Btrfs: check return value of alloc_extent_map()

I add the check on the return value of alloc_extent_map() to several places.
In addition, alloc_extent_map() returns only the address or NULL.
Therefore, check by IS_ERR() is unnecessary. So, I remove IS_ERR() checking.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index b0ff34b96607..65338a1d14ad 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -185,6 +185,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
                         split = alloc_extent_map(GFP_NOFS);
                 if (!split2)
                         split2 = alloc_extent_map(GFP_NOFS);
+                BUG_ON(!split || !split2);
 
                 write_lock(&em_tree->lock);
                 em = lookup_extent_mapping(em_tree, start, len);