On 13/02/2024 17:59, Darrick J. Wong wrote:
Shouldn't we check that the device supports AWU at all before turning on
the FMODE flag?
Can we easily get this sort of bdev info here?
Currently if we do try to issue an atomic write and AWU for the bdev is
zero, then XFS iomap code will reject it.
Hmm. Well, if we move towards pushing all the hardware checks out of
xfs/iomap and into whatever goes on underneath submit_bio then I guess
we don't need to check device support here at all.
Yeah, I have been thinking about this. But I was still planning on
putting a "bdev on atomic write" check here, as you mentioned.
But is this a proper method to access the bdev for an xfs inode:
STATIC bool
xfs_file_can_atomic_write(
struct xfs_inode *inode)
{
struct xfs_buftarg *target = xfs_inode_buftarg(inode);
struct block_device *bdev = target->bt_bdev;
if (!xfs_inode_atomicwrites(inode))
return false;
return bdev_can_atomic_write(bdev);
}
I do notice the dax check in xfs_bmbt_to_iomap() when assigning
iomap->bdev, which is creating some doubt?
Thanks,
John
