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| author | Dan Williams <dan.j.williams@intel.com> | 2008-06-27 21:44:04 -0700 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2008-06-30 17:18:19 -0700 |
| commit | b5470dc5fc18a8ff6517c3bb538d1479e58ecb02 (patch) | |
| tree | 37b0eb3a4691bdbe58dc5c6c73b2dc8d3925b332 /drivers/md/raid1.c | |
| parent | 1fe797e67fb07d605b82300934d0de67068a0aca (diff) | |
| download | op-kernel-dev-b5470dc5fc18a8ff6517c3bb538d1479e58ecb02.zip op-kernel-dev-b5470dc5fc18a8ff6517c3bb538d1479e58ecb02.tar.gz | |
md: resolve external metadata handling deadlock in md_allow_write
md_allow_write() marks the metadata dirty while holding mddev->lock and then
waits for the write to complete. For externally managed metadata this causes a
deadlock as userspace needs to take the lock to communicate that the metadata
update has completed.
Change md_allow_write() in the 'external' case to start the 'mark active'
operation and then return -EAGAIN. The expected side effects while waiting for
userspace to write 'active' to 'array_state' are holding off reshape (code
currently handles -ENOMEM), cause some 'stripe_cache_size' change requests to
fail, cause some GET_BITMAP_FILE ioctl requests to fall back to GFP_NOIO, and
cause updates to 'raid_disks' to fail. Except for 'stripe_cache_size' changes
these failures can be mitigated by coordinating with mdmon.
md_write_start() still prevents writes from occurring until the metadata
handler has had a chance to take action as it unconditionally waits for
MD_CHANGE_CLEAN to be cleared.
[neilb@suse.de: return -EAGAIN, try GFP_NOIO]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/md/raid1.c')
| -rw-r--r-- | drivers/md/raid1.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index f05d598..491dc2d 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -2136,7 +2136,7 @@ static int raid1_reshape(mddev_t *mddev) conf_t *conf = mddev_to_conf(mddev); int cnt, raid_disks; unsigned long flags; - int d, d2; + int d, d2, err; /* Cannot change chunk_size, layout, or level */ if (mddev->chunk_size != mddev->new_chunk || @@ -2148,7 +2148,9 @@ static int raid1_reshape(mddev_t *mddev) return -EINVAL; } - md_allow_write(mddev); + err = md_allow_write(mddev); + if (err) + return err; raid_disks = mddev->raid_disks + mddev->delta_disks; |
