diff options
author | Kent Overstreet <kmo@daterainc.com> | 2014-03-04 16:42:42 -0800 |
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committer | Kent Overstreet <kmo@daterainc.com> | 2014-03-18 12:23:35 -0700 |
commit | 2a285686c109816ba71a00b9278262cf02648258 (patch) | |
tree | 83be424d1b213a72a36de69b7ed98357c28cbfca /drivers/md/bcache/journal.c | |
parent | 05335cff9f01555b769ac97b7bacc472b7ed047a (diff) | |
download | linux-2a285686c109816ba71a00b9278262cf02648258.tar.bz2 |
bcache: btree locking rework
Add a new lock, b->write_lock, which is required to actually modify - or write -
a btree node; this lock is only held for short durations.
This means we can write out a btree node without taking b->lock, which _is_ held
for long durations - solving a deadlock when btree_flush_write() (from the
journalling code) is called with a btree node locked.
Right now just occurs in bch_btree_set_root(), but with an upcoming journalling
rework is going to happen a lot more.
This also turns b->lock is now more of a read/intent lock instead of a
read/write lock - but not completely, since it still blocks readers. May turn it
into a real intent lock at some point in the future.
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Diffstat (limited to 'drivers/md/bcache/journal.c')
-rw-r--r-- | drivers/md/bcache/journal.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index c8bfc28cd2bd..59e82021b5bb 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -381,16 +381,15 @@ retry: b = best; if (b) { - rw_lock(true, b, b->level); - + mutex_lock(&b->write_lock); if (!btree_current_write(b)->journal) { - rw_unlock(true, b); + mutex_unlock(&b->write_lock); /* We raced */ goto retry; } - bch_btree_node_write(b, NULL); - rw_unlock(true, b); + __bch_btree_node_write(b, NULL); + mutex_unlock(&b->write_lock); } } |