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Subject[md PATCH 4/6] md/raid1: add failfast handling for writes.
When writing to a fastfail device we use MD_FASTFAIL unless
it is the only device being written to.

For resync/recovery, assume there was a working device to
read from so always use REQ_FASTFAIL_DEV.

If a write for resync/recovery fails, we just fail the
device - there is not much else to do.

If a normal failfast write fails, but the device cannot be
failed (must be only one left), we queue for write error
handling. This will call narrow_write_error() to retry the
write synchronously and without any FAILFAST flags.

Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/md/raid1.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 44f93297698d..731fd9fe79ef 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -423,7 +423,24 @@ static void raid1_end_write_request(struct bio *bio)
set_bit(MD_RECOVERY_NEEDED, &
conf->mddev->recovery);

- set_bit(R1BIO_WriteError, &r1_bio->state);
+ if (test_bit(FailFast, &rdev->flags) &&
+ (bio->bi_opf & MD_FAILFAST) &&
+ /* We never try FailFast to WriteMostly devices */
+ !test_bit(WriteMostly, &rdev->flags)) {
+ md_error(r1_bio->mddev, rdev);
+ if (!test_bit(Faulty, &rdev->flags))
+ /* This is the only remaining device,
+ * We need to retry the write without
+ * FailFast
+ */
+ set_bit(R1BIO_WriteError, &r1_bio->state);
+ else {
+ /* Finished with this branch */
+ r1_bio->bios[mirror] = NULL;
+ to_put = bio;
+ }
+ } else
+ set_bit(R1BIO_WriteError, &r1_bio->state);
} else {
/*
* Set R1BIO_Uptodate in our master bio, so that we
@@ -1393,6 +1410,10 @@ static void raid1_make_request(struct mddev *mddev, struct bio * bio)
mbio->bi_bdev = conf->mirrors[i].rdev->bdev;
mbio->bi_end_io = raid1_end_write_request;
bio_set_op_attrs(mbio, op, do_flush_fua | do_sync);
+ if (test_bit(FailFast, &conf->mirrors[i].rdev->flags) &&
+ !test_bit(WriteMostly, &conf->mirrors[i].rdev->flags) &&
+ conf->raid_disks - mddev->degraded > 1)
+ mbio->bi_opf |= MD_FAILFAST;
mbio->bi_private = r1_bio;

atomic_inc(&r1_bio->remaining);
@@ -2061,6 +2082,9 @@ static void sync_request_write(struct mddev *mddev, struct r1bio *r1_bio)
continue;

bio_set_op_attrs(wbio, REQ_OP_WRITE, 0);
+ if (test_bit(FailFast, &conf->mirrors[i].rdev->flags))
+ wbio->bi_opf |= MD_FAILFAST;
+
wbio->bi_end_io = end_sync_write;
atomic_inc(&r1_bio->remaining);
md_sync_acct(conf->mirrors[i].rdev->bdev, bio_sectors(wbio));

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