On 11/4/2021 12:14 AM, Christoph Hellwig wrote:
> External email: Use caution opening links or attachments
>
>
> What is the actual use case here?
>
One of the immediate use-case is to use this interface with XFS
scrubbing infrastructure [1] (by replacing any SCSI calls e.g. sg_io()
with BLKVERIFY ioctl() calls corresponding to REQ_OP_VERIFY) and
eventually allow and extend other file systems to use it for scrubbing.
[1] man xfs_scrub :-
-x Read all file data extents to look for disk errors.
xfs_scrub will issue O_DIRECT reads to the block device
directly. If the block device is a SCSI disk, it will
instead issue READ VERIFY commands directly to the disk.
If media errors are found, the error report will include
the disk offset, in bytes. If the media errors affect a
file, the report will also include the inode number and
file offset, in bytes. These actions will confirm that
all file data blocks can be read from storage.
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