[PATCH 1/4] Add buffer head related helper functions

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

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>
---
 include/linux/buffer_head.h |   29 +++++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index da0d83f..82cc9ef 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -327,6 +327,35 @@ static inline void lock_buffer(struct buffer_head *bh)
 
 extern int __set_page_dirty_buffers(struct page *page);
 
+/* Return true if the buffer is up-to-date.
+ * Return false, with the buffer locked, if not.
+ */
+static inline 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;
+}
+/*
+ * Submit a locked buffer for reading,
+ * return a negative error and release
+ * the buffer if failed.
+ */
+static inline int bh_submit_read(struct buffer_head *bh)
+{
+	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;
+	brelse(bh);
+	return -EIO;
+}
 #else /* CONFIG_BLOCK */
 
 static inline void buffer_init(void) {}
-- 
1.5.3.5.652.gf192c-dirty