[PATCH 1/2] btrfs: fix the possible bioc_list memory leak during error

There are two possible ways to leak bioc memory on
btrfs_ordered_extent::bioc_list:

- An error occurred for btrfs_insert_one_raid_extent()
  Then the function btrfs_insert_raid_extent() immediately return
  without freeing any bioc in the bioc_list.

- An ordered extent hit an IO error
  In that case the ordered extent will have BTRFS_ORDERED_IOERR set, and
  skip the call on btrfs_insert_raid_extent() completely.

Fix the problem by:

- Introduce a new helper, btrfs_cleanup_ordered_bioc_list()
  Which will remove all bioc from the bioc_list, and release the bioc.

- Call the above helper for btrfs_insert_raid_extent()
  So that the cleanup helper is always called no matter what.

- Call the above helper for btrfs_finish_one_ordered()
  This is called just before the final release on the ordered extent.

This is reported by Sashiko when reviewing another patch.

Link: https://sashiko.dev/#/patchset/20260817021512.3010812-1-shuangpeng.kernel%40gmail.com
Fixes: 02c372e1f016 ("btrfs: add support for inserting raid stripe extents")
Signed-off-by: Qu Wenruo <[email protected]>
---
 fs/btrfs/inode.c            |  3 +++
 fs/btrfs/raid-stripe-tree.c | 18 ++++++++++++------
 fs/btrfs/raid-stripe-tree.h |  1 +
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8a9b52848fbc..b896358678ab 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3436,6 +3436,9 @@ int btrfs_finish_one_ordered(struct btrfs_ordered_extent *ordered_extent)
 	 */
 	btrfs_remove_ordered_extent(ordered_extent);
 
+	/* Cleanup any remaining biocs attached to the OE. */
+	btrfs_cleanup_ordered_bioc_list(ordered_extent);
+
 	/* once for us */
 	btrfs_put_ordered_extent(ordered_extent);
 	/* once for the tree */
diff --git a/fs/btrfs/raid-stripe-tree.c b/fs/btrfs/raid-stripe-tree.c
index 89e259a47d8d..6291775dbe0e 100644
--- a/fs/btrfs/raid-stripe-tree.c
+++ b/fs/btrfs/raid-stripe-tree.c
@@ -373,7 +373,7 @@ int btrfs_insert_raid_extent(struct btrfs_trans_handle *trans,
 			     struct btrfs_ordered_extent *ordered_extent)
 {
 	struct btrfs_io_context *bioc;
-	int ret;
+	int ret = 0;
 
 	if (!btrfs_fs_incompat(trans->fs_info, RAID_STRIPE_TREE))
 		return 0;
@@ -381,17 +381,23 @@ int btrfs_insert_raid_extent(struct btrfs_trans_handle *trans,
 	list_for_each_entry(bioc, &ordered_extent->bioc_list, rst_ordered_entry) {
 		ret = btrfs_insert_one_raid_extent(trans, bioc);
 		if (ret)
-			return ret;
+			break;
 	}
 
-	while (!list_empty(&ordered_extent->bioc_list)) {
-		bioc = list_first_entry(&ordered_extent->bioc_list,
+	btrfs_cleanup_ordered_bioc_list(ordered_extent);
+	return ret;
+}
+
+void btrfs_cleanup_ordered_bioc_list(struct btrfs_ordered_extent *ordered)
+{
+	while (!list_empty(&ordered->bioc_list)) {
+		struct btrfs_io_context *bioc;
+
+		bioc = list_first_entry(&ordered->bioc_list,
 					typeof(*bioc), rst_ordered_entry);
 		list_del(&bioc->rst_ordered_entry);
 		btrfs_put_bioc(bioc);
 	}
-
-	return 0;
 }
 
 int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
diff --git a/fs/btrfs/raid-stripe-tree.h b/fs/btrfs/raid-stripe-tree.h
index 69942ad43140..eb02cf48511b 100644
--- a/fs/btrfs/raid-stripe-tree.h
+++ b/fs/btrfs/raid-stripe-tree.h
@@ -28,6 +28,7 @@ int btrfs_get_raid_extent_offset(struct btrfs_fs_info *fs_info,
 				 u32 stripe_index, struct btrfs_io_stripe *stripe);
 int btrfs_insert_raid_extent(struct btrfs_trans_handle *trans,
 			     struct btrfs_ordered_extent *ordered_extent);
+void btrfs_cleanup_ordered_bioc_list(struct btrfs_ordered_extent *ordered);
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 int btrfs_insert_one_raid_extent(struct btrfs_trans_handle *trans,
-- 
2.54.0