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| author |   Coly Li <colyli@suse.de> | 2019-06-28 19:59:29 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2019-06-28 07:39:14 -0600 |
| commit | 578df99b1b0531d19af956530fe4da63d01a1604 (patch) | |
| tree | fc8d3d317790dffc9f8651f8f59517d11ef3f977 | |
| parent | bcache: avoid flushing btree node in cache_set_flush() if io disabled (diff) | |
| download | linux-dev-578df99b1b0531d19af956530fe4da63d01a1604.tar.xz linux-dev-578df99b1b0531d19af956530fe4da63d01a1604.zip | |
bcache: ignore read-ahead request failure on backing device
When md raid device (e.g. raid456) is used as backing device, read-ahead
requests on a degrading and recovering md raid device might be failured
immediately by md raid code, but indeed this md raid array can still be
read or write for normal I/O requests. Therefore such failed read-ahead
request are not real hardware failure. Further more, after degrading and
recovering accomplished, read-ahead requests will be handled by md raid
array again.
For such condition, I/O failures of read-ahead requests don't indicate
real health status (because normal I/O still be served), they should not
be counted into I/O error counter dc->io_errors.
Since there is no simple way to detect whether the backing divice is a
md raid device, this patch simply ignores I/O failures for read-ahead
bios on backing device, to avoid bogus backing device failure on a
degrading md raid array.
Suggested-and-tested-by: Thorsten Knabe <linux@thorsten-knabe.de>
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/md/bcache/io.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/md/bcache/io.c b/drivers/md/bcache/io.c index c25097968319..4d93f07f63e5 100644 --- a/drivers/md/bcache/io.c +++ b/drivers/md/bcache/io.c @@ -58,6 +58,18 @@ void bch_count_backing_io_errors(struct cached_dev *dc, struct bio *bio) WARN_ONCE(!dc, "NULL pointer of struct cached_dev"); + /* + * Read-ahead requests on a degrading and recovering md raid + * (e.g. raid6) device might be failured immediately by md + * raid code, which is not a real hardware media failure. So + * we shouldn't count failed REQ_RAHEAD bio to dc->io_errors. + */ + if (bio->bi_opf & REQ_RAHEAD) { + pr_warn_ratelimited("%s: Read-ahead I/O failed on backing device, ignore", + dc->backing_dev_name); + return; + } + errors = atomic_add_return(1, &dc->io_errors); if (errors < dc->error_limit) pr_err("%s: IO error on backing device, unrecoverable", |