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md: Use REQ_FAILFAST_* on metadata writes where appropriate

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This can only be supported on personalities which ensure
that md_error() never causes an array to enter the 'failed'
state.  i.e. if marking a device Faulty would cause some
data to be inaccessible, the device is status is left as
non-Faulty.  This is true for RAID1 and RAID10.

If we get a failure writing metadata but the device doesn't
fail, it must be the last device so we re-write without
FAILFAST to improve chance of success.  We also flag the
device as LastDev so that future metadata updates don't
waste time on failfast writes.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
This commit is contained in:
NeilBrown
2016-11-18 16:16:11 +11:00
committed by Shaohua Li
parent 688834e6ae
commit 46533ff7fe
5 changed files with 68 additions and 14 deletions
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44
drivers/md/md.c
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@@ -727,7 +727,13 @@ static void super_written(struct bio *bio)
if (bio->bi_error) {
pr_err("md: super_written gets error=%d\n", bio->bi_error);
md_error(mddev, rdev);
}
if (!test_bit(Faulty, &rdev->flags)
&& (bio->bi_opf & MD_FAILFAST)) {
set_bit(MD_NEED_REWRITE, &mddev->flags);
set_bit(LastDev, &rdev->flags);
}
} else
clear_bit(LastDev, &rdev->flags);
if (atomic_dec_and_test(&mddev->pending_writes))
wake_up(&mddev->sb_wait);
@@ -744,7 +750,13 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
* if zero is reached.
* If an error occurred, call md_error
*/
struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);
struct bio *bio;
int ff = 0;
if (test_bit(Faulty, &rdev->flags))
return;
bio = bio_alloc_mddev(GFP_NOIO, 1, mddev);
atomic_inc(&rdev->nr_pending);
@@ -753,16 +765,24 @@ void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
bio_add_page(bio, page, size, 0);
bio->bi_private = rdev;
bio->bi_end_io = super_written;
bio_set_op_attrs(bio, REQ_OP_WRITE, WRITE_FLUSH_FUA);
if (test_bit(MD_FAILFAST_SUPPORTED, &mddev->flags) &&
test_bit(FailFast, &rdev->flags) &&
!test_bit(LastDev, &rdev->flags))
ff = MD_FAILFAST;
bio_set_op_attrs(bio, REQ_OP_WRITE, WRITE_FLUSH_FUA | ff);
atomic_inc(&mddev->pending_writes);
submit_bio(bio);
}
void md_super_wait(struct mddev *mddev)
int md_super_wait(struct mddev *mddev)
{
/* wait for all superblock writes that were scheduled to complete */
wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
if (test_and_clear_bit(MD_NEED_REWRITE, &mddev->flags))
return -EAGAIN;
return 0;
}
int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
@@ -1334,9 +1354,10 @@ super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
if (IS_ENABLED(CONFIG_LBDAF) && (u64)num_sectors >= (2ULL << 32) &&
rdev->mddev->level >= 1)
num_sectors = (sector_t)(2ULL << 32) - 2;
md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
do {
md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
rdev->sb_page);
md_super_wait(rdev->mddev);
} while (md_super_wait(rdev->mddev) < 0);
return num_sectors;
}
@@ -1877,9 +1898,10 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
sb->data_size = cpu_to_le64(num_sectors);
sb->super_offset = rdev->sb_start;
sb->sb_csum = calc_sb_1_csum(sb);
md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
rdev->sb_page);
md_super_wait(rdev->mddev);
do {
md_super_write(rdev->mddev, rdev, rdev->sb_start, rdev->sb_size,
rdev->sb_page);
} while (md_super_wait(rdev->mddev) < 0);
return num_sectors;
}
@@ -2416,6 +2438,7 @@ repeat:
if (mddev->queue)
blk_add_trace_msg(mddev->queue, "md md_update_sb");
rewrite:
bitmap_update_sb(mddev->bitmap);
rdev_for_each(rdev, mddev) {
char b[BDEVNAME_SIZE];
@@ -2447,7 +2470,8 @@ repeat:
/* only need to write one superblock... */
break;
}
md_super_wait(mddev);
if (md_super_wait(mddev) < 0)
goto rewrite;
/* if there was a failure, MD_CHANGE_DEVS was set, and we re-write super */
if (mddev_is_clustered(mddev) && ret == 0)