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dm raid1: clear region outside spinlock 

A clear_region function is permitted to block (in practice, rare) but gets
called in rh_update_states() with a spinlock held.

The bits being marked and cleared by the above functions are used
to update the on-disk log, but are never read directly.  We can
perform these operations outside the spinlock since the
bits are only changed within one thread viz.
   - mark_region in rh_inc()
   - clear_region in rh_update_states().

So, we grab the clean_regions list items via list_splice() within the
spinlock and defer clear_region() until we iterate over the list for
deletion - similar to how the recovered_regions list is already handled.
We then move the flush() call down to ensure it encapsulates the changes
which are done by the later calls to clear_region().

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jonathan Brassow 2007-07-12 17:28:25 +01:00 committed by Linus Torvalds
parent 0764147b11
commit 943317efdb
1 changed files with 6 additions and 6 deletions
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12
drivers/md/dm-raid1.c
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@ -378,10 +378,8 @@ static void rh_update_states(struct region_hash *rh)
list_splice(&rh->clean_regions, &clean);
INIT_LIST_HEAD(&rh->clean_regions);
list_for_each_entry (reg, &clean, list) {
rh->log->type->clear_region(rh->log, reg->key);
list_for_each_entry(reg, &clean, list)
list_del(&reg->hash_list);
}
}
if (!list_empty(&rh->recovered_regions)) {
@ -405,10 +403,12 @@ static void rh_update_states(struct region_hash *rh)
mempool_free(reg, rh->region_pool);
}
rh->log->type->flush(rh->log);
list_for_each_entry_safe (reg, next, &clean, list)
list_for_each_entry_safe(reg, next, &clean, list) {
rh->log->type->clear_region(rh->log, reg->key);
mempool_free(reg, rh->region_pool);
}
rh->log->type->flush(rh->log);
}
static void rh_inc(struct region_hash *rh, region_t region)