This is a question regarding the atomic writes work, and whether it is
proper to store atomic write-related bdev request_queue limits in
xfs_buftarg, as already discussed in
https://lore.kernel.org/linux-xfs/6430d813-cb30-4a66-94e1-ea89bdc921da@xxxxxxxxxx/
(and also in the v2 series).
I can't get a conclusion, so I am sending a separate mail.
A suggestion is to store atomic_write_unit_{min, max} in xfs_buftarg,
like we do for bdev logical block size. But the concern is "geometry of
the device can change underneath", see
https://lore.kernel.org/linux-xfs/20231003161029.GG21298@frogsfrogsfrogs/#t
(so do not do it).
We only need those limits in XFS for statx reporting of
atomic_write_unit_{min, max}, as in that series the block layer will
reject out-of-limit atomic writes.
If those limits did change after mount, then the worst that happens is
that we report incorrect atomic_write_unit_{min, max} values and the
user may have IOs rejected unexpectedly.
I assume that we would not normally consider adding other bdev
request_queue limits to xfs_buftarg, and we rely on the block layer to
handle all sizes of BIOs submitted.
Please advise.
John
