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authorNeilBrown <neilb@cse.unsw.edu.au>2005-09-09 16:23:54 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-09 16:39:12 -0700
commit72626685dc66d455742a7f215a0535c551628b9e (patch)
tree91e19a61a5a3b782007132b6b2e353e8936dd656 /arch/s390/math-emu
parent0002b2718dd04da67c21f8a7830de8d95a9b0345 (diff)
[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 <neilb@cse.unsw.edu.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/s390/math-emu')
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