Add buffer head related helper functions

Add buffer head related helper function bh_uptodate_or_lock and
bh_submit_read which can be used by file system

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 7249e014819e..456c9ab7705b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3213,6 +3213,50 @@ static int buffer_cpu_notify(struct notifier_block *self,
         return NOTIFY_OK;
 }
 
+/**
+ * bh_uptodate_or_lock: Test whether the buffer is uptodate
+ * @bh: struct buffer_head
+ *
+ * Return true if the buffer is up-to-date and false,
+ * with the buffer locked, if not.
+ */
+int bh_uptodate_or_lock(struct buffer_head *bh)
+{
+        if (!buffer_uptodate(bh)) {
+                lock_buffer(bh);
+                if (!buffer_uptodate(bh))
+                        return 0;
+                unlock_buffer(bh);
+        }
+        return 1;
+}
+EXPORT_SYMBOL(bh_uptodate_or_lock);
+
+/**
+ * bh_submit_read: Submit a locked buffer for reading
+ * @bh: struct buffer_head
+ *
+ * Returns zero on success and -EIO on error.
+ */
+int bh_submit_read(struct buffer_head *bh)
+{
+        BUG_ON(!buffer_locked(bh));
+
+        if (buffer_uptodate(bh)) {
+                unlock_buffer(bh);
+                return 0;
+        }
+
+        get_bh(bh);
+        bh->b_end_io = end_buffer_read_sync;
+        submit_bh(READ, bh);
+        wait_on_buffer(bh);
+        if (buffer_uptodate(bh))
+                return 0;
+        return -EIO;
+}
+EXPORT_SYMBOL(bh_submit_read);
+
 void __init buffer_init(void)
 {
         int nrpages;