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SubjectRe: [PATCH] update ctime and mtime for mmaped write
Miklos Szeredi wrote:
>>>> Why is the flag checked in __fput()?
>>> It's because of this bit in the standard:
>>> If there is no such call and if the underlying file is modified
>>> as a result of a write reference, then these fields shall be
>>> marked for update at some time after the write reference.
>>> It could be done in munmap/mremap, but it seemed more difficult to
>>> track down all the places where the vma is removed. But yes, that may
>>> be a nicer solution.
>> It seems to me that, with this support, a file, which is mmap'd,
>> modified, but never msync'd or munmap'd, will never get its mtime
>> updated. Or did I miss that?
>> I also don't see how an mmap'd block device will get its mtime
>> updated either.
> __fput() will be called when there are no more references to 'file',
> then it will update the time if the flag is set. This applies to
> regular files as well as devices.

I suspect that you will find that, for a block device, the wrong inode
gets updated. That's where the bd_inode_update_time() portion of my
proposed patch came from.

> But I've moved the check from __fput to remove_vma() in the next
> revision of the patch, which would give slightly nicer semantics, and
> be equally conforming.

This still does not address the situation where a file is 'permanently'
mmap'd, does it?


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