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| author | Jonathan Brassow <jbrassow@redhat.com> | 2013-02-21 13:28:10 +1100 |
|---|---|---|
| committer | NeilBrown <neilb@suse.de> | 2013-02-26 11:55:33 +1100 |
| commit | 9a3152ab024867100f2f50d124b998d05fb1c3f6 (patch) | |
| tree | 15b97c56d117340fa5db609ced6e0d51a91f2f37 /drivers/md | |
| parent | 475901aff15841fb0a81e7546517407779a9b061 (diff) | |
| download | linux-9a3152ab024867100f2f50d124b998d05fb1c3f6.tar.bz2 | |
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
MD RAID10: Improve redundancy for 'far' and 'offset' algorithms (part 2)
This patch addresses raid arrays that have a number of devices that cannot
be evenly divided by 'far_copies'. (E.g. 5 devices, far_copies = 2) This
case must be handled differently because it causes that last set to be of
a different size than the rest of the sets. We must compute a new modulo
for this last set so that copied chunks are properly wrapped around.
Example use_far_sets=1, far_copies=2, near_copies=1, devices=5:
"far" algorithm
dev1 dev2 dev3 dev4 dev5
==== ==== ==== ==== ====
[ A B ] [ C D E ]
[ G H ] [ I J K ]
...
[ B A ] [ E C D ] --> nominal set of 2 and last set of 3
[ H G ] [ K I J ] []'s show far/offset sets
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/raid10.c | 30 |
1 files changed, 28 insertions, 2 deletions
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 70b58b4bcf89..61ed150bd0cf 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -550,6 +550,13 @@ static void __raid10_find_phys(struct geom *geo, struct r10bio *r10bio) sector_t stripe; int dev; int slot = 0; + int last_far_set_start, last_far_set_size; + + last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1; + last_far_set_start *= geo->far_set_size; + + last_far_set_size = geo->far_set_size; + last_far_set_size += (geo->raid_disks % geo->far_set_size); /* now calculate first sector/dev */ chunk = r10bio->sector >> geo->chunk_shift; @@ -575,9 +582,16 @@ static void __raid10_find_phys(struct geom *geo, struct r10bio *r10bio) for (f = 1; f < geo->far_copies; f++) { set = d / geo->far_set_size; d += geo->near_copies; - d %= geo->far_set_size; - d += geo->far_set_size * set; + if ((geo->raid_disks % geo->far_set_size) && + (d > last_far_set_start)) { + d -= last_far_set_start; + d %= last_far_set_size; + d += last_far_set_start; + } else { + d %= geo->far_set_size; + d += geo->far_set_size * set; + } s += geo->stride; r10bio->devs[slot].devnum = d; r10bio->devs[slot].addr = s; @@ -615,6 +629,18 @@ static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev) struct geom *geo = &conf->geo; int far_set_start = (dev / geo->far_set_size) * geo->far_set_size; int far_set_size = geo->far_set_size; + int last_far_set_start; + + if (geo->raid_disks % geo->far_set_size) { + last_far_set_start = (geo->raid_disks / geo->far_set_size) - 1; + last_far_set_start *= geo->far_set_size; + + if (dev >= last_far_set_start) { + far_set_size = geo->far_set_size; + far_set_size += (geo->raid_disks % geo->far_set_size); + far_set_start = last_far_set_start; + } + } offset = sector & geo->chunk_mask; if (geo->far_offset) { |