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authorhui jiao <simonjiaoh@gmail.com>2014-06-05 11:34:24 +0800
committerNeilBrown <neilb@suse.de>2014-06-05 17:18:19 +1000
commit2844dc32ea67044b345221067207ce67ffe8da76 (patch)
tree4f235e9eacd5a86110b70c39fa21673bb2916946 /drivers/md/dm-stats.h
parentd592a9969141e67a3874c808999a4db4bf82ed83 (diff)
downloadlinux-2844dc32ea67044b345221067207ce67ffe8da76.tar.bz2
md/raid5: deadlock between retry_aligned_read with barrier io
A chunk aligned read increases counter active_aligned_reads and decreases it after sub-device handle it successfully. But when a read error occurs, the read redispatched by raid5d, and the active_aligned_reads will not be decreased until we can grab a stripe head in retry_aligned_read. Now suppose, a barrier io comes, set conf->quiesce to 2, and wait until both active_stripes and active_aligned_reads are zero. The retried chunk aligned read gets stuck at get_active_stripe waiting until conf->quiesce becomes 0. Retry_aligned_read and barrier io are waiting each other now. One possible solution is that we ignore conf->quiesce, let the retried aligned read finish. I reproduced this deadlock and test this patch on centos6.0 Signed-off-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'drivers/md/dm-stats.h')
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