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authorNeilBrown <neilb@suse.com>2017-04-05 14:05:50 +1000
committerShaohua Li <shli@fb.com>2017-04-11 10:07:27 -0700
commitc230e7e53526c223a3e1caf40747d6e37c0e4394 (patch)
tree9d7d0696a720d4b49f74e51d9571fb4ee47d7781 /drivers/md/raid1.h
parentae1713e296449caf820635d384a99936ce281a71 (diff)
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md/raid1: simplify the splitting of requests.
raid1 currently splits requests in two different ways for two different reasons. First, bio_split() is used to ensure the bio fits within a resync accounting region. Second, multiple r1bios are allocated for each bio to handle the possiblity of known bad blocks on some devices. This can be simplified to just use bio_split() once, and not use multiple r1bios. We delay the split until we know a maximum bio size that can be handled with a single r1bio, and then split the bio and queue the remainder for later handling. This avoids all loops inside raid1.c request handling. Just a single read, or a single set of writes, is submitted to lower-level devices for each bio that comes from generic_make_request(). When the bio needs to be split, generic_make_request() will do the necessary looping and call md_make_request() multiple times. raid1_make_request() no longer queues request for raid1 to handle, so we can remove that branch from the 'if'. This patch also creates a new private bio_set (conf->bio_split) for splitting bios. Using fs_bio_set is wrong, as it is meant to be used by filesystems, not block devices. Using it inside md can lead to deadlocks under high memory pressure. Delete unused variable in raid1_write_request() (Shaohua) Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'drivers/md/raid1.h')
-rw-r--r--drivers/md/raid1.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index 4271cd7ac2de..b0ab0da6e39e 100644
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -107,6 +107,8 @@ struct r1conf {
mempool_t *r1bio_pool;
mempool_t *r1buf_pool;
+ struct bio_set *bio_split;
+
/* temporary buffer to synchronous IO when attempting to repair
* a read error.
*/