On 03/10/2023 16:46, Darrick J. Wong wrote:
stat->result_mask |= STATX_WRITE_ATOMIC;The result_mask (which becomes the statx stx_mask) needs to have STATX_WRITE_ATOMIC set any time a filesystem responds to STATX_WRITE_ATOMIC being set in the request_mask, even if the response is "not supported". The attributes_mask also needs to have STATX_ATTR_WRITE_ATOMIC set if the filesystem+file can support the flag, even if it's not currently set for that file. This should get turned into a generic vfs helper for the next fs that wants to support atomic write units: static void generic_fill_statx_atomic_writes(struct kstat *stat, struct block_device *bdev) { u64 min_bytes; /* Confirm that the fs driver knows about this statx request */ stat->result_mask |= STATX_WRITE_ATOMIC; /* Confirm that the file attribute is known to the fs. */ stat->attributes_mask |= STATX_ATTR_WRITE_ATOMIC; /* Fill out the rest of the atomic write fields if supported */ min_bytes = queue_atomic_write_unit_min_bytes(bdev->bd_queue); if (min_bytes == 0) return; stat->atomic_write_unit_min = min_bytes; stat->atomic_write_unit_max = queue_atomic_write_unit_max_bytes(bdev->bd_queue); /* Atomic writes actually supported on this file. */ stat->attributes |= STATX_ATTR_WRITE_ATOMIC; } and then: if (request_mask & STATX_WRITE_ATOMIC) generic_fill_statx_atomic_writes(stat, bdev);
That looks sensible, but, if used by an FS, we would still need a method to include extra FS restrictions, like extent alignment as in 15/21.
Thanks, John
