From: Filipe Manana <fdmanana@suse.com>
Date: Tue, 18 Jun 2024 11:15:01 +0000 (+0100)
Subject: btrfs: don't BUG_ON() when 0 reference count at btrfs_lookup_extent_info()
X-Git-Tag: v5.10.238~159
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=9c309d2434abbe880712af7e60da9ead8b6703fe;p=thirdparty%2Fkernel%2Fstable.git

btrfs: don't BUG_ON() when 0 reference count at btrfs_lookup_extent_info()

commit 28cb13f29faf6290597b24b728dc3100c019356f upstream.

Instead of doing a BUG_ON() handle the error by returning -EUCLEAN,
aborting the transaction and logging an error message.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[Minor conflict resolved due to code context change.]
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cf2b65be04b5a..d652d4091b2bd 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -174,6 +174,14 @@ search_again:
 			ei = btrfs_item_ptr(leaf, path->slots[0],
 					    struct btrfs_extent_item);
 			num_refs = btrfs_extent_refs(leaf, ei);
+			if (unlikely(num_refs == 0)) {
+				ret = -EUCLEAN;
+				btrfs_err(fs_info,
+			"unexpected zero reference count for extent item (%llu %u %llu)",
+					  key.objectid, key.type, key.offset);
+				btrfs_abort_transaction(trans, ret);
+				goto out_free;
+			}
 			extent_flags = btrfs_extent_flags(leaf, ei);
 		} else {
 			ret = -EINVAL;
@@ -185,8 +193,6 @@ search_again:
 
 			goto out_free;
 		}
-
-		BUG_ON(num_refs == 0);
 	} else {
 		num_refs = 0;
 		extent_flags = 0;
@@ -216,10 +222,19 @@ search_again:
 			goto search_again;
 		}
 		spin_lock(&head->lock);
-		if (head->extent_op && head->extent_op->update_flags)
+		if (head->extent_op && head->extent_op->update_flags) {
 			extent_flags |= head->extent_op->flags_to_set;
-		else
-			BUG_ON(num_refs == 0);
+		} else if (unlikely(num_refs == 0)) {
+			spin_unlock(&head->lock);
+			mutex_unlock(&head->mutex);
+			spin_unlock(&delayed_refs->lock);
+			ret = -EUCLEAN;
+			btrfs_err(fs_info,
+			  "unexpected zero reference count for extent %llu (%s)",
+				  bytenr, metadata ? "metadata" : "data");
+			btrfs_abort_transaction(trans, ret);
+			goto out_free;
+		}
 
 		num_refs += head->ref_mod;
 		spin_unlock(&head->lock);