2 files changed, 103 insertions, 0 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index a0b70b3239f3..a6bc769e665d 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3018,6 +3018,71 @@ int bh_uptodate_or_lock(struct buffer_head *bh)
 EXPORT_SYMBOL(bh_uptodate_or_lock);
 
 /**
+ * __bh_read - Submit read for a locked buffer
+ * @bh: struct buffer_head
+ * @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
+ * @wait: wait until reading finish
+ *
+ * Returns zero on success or don't wait, and -EIO on error.
+ */
+int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait)
+{
+	int ret = 0;
+
+	BUG_ON(!buffer_locked(bh));
+
+	get_bh(bh);
+	bh->b_end_io = end_buffer_read_sync;
+	submit_bh(REQ_OP_READ | op_flags, bh);
+	if (wait) {
+		wait_on_buffer(bh);
+		if (!buffer_uptodate(bh))
+			ret = -EIO;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(__bh_read);
+
+/**
+ * __bh_read_batch - Submit read for a batch of unlocked buffers
+ * @nr: entry number of the buffer batch
+ * @bhs: a batch of struct buffer_head
+ * @op_flags: appending REQ_OP_* flags besides REQ_OP_READ
+ * @force_lock: force to get a lock on the buffer if set, otherwise drops any
+ *              buffer that cannot lock.
+ *
+ * Returns zero on success or don't wait, and -EIO on error.
+ */
+void __bh_read_batch(int nr, struct buffer_head *bhs[],
+		     blk_opf_t op_flags, bool force_lock)
+{
+	int i;
+
+	for (i = 0; i < nr; i++) {
+		struct buffer_head *bh = bhs[i];
+
+		if (buffer_uptodate(bh))
+			continue;
+
+		if (force_lock)
+			lock_buffer(bh);
+		else
+			if (!trylock_buffer(bh))
+				continue;
+
+		if (buffer_uptodate(bh)) {
+			unlock_buffer(bh);
+			continue;
+		}
+
+		bh->b_end_io = end_buffer_read_sync;
+		get_bh(bh);
+		submit_bh(REQ_OP_READ | op_flags, bh);
+	}
+}
+EXPORT_SYMBOL(__bh_read_batch);
+
+/**
  * bh_submit_read - Submit a locked buffer for reading
  * @bh: struct buffer_head
  *
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index c3863c417b00..6d09785bed9f 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -232,6 +232,9 @@ void write_boundary_block(struct block_device *bdev,
 			sector_t bblock, unsigned blocksize);
 int bh_uptodate_or_lock(struct buffer_head *bh);
 int bh_submit_read(struct buffer_head *bh);
+int __bh_read(struct buffer_head *bh, blk_opf_t op_flags, bool wait);
+void __bh_read_batch(int nr, struct buffer_head *bhs[],
+		     blk_opf_t op_flags, bool force_lock);
 
 extern int buffer_heads_over_limit;
 
@@ -399,6 +402,41 @@ static inline struct buffer_head *__getblk(struct block_device *bdev,
 	return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
 }
 
+static inline void bh_readahead(struct buffer_head *bh, blk_opf_t op_flags)
+{
+	if (!buffer_uptodate(bh) && trylock_buffer(bh)) {
+		if (!buffer_uptodate(bh))
+			__bh_read(bh, op_flags, false);
+		else
+			unlock_buffer(bh);
+	}
+}
+
+static inline void bh_read_nowait(struct buffer_head *bh, blk_opf_t op_flags)
+{
+	if (!bh_uptodate_or_lock(bh))
+		__bh_read(bh, op_flags, false);
+}
+
+/* Returns 1 if buffer uptodated, 0 on success, and -EIO on error. */
+static inline int bh_read(struct buffer_head *bh, blk_opf_t op_flags)
+{
+	if (bh_uptodate_or_lock(bh))
+		return 1;
+	return __bh_read(bh, op_flags, true);
+}
+
+static inline void bh_read_batch(int nr, struct buffer_head *bhs[])
+{
+	__bh_read_batch(nr, bhs, 0, true);
+}
+
+static inline void bh_readahead_batch(int nr, struct buffer_head *bhs[],
+				      blk_opf_t op_flags)
+{
+	__bh_read_batch(nr, bhs, op_flags, false);
+}
+
 /**
  *  __bread() - reads a specified block and returns the bh
  *  @bdev: the block_device to read from