Btrfs: Hold a reference on bios during submit_bio, add some extra bio checks

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 18db4cbe2794..0de51e37e789 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -180,7 +180,11 @@ loop:
                 pending = pending->bi_next;
                 cur->bi_next = NULL;
                 atomic_dec(&device->dev_root->fs_info->nr_async_submits);
+
+                BUG_ON(atomic_read(&cur->bi_cnt) == 0);
+                bio_get(cur);
                 submit_bio(cur->bi_rw, cur);
+                bio_put(cur);
                 num_run++;
 
                 /*
@@ -188,10 +192,11 @@ loop:
                  * is now congested.  Back off and let other work structs
                  * run instead
                  */
-                if (pending && num_run && bdi_write_congested(bdi)) {
+                if (pending && bdi_write_congested(bdi)) {
                         struct bio *old_head;
 
                         spin_lock(&device->io_lock);
+
                         old_head = device->pending_bios;
                         device->pending_bios = pending;
                         if (device->pending_bio_tail)
@@ -2125,7 +2130,9 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
 
         /* don't bother with additional async steps for reads, right now */
         if (!(rw & (1 << BIO_RW))) {
+                bio_get(bio);
                 submit_bio(rw, bio);
+                bio_put(bio);
                 return 0;
         }
 
@@ -2136,6 +2143,7 @@ int schedule_bio(struct btrfs_root *root, struct btrfs_device *device,
          * on a queue for later
          */
         atomic_inc(&root->fs_info->nr_async_submits);
+        WARN_ON(bio->bi_next);
         bio->bi_next = NULL;
         bio->bi_rw |= rw;