btrfs: Don't BUG_ON() errors in update_ref_for_cow()

The only caller of update_ref_for_cow() is __btrfs_cow_block() which was
originally ignoring any return values. update_ref_for_cow() however doesn't
look like a candidate to become a void function - there are a few places
where errors can occur.

So instead I changed update_ref_for_cow() to bubble all errors up (instead
of BUG_ON). __btrfs_cow_block() was then updated to catch and BUG_ON() any
errors from update_ref_for_cow(). The end effect is that we have no change
in behavior, but about 8 different places where a BUG_ON(ret) was removed.

Obviously a future patch will have to address the BUG_ON() in
__btrfs_cow_block().

Signed-off-by: Mark Fasheh <mfasheh@suse.de>

1 files changed, 7 insertions, 4 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 9d472c2a8de8..e2e43c07f6b1 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -331,7 +331,8 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
         if (btrfs_block_can_be_shared(root, buf)) {
                 ret = btrfs_lookup_extent_info(trans, root, buf->start,
                                                buf->len, &refs, &flags);
-                BUG_ON(ret);
+                if (ret)
+                        return ret;
                 BUG_ON(refs == 0);
         } else {
                 refs = 1;
@@ -375,7 +376,8 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
                                                           buf->start,
                                                           buf->len,
                                                           new_flags, 0);
-                        BUG_ON(ret);
+                        if (ret)
+                                return ret;
                 }
         } else {
                 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
@@ -415,7 +417,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 {
         struct btrfs_disk_key disk_key;
         struct extent_buffer *cow;
-        int level;
+        int level, ret;
         int last_ref = 0;
         int unlock_orig = 0;
         u64 parent_start;
@@ -467,7 +469,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
                             (unsigned long)btrfs_header_fsid(cow),
                             BTRFS_FSID_SIZE);
 
-        update_ref_for_cow(trans, root, buf, cow, &last_ref);
+        ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
+        BUG_ON(ret);
 
         if (root->ref_cows)
                 btrfs_reloc_cow_block(trans, root, buf, cow);