Commit c5b4a50b authored Jun 11, 2018 by Filipe Manana Committed by David Sterba Jun 22, 2018

Btrfs: fix return value on rename exchange failure



If we failed during a rename exchange operation after starting/joining a
transaction, we would end up replacing the return value, stored in the
local 'ret' variable, with the return value from btrfs_end_transaction().
So this could end up returning 0 (success) to user space despite the
operation having failed and aborted the transaction, because if there are
multiple tasks having a reference on the transaction at the time
btrfs_end_transaction() is called by the rename exchange, that function
returns 0 (otherwise it returns -EIO and not the original error value).
So fix this by not overwriting the return value on error after getting
a transaction handle.

Fixes: cdd1fedf ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.9+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 22883ddc

fs/btrfs/inode.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -9443,6 +9443,7 @@ static int btrfs_rename_exchange(struct inode *old_dir,
		u64 new_idx = 0;
		u64 root_objectid;
		int ret;
		int ret2;
		bool root_log_pinned = false;
		bool dest_log_pinned = false;

		@@ -9639,7 +9640,8 @@ out_fail:
		dest_log_pinned = false;
		}
		}
		ret = btrfs_end_transaction(trans);
		ret2 = btrfs_end_transaction(trans);
		ret = ret ? ret : ret2;
		out_notrans:
		if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
		up_read(&fs_info->subvol_sem);

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