Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Thu, 22 Apr 1999 23:03:13 +0100 (BST) | Subject | Re: Q: generic_file_write sets PG_locked??? |
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Hi,
On 21 Apr 1999 19:46:21 -0500, ebiederm+eric@ccr.net (Eric W. Biederman) said:
> As note on the PG_locked flag. > That simply indicates that there is I/O inprocess on the page and you > can use wait_on_page to wait for it to complete.
> This does not prevent pages from being mapped.
> If we count on PageLocked from keeping a page from being mapped in > while it is being written out, I think that is a part of the current > NFS design that needs to be redesigned.
Yes and no. PageLocked may just indicate a background writeback in progress. That definitely happens in the swap cache right now, but the vfs code doesn't use it for the page cache (yet). It will do. However, if a given filesystem provides its own write-page strategy functions which have their own locking semantics, there's no real reason to prevent it from doing so as long as the page mapping functions continue to block on a non-uptodate page.
> I'm not prepared quite yet, for a large discussion on the code as I > haven't finished testing my prototypes. Once that is done I'll write > up some documentation and start pushing for integration of generic > dirty page handling for 2.3
_Good_. :)
--Stephen
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