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Subject[PATCH] rd: Mark ramdisk buffers heads dirty
Date

I have not observed this case but it is possible to get a dirty page
cache with clean buffer heads if we get a clean ramdisk page with
buffer heads generated by a filesystem calling __getblk and then write
to that page from user space through the block device. Then we just
need to hit the proper window and try_to_free_buffers() will mark that
page clean and eventually drop it. Ouch!

To fix this use the generic __set_page_dirty_buffers in the ramdisk
code so that when we mark a page dirty we also mark it's buffer heads
dirty.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
drivers/block/rd.c | 13 +------------
1 files changed, 1 insertions(+), 12 deletions(-)
diff --git a/drivers/block/rd.c b/drivers/block/rd.c
index 701ea77..84163da 100644
--- a/drivers/block/rd.c
+++ b/drivers/block/rd.c
@@ -178,23 +178,12 @@ static int ramdisk_writepages(struct address_space *mapping,
return 0;
}

-/*
- * ramdisk blockdev pages have their own ->set_page_dirty() because we don't
- * want them to contribute to dirty memory accounting.
- */
-static int ramdisk_set_page_dirty(struct page *page)
-{
- if (!TestSetPageDirty(page))
- return 1;
- return 0;
-}
-
static const struct address_space_operations ramdisk_aops = {
.readpage = ramdisk_readpage,
.prepare_write = ramdisk_prepare_write,
.commit_write = ramdisk_commit_write,
.writepage = ramdisk_writepage,
- .set_page_dirty = ramdisk_set_page_dirty,
+ .set_page_dirty = __set_page_dirty_buffers,
.writepages = ramdisk_writepages,
};

--
1.5.3.rc6.17.g1911
-
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