Merge tag 'md-3.3' of git://neil.brown.name/md

md update for 3.3

Big change is new hot-replacement.
A slot in an array can hold 2 devices - one that
wants-replacement and one that is the replacement.
Once the replacement is built - either from the
original or (in the case of errors) from elsewhere,
the wants-replacement device will be removed.

* tag 'md-3.3' of git://neil.brown.name/md: (36 commits)
  md/raid1: Mark device want_replacement when we see a write error.
  md/raid1: If there is a spare and a want_replacement device, start replacement.
  md/raid1: recognise replacements when assembling arrays.
  md/raid1: handle activation of replacement device when recovery completes.
  md/raid1: Allow a failed replacement device to be removed.
  md/raid1: Allocate spare to store replacement devices and their bios.
  md/raid1:  Replace use of mddev->raid_disks with conf->raid_disks.
  md/raid10: If there is a spare and a want_replacement device, start replacement.
  md/raid10: recognise replacements when assembling array.
  md/raid10: Allow replacement device to be replace old drive.
  md/raid10: handle recovery of replacement devices.
  md/raid10:  Handle replacement devices during resync.
  md/raid10: writes should get directed to replacement as well as original.
  md/raid10: allow removal of failed replacement devices.
  md/raid10: preferentially read from replacement device if possible.
  md/raid10:  change read_balance to return an rdev
  md/raid10: prepare data structures for handling replacement.
  md/raid5: Mark device want_replacement when we see a write error.
  md/raid5: If there is a spare and a want_replacement device, start replacement.
  md/raid5: recognise replacements when assembling array.
  ...

1 files changed, 55 insertions, 43 deletions

diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index e10c5531f9c..8d8e13934a4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -27,7 +27,7 @@
  * The possible state transitions are:
  *
  *  Empty -> Want   - on read or write to get old data for  parity calc
- *  Empty -> Dirty  - on compute_parity to satisfy write/sync request.(RECONSTRUCT_WRITE)
+ *  Empty -> Dirty  - on compute_parity to satisfy write/sync request.
  *  Empty -> Clean  - on compute_block when computing a block for failed drive
  *  Want  -> Empty  - on failed read
  *  Want  -> Clean  - on successful completion of read request
@@ -226,8 +226,11 @@ struct stripe_head {
 		#endif
 	} ops;
 	struct r5dev {
-		struct bio	req;
-		struct bio_vec	vec;
+		/* rreq and rvec are used for the replacement device when
+		 * writing data to both devices.
+		 */
+		struct bio	req, rreq;
+		struct bio_vec	vec, rvec;
 		struct page	*page;
 		struct bio	*toread, *read, *towrite, *written;
 		sector_t	sector;			/* sector of this page */
@@ -239,7 +242,13 @@ struct stripe_head {
  *     for handle_stripe.
  */
 struct stripe_head_state {
-	int syncing, expanding, expanded;
+	/* 'syncing' means that we need to read all devices, either
+	 * to check/correct parity, or to reconstruct a missing device.
+	 * 'replacing' means we are replacing one or more drives and
+	 * the source is valid at this point so we don't need to
+	 * read all devices, just the replacement targets.
+	 */
+	int syncing, expanding, expanded, replacing;
 	int locked, uptodate, to_read, to_write, failed, written;
 	int to_fill, compute, req_compute, non_overwrite;
 	int failed_num[2];
@@ -252,38 +261,41 @@ struct stripe_head_state {
 	int handle_bad_blocks;
 };
 
