tree 0862eee6405297ef23a5b3d8906cfef5783c0c77
parent 5a3d5c9813db56a75934eb1015367fda23a8b0b4
author Nick Piggin <npiggin@suse.de> 1231281550 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1231286339 -0800

mm: write_cache_pages optimise page cleaning

In write_cache_pages, if we get stuck behind another process that is
cleaning pages, we will be forced to wait for them to finish, then perform
our own writeout (if it was redirtied during the long wait), then wait for
that.

If a page under writeout is still clean, we can skip waiting for it (if
we're part of a data integrity sync, we'll be waiting for all writeout
pages afterwards, so we'll still be waiting for the other guy's write
that's cleaned the page).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>