From 671488cc25f7c194c7c7a9f258bab1df17a6ff69 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 23 Dec 2011 10:17:52 +1100 Subject: [PATCH] md/raid5: allow each slot to have an extra replacement device Just enhance data structures to record a second device per slot to be used as a 'replacement' device, replacing the original. We also have a second bio in each slot in each stripe_head. This will only be used when writing to the array - we need to write to both the original and the replacement at the same time, so will need two bios. For now, only try using the replacement drive for aligned-reads. In this case, we prefer the replacement if it has been recovered far enough, otherwise use the original. This includes a small enhancement. Previously we would only do aligned reads if the target device was fully recovered. Now we also do them if it has recovered far enough. Reviewed-by: Dan Williams Signed-off-by: NeilBrown --- drivers/md/raid5.c | 15 ++++++++++-- drivers/md/raid5.h | 57 +++++++++++++++++++++++++++------------------- 2 files changed, 46 insertions(+), 26 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 6b9fc58e8f2d..94bc35ba4c81 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -3594,6 +3594,7 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio) int dd_idx; struct bio* align_bi; struct md_rdev *rdev; + sector_t end_sector; if (!in_chunk_boundary(mddev, raid_bio)) { pr_debug("chunk_aligned_read : non aligned\n"); @@ -3618,9 +3619,19 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio) 0, &dd_idx, NULL); + end_sector = align_bi->bi_sector + (align_bi->bi_size >> 9); rcu_read_lock(); - rdev = rcu_dereference(conf->disks[dd_idx].rdev); - if (rdev && test_bit(In_sync, &rdev->flags)) { + rdev = rcu_dereference(conf->disks[dd_idx].replacement); + if (!rdev || test_bit(Faulty, &rdev->flags) || + rdev->recovery_offset < end_sector) { + rdev = rcu_dereference(conf->disks[dd_idx].rdev); + if (rdev && + (test_bit(Faulty, &rdev->flags) || + !(test_bit(In_sync, &rdev->flags) || + rdev->recovery_offset >= end_sector))) + rdev = NULL; + } + if (rdev) { sector_t first_bad; int bad_sectors; diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index e10c5531f9c5..43106f01862d 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -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 */ @@ -252,29 +255,35 @@ 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_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*/ + 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 */ +}; /* * Write method */ @@ -344,7 +353,7 @@ enum { struct disk_info { - struct md_rdev *rdev; + struct md_rdev *rdev, *replacement; }; struct r5conf { -- 2.39.5