[PATCH] Btrfs: cleanup btrfs_alloc_path()'s caller code

[PATCH] Btrfs: cleanup btrfs_alloc_path()'s caller code

[Yoshinori Sano]

This patch checks return value of btrfs_alloc_path() and removes BUG_ON().

Signed-off-by: Yoshinori Sano <yoshinori.sano@gmail.com>
---
 fs/btrfs/dir-item.c    |    2 ++
 fs/btrfs/extent-tree.c |   12 ++++++++----
 fs/btrfs/file-item.c   |    6 ++++--
 fs/btrfs/file.c        |    3 ++-
 fs/btrfs/inode.c       |   34 ++++++++++++++++++++++++----------
 fs/btrfs/relocation.c  |    1 +
 fs/btrfs/root-tree.c   |    6 ++++--
 fs/btrfs/tree-log.c    |    3 ++-
 fs/btrfs/volumes.c     |    8 ++++++--
 9 files changed, 53 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index c62f02f..e60bf8e 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -142,6 +142,8 @@ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
 	key.offset = btrfs_name_hash(name, name_len);
 
 	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;
 
 	data_size = sizeof(*dir_item) + name_len;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f619c3c..b830db8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -645,7 +645,8 @@ int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
 	struct btrfs_path *path;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	key.objectid = start;
 	key.offset = len;
 	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
@@ -5531,7 +5532,8 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
 	u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	path->leave_spinning = 1;
 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
@@ -6302,7 +6304,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 	int level;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
 	BUG_ON(!wc);
@@ -8699,7 +8702,8 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
 	spin_unlock(&cluster->refill_lock);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	inode = lookup_free_space_inode(root, block_group, path);
 	if (!IS_ERR(inode)) {
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index a6a9d4e..097911e 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -281,7 +281,8 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
 	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 	key.offset = start;
@@ -665,7 +666,8 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 		btrfs_super_csum_size(&root->fs_info->super_copy);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	sector_sum = sums->sums;
 again:
 	next_offset = (u64)-1;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e621ea5..fe623ea 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -599,7 +599,8 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
 	btrfs_drop_extent_cache(inode, start, end - 1, 0);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 again:
 	recow = 0;
 	split = start;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cc60228..aa116dc 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1007,6 +1007,7 @@ static noinline int csum_exist_in_range(struct btrfs_root *root,
 
 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, bytenr,
 				       bytenr + num_bytes - 1, &list);
+	BUG_ON(ret);
 	if (ret == 0 && list_empty(&list))
 		return 0;
 
@@ -1050,7 +1051,8 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 	bool nolock = false;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	if (root == root->fs_info->tree_root) {
 		nolock = true;
 		trans = btrfs_join_transaction_nolock(root, 1);
@@ -1496,13 +1498,15 @@ static noinline int add_pending_csums(struct btrfs_trans_handle *trans,
 			     struct inode *inode, u64 file_offset,
 			     struct list_head *list)
 {
+	int ret;
 	struct btrfs_ordered_sum *sum;
 
 	btrfs_set_trans_block_group(trans, inode);
 
 	list_for_each_entry(sum, list, list) {
-		btrfs_csum_file_blocks(trans,
+		ret = btrfs_csum_file_blocks(trans,
 		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
+		BUG_ON(ret);
 	}
 	return 0;
 }
@@ -1625,8 +1629,8 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
 	int ret;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
-
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;
 
 	/*
@@ -2493,7 +2497,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	int ret;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	BUG_ON(!path); /* FIXME, should not use BUG_ON */
 	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
 
 	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
@@ -2631,7 +2635,8 @@ noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
 	int ret;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;
 	ret = btrfs_lookup_inode(trans, root, path,
 				 &BTRFS_I(inode)->location, 1);
@@ -3290,7 +3295,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
 		btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	path->reada = -1;
 
 	key.objectid = inode->i_ino;
@@ -3817,7 +3823,8 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
 	int ret = 0;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	di = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
 				    namelen, 0);
@@ -4243,6 +4250,8 @@ static int btrfs_real_readdir(struct file *filp, void *dirent,
 		filp->f_pos = 2;
 	}
 	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
 	path->reada = 2;
 
 	btrfs_set_key_type(&key, key_type);
@@ -4523,7 +4532,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	int owner;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return ERR_PTR(-ENOMEM);
 
 	inode = new_inode(root->fs_info->sb);
 	if (!inode)
@@ -7235,7 +7245,11 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 		goto out_unlock;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path) {
+		err = -ENOMEM;
+		drop_inode = 1;
+		goto out_unlock;
+	}
 	key.objectid = inode->i_ino;
 	key.offset = 0;
 	btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 58250e0..7201c24 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4243,6 +4243,7 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
 	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
 				       disk_bytenr + len - 1, &list);
+	BUG_ON(ret);
 
 	while (!list_empty(&list)) {
 		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 6928bff..c330cad 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -40,7 +40,8 @@ int btrfs_search_root(struct btrfs_root *root, u64 search_start,
 	search_key.offset = (u64)-1;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 again:
 	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
 	if (ret < 0)
@@ -141,7 +142,8 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 	unsigned long ptr;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 	if (ret < 0)
 		goto out;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c50271a..5aecd02 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1601,7 +1601,8 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
 		return 0;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	nritems = btrfs_header_nritems(eb);
 	for (i = 0; i < nritems; i++) {
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8b9fb8c..fa84172 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1058,7 +1058,8 @@ static noinline int find_next_chunk(struct btrfs_root *root,
 	struct btrfs_key found_key;
 
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 
 	key.objectid = objectid;
 	key.offset = (u64)-1;
@@ -2067,7 +2068,10 @@ int btrfs_balance(struct btrfs_root *dev_root)
 
