In func 'ops_run_bio' if you read the dev which the last reading
of this dev didn't return,it will destrory the req/rreq'source of rdev.
It may call hung-task.
For example, for badsector or other reasons, read-operation only used
stripe instead of chunk_aligned_read.
First:stripe 0;second: stripe 8;third:stripe 16.At the block-layer,three
bios merged.
Because media error of sector from 0 to 7, the request retried.
At this time, raid5d readed stripe0 again.But it will set 'bio->next =
NULL'.So the stripe 8 and 16 didn't return.
Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
---
drivers/md/raid5.c | 13 ++++++++++---
drivers/md/raid5.h | 1 +
2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index adda94d..e52ba1b 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -547,9 +547,14 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
rw = WRITE_FUA;
else
rw = WRITE;
- } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
- rw = READ;
- else if (test_and_clear_bit(R5_WantReplace,
+ } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags)) {
+ /*The last read did not return,so skip this read*/
+ if (test_and_set_bit(R5_Reading, &sh->dev[i].flags)) {
+ clear_bit(R5_LOCKED, &sh->dev[i].flags);
+ continue;
+ } else
+ rw = READ;
+ } else if (test_and_clear_bit(R5_WantReplace,
&sh->dev[i].flags)) {
rw = WRITE;
replace_only = 1;
@@ -700,6 +705,7 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
pr_debug("skip op %ld on disc %d for sector %llu\n",
bi->bi_rw, i, (unsigned long long)sh->sector);
clear_bit(R5_LOCKED, &sh->dev[i].flags);
+ clear_bit(R5_Reading, &sh->dev[i].flags);
set_bit(STRIPE_HANDLE, &sh->state);
}
}
@@ -1818,6 +1824,7 @@ static void raid5_end_read_request(struct bio * bi, int error)
}
rdev_dec_pending(rdev, conf->mddev);
clear_bit(R5_LOCKED, &sh->dev[i].flags);
+ clear_bit(R5_Reading, &sh->dev[i].flags);
set_bit(STRIPE_HANDLE, &sh->state);
release_stripe(sh);
}
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index a9fc249..a596df8 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -298,6 +298,7 @@ enum r5dev_flags {
R5_WantReplace, /* We need to update the replacement, we have read
* data in, and now is a good time to write it out.
*/
+ R5_Reading, /* this dev on reading on lld*/
};
/*
--
1.7.9.5
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