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* Can we change the S_DAX flag immediately on XFS without dropping caches?
@ 2020-07-28  2:00 Li, Hao
  2020-07-28  2:20 ` Dave Chinner
  0 siblings, 1 reply; 14+ messages in thread
From: Li, Hao @ 2020-07-28  2:00 UTC (permalink / raw)
  To: linux-xfs, linux-nvdimm; +Cc: ira.weiny, Gotou, Yasunori

Hi,

I have noticed that we have to drop caches to make the changing of S_DAX
flag take effect after using chattr +x to turn on DAX for a existing
regular file. The related function is xfs_diflags_to_iflags, whose
second parameter determines whether we should set S_DAX immediately.

I can't figure out why we do this. Is this because the page caches in
address_space->i_pages are hard to deal with? I also wonder what will
happen if we set S_DAX unconditionally. Thanks!

Regards,
Hao Li



^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2020-08-18  9:16 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-28  2:00 Can we change the S_DAX flag immediately on XFS without dropping caches? Li, Hao
2020-07-28  2:20 ` Dave Chinner
2020-07-29  2:23   ` Yasunori Goto
2020-07-29 16:10     ` Ira Weiny
2020-07-31  9:12       ` Li, Hao
2020-08-05  8:10         ` Li, Hao
2020-08-05 15:44           ` Darrick J. Wong
2020-08-07 16:57             ` Ira Weiny
2020-07-31 10:04       ` Yasunori Goto
2020-07-29 23:21     ` Dave Chinner
2020-07-31  9:15       ` Li, Hao
2020-07-31  9:59       ` Yasunori Goto
2020-08-07 17:09         ` Ira Weiny
2020-08-18  9:16           ` Li, Hao

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