FAILED: patch "[PATCH] btrfs: do not BUG_ON() on ENOMEM when dropping extent items" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

162d053e15fe ("btrfs: do not BUG_ON() on ENOMEM when dropping extent items for a range") 2766ff61762c ("btrfs: update the number of bytes used by an inode atomically") 5893dfb98f25 ("btrfs: refactor btrfs_drop_extents() to make it easier to extend") ac5887c8e013 ("btrfs: locking: remove all the blocking helpers") a14b78ad06ab ("btrfs: introduce btrfs_inode_lock()/unlock()")
b8d8e1fd570a ("btrfs: introduce btrfs_write_check()")
c86537a42f86 ("btrfs: check FS error state bit early during write") 5e8b9ef30392 ("btrfs: move pos increment and pagecache extension to btrfs_buffered_write") 4e4cabece9f9 ("btrfs: split btrfs_direct_IO to read and write") 196d59ab9ccc ("btrfs: switch extent buffer tree lock to rw_semaphore")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 162d053e15fe985f754ef495a96eb3db970c43ed Mon Sep 17 00:00:00 2001
From: Filipe Manana <[email protected]>
Date: Mon, 28 Nov 2022 15:07:30 +0000
Subject: [PATCH] btrfs: do not BUG_ON() on ENOMEM when dropping extent items
for a range

If we get -ENOMEM while dropping file extent items in a given range, at btrfs_drop_extents(), due to failure to allocate memory when attempting to increment the reference count for an extent or drop the reference count, we handle it with a BUG_ON(). This is excessive, instead we can simply abort the transaction and return the error to the caller. In fact most callers of btrfs_drop_extents(), directly or indirectly, already abort the transaction if btrfs_drop_extents() returns any error.

Also, we already have error paths at btrfs_drop_extents() that may return -ENOMEM and in those cases we abort the transaction, like for example anything that changes the b+tree may return -ENOMEM due to a failure to allocate a new extent buffer when COWing an existing extent buffer, such as a call to btrfs_duplicate_item() for example.

So replace the BUG_ON() calls with proper logic to abort the transaction and return the error.

index 448b143a5cb2..91b00eb2440e 100644
@@ -380,7 +380,10 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 						args->start - extent_offset,
 						0, false);
 				ret = btrfs_inc_extent_ref(trans, &ref);
-				BUG_ON(ret); /* -ENOMEM */
+				if (ret) {
+					btrfs_abort_transaction(trans, ret);
+					break;
+				}
 			}
 			key.offset = args->start;
 		}

@@ -467,7 +470,10 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
 						key.offset - extent_offset, 0,
 						false);
 				ret = btrfs_free_extent(trans, &ref);
-				BUG_ON(ret); /* -ENOMEM */
+				if (ret) {
+					btrfs_abort_transaction(trans, ret);
+					break;
+				}
 				args->bytes_found += extent_end - key.offset;
 			}