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Hugh Dickins 3066a9670b osd fs: __r4w_get_page rely on PageUptodate for uptodate ... Commit 42cb14b110 ("mm: migrate dirty page without clear_page_dirty_for_io etc") simplified the migration of a PageDirty pagecache page: one stat needs moving from zone to zone and that's about all. It's convenient and safest for it to shift the PageDirty bit from old page to new, just before updating the zone stats: before copying data and marking the new PageUptodate. This is all done while both pages are isolated and locked, just as before; and just as before, there's a moment when the new page is visible in the radix_tree, but not yet PageUptodate. What's new is that it may now be briefly visible as PageDirty before it is PageUptodate. When I scoured the tree to see if this could cause a problem anywhere, the only places I found were in two similar functions __r4w_get_page(): which look up a page with find_get_page() (not using page lock), then claim it's uptodate if it's PageDirty or PageWriteback or PageUptodate. I'm not sure whether that was right before, but now it might be wrong (on rare occasions): only claim the page is uptodate if PageUptodate. Or perhaps the page in question could never be migratable anyway? Signed-off-by: Hugh Dickins <hughd@google.com> Tested-by: Boaz Harrosh <ooo@electrozaur.com> Cc: Benny Halevy <bhalevy@panasas.com> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		History 2015-12-12 10:15:34 -08:00
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Kbuild	pnfs-obj: decode layout, alloc/free lseg	2011-05-29 20:53:06 +03:00
objio_osd.c	osd fs: __r4w_get_page rely on PageUptodate for uptodate	2015-12-12 10:15:34 -08:00
objlayout.c	Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd	2014-10-21 12:53:45 -07:00
objlayout.h	Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd	2014-10-21 12:53:45 -07:00
pnfs_osd_xdr_cli.c	Boaz Harrosh - Fix broken email address	2014-10-19 20:22:32 +03:00