Btrfs: Add a thread pool just for submit_bio
If a bio submission is after a lock holder waiting for the bio
on the work queue, it is possible to deadlock. Move the bios
into their own pool.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 181c81d..dcea9d7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -529,9 +529,13 @@
* can run with FS locks held, and the writers may be waiting for
* those locks. We don't want ordering in the pending list to cause
* deadlocks, and so the two are serviced separately.
+ *
+ * A third pool does submit_bio to avoid deadlocking with the other
+ * two
*/
struct btrfs_workers workers;
struct btrfs_workers endio_workers;
+ struct btrfs_workers submit_workers;
int thread_pool_size;
#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c6a710a..e5c758e 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1233,8 +1233,10 @@
* cannot dynamically grow.
*/
btrfs_init_workers(&fs_info->workers, fs_info->thread_pool_size);
+ btrfs_init_workers(&fs_info->submit_workers, fs_info->thread_pool_size);
btrfs_init_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
btrfs_start_workers(&fs_info->workers, 1);
+ btrfs_start_workers(&fs_info->submit_workers, 1);
btrfs_start_workers(&fs_info->endio_workers, fs_info->thread_pool_size);
@@ -1343,6 +1345,7 @@
extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
btrfs_stop_workers(&fs_info->workers);
btrfs_stop_workers(&fs_info->endio_workers);
+ btrfs_stop_workers(&fs_info->submit_workers);
fail_iput:
iput(fs_info->btree_inode);
fail:
@@ -1597,6 +1600,7 @@
btrfs_stop_workers(&fs_info->workers);
btrfs_stop_workers(&fs_info->endio_workers);
+ btrfs_stop_workers(&fs_info->submit_workers);
iput(fs_info->btree_inode);
#if 0
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c57458c..ba39685 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2112,7 +2112,8 @@
spin_unlock(&device->io_lock);
if (should_queue)
- btrfs_queue_worker(&root->fs_info->workers, &device->work);
+ btrfs_queue_worker(&root->fs_info->submit_workers,
+ &device->work);
return 0;
}