ext4: factor out common code in ext4_file_write()

This shouldn't change any logic flow; just delete duplicated code.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/ext4/file.c

@@ -97,8 +97,9 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(iocb->ki_filp);
+	struct mutex *aio_mutex = NULL;
 	struct blk_plug plug;
-	int unaligned_aio = 0;
+	int o_direct = file->f_flags & O_DIRECT;
 	int overwrite = 0;
 	size_t length = iov_length(iov, nr_segs);
 	ssize_t ret;
@@ -123,15 +124,13 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		}
 	}
 
-	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);
-
+	if (o_direct) {
 		/* Unaligned direct AIO must be serialized; see comment above */
-		if (unaligned_aio) {
-			mutex_lock(ext4_aio_mutex(inode));
+		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
+		    !is_sync_kiocb(iocb) &&
+		    ext4_unaligned_aio(inode, iov, nr_segs, pos)) {
+			aio_mutex = ext4_aio_mutex(inode);
+			mutex_lock(aio_mutex);
 			ext4_unwritten_wait(inode);
 		}
 
@@ -141,7 +140,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		iocb->private = &overwrite;
 
 		/* check whether we do a DIO overwrite or not */
-		if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
+		if (ext4_should_dioread_nolock(inode) && !aio_mutex &&
 		    !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
 			struct ext4_map_blocks map;
 			unsigned int blkbits = inode->i_blkbits;
@@ -168,6 +167,8 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 			if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
 				overwrite = 1;
 		}
+	} else
+		mutex_lock(&inode->i_mutex);
 
 	ret = __generic_file_aio_write(iocb, iov, nr_segs);
 	mutex_unlock(&inode->i_mutex);
@@ -179,24 +180,11 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		if (err < 0)
 			ret = err;
 	}
+	if (o_direct)
 		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);
-
-		if (ret > 0) {
-			ssize_t err;
-
-			err = generic_write_sync(file, iocb->ki_pos - ret, ret);
-			if (err < 0)
-				ret = err;
-		}
-	}
-
+	if (aio_mutex)
+		mutex_unlock(aio_mutex);
 	return ret;
 }