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Subject[RFC PATCH 2/2] jbd: Stabilize pages during writes when in ordered mode
When writing buffers out to disk ahead of committing a transaction, set the
Stable bit on the page to prevent others from wandering in and modifying the
page.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/jbd/commit.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c
index 86b39b1..b1f0eed 100644
--- a/fs/jbd/commit.c
+++ b/fs/jbd/commit.c
@@ -155,13 +155,29 @@ static int journal_write_commit_record(journal_t *journal,
return (ret == -EIO);
}

+static void end_stable_write_sync(struct buffer_head *bh, int uptodate)
+{
+ clear_page_stable(bh->b_page);
+ end_buffer_write_sync(bh, uptodate);
+}
+
static void journal_do_submit_data(struct buffer_head **wbuf, int bufs,
int write_op)
{
int i;

for (i = 0; i < bufs; i++) {
- wbuf[i]->b_end_io = end_buffer_write_sync;
+ struct page *p = wbuf[i]->b_page;
+ if (TestSetPageStable(p))
+ wbuf[i]->b_end_io = end_buffer_write_sync;
+ else
+ wbuf[i]->b_end_io = end_stable_write_sync;
+
+ if (trylock_page(p)) {
+ clear_page_dirty_for_io(p);
+ unlock_page(p);
+ }
+
/* We use-up our safety reference in submit_bh() */
submit_bh(write_op, wbuf[i]);
}

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