 	/* step two, relocate all the chunks */
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path) {
+		mutex_unlock(&dev_root->fs_info->volume_mutex);
+		return -ENOMEM;
+	}
 
 	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
 	key.offset = (u64)-1;
-- 
1.7.1

Re: [PATCH] Btrfs: cleanup btrfs_alloc_path()'s caller code

[Tsutomu Itoh]

(2011/04/09 11:23), Yoshinori Sano wrote:
> This patch checks return value of btrfs_alloc_path() and removes BUG_ON().
> 
> Signed-off-by: Yoshinori Sano <yoshinori.sano@gmail.com>
> ---
>  fs/btrfs/dir-item.c    |    2 ++
>  fs/btrfs/extent-tree.c |   12 ++++++++----
>  fs/btrfs/file-item.c   |    6 ++++--
>  fs/btrfs/file.c        |    3 ++-
>  fs/btrfs/inode.c       |   34 ++++++++++++++++++++++++----------
>  fs/btrfs/relocation.c  |    1 +
>  fs/btrfs/root-tree.c   |    6 ++++--
>  fs/btrfs/tree-log.c    |    3 ++-
>  fs/btrfs/volumes.c     |    8 ++++++--
>  9 files changed, 53 insertions(+), 22 deletions(-)
> 
> diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
> index c62f02f..e60bf8e 100644
> --- a/fs/btrfs/dir-item.c
> +++ b/fs/btrfs/dir-item.c
> @@ -142,6 +142,8 @@ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
>  	key.offset = btrfs_name_hash(name, name_len);
>  
>  	path = btrfs_alloc_path();
> +	if (!path)
> +		return -ENOMEM;
>  	path->leave_spinning = 1;
>  
>  	data_size = sizeof(*dir_item) + name_len;
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index f619c3c..b830db8 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -645,7 +645,8 @@ int btrfs_lookup_extent(struct btrfs_root *root, u64 start, u64 len)
>  	struct btrfs_path *path;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	key.objectid = start;
>  	key.offset = len;
>  	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
> @@ -5531,7 +5532,8 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
>  	u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	path->leave_spinning = 1;
>  	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
> @@ -6302,7 +6304,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
>  	int level;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

If you change this, I think that it is better to change the following caller.  

for example:
  fs/btrfs/relocation.c:
  2231                 btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);

>  
>  	wc = kzalloc(sizeof(*wc), GFP_NOFS);
>  	BUG_ON(!wc);
> @@ -8699,7 +8702,8 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans,
>  	spin_unlock(&cluster->refill_lock);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	inode = lookup_free_space_inode(root, block_group, path);
>  	if (!IS_ERR(inode)) {
> diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
> index a6a9d4e..097911e 100644
> --- a/fs/btrfs/file-item.c
> +++ b/fs/btrfs/file-item.c
> @@ -281,7 +281,8 @@ int btrfs_lookup_csums_range(struct btrfs_root *root, u64 start, u64 end,
>  	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
>  	key.offset = start;
> @@ -665,7 +666,8 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
>  		btrfs_super_csum_size(&root->fs_info->super_copy);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	sector_sum = sums->sums;
>  again:
>  	next_offset = (u64)-1;
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index e621ea5..fe623ea 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -599,7 +599,8 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
>  	btrfs_drop_extent_cache(inode, start, end - 1, 0);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  again:
>  	recow = 0;
>  	split = start;
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index cc60228..aa116dc 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1007,6 +1007,7 @@ static noinline int csum_exist_in_range(struct btrfs_root *root,
>  
>  	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, bytenr,
>  				       bytenr + num_bytes - 1, &list);
> +	BUG_ON(ret);
>  	if (ret == 0 && list_empty(&list))
>  		return 0;
>  
> @@ -1050,7 +1051,8 @@ static noinline int run_delalloc_nocow(struct inode *inode,
>  	bool nolock = false;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	if (root == root->fs_info->tree_root) {
>  		nolock = true;
>  		trans = btrfs_join_transaction_nolock(root, 1);
> @@ -1496,13 +1498,15 @@ static noinline int add_pending_csums(struct btrfs_trans_handle *trans,
>  			     struct inode *inode, u64 file_offset,
>  			     struct list_head *list)
>  {
> +	int ret;
>  	struct btrfs_ordered_sum *sum;
>  
>  	btrfs_set_trans_block_group(trans, inode);
>  
>  	list_for_each_entry(sum, list, list) {
> -		btrfs_csum_file_blocks(trans,
> +		ret = btrfs_csum_file_blocks(trans,
>  		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
> +		BUG_ON(ret);
>  	}
>  	return 0;
>  }
> @@ -1625,8 +1629,8 @@ static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
>  	int ret;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> -
> +	if (!path)
> +		return -ENOMEM;
>  	path->leave_spinning = 1;
>  
>  	/*
> @@ -2493,7 +2497,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
>  	int ret;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	BUG_ON(!path); /* FIXME, should not use BUG_ON */
>  	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
>  
>  	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
> @@ -2631,7 +2635,8 @@ noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
>  	int ret;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

I think that you better change the following.

for ex.
  fs/btrfs/inode.c
  2739         btrfs_update_inode(trans, root, dir);

