Btrfs: don't re-enter when allocating a chunk

If we start running low on metadata space we will try to allocate a chunk,
which could then try to allocate a chunk to add the device entry.  The thing
is we allocate a chunk before we try really hard to make the allocation, so
we should be able to find space for the device entry.  Add a flag to the
trans handle so we know we're currently allocating a chunk so we can just
bail out if we try to allocate another chunk.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

3 files changed, 9 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index d5e60d25ca51..c642fc2cfc2b 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3570,6 +3570,10 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
         int wait_for_alloc = 0;
         int ret = 0;
 
+        /* Don't re-enter if we're already allocating a chunk */
+        if (trans->allocating_chunk)
+                return -ENOSPC;
+
         space_info = __find_space_info(extent_root->fs_info, flags);
         if (!space_info) {
                 ret = update_space_info(extent_root->fs_info, flags,
@@ -3612,6 +3616,8 @@ again:
                 goto again;
         }
 
+        trans->allocating_chunk = true;
+
         /*
          * If we have mixed data/metadata chunks we want to make sure we keep
          * allocating mixed chunks instead of individual chunks.
@@ -3638,6 +3644,7 @@ again:
         check_system_chunk(trans, extent_root, flags);
 
         ret = btrfs_alloc_chunk(trans, extent_root, flags);
+        trans->allocating_chunk = false;
         if (ret < 0 && ret != -ENOSPC)
                 goto out;
 
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 86bb105b3982..24fde97cba81 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -385,6 +385,7 @@ again:
         h->qgroup_reserved = qgroup_reserved;
         h->delayed_ref_elem.seq = 0;
         h->type = type;
+        h->allocating_chunk = false;
         INIT_LIST_HEAD(&h->qgroup_ref_list);
         INIT_LIST_HEAD(&h->new_bgs);
 
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 0e8aa1e6c287..69700f7b20ac 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -68,6 +68,7 @@ struct btrfs_trans_handle {
         struct btrfs_block_rsv *orig_rsv;
         short aborted;
         short adding_csums;
+        bool allocating_chunk;
         enum btrfs_trans_type type;
         /*
          * this root is only needed to validate that the root passed to