1 files changed, 93 insertions, 17 deletions

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index b52c672f4c18..5b163572e0ca 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -591,7 +591,7 @@ static int btrfs_delayed_item_reserve_metadata(struct btrfs_trans_handle *trans,
                 return 0;
 
         src_rsv = trans->block_rsv;
-        dst_rsv = &root->fs_info->global_block_rsv;
+        dst_rsv = &root->fs_info->delayed_block_rsv;
 
         num_bytes = btrfs_calc_trans_metadata_size(root, 1);
         ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
@@ -609,7 +609,7 @@ static void btrfs_delayed_item_release_metadata(struct btrfs_root *root,
         if (!item->bytes_reserved)
                 return;
 
-        rsv = &root->fs_info->global_block_rsv;
+        rsv = &root->fs_info->delayed_block_rsv;
         btrfs_block_rsv_release(root, rsv,
                                 item->bytes_reserved);
 }
@@ -617,24 +617,102 @@ static void btrfs_delayed_item_release_metadata(struct btrfs_root *root,
 static int btrfs_delayed_inode_reserve_metadata(
                                         struct btrfs_trans_handle *trans,
                                         struct btrfs_root *root,
+                                        struct inode *inode,
                                         struct btrfs_delayed_node *node)
 {
         struct btrfs_block_rsv *src_rsv;
         struct btrfs_block_rsv *dst_rsv;
         u64 num_bytes;
         int ret;
-
-        if (!trans->bytes_reserved)
-                return 0;
+        int release = false;
 
         src_rsv = trans->block_rsv;
-        dst_rsv = &root->fs_info->global_block_rsv;
+        dst_rsv = &root->fs_info->delayed_block_rsv;
 
         num_bytes = btrfs_calc_trans_metadata_size(root, 1);
+
+        /*
+         * btrfs_dirty_inode will update the inode under btrfs_join_transaction
+         * which doesn't reserve space for speed.  This is a problem since we
+         * still need to reserve space for this update, so try to reserve the
+         * space.
+         *
+         * Now if src_rsv == delalloc_block_rsv we'll let it just steal since
+         * we're accounted for.
+         */
+        if (!trans->bytes_reserved &&
+            src_rsv != &root->fs_info->delalloc_block_rsv) {
+                ret = btrfs_block_rsv_add_noflush(root, dst_rsv, num_bytes);
+                /*
+                 * Since we're under a transaction reserve_metadata_bytes could
+                 * try to commit the transaction which will make it return
+                 * EAGAIN to make us stop the transaction we have, so return
+                 * ENOSPC instead so that btrfs_dirty_inode knows what to do.
+                 */
+                if (ret == -EAGAIN)
+                        ret = -ENOSPC;
+                if (!ret)
+                        node->bytes_reserved = num_bytes;
+                return ret;
+        } else if (src_rsv == &root->fs_info->delalloc_block_rsv) {
+                spin_lock(&BTRFS_I(inode)->lock);
+                if (BTRFS_I(inode)->delalloc_meta_reserved) {
+                        BTRFS_I(inode)->delalloc_meta_reserved = 0;
+                        spin_unlock(&BTRFS_I(inode)->lock);
+                        release = true;
+                        goto migrate;
+                }
+                spin_unlock(&BTRFS_I(inode)->lock);
+
+                /* Ok we didn't have space pre-reserved.  This shouldn't happen
+                 * too often but it can happen if we do delalloc to an existing
+                 * inode which gets dirtied because of the time update, and then
+                 * isn't touched again until after the transaction commits and
+                 * then we try to write out the data.  First try to be nice and
+                 * reserve something strictly for us.  If not be a pain and try
+                 * to steal from the delalloc block rsv.
+                 */
+                ret = btrfs_block_rsv_add_noflush(root, dst_rsv, num_bytes);
+                if (!ret)
+                        goto out;
+
+                ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
+                if (!ret)
+                        goto out;
+
+                /*
+                 * Ok this is a problem, let's just steal from the global rsv
+                 * since this really shouldn't happen that often.
+                 */
+                WARN_ON(1);
+                ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
+                                              dst_rsv, num_bytes);
+                goto out;
+        }
+
+migrate:
         ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
+
+out:
+        /*
+         * Migrate only takes a reservation, it doesn't touch the size of the
+         * block_rsv.  This is to simplify people who don't normally have things
+         * migrated from their block rsv.  If they go to release their
+         * reservation, that will decrease the size as well, so if migrate
+         * reduced size we'd end up with a negative size.  But for the
+         * delalloc_meta_reserved stuff we will only know to drop 1 reservation,
+         * but we could in fact do this reserve/migrate dance several times
+         * between the time we did the original reservation and we'd clean it
+         * up.  So to take care of this, release the space for the meta
+         * reservation here.  I think it may be time for a documentation page on
+         * how block rsvs. work.
+         */
         if (!ret)
                 node->bytes_reserved = num_bytes;
 