>  	path->leave_spinning = 1;
>  	ret = btrfs_lookup_inode(trans, root, path,
>  				 &BTRFS_I(inode)->location, 1);
> @@ -3290,7 +3295,8 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
>  		btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	path->reada = -1;
>  
>  	key.objectid = inode->i_ino;
> @@ -3817,7 +3823,8 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
>  	int ret = 0;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	di = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
>  				    namelen, 0);
> @@ -4243,6 +4250,8 @@ static int btrfs_real_readdir(struct file *filp, void *dirent,
>  		filp->f_pos = 2;
>  	}
>  	path = btrfs_alloc_path();
> +	if (!path)
> +		return -ENOMEM;
>  	path->reada = 2;
>  
>  	btrfs_set_key_type(&key, key_type);
> @@ -4523,7 +4532,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
>  	int owner;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return ERR_PTR(-ENOMEM);
>  
>  	inode = new_inode(root->fs_info->sb);
>  	if (!inode)
> @@ -7235,7 +7245,11 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
>  		goto out_unlock;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path) {
> +		err = -ENOMEM;
> +		drop_inode = 1;
> +		goto out_unlock;
> +	}
>  	key.objectid = inode->i_ino;
>  	key.offset = 0;
>  	btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 58250e0..7201c24 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -4243,6 +4243,7 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
>  	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
>  	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
>  				       disk_bytenr + len - 1, &list);
> +	BUG_ON(ret);
>  
>  	while (!list_empty(&list)) {
>  		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
> diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
> index 6928bff..c330cad 100644
> --- a/fs/btrfs/root-tree.c
> +++ b/fs/btrfs/root-tree.c
> @@ -40,7 +40,8 @@ int btrfs_search_root(struct btrfs_root *root, u64 search_start,
>  	search_key.offset = (u64)-1;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  again:
>  	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
>  	if (ret < 0)
> @@ -141,7 +142,8 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
>  	unsigned long ptr;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
>  	if (ret < 0)
>  		goto out;
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index c50271a..5aecd02 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -1601,7 +1601,8 @@ static int replay_one_buffer(struct btrfs_root *log, struct extent_buffer *eb,
>  		return 0;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

I think that you better change the following, too.

for ex.
  fs/btrfs/tree-log.c:
  1775                         wc->process_func(root, path->nodes[*level], wc,
  1776                                  btrfs_header_generation(path->nodes[*level]));


Thanks,
Tsutomu


>  
>  	nritems = btrfs_header_nritems(eb);
>  	for (i = 0; i < nritems; i++) {
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 8b9fb8c..fa84172 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1058,7 +1058,8 @@ static noinline int find_next_chunk(struct btrfs_root *root,
>  	struct btrfs_key found_key;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	key.objectid = objectid;
>  	key.offset = (u64)-1;
> @@ -2067,7 +2068,10 @@ int btrfs_balance(struct btrfs_root *dev_root)
>  
>  	/* step two, relocate all the chunks */
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path) {
> +		mutex_unlock(&dev_root->fs_info->volume_mutex);
> +		return -ENOMEM;
> +	}
>  
>  	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
>  	key.offset = (u64)-1;

Re: [PATCH] Btrfs: cleanup btrfs_alloc_path()'s caller code

[Yoshinori Sano]

Thank you for your review.
I modified the previous patch.

Specifically, all the callers that calls the following are modified
because of the lack of return value check:
- btrfs_drop_snapshot()
- btrfs_update_inode()
- wc->process_func()

However, BUG_ON() code are increased by this modification.

Regards,

Signed-off-by: Yoshinori Sano <yoshinori.sano@gmail.com>
---
 fs/btrfs/dir-item.c         |    2 +
 fs/btrfs/extent-tree.c      |   12 +++++++---
 fs/btrfs/file-item.c        |    6 +++-
 fs/btrfs/file.c             |    3 +-
 fs/btrfs/free-space-cache.c |    4 ++-
 fs/btrfs/inode.c            |   44 ++++++++++++++++++++++++++++--------------
 fs/btrfs/relocation.c       |    4 ++-
 fs/btrfs/root-tree.c        |    6 +++-
 fs/btrfs/transaction.c      |    9 ++++++-
 fs/btrfs/tree-log.c         |   24 +++++++++++++++-------
 fs/btrfs/volumes.c          |    8 +++++-
 11 files changed, 84 insertions(+), 38 deletions(-)

diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index c62f02f..e60bf8e 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -142,6 +142,8 @@ int btrfs_insert_dir_item(struct
btrfs_trans_handle *trans, struct btrfs_root
 	key.offset = btrfs_name_hash(name, name_len);

 	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;

 	data_size = sizeof(*dir_item) + name_len;
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index f619c3c..b830db8 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -645,7 +645,8 @@ int btrfs_lookup_extent(struct btrfs_root *root,
u64 start, u64 len)
 	struct btrfs_path *path;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	key.objectid = start;
 	key.offset = len;
 	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
@@ -5531,7 +5532,8 @@ static int alloc_reserved_tree_block(struct
btrfs_trans_handle *trans,
 	u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	path->leave_spinning = 1;
 	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
@@ -6302,7 +6304,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 	int level;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	wc = kzalloc(sizeof(*wc), GFP_NOFS);
 	BUG_ON(!wc);
@@ -8699,7 +8702,8 @@ int btrfs_remove_block_group(struct
btrfs_trans_handle *trans,
 	spin_unlock(&cluster->refill_lock);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	inode = lookup_free_space_inode(root, block_group, path);
 	if (!IS_ERR(inode)) {
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index a6a9d4e..097911e 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -281,7 +281,8 @@ int btrfs_lookup_csums_range(struct btrfs_root
*root, u64 start, u64 end,
 	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 	key.offset = start;
@@ -665,7 +666,8 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
 		btrfs_super_csum_size(&root->fs_info->super_copy);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	sector_sum = sums->sums;
 again:
 	next_offset = (u64)-1;
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e621ea5..fe623ea 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -599,7 +599,8 @@ int btrfs_mark_extent_written(struct
btrfs_trans_handle *trans,
 	btrfs_drop_extent_cache(inode, start, end - 1, 0);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 again:
 	recow = 0;
 	split = start;
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f561c95..101b96c 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -522,6 +522,7 @@ int btrfs_write_out_cache(struct btrfs_root *root,
 	int num_checksums;
 	int entries = 0;
 	int bitmaps = 0;
+	int err;
 	int ret = 0;
 	bool next_page = false;

@@ -853,7 +854,8 @@ out_free:
 		BTRFS_I(inode)->generation = 0;
 	}
 	kfree(checksums);
-	btrfs_update_inode(trans, root, inode);
+	err = btrfs_update_inode(trans, root, inode);
+	BUG_ON(err);
 	iput(inode);
 	return ret;
 }
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index cc60228..c023053 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -201,9 +201,9 @@ static noinline int insert_inline_extent(struct
btrfs_trans_handle *trans,
 	 * could end up racing with unlink.
 	 */
 	BTRFS_I(inode)->disk_i_size = inode->i_size;
-	btrfs_update_inode(trans, root, inode);
+	ret = btrfs_update_inode(trans, root, inode);

-	return 0;
+	return ret;
 fail:
 	btrfs_free_path(path);
 	return err;
@@ -1007,6 +1007,7 @@ static noinline int csum_exist_in_range(struct
btrfs_root *root,

 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, bytenr,
 				       bytenr + num_bytes - 1, &list);
+	BUG_ON(ret);
 	if (ret == 0 && list_empty(&list))
 		return 0;

@@ -1050,7 +1051,8 @@ static noinline int run_delalloc_nocow(struct
inode *inode,
 	bool nolock = false;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	if (root == root->fs_info->tree_root) {
 		nolock = true;
 		trans = btrfs_join_transaction_nolock(root, 1);
@@ -1496,13 +1498,15 @@ static noinline int add_pending_csums(struct
btrfs_trans_handle *trans,
 			     struct inode *inode, u64 file_offset,
 			     struct list_head *list)
 {
+	int ret;
 	struct btrfs_ordered_sum *sum;

 	btrfs_set_trans_block_group(trans, inode);

 	list_for_each_entry(sum, list, list) {
-		btrfs_csum_file_blocks(trans,
+		ret = btrfs_csum_file_blocks(trans,
 		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
+		BUG_ON(ret);
 	}
 	return 0;
 }
@@ -1625,8 +1629,8 @@ static int insert_reserved_file_extent(struct
btrfs_trans_handle *trans,
 	int ret;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
-
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;

 	/*
@@ -2493,7 +2497,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
 	int ret;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	BUG_ON(!path); /* FIXME, should not use BUG_ON */
 	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));

 	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
@@ -2631,7 +2635,8 @@ noinline int btrfs_update_inode(struct
btrfs_trans_handle *trans,
 	int ret;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	path->leave_spinning = 1;
 	ret = btrfs_lookup_inode(trans, root, path,
 				 &BTRFS_I(inode)->location, 1);
@@ -2735,7 +2740,7 @@ err:

 	btrfs_i_size_write(dir, dir->i_size - name_len * 2);
 	inode->i_ctime = dir->i_mtime = dir->i_ctime = CURRENT_TIME;
-	btrfs_update_inode(trans, root, dir);
+	ret = btrfs_update_inode(trans, root, dir);
 out:
 	return ret;
 }
@@ -3290,7 +3295,8 @@ int btrfs_truncate_inode_items(struct
btrfs_trans_handle *trans,
 		btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	path->reada = -1;

 	key.objectid = inode->i_ino;
@@ -3817,7 +3823,8 @@ static int btrfs_inode_by_name(struct inode
*dir, struct dentry *dentry,
 	int ret = 0;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (path)
+		return -ENOMEM;

 	di = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
 				    namelen, 0);
@@ -4523,7 +4530,8 @@ static struct inode *btrfs_new_inode(struct
btrfs_trans_handle *trans,
 	int owner;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return ERR_PTR(-ENOMEM);

 	inode = new_inode(root->fs_info->sb);
 	if (!inode)
@@ -4737,7 +4745,8 @@ static int btrfs_mknod(struct inode *dir, struct
dentry *dentry,
 	else {
 		inode->i_op = &btrfs_special_inode_operations;
 		init_special_inode(inode, inode->i_mode, rdev);
-		btrfs_update_inode(trans, root, inode);
+		err = btrfs_update_inode(trans, root, inode);
+		BUG_ON(err);
 	}
 	btrfs_update_inode_block_group(trans, inode);
 	btrfs_update_inode_block_group(trans, dir);
@@ -5854,7 +5863,8 @@ again:

 	add_pending_csums(trans, inode, ordered->file_offset, &ordered->list);
 	btrfs_ordered_update_i_size(inode, 0, ordered);
-	btrfs_update_inode(trans, root, inode);
+	ret = btrfs_update_inode(trans, root, inode);
+	BUG_ON(ret);
 out_unlock:
 	unlock_extent_cached(&BTRFS_I(inode)->io_tree, ordered->file_offset,
 			     ordered->file_offset + ordered->len - 1,
@@ -7235,7 +7245,11 @@ static int btrfs_symlink(struct inode *dir,
struct dentry *dentry,
 		goto out_unlock;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path) {
+		err = -ENOMEM;
+		drop_inode = 1;
+		goto out_unlock;
+	}
 	key.objectid = inode->i_ino;
 	key.offset = 0;
 	btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 58250e0..d336517 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2228,7 +2228,8 @@ again:
 		} else {
 			list_del_init(&reloc_root->root_list);
 		}
-		btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
+		ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
+		BUG_ON(ret);
 	}

 	if (found) {
@@ -4243,6 +4244,7 @@ int btrfs_reloc_clone_csums(struct inode *inode,
u64 file_pos, u64 len)
 	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
 	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
 				       disk_bytenr + len - 1, &list);
+	BUG_ON(ret);

 	while (!list_empty(&list)) {
 		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 6928bff..c330cad 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -40,7 +40,8 @@ int btrfs_search_root(struct btrfs_root *root, u64
search_start,
 	search_key.offset = (u64)-1;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 again:
 	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
 	if (ret < 0)
@@ -141,7 +142,8 @@ int btrfs_update_root(struct btrfs_trans_handle
*trans, struct btrfs_root
 	unsigned long ptr;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;
 	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 	if (ret < 0)
 		goto out;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 5b158da..c53469c 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1417,6 +1417,8 @@ int btrfs_commit_transaction(struct
btrfs_trans_handle *trans,
  */
 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 {
+	int err;
+	int update_ref;
 	LIST_HEAD(list);
 	struct btrfs_fs_info *fs_info = root->fs_info;

@@ -1430,9 +1432,12 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root)

 		if (btrfs_header_backref_rev(root->node) <
 		    BTRFS_MIXED_BACKREF_REV)
-			btrfs_drop_snapshot(root, NULL, 0);
+			update_ref = 0;
 		else
-			btrfs_drop_snapshot(root, NULL, 1);
+			update_ref = 1;
+
+		err = btrfs_drop_snapshot(root, NULL, update_ref);
+		BUG_ON(err);
 	}
 	return 0;
 }
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c50271a..eff407c 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -638,7 +638,8 @@ static noinline int replay_one_extent(struct
btrfs_trans_handle *trans,
 	}

 	inode_set_bytes(inode, saved_nbytes);
-	btrfs_update_inode(trans, root, inode);
+	ret = btrfs_update_inode(trans, root, inode);
+	BUG_ON(ret);
 out:
 	if (inode)
 		iput(inode);
@@ -909,7 +910,8 @@ insert:
 			     btrfs_inode_ref_index(eb, ref));
 	BUG_ON(ret);

-	btrfs_update_inode(trans, root, inode);
+	ret = btrfs_update_inode(trans, root, inode);
+	BUG_ON(ret);

 out:
 	ref_ptr = (unsigned long)(ref + 1) + namelen;
@@ -1004,7 +1006,8 @@ static noinline int
fixup_inode_link_count(struct btrfs_trans_handle *trans,
 	btrfs_release_path(root, path);
 	if (nlink != inode->i_nlink) {
 		inode->i_nlink = nlink;
-		btrfs_update_inode(trans, root, inode);
+		ret = btrfs_update_inode(trans, root, inode);
+		BUG_ON(ret);
 	}
 	BTRFS_I(inode)->index_cnt = (u64)-1;

@@ -1099,7 +1102,8 @@ static noinline int link_to_fixup_dir(struct
btrfs_trans_handle *trans,
 	btrfs_release_path(root, path);
 	if (ret == 0) {
 		btrfs_inc_nlink(inode);
-		btrfs_update_inode(trans, root, inode);
+		ret = btrfs_update_inode(trans, root, inode);
+		BUG_ON(ret);
 	} else if (ret == -EEXIST) {
 		ret = 0;
 	} else {
@@ -1601,7 +1605,8 @@ static int replay_one_buffer(struct btrfs_root
*log, struct extent_buffer *eb,
 		return 0;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	nritems = btrfs_header_nritems(eb);
 	for (i = 0; i < nritems; i++) {
@@ -1707,7 +1712,8 @@ static noinline int walk_down_log_tree(struct
btrfs_trans_handle *trans,
 			return -ENOMEM;

 		if (*level == 1) {
-			wc->process_func(root, next, wc, ptr_gen);
+			ret = wc->process_func(root, next, wc, ptr_gen);
+			BUG_ON(ret);

 			path->slots[*level]++;
 			if (wc->free) {
@@ -1772,8 +1778,9 @@ static noinline int walk_up_log_tree(struct
btrfs_trans_handle *trans,
 				parent = path->nodes[*level + 1];

 			root_owner = btrfs_header_owner(parent);
-			wc->process_func(root, path->nodes[*level], wc,
+			ret = wc->process_func(root, path->nodes[*level], wc,
 				 btrfs_header_generation(path->nodes[*level]));
+			BUG_ON(ret);
 			if (wc->free) {
 				struct extent_buffer *next;

@@ -1840,8 +1847,9 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,

 	/* was the root node processed? if not, catch it here */
 	if (path->nodes[orig_level]) {
-		wc->process_func(log, path->nodes[orig_level], wc,
+		ret = wc->process_func(log, path->nodes[orig_level], wc,
 			 btrfs_header_generation(path->nodes[orig_level]));
+		BUG_ON(ret);
 		if (wc->free) {
 			struct extent_buffer *next;

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8b9fb8c..fa84172 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1058,7 +1058,8 @@ static noinline int find_next_chunk(struct
btrfs_root *root,
 	struct btrfs_key found_key;

 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path)
+		return -ENOMEM;

 	key.objectid = objectid;
 	key.offset = (u64)-1;
@@ -2067,7 +2068,10 @@ int btrfs_balance(struct btrfs_root *dev_root)

 	/* step two, relocate all the chunks */
 	path = btrfs_alloc_path();
-	BUG_ON(!path);
+	if (!path) {
+		mutex_unlock(&dev_root->fs_info->volume_mutex);
+		return -ENOMEM;
+	}

 	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
 	key.offset = (u64)-1;
-- 
1.7.1

Re: [PATCH] Btrfs: cleanup btrfs_alloc_path()'s caller code

[Tsutomu Itoh]

(2011/04/12 7:46), Yoshinori Sano wrote:
> Thank you for your review.
> I modified the previous patch.

Other points still existed. I'm sorry not to point it out at a time.

> 
> Specifically, all the callers that calls the following are modified
> because of the lack of return value check:
> - btrfs_drop_snapshot()
> - btrfs_update_inode()
> - wc->process_func()
> 
> However, BUG_ON() code are increased by this modification.
> 
> Regards,
> 
> Signed-off-by: Yoshinori Sano <yoshinori.sano@gmail.com>
> ---
>  fs/btrfs/dir-item.c         |    2 +
>  fs/btrfs/extent-tree.c      |   12 +++++++---
>  fs/btrfs/file-item.c        |    6 +++-
>  fs/btrfs/file.c             |    3 +-
>  fs/btrfs/free-space-cache.c |    4 ++-
>  fs/btrfs/inode.c            |   44 ++++++++++++++++++++++++++++--------------
>  fs/btrfs/relocation.c       |    4 ++-
>  fs/btrfs/root-tree.c        |    6 +++-
>  fs/btrfs/transaction.c      |    9 ++++++-
>  fs/btrfs/tree-log.c         |   24 +++++++++++++++-------
>  fs/btrfs/volumes.c          |    8 +++++-
>  11 files changed, 84 insertions(+), 38 deletions(-)
> 
> diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
> index c62f02f..e60bf8e 100644
> --- a/fs/btrfs/dir-item.c
> +++ b/fs/btrfs/dir-item.c
> @@ -142,6 +142,8 @@ int btrfs_insert_dir_item(struct
> btrfs_trans_handle *trans, struct btrfs_root
>  	key.offset = btrfs_name_hash(name, name_len);
> 
>  	path = btrfs_alloc_path();
> +	if (!path)
> +		return -ENOMEM;
>  	path->leave_spinning = 1;
> 
>  	data_size = sizeof(*dir_item) + name_len;
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index f619c3c..b830db8 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -645,7 +645,8 @@ int btrfs_lookup_extent(struct btrfs_root *root,
> u64 start, u64 len)
>  	struct btrfs_path *path;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	key.objectid = start;
>  	key.offset = len;
>  	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
> @@ -5531,7 +5532,8 @@ static int alloc_reserved_tree_block(struct
> btrfs_trans_handle *trans,
>  	u32 size = sizeof(*extent_item) + sizeof(*block_info) + sizeof(*iref);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
> 
>  	path->leave_spinning = 1;
>  	ret = btrfs_insert_empty_item(trans, fs_info->extent_root, path,
> @@ -6302,7 +6304,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
>  	int level;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
> 
>  	wc = kzalloc(sizeof(*wc), GFP_NOFS);
>  	BUG_ON(!wc);
> @@ -8699,7 +8702,8 @@ int btrfs_remove_block_group(struct
> btrfs_trans_handle *trans,
>  	spin_unlock(&cluster->refill_lock);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
> 
>  	inode = lookup_free_space_inode(root, block_group, path);
>  	if (!IS_ERR(inode)) {
> diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
> index a6a9d4e..097911e 100644
> --- a/fs/btrfs/file-item.c
> +++ b/fs/btrfs/file-item.c
> @@ -281,7 +281,8 @@ int btrfs_lookup_csums_range(struct btrfs_root
> *root, u64 start, u64 end,
>  	u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
> 
>  	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
>  	key.offset = start;
> @@ -665,7 +666,8 @@ int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
>  		btrfs_super_csum_size(&root->fs_info->super_copy);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	sector_sum = sums->sums;
>  again:
>  	next_offset = (u64)-1;
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index e621ea5..fe623ea 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -599,7 +599,8 @@ int btrfs_mark_extent_written(struct
> btrfs_trans_handle *trans,
>  	btrfs_drop_extent_cache(inode, start, end - 1, 0);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

 fs/btrfs/inode.c
  5827                 ret = btrfs_mark_extent_written(trans, inode,
  5828                                                 ordered->file_offset,
  5829                                                 ordered->file_offset +
  5830                                                 ordered->len);
  5831                 if (ret) {
  5832                         err = ret;
  5833                         goto out_unlock;
  5834                 }

I think that you should insert WARN_ON() or BUG_ON() before 'goto out_unlock'.

>  again:
>  	recow = 0;
>  	split = start;
> diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
> index f561c95..101b96c 100644
> --- a/fs/btrfs/free-space-cache.c
> +++ b/fs/btrfs/free-space-cache.c
> @@ -522,6 +522,7 @@ int btrfs_write_out_cache(struct btrfs_root *root,
>  	int num_checksums;
>  	int entries = 0;
>  	int bitmaps = 0;
> +	int err;
>  	int ret = 0;
>  	bool next_page = false;
> 
> @@ -853,7 +854,8 @@ out_free:
>  		BTRFS_I(inode)->generation = 0;
>  	}
>  	kfree(checksums);
> -	btrfs_update_inode(trans, root, inode);
> +	err = btrfs_update_inode(trans, root, inode);
> +	BUG_ON(err);
>  	iput(inode);
>  	return ret;
>  }
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index cc60228..c023053 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -201,9 +201,9 @@ static noinline int insert_inline_extent(struct
> btrfs_trans_handle *trans,
>  	 * could end up racing with unlink.
>  	 */
>  	BTRFS_I(inode)->disk_i_size = inode->i_size;
> -	btrfs_update_inode(trans, root, inode);
> +	ret = btrfs_update_inode(trans, root, inode);
> 
> -	return 0;
> +	return ret;
>  fail:
>  	btrfs_free_path(path);
>  	return err;
> @@ -1007,6 +1007,7 @@ static noinline int csum_exist_in_range(struct
> btrfs_root *root,
> 
>  	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, bytenr,
>  				       bytenr + num_bytes - 1, &list);
> +	BUG_ON(ret);
>  	if (ret == 0 && list_empty(&list))
>  		return 0;
> 
> @@ -1050,7 +1051,8 @@ static noinline int run_delalloc_nocow(struct
> inode *inode,
>  	bool nolock = false;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

If you change this, you should change following caller.

 fs/btrfs/extent_io.c
  2240                         tree->ops->fill_delalloc(inode, page, delalloc_start,
  2241                                                  delalloc_end, &page_started,
  2242                                                  &nr_written);

>  	if (root == root->fs_info->tree_root) {
>  		nolock = true;
>  		trans = btrfs_join_transaction_nolock(root, 1);
> @@ -1496,13 +1498,15 @@ static noinline int add_pending_csums(struct
> btrfs_trans_handle *trans,
>  			     struct inode *inode, u64 file_offset,
>  			     struct list_head *list)
>  {
> +	int ret;
>  	struct btrfs_ordered_sum *sum;
> 
>  	btrfs_set_trans_block_group(trans, inode);
> 
>  	list_for_each_entry(sum, list, list) {
> -		btrfs_csum_file_blocks(trans,
> +		ret = btrfs_csum_file_blocks(trans,
>  		       BTRFS_I(inode)->root->fs_info->csum_root, sum);
> +		BUG_ON(ret);
>  	}
>  	return 0;
>  }
> @@ -1625,8 +1629,8 @@ static int insert_reserved_file_extent(struct
> btrfs_trans_handle *trans,
>  	int ret;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> -
> +	if (!path)
> +		return -ENOMEM;
>  	path->leave_spinning = 1;
> 
>  	/*
> @@ -2493,7 +2497,7 @@ static void btrfs_read_locked_inode(struct inode *inode)
>  	int ret;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	BUG_ON(!path); /* FIXME, should not use BUG_ON */
>  	memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
> 
>  	ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
> @@ -2631,7 +2635,8 @@ noinline int btrfs_update_inode(struct
> btrfs_trans_handle *trans,
>  	int ret;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	path->leave_spinning = 1;
>  	ret = btrfs_lookup_inode(trans, root, path,
>  				 &BTRFS_I(inode)->location, 1);
> @@ -2735,7 +2740,7 @@ err:
> 
>  	btrfs_i_size_write(dir, dir->i_size - name_len * 2);
>  	inode->i_ctime = dir->i_mtime = dir->i_ctime = CURRENT_TIME;
> -	btrfs_update_inode(trans, root, dir);
> +	ret = btrfs_update_inode(trans, root, dir);
>  out:
>  	return ret;
>  }
> @@ -3290,7 +3295,8 @@ int btrfs_truncate_inode_items(struct
> btrfs_trans_handle *trans,
>  		btrfs_drop_extent_cache(inode, new_size & (~mask), (u64)-1, 0);
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

If you return ENOMEM here, I think that following codes lead the problem.

 fs/btrfs/inode.c
  3782                 ret = btrfs_truncate_inode_items(trans, root, inode, 0, 0);
  3783                 if (ret != -EAGAIN)
  3784                         break;
  ...
  3791         }
  ...
  3802         end_writeback(inode);
  3803         return;
  3804 }

