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authorHugh Dickins <hughd@google.com>2015-12-11 13:40:38 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-12-12 10:15:34 -0800
commit3066a9670ba6f57dd5046640a2494912a2110f1e (patch)
treee82649341e0c55c8863b3caeb41da4c88f0dd140
parented0f1e2102b6f245210be5f93a08d708b6ac070f (diff)
downloadlinux-3066a9670ba6f57dd5046640a2494912a2110f1e.tar.gz
osd fs: __r4w_get_page rely on PageUptodate for uptodate
Commit 42cb14b110a5 ("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>
-rw-r--r--fs/exofs/inode.c5
-rw-r--r--fs/nfs/objlayout/objio_osd.c5
2 files changed, 2 insertions, 8 deletions
diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index 73c64daa0f55..60f03b78914e 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -592,10 +592,7 @@ static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
}
unlock_page(page);
}
- if (PageDirty(page) || PageWriteback(page))
- *uptodate = true;
- else
- *uptodate = PageUptodate(page);
+ *uptodate = PageUptodate(page);
EXOFS_DBGMSG2("index=0x%lx uptodate=%d\n", index, *uptodate);
return page;
} else {
diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 5c0c6b58157f..9aebffb40505 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -476,10 +476,7 @@ static struct page *__r4w_get_page(void *priv, u64 offset, bool *uptodate)
}
unlock_page(page);
}
- if (PageDirty(page) || PageWriteback(page))
- *uptodate = true;
- else
- *uptodate = PageUptodate(page);
+ *uptodate = PageUptodate(page);
dprintk("%s: index=0x%lx uptodate=%d\n", __func__, index, *uptodate);
return page;
}