identify multipage ->writepages() calls
NFS needs to be able to distinguish between single-page ->writepage() calls and
multipage ->writepages() calls.
For the single-page writepage calls NFS can kick off the I/O within the
context of ->writepage().
For multipage ->writepages calls, nfs_writepage() will leave the I/O pending
and nfs_writepages() will kick off the I/O when it all has been queued up
within NFS.
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 64a36ba..b096159 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -53,10 +53,11 @@
loff_t start;
loff_t end;
- unsigned nonblocking:1; /* Don't get stuck on request queues */
- unsigned encountered_congestion:1; /* An output: a queue is full */
- unsigned for_kupdate:1; /* A kupdate writeback */
- unsigned for_reclaim:1; /* Invoked from the page allocator */
+ unsigned nonblocking:1; /* Don't get stuck on request queues */
+ unsigned encountered_congestion:1; /* An output: a queue is full */
+ unsigned for_kupdate:1; /* A kupdate writeback */
+ unsigned for_reclaim:1; /* Invoked from the page allocator */
+ unsigned for_writepages:1; /* This is a writepages() call */
};
/*
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0166ea15..5240e42 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -550,11 +550,17 @@
int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
+ int ret;
+
if (wbc->nr_to_write <= 0)
return 0;
+ wbc->for_writepages = 1;
if (mapping->a_ops->writepages)
- return mapping->a_ops->writepages(mapping, wbc);
- return generic_writepages(mapping, wbc);
+ ret = mapping->a_ops->writepages(mapping, wbc);
+ else
+ ret = generic_writepages(mapping, wbc);
+ wbc->for_writepages = 0;
+ return ret;
}
/**