fat: add renameat2 RENAME_EXCHANGE flag support

The renameat2 RENAME_EXCHANGE flag allows to atomically exchange two paths
but is currently not supported by the Linux vfat filesystem driver.

Add a vfat_rename_exchange() helper function that implements this support.

The super block lock is acquired during the operation to ensure atomicity,
and in the error path actions made are reversed also with the mutex held.

It makes the operation as transactional as possible, within the limitation
impossed by vfat due not having a journal with logs to replay.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Javier Martinez Canillas <[email protected]>
Acked-by: OGAWA Hirofumi <[email protected]>
Cc: Alexander Larsson <[email protected]>
Cc: Christian Kellner <[email protected]>
Cc: Chung-Chiang Cheng <[email protected]>
Cc: Colin Walters <[email protected]>
Cc: Lennart Poettering <[email protected]>
Cc: Muhammad Usama Anjum <[email protected]>
Cc: Peter Jones <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions