On 8/11/25 3:52 AM, Christoph Hellwig wrote:
On Thu, Aug 07, 2025 at 11:48:38AM +0800, Chao Yu wrote:
This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy
in order to tune performance of f2fs data flush flow.
For example, checkpoint will use REQ_FUA to persist CP metadata, however,
some kind device has bad performance on REQ_FUA command, result in that
checkpoint being blocked for long time, w/ this sysfs entry, we can give
an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint,
it can help to mitigate long latency of checkpoint.
That's and odd place to deal with this. If that's a real issue it
should be a block layer tweak to disable FUA, potentially with a quirk
entry in the driver to disable it rather than having to touch a file
system sysfs attribute.
Chao, two years ago Christoph already suggested to integrate this
functionality in the UFS driver. From
https://lore.kernel.org/linux-scsi/[email protected]/:
"Please add quirks for the actually affected devices, and do not
block fua for an entire transport."
See also the ufs_fixups[] array in drivers/ufs/core/ufshcd.c.
Bart.
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