[PATCH 5.10 014/199] btrfs: dont get an EINTR during drop_snapshot for reloc

Greg Kroah-Hartman
2021-01-26T09:16:16Z

From: Josef Bacik <josef@toxicpanda.com>

commit 18d3bff411c8d46d40537483bdc0b61b33ce0371 upstream.

This was partially fixed by f3e3d9cc3525 ("btrfs: avoid possible signal
interruption of btrfs_drop_snapshot() on relocation tree"), however it
missed a spot when we restart a trans handle because we need to end the
transaction. The fix is the same, simply use btrfs_join_transaction()
instead of btrfs_start_transaction() when deleting reloc roots.

Fixes: f3e3d9cc3525 ("btrfs: avoid possible signal interruption of btrfs_drop_snapshot() on relocation tree")
CC: stable@vger.kernel.org # 5.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/extent-tree.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5571,7 +5571,15 @@ int btrfs_drop_snapshot(struct btrfs_roo
goto out_free;
}

- trans = btrfs_start_transaction(tree_root, 0);
+ /*
+ * Use join to avoid potential EINTR from transaction
+ * start. See wait_reserve_ticket and the whole
+ * reservation callchain.
+ */
+ if (for_reloc)
+ trans = btrfs_join_transaction(tree_root);
+ else
+ trans = btrfs_start_transaction(tree_root, 0);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_free;