From: Dan Williams Date: Fri, 6 Jun 2008 05:45:52 +0000 (-0700) Subject: md: fix prexor vs sync_request race X-Git-Tag: v2.6.26-rc6~92 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e0a115e5aa554b93150a8dc1c3fe15467708abb2;p=pandora-kernel.git md: fix prexor vs sync_request race During the initial array synchronization process there is a window between when a prexor operation is scheduled to a specific stripe and when it completes for a sync_request to be scheduled to the same stripe. When this happens the prexor completes and the stripe is unconditionally marked "insync", effectively canceling the sync_request for the stripe. Prior to 2.6.23 this was not a problem because the prexor operation was done under sh->lock. The effect in older kernels being that the prexor would still erroneously mark the stripe "insync", but sync_request would be held off and re-mark the stripe as "!in_sync". Change the write completion logic to not mark the stripe "in_sync" if a prexor was performed. The effect of the change is to sometimes not set STRIPE_INSYNC. The worst this can do is cause the resync to stall waiting for STRIPE_INSYNC to be set. If this were happening, then STRIPE_SYNCING would be set and handle_issuing_new_read_requests would cause all available blocks to eventually be read, at which point prexor would never be used on that stripe any more and STRIPE_INSYNC would eventually be set. echo repair > /sys/block/mdN/md/sync_action will correct arrays that may have lost this race. Cc: Signed-off-by: Dan Williams Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed