[PATCH] btrfs: remove BUG_ON used as assertions

[Aditya Pakki <pakki001@umn.edu>]

alloc_extent_state_atomic() allocates extents via GFP_ATOMIC flag
and cannot fail. There are multiple invocations of BUG_ON on the
return value to check for failure. The patch replaces certain
invocations of BUG_ON by returning the error upstream.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
---
 fs/btrfs/extent_io.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index eb8bd0258360..e72e5a333e71 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -989,7 +989,10 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	node = tree_search_for_insert(tree, start, &p, &parent);
 	if (!node) {
 		prealloc = alloc_extent_state_atomic(prealloc);
-		BUG_ON(!prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
 		err = insert_state(tree, prealloc, start, end,
 				   &p, &parent, &bits, changeset);
 		if (err)
@@ -1054,7 +1057,10 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		}
 
 		prealloc = alloc_extent_state_atomic(prealloc);
-		BUG_ON(!prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
 		err = split_state(tree, state, prealloc, start);
 		if (err)
 			extent_io_tree_panic(tree, err);
@@ -1091,7 +1097,10 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			this_end = last_start - 1;
 
 		prealloc = alloc_extent_state_atomic(prealloc);
-		BUG_ON(!prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
 
 		/*
 		 * Avoid to free 'prealloc' if it can be merged with
@@ -1121,7 +1130,10 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		}
 
 		prealloc = alloc_extent_state_atomic(prealloc);
-		BUG_ON(!prealloc);
+		if (!prealloc) {
+			err = -ENOMEM;
+			goto out;
+		}
 		err = split_state(tree, state, prealloc, end + 1);
 		if (err)
 			extent_io_tree_panic(tree, err);
-- 
2.20.1