From: NeilBrown Date: Fri, 9 Sep 2005 23:23:54 +0000 (-0700) Subject: [PATCH] md: add write-intent-bitmap support to raid5 X-Git-Tag: v2.6.14-rc1~238 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=72626685dc66d455742a7f215a0535c551628b9e;p=pandora-kernel.git [PATCH] md: add write-intent-bitmap support to raid5 Most awkward part of this is delaying write requests until bitmap updates have been flushed. To achieve this, we have a sequence number (seq_flush) which is incremented each time the raid5 is unplugged. If the raid thread notices that this has changed, it flushes bitmap changes, and assigned the value of seq_flush to seq_write. When a write request arrives, it is given the number from seq_write, and that write request may not complete until seq_flush is larger than the saved seq number. We have a new queue for storing stripes which are waiting for a bitmap flush and an extra flag for stripes to record if the write was 'degraded' and so should not clear the a bit in the bitmap. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed