Re: [PATCH RESEND 3/10] ext4: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate

From: Theodore Ts'o
Date: Tue Feb 18 2014 - 09:30:30 EST


Namjae,

Did you respond to Matthew Wilcox's comments/question from Feb. 2nd?

> > What if the file is mmaped at the time somebody issues this command?
> > Seems to me we should drop pagecache pages that overlap with the
> > removed blocks. If the removed range is not a multiple of PAGE_SIZE,
> > then we should also drop any pagecache pages after the removed range.
>
> Oops, forgot to add "and if it is a multiple of page size, then we need
> to update the offsets of any pages after the removed page".

Dave responded that XFS does the right thing when doing a punch hole
operation, but it wasn't obvious to me whether FL_COLLAPSE_RANGE does
the right thing with ext4.

Thanks,

- Ted
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