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dm raid1: hold all write bios when leg fails

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Hold all write bios when leg fails and errors are handled

When using a userspace daemon such as dmeventd to handle errors, we must
delay completing  bios until it has done its job.
This patch prevents the following race:
  - primary leg fails
  - write "1" fail, the write is held, secondary leg is set default
  - write "2" goes straight to the secondary leg

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Takahiro Yasui <tyasui@redhat.com>
Tested-by: Takahiro Yasui <tyasui@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Mikulas Patocka 2009-12-10 23:52:06 +00:00 committed by Alasdair G Kergon
parent 60f355ead3
commit 929be8fcb4
1 changed files with 10 additions and 2 deletions
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12
drivers/md/dm-raid1.c
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@ -69,6 +69,7 @@ struct mirror_set {
region_t nr_regions;
int in_sync;
int log_failure;
int leg_failure;
atomic_t suspend;
atomic_t default_mirror; /* Default mirror */
@ -211,6 +212,8 @@ static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
struct mirror_set *ms = m->ms;
struct mirror *new;
ms->leg_failure = 1;
/*
* error_count is used for nothing more than a
* simple way to tell if a device has encountered
@ -734,8 +737,12 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
dm_rh_delay(ms->rh, bio);
while ((bio = bio_list_pop(&nosync))) {
map_bio(get_default_mirror(ms), bio);
generic_make_request(bio);
if (unlikely(ms->leg_failure) && errors_handled(ms))
hold_bio(ms, bio);
else {
map_bio(get_default_mirror(ms), bio);
generic_make_request(bio);
}
}
}
@ -848,6 +855,7 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
ms->nr_regions = dm_sector_div_up(ti->len, region_size);
ms->in_sync = 0;
ms->log_failure = 0;
ms->leg_failure = 0;
atomic_set(&ms->suspend, 0);
atomic_set(&ms->default_mirror, DEFAULT_MIRROR);