ext4: move ext4_file_dio_write() into ext4_file_write()

This commit doesn't actually change anything; it just moves code
around in preparation for some code simplification work.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/file.c

@@ -92,82 +92,15 @@ ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
 }
 
 static ssize_t
-ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
-		    unsigned long nr_segs, loff_t pos)
+ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
+		unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
+	struct inode *inode = file_inode(iocb->ki_filp);
 	struct blk_plug plug;
 	int unaligned_aio = 0;
-	ssize_t ret;
 	int overwrite = 0;
 	size_t length = iov_length(iov, nr_segs);
-
-	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
-	    !is_sync_kiocb(iocb))
-		unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);
-
-	/* Unaligned direct AIO must be serialized; see comment above */
-	if (unaligned_aio) {
-		mutex_lock(ext4_aio_mutex(inode));
-		ext4_unwritten_wait(inode);
-	}
-
-	mutex_lock(&inode->i_mutex);
-	blk_start_plug(&plug);
-
-	iocb->private = &overwrite;
-
-	/* check whether we do a DIO overwrite or not */
-	if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
-	    !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
-		struct ext4_map_blocks map;
-		unsigned int blkbits = inode->i_blkbits;
-		int err, len;
-
-		map.m_lblk = pos >> blkbits;
-		map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
-			- map.m_lblk;
-		len = map.m_len;
-
-		err = ext4_map_blocks(NULL, inode, &map, 0);
-		/*
-		 * 'err==len' means that all of blocks has been preallocated no
-		 * matter they are initialized or not.  For excluding
-		 * unwritten extents, we need to check m_flags.  There are
-		 * two conditions that indicate for initialized extents.
-		 * 1) If we hit extent cache, EXT4_MAP_MAPPED flag is returned;
-		 * 2) If we do a real lookup, non-flags are returned.
-		 * So we should check these two conditions.
-		 */
-		if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
-			overwrite = 1;
-	}
-
-	ret = __generic_file_aio_write(iocb, iov, nr_segs);
-	mutex_unlock(&inode->i_mutex);
-
-	if (ret > 0) {
-		ssize_t err;
-
-		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-		if (err < 0)
-			ret = err;
-	}
-	blk_finish_plug(&plug);
-
-	if (unaligned_aio)
-		mutex_unlock(ext4_aio_mutex(inode));
-
-	return ret;
-}
-
-static ssize_t
-ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
-		unsigned long nr_segs, loff_t pos)
-{
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file_inode(iocb->ki_filp);
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
@@ -179,7 +112,6 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 
 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-		size_t length = iov_length(iov, nr_segs);
 
 		if ((pos > sbi->s_bitmap_maxbytes ||
 		    (pos == sbi->s_bitmap_maxbytes && length > 0)))
@@ -191,9 +123,67 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		}
 	}
 
-	if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
-		ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
-	else {
+	if (unlikely(iocb->ki_filp->f_flags & O_DIRECT)) {
+		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+		    !is_sync_kiocb(iocb))
+			unaligned_aio = ext4_unaligned_aio(inode, iov,
+							   nr_segs, pos);
+
+		/* Unaligned direct AIO must be serialized; see comment above */
+		if (unaligned_aio) {
+			mutex_lock(ext4_aio_mutex(inode));
+			ext4_unwritten_wait(inode);
+		}
+
+		mutex_lock(&inode->i_mutex);
+		blk_start_plug(&plug);
+
+		iocb->private = &overwrite;
+
+		/* check whether we do a DIO overwrite or not */
+		if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
+		    !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
+			struct ext4_map_blocks map;
+			unsigned int blkbits = inode->i_blkbits;
+			int err, len;
+
+			map.m_lblk = pos >> blkbits;
+			map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
+				- map.m_lblk;
+			len = map.m_len;
+
+			err = ext4_map_blocks(NULL, inode, &map, 0);
+			/*
+			 * 'err==len' means that all of blocks has
+			 * been preallocated no matter they are
+			 * initialized or not.  For excluding
+			 * unwritten extents, we need to check
+			 * m_flags.  There are two conditions that
+			 * indicate for initialized extents.  1) If we
+			 * hit extent cache, EXT4_MAP_MAPPED flag is
+			 * returned; 2) If we do a real lookup,
+			 * non-flags are returned.  So we should check
+			 * these two conditions.
+			 */
+			if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
+				overwrite = 1;
+		}
+
+		ret = __generic_file_aio_write(iocb, iov, nr_segs);
+		mutex_unlock(&inode->i_mutex);
+
+		if (ret > 0) {
+			ssize_t err;
+
+			err = generic_write_sync(file, iocb->ki_pos - ret, ret);
+			if (err < 0)
+				ret = err;
+		}
+		blk_finish_plug(&plug);
+
+		if (unaligned_aio)
+			mutex_unlock(ext4_aio_mutex(inode));
+	} else {
 		mutex_lock(&inode->i_mutex);
 		ret = __generic_file_aio_write(iocb, iov, nr_segs);
 		mutex_unlock(&inode->i_mutex);