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> |
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.. | ||
raid6test | ||
Kconfig | ||
Makefile | ||
bitmap.c | ||
dm-bio-list.h | ||
dm-bio-record.h | ||
dm-crypt.c | ||
dm-emc.c | ||
dm-exception-store.c | ||
dm-hw-handler.c | ||
dm-hw-handler.h | ||
dm-io.c | ||
dm-io.h | ||
dm-ioctl.c | ||
dm-linear.c | ||
dm-log.c | ||
dm-log.h | ||
dm-mpath.c | ||
dm-mpath.h | ||
dm-path-selector.c | ||
dm-path-selector.h | ||
dm-raid1.c | ||
dm-round-robin.c | ||
dm-snap.c | ||
dm-snap.h | ||
dm-stripe.c | ||
dm-table.c | ||
dm-target.c | ||
dm-zero.c | ||
dm.c | ||
dm.h | ||
faulty.c | ||
kcopyd.c | ||
kcopyd.h | ||
linear.c | ||
md.c | ||
mktables.c | ||
multipath.c | ||
raid0.c | ||
raid1.c | ||
raid5.c | ||
raid6.h | ||
raid6algos.c | ||
raid6altivec.uc | ||
raid6int.uc | ||
raid6main.c | ||
raid6mmx.c | ||
raid6recov.c | ||
raid6sse1.c | ||
raid6sse2.c | ||
raid6x86.h | ||
raid10.c | ||
unroll.pl | ||
xor.c |