+        if (release)
+                btrfs_block_rsv_release(root, src_rsv, num_bytes);
+
         return ret;
 }
 
@@ -646,7 +724,7 @@ static void btrfs_delayed_inode_release_metadata(struct btrfs_root *root,
         if (!node->bytes_reserved)
                 return;
 
-        rsv = &root->fs_info->global_block_rsv;
+        rsv = &root->fs_info->delayed_block_rsv;
         btrfs_block_rsv_release(root, rsv,
                                 node->bytes_reserved);
         node->bytes_reserved = 0;
@@ -1026,7 +1104,7 @@ int btrfs_run_delayed_items(struct btrfs_trans_handle *trans,
         path->leave_spinning = 1;
 
         block_rsv = trans->block_rsv;
-        trans->block_rsv = &root->fs_info->global_block_rsv;
+        trans->block_rsv = &root->fs_info->delayed_block_rsv;
 
         delayed_root = btrfs_get_delayed_root(root);
 
@@ -1069,7 +1147,7 @@ static int __btrfs_commit_inode_delayed_items(struct btrfs_trans_handle *trans,
         path->leave_spinning = 1;
 
         block_rsv = trans->block_rsv;
-        trans->block_rsv = &node->root->fs_info->global_block_rsv;
+        trans->block_rsv = &node->root->fs_info->delayed_block_rsv;
 
         ret = btrfs_insert_delayed_items(trans, path, node->root, node);
         if (!ret)
@@ -1149,7 +1227,7 @@ static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
                 goto free_path;
 
         block_rsv = trans->block_rsv;
-        trans->block_rsv = &root->fs_info->global_block_rsv;
+        trans->block_rsv = &root->fs_info->delayed_block_rsv;
 
         ret = btrfs_insert_delayed_items(trans, path, root, delayed_node);
         if (!ret)
@@ -1641,7 +1719,7 @@ int btrfs_fill_inode(struct inode *inode, u32 *rdev)
         inode->i_gid = btrfs_stack_inode_gid(inode_item);
         btrfs_i_size_write(inode, btrfs_stack_inode_size(inode_item));
         inode->i_mode = btrfs_stack_inode_mode(inode_item);
-        inode->i_nlink = btrfs_stack_inode_nlink(inode_item);
+        set_nlink(inode, btrfs_stack_inode_nlink(inode_item));
         inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
         BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);
         BTRFS_I(inode)->sequence = btrfs_stack_inode_sequence(inode_item);
@@ -1685,12 +1763,10 @@ int btrfs_delayed_update_inode(struct btrfs_trans_handle *trans,
                 goto release_node;
         }
 
-        ret = btrfs_delayed_inode_reserve_metadata(trans, root, delayed_node);
-        /*
-         * we must reserve enough space when we start a new transaction,
-         * so reserving metadata failure is impossible
-         */
-        BUG_ON(ret);
+        ret = btrfs_delayed_inode_reserve_metadata(trans, root, inode,
+                                                   delayed_node);
+        if (ret)
+                goto release_node;
 
         fill_stack_inode_item(trans, &delayed_node->inode_item, inode);
         delayed_node->inode_dirty = 1;