Messages in this thread | | | Date | Wed, 23 Jan 2002 12:55:28 -0800 | From | Andrew Morton <> | Subject | Re: [Ext2-devel] Re: Possible Idea with filesystem buffering. |
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"Stephen C. Tweedie" wrote: > > Hi, > > On Tue, Jan 22, 2002 at 05:03:02PM -0200, Rik van Riel wrote: > > On Tue, 22 Jan 2002, Andrew Morton wrote: > > > Hans Reiser wrote: > > > > > > Note that writepage() doesn't get used much. Most VM-initiated > > > filesystem writeback activity is via try_to_release_page(), which > > > has somewhat more vague and flexible semantics. > > > > We may want to change this though, or at the very least get > > rid of the horrible interplay between ->writepage and > > try_to_release_page() ... > > This is actually really important --- writepage on its own cannot > distinguish between requests to flush something to disk (eg. msync or > fsync), and requests to evict dirty data from memory. > > This is really important for ext3's data journaling mode --- syncing > to disk only requires flushing as far as the journal, but evicting > dirty pages requires a full writeback too. That's one place where our > traditional VM notion of writepage just isn't quite fine-grained > enough.
And we use currently use PF_MEMALLOC to work out which context we're being called from. Sigh.
I wish I'd taken better notes of all the square pegs which ext3 had to push into the kernel's round holes. But there were so many :)
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