Commit a7854487 authored by Alexander Lyakas's avatar Alexander Lyakas Committed by NeilBrown
Browse files

md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write. 



Signed-off-by: default avatarAlex Lyakas <alex@zadarastorage.com>
Suggested-by: default avatarYair Hershko <yair@zadarastorage.com>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent b97390ae

drivers/md/raid5.c

+16 −3
Original line number Diff line number Diff line
@@ -2806,12 +2806,25 @@ static void handle_stripe_dirtying(struct r5conf *conf, 
				   int disks)

{

	int rmw = 0, rcw = 0, i;

	if (conf->max_degraded == 2) {

		/* RAID6 requires 'rcw' in current implementation

		 * Calculate the real rcw later - for now fake it

	sector_t recovery_cp = conf->mddev->recovery_cp;



	/* RAID6 requires 'rcw' in current implementation.

	 * Otherwise, check whether resync is now happening or should start.

	 * If yes, then the array is dirty (after unclean shutdown or

	 * initial creation), so parity in some stripes might be inconsistent.

	 * In this case, we need to always do reconstruct-write, to ensure

	 * that in case of drive failure or read-error correction, we

	 * generate correct data from the parity.

	 */

	if (conf->max_degraded == 2 ||

	    (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {

		/* Calculate the real rcw later - for now make it

		 * look like rcw is cheaper

		 */

		rcw = 1; rmw = 2;

		pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",

			 conf->max_degraded, (unsigned long long)recovery_cp,

			 (unsigned long long)sh->sector);

	} else for (i = disks; i--; ) {

		/* would I have to read this buffer for read_modify_write */

		struct r5dev *dev = &sh->dev[i];