Re: [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event

From: Zach Brown
Date: Tue Feb 20 2007 - 13:41:33 EST

There are some strange O_DIRECT corner cases in here such that the 'last
writer' may actually be a 'last reader' and winning can mean have a copy
of the page in page cache older than the copy on disk.

As long as it is marked dirty so that it eventually gets synced to disk,
it shouldn't matter.

No, Chris is pointing out that an an O_DIRECT write can leave clean read pages in the page cache.

All it takes is giving a source buffer for the write which is an mmap ()ed apeture of the region that is being written to. If you get the offsets right you can get the get_user_pages() down in fs/direct-io.c will populate the page cache before the actual O_DIRECT write gets to it.

- z
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