers/md | |
| parent | [PATCH] md: enable bypassing cache for reads (diff) | |
| download | linux-dev-b875e531fc82db592d6093594593d5cafde0a1cd.tar.xz linux-dev-b875e531fc82db592d6093594593d5cafde0a1cd.zip | |
[PATCH] md: fix innocuous bug in raid6 stripe_to_pdidx
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@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid5.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 2e676e33744c..d855f9f59b02 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -823,7 +823,8 @@ static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks, 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 stripe_head *sh, int i) } 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 stripe, raid5_conf_t *conf, int disks) 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; } |