md/raid10: add failfast handling for reads.
If a device is marked FailFast, and it is not the only
device we can read from, we mark the bio as MD_FAILFAST.
If this does fail-fast, we don't try read repair but just
allow failure.
If it was the last device, it doesn't get marked Faulty so
the retry happens on the same device - this time without
FAILFAST. A subsequent failure will not retry but will just
pass up the error.
During resync we may use FAILFAST requests, and on a failure
we will simply use the other device(s).
During recovery we will only use FAILFAST in the unusual
case were there are multiple places to read from - i.e. if
there are > 2 devices. If we get a failure we will fail the
device and complete the resync/recovery with remaining
devices.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid10.h b/drivers/md/raid10.h
index 18ec1f7..3162615 100644
--- a/drivers/md/raid10.h
+++ b/drivers/md/raid10.h
@@ -156,5 +156,7 @@ enum r10bio_state {
* flag is set
*/
R10BIO_Previous,
+/* failfast devices did receive failfast requests. */
+ R10BIO_FailFast,
};
#endif