-/* Flags */
-#define	R5_UPTODATE	0	/* page contains current data */
-#define	R5_LOCKED	1	/* IO has been submitted on "req" */
-#define	R5_OVERWRITE	2	/* towrite covers whole page */
+/* Flags for struct r5dev.flags */
+enum r5dev_flags {
+	R5_UPTODATE,	/* page contains current data */
+	R5_LOCKED,	/* IO has been submitted on "req" */
+	R5_DOUBLE_LOCKED,/* Cannot clear R5_LOCKED until 2 writes complete */
+	R5_OVERWRITE,	/* towrite covers whole page */
 /* and some that are internal to handle_stripe */
-#define	R5_Insync	3	/* rdev && rdev->in_sync at start */
-#define	R5_Wantread	4	/* want to schedule a read */
-#define	R5_Wantwrite	5
-#define	R5_Overlap	7	/* There is a pending overlapping request on this block */
-#define	R5_ReadError	8	/* seen a read error here recently */
-#define	R5_ReWrite	9	/* have tried to over-write the readerror */
+	R5_Insync,	/* rdev && rdev->in_sync at start */
+	R5_Wantread,	/* want to schedule a read */
+	R5_Wantwrite,
+	R5_Overlap,	/* There is a pending overlapping request
+			 * on this block */
+	R5_ReadError,	/* seen a read error here recently */
+	R5_ReWrite,	/* have tried to over-write the readerror */
 
-#define	R5_Expanded	10	/* This block now has post-expand data */
-#define	R5_Wantcompute	11	/* compute_block in progress treat as
-				 * uptodate
-				 */
-#define	R5_Wantfill	12	/* dev->toread contains a bio that needs
-				 * filling
-				 */
-#define	R5_Wantdrain	13	/* dev->towrite needs to be drained */
-#define	R5_WantFUA	14	/* Write should be FUA */
-#define	R5_WriteError	15	/* got a write error - need to record it */
-#define	R5_MadeGood	16	/* A bad block has been fixed by writing to it*/
-/*
- * Write method
- */
-#define RECONSTRUCT_WRITE	1
-#define READ_MODIFY_WRITE	2
-/* not a write method, but a compute_parity mode */
-#define	CHECK_PARITY		3
-/* Additional compute_parity mode -- updates the parity w/o LOCKING */
-#define UPDATE_PARITY		4
+	R5_Expanded,	/* This block now has post-expand data */
+	R5_Wantcompute,	/* compute_block in progress treat as
+			 * uptodate
+			 */
+	R5_Wantfill,	/* dev->toread contains a bio that needs
+			 * filling
+			 */
+	R5_Wantdrain,	/* dev->towrite needs to be drained */
+	R5_WantFUA,	/* Write should be FUA */
+	R5_WriteError,	/* got a write error - need to record it */
+	R5_MadeGood,	/* A bad block has been fixed by writing to it */
+	R5_ReadRepl,	/* Will/did read from replacement rather than orig */
+	R5_MadeGoodRepl,/* A bad block on the replacement device has been
+			 * fixed by writing to it */
+	R5_NeedReplace,	/* This device has a replacement which is not
+			 * up-to-date at this stripe. */
+	R5_WantReplace, /* We need to update the replacement, we have read
+			 * data in, and now is a good time to write it out.
+			 */
+};
 
 /*
  * Stripe state
@@ -311,13 +323,14 @@ enum {
 /*
  * Operation request flags
  */
-#define STRIPE_OP_BIOFILL	0
-#define STRIPE_OP_COMPUTE_BLK	1
-#define STRIPE_OP_PREXOR	2
-#define STRIPE_OP_BIODRAIN	3
-#define STRIPE_OP_RECONSTRUCT	4
-#define STRIPE_OP_CHECK	5
-
+enum {
+	STRIPE_OP_BIOFILL,
+	STRIPE_OP_COMPUTE_BLK,
+	STRIPE_OP_PREXOR,
+	STRIPE_OP_BIODRAIN,
+	STRIPE_OP_RECONSTRUCT,
+	STRIPE_OP_CHECK,
+};
 /*
  * Plugging:
  *
@@ -344,13 +357,12 @@ enum {
 
 
 struct disk_info {
-	struct md_rdev	*rdev;
+	struct md_rdev	*rdev, *replacement;
 };
 
 struct r5conf {
 	struct hlist_head	*stripe_hashtbl;
 	struct mddev		*mddev;
-	struct disk_info	*spare;
 	int			chunk_sectors;
 	int			level, algorithm;
 	int			max_degraded;