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libceph: resend all writes after the osdmap loses the full flag
With the current full handling, there is a race between osds and clients getting the first map marked full. If the osd wins, it will return -ENOSPC to any writes, but the client may already have writes in flight. This results in the client getting the error and propagating it up the stack. For rbd, the block layer turns this into EIO, which can cause corruption in filesystems above it. To avoid this race, osds are being changed to drop writes that came from clients with an osdmap older than the last osdmap marked full. In order for this to work, clients must resend all writes after they encounter a full -> not full transition in the osdmap. osds will wait for an updated map instead of processing a request from a client with a newer map, so resent writes will not be dropped by the osd unless there is another not full -> full transition. This approach requires both osds and clients to be fixed to avoid the race. Old clients talking to osds with this fix may hang instead of returning EIO and potentially corrupting an fs. New clients talking to old osds have the same behavior as before if they encounter this race. Fixes: http://tracker.ceph.com/issues/6938 Reviewed-by:Sage Weil <sage@inktank.com> Signed-off-by: