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.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
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 27056d3..e6d10df 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3573,6 +3573,7 @@ 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");
@@ -3597,9 +3598,19 @@ 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 e10c553..43106f0 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 {
--
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