ext4: Add API to bring in support for unwritten io_end_vec conversion

This patch just brings in the API for conversion of unwritten io_end_vec
extents which will be required for blocksize < pagesize support
for dioread_nolock feature.

No functional changes in this patch.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20191016073711.4141-3-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -3264,6 +3264,8 @@ extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
 			  loff_t len);
 extern int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 					  loff_t offset, ssize_t len);
+extern int ext4_convert_unwritten_io_end_vec(handle_t *handle,
+					     ext4_io_end_t *io_end);
 extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
 			   struct ext4_map_blocks *map, int flags);
 extern int ext4_ext_calc_metadata_amount(struct inode *inode,

fs/ext4/extents.c

@@ -4962,23 +4962,13 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 	int ret = 0;
 	int ret2 = 0;
 	struct ext4_map_blocks map;
-	unsigned int credits, blkbits = inode->i_blkbits;
+	unsigned int blkbits = inode->i_blkbits;
+	unsigned int credits = 0;
 
 	map.m_lblk = offset >> blkbits;
 	max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
 
-	/*
-	 * This is somewhat ugly but the idea is clear: When transaction is
-	 * reserved, everything goes into it. Otherwise we rather start several
-	 * smaller transactions for conversion of each extent separately.
-	 */
-	if (handle) {
-		handle = ext4_journal_start_reserved(handle,
-						     EXT4_HT_EXT_CONVERT);
-		if (IS_ERR(handle))
-			return PTR_ERR(handle);
-		credits = 0;
-	} else {
+	if (!handle) {
 		/*
 		 * credits to insert 1 extent into extent tree
 		 */
@@ -5009,11 +4999,33 @@ int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
 		if (ret <= 0 || ret2)
 			break;
 	}
-	if (!credits)
-		ret2 = ext4_journal_stop(handle);
 	return ret > 0 ? ret2 : ret;
 }
 
+int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
+{
+	int ret, err = 0;
+
+	/*
+	 * This is somewhat ugly but the idea is clear: When transaction is
+	 * reserved, everything goes into it. Otherwise we rather start several
+	 * smaller transactions for conversion of each extent separately.
+	 */
+	if (handle) {
+		handle = ext4_journal_start_reserved(handle,
+						     EXT4_HT_EXT_CONVERT);
+		if (IS_ERR(handle))
+			return PTR_ERR(handle);
+	}
+
+	ret = ext4_convert_unwritten_extents(handle, io_end->inode,
+					     io_end->offset, io_end->size);
+	if (handle)
+		err = ext4_journal_stop(handle);
+
+	return ret < 0 ? ret : err;
+}
+
 /*
  * If newes is not existing extent (newes->ec_pblk equals zero) find
  * delayed extent at start of newes and update newes accordingly and

fs/ext4/page-io.c

@@ -149,7 +149,7 @@ static int ext4_end_io_end(ext4_io_end_t *io_end)
 		   io_end, inode->i_ino, io_end->list.next, io_end->list.prev);
 
 	io_end->handle = NULL;	/* Following call will use up the handle */
-	ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
+	ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
 	if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) {
 		ext4_msg(inode->i_sb, KERN_EMERG,
 			 "failed to convert unwritten extents to written "
@@ -269,9 +269,8 @@ int ext4_put_io_end(ext4_io_end_t *io_end)
 
 	if (atomic_dec_and_test(&io_end->count)) {
 		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
-			err = ext4_convert_unwritten_extents(io_end->handle,
-						io_end->inode, io_end->offset,
-						io_end->size);
+			err = ext4_convert_unwritten_io_end_vec(io_end->handle,
+								io_end);
 			io_end->handle = NULL;
 			ext4_clear_io_unwritten_flag(io_end);
 		}