Commits
NeilBrown committed 133d4527eab
md: flush writes before starting a recovery. When we write to a degraded array which has a bitmap, we make sure the relevant bit in the bitmap remains set when the write completes (so a 're-add' can quickly rebuilt a temporarily-missing device). If, immediately after such a write starts, we incorporate a spare, commence recovery, and skip over the region where the write is happening (because the 'needs recovery' flag isn't set yet), then that write will not get to the new device. Once the recovery finishes the new device will be trusted, but will have incorrect data, leading to possible corruption. We cannot set the 'needs recovery' flag when we start the write as we do not know easily if the write will be "degraded" or not. That depends on details of the particular raid level and particular write request. This patch fixes a corruption issue of long standing and so it suitable for any -stable kernel. It applied correctly to 3.0 at least and will minor editing to earlier kernels. Reported-by: Bill <billstuff2001@sbcglobal.net> Tested-by: Bill <billstuff2001@sbcglobal.net> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/53A518BB.60709@sbcglobal.net Signed-off-by: NeilBrown <neilb@suse.de>