>  	path->reada = -1;
> 
>  	key.objectid = inode->i_ino;
> @@ -3817,7 +3823,8 @@ static int btrfs_inode_by_name(struct inode
> *dir, struct dentry *dentry,
>  	int ret = 0;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (path)
> +		return -ENOMEM;
> 
>  	di = btrfs_lookup_dir_item(NULL, root, path, dir->i_ino, name,
>  				    namelen, 0);
> @@ -4523,7 +4530,8 @@ static struct inode *btrfs_new_inode(struct
> btrfs_trans_handle *trans,
>  	int owner;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return ERR_PTR(-ENOMEM);
> 
>  	inode = new_inode(root->fs_info->sb);
>  	if (!inode)
> @@ -4737,7 +4745,8 @@ static int btrfs_mknod(struct inode *dir, struct
> dentry *dentry,
>  	else {
>  		inode->i_op = &btrfs_special_inode_operations;
>  		init_special_inode(inode, inode->i_mode, rdev);
> -		btrfs_update_inode(trans, root, inode);
> +		err = btrfs_update_inode(trans, root, inode);
> +		BUG_ON(err);
>  	}
>  	btrfs_update_inode_block_group(trans, inode);
>  	btrfs_update_inode_block_group(trans, dir);
> @@ -5854,7 +5863,8 @@ again:
> 
>  	add_pending_csums(trans, inode, ordered->file_offset, &ordered->list);
>  	btrfs_ordered_update_i_size(inode, 0, ordered);
> -	btrfs_update_inode(trans, root, inode);
> +	ret = btrfs_update_inode(trans, root, inode);
> +	BUG_ON(ret);
>  out_unlock:
>  	unlock_extent_cached(&BTRFS_I(inode)->io_tree, ordered->file_offset,
>  			     ordered->file_offset + ordered->len - 1,
> @@ -7235,7 +7245,11 @@ static int btrfs_symlink(struct inode *dir,
> struct dentry *dentry,
>  		goto out_unlock;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path) {
> +		err = -ENOMEM;
> +		drop_inode = 1;
> +		goto out_unlock;
> +	}
>  	key.objectid = inode->i_ino;
>  	key.offset = 0;
>  	btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 58250e0..d336517 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -2228,7 +2228,8 @@ again:
>  		} else {
>  			list_del_init(&reloc_root->root_list);
>  		}
> -		btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
> +		ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0);
> +		BUG_ON(ret);
>  	}
> 
>  	if (found) {
> @@ -4243,6 +4244,7 @@ int btrfs_reloc_clone_csums(struct inode *inode,
> u64 file_pos, u64 len)
>  	disk_bytenr = file_pos + BTRFS_I(inode)->index_cnt;
>  	ret = btrfs_lookup_csums_range(root->fs_info->csum_root, disk_bytenr,
>  				       disk_bytenr + len - 1, &list);
> +	BUG_ON(ret);
> 
>  	while (!list_empty(&list)) {
>  		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
> diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
> index 6928bff..c330cad 100644
> --- a/fs/btrfs/root-tree.c
> +++ b/fs/btrfs/root-tree.c
> @@ -40,7 +40,8 @@ int btrfs_search_root(struct btrfs_root *root, u64
> search_start,
>  	search_key.offset = (u64)-1;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  again:
>  	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
>  	if (ret < 0)
> @@ -141,7 +142,8 @@ int btrfs_update_root(struct btrfs_trans_handle
> *trans, struct btrfs_root
>  	unsigned long ptr;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
>  	if (ret < 0)
>  		goto out;
> diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
> index 5b158da..c53469c 100644
> --- a/fs/btrfs/transaction.c
> +++ b/fs/btrfs/transaction.c
> @@ -1417,6 +1417,8 @@ int btrfs_commit_transaction(struct
> btrfs_trans_handle *trans,
>   */
>  int btrfs_clean_old_snapshots(struct btrfs_root *root)
>  {
> +	int err;
> +	int update_ref;
>  	LIST_HEAD(list);
>  	struct btrfs_fs_info *fs_info = root->fs_info;
> 
> @@ -1430,9 +1432,12 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root)
> 
>  		if (btrfs_header_backref_rev(root->node) <
>  		    BTRFS_MIXED_BACKREF_REV)
> -			btrfs_drop_snapshot(root, NULL, 0);
> +			update_ref = 0;
>  		else
> -			btrfs_drop_snapshot(root, NULL, 1);
> +			update_ref = 1;
> +
> +		err = btrfs_drop_snapshot(root, NULL, update_ref);
> +		BUG_ON(err);
>  	}
>  	return 0;
>  }
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index c50271a..eff407c 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -638,7 +638,8 @@ static noinline int replay_one_extent(struct
> btrfs_trans_handle *trans,
>  	}
> 
>  	inode_set_bytes(inode, saved_nbytes);
> -	btrfs_update_inode(trans, root, inode);
> +	ret = btrfs_update_inode(trans, root, inode);
> +	BUG_ON(ret);
>  out:
>  	if (inode)
>  		iput(inode);
> @@ -909,7 +910,8 @@ insert:
>  			     btrfs_inode_ref_index(eb, ref));
>  	BUG_ON(ret);
> 
> -	btrfs_update_inode(trans, root, inode);
> +	ret = btrfs_update_inode(trans, root, inode);
> +	BUG_ON(ret);
> 
>  out:
>  	ref_ptr = (unsigned long)(ref + 1) + namelen;
> @@ -1004,7 +1006,8 @@ static noinline int
> fixup_inode_link_count(struct btrfs_trans_handle *trans,
>  	btrfs_release_path(root, path);
>  	if (nlink != inode->i_nlink) {
>  		inode->i_nlink = nlink;
> -		btrfs_update_inode(trans, root, inode);
> +		ret = btrfs_update_inode(trans, root, inode);
> +		BUG_ON(ret);
>  	}
>  	BTRFS_I(inode)->index_cnt = (u64)-1;
> 
> @@ -1099,7 +1102,8 @@ static noinline int link_to_fixup_dir(struct
> btrfs_trans_handle *trans,
>  	btrfs_release_path(root, path);
>  	if (ret == 0) {
>  		btrfs_inc_nlink(inode);
> -		btrfs_update_inode(trans, root, inode);
> +		ret = btrfs_update_inode(trans, root, inode);
> +		BUG_ON(ret);
>  	} else if (ret == -EEXIST) {
>  		ret = 0;
>  	} else {
> @@ -1601,7 +1605,8 @@ static int replay_one_buffer(struct btrfs_root
> *log, struct extent_buffer *eb,
>  		return 0;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
> 
>  	nritems = btrfs_header_nritems(eb);
>  	for (i = 0; i < nritems; i++) {
> @@ -1707,7 +1712,8 @@ static noinline int walk_down_log_tree(struct
> btrfs_trans_handle *trans,
>  			return -ENOMEM;
> 
>  		if (*level == 1) {
> -			wc->process_func(root, next, wc, ptr_gen);
> +			ret = wc->process_func(root, next, wc, ptr_gen);
> +			BUG_ON(ret);
> 
>  			path->slots[*level]++;
>  			if (wc->free) {
> @@ -1772,8 +1778,9 @@ static noinline int walk_up_log_tree(struct
> btrfs_trans_handle *trans,
>  				parent = path->nodes[*level + 1];
> 
>  			root_owner = btrfs_header_owner(parent);
> -			wc->process_func(root, path->nodes[*level], wc,
> +			ret = wc->process_func(root, path->nodes[*level], wc,
>  				 btrfs_header_generation(path->nodes[*level]));
> +			BUG_ON(ret);
>  			if (wc->free) {
>  				struct extent_buffer *next;
> 
> @@ -1840,8 +1847,9 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
> 
>  	/* was the root node processed? if not, catch it here */
>  	if (path->nodes[orig_level]) {
> -		wc->process_func(log, path->nodes[orig_level], wc,
> +		ret = wc->process_func(log, path->nodes[orig_level], wc,
>  			 btrfs_header_generation(path->nodes[orig_level]));
> +		BUG_ON(ret);
>  		if (wc->free) {
>  			struct extent_buffer *next;
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 8b9fb8c..fa84172 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1058,7 +1058,8 @@ static noinline int find_next_chunk(struct
> btrfs_root *root,
>  	struct btrfs_key found_key;
> 
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;

I think that you should review the callers(do_chunk_alloc(),
btrfs_check_data_free_space(), btrfs_reserve_extent(), and so on).


Thanks,
Tsutomu


> 
>  	key.objectid = objectid;
>  	key.offset = (u64)-1;
> @@ -2067,7 +2068,10 @@ int btrfs_balance(struct btrfs_root *dev_root)
> 
>  	/* step two, relocate all the chunks */
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path) {
> +		mutex_unlock(&dev_root->fs_info->volume_mutex);
> +		return -ENOMEM;
> +	}
> 
>  	key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
>  	key.offset = (u64)-1;