f2fs: atomic: fix to forbid dio in atomic_file

atomic write can only be used via buffered IO, let's fail direct IO on
atomic_file and return -EOPNOTSUPP.
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -2162,6 +2162,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		goto out;
 
 	f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
+	f2fs_down_write(&fi->i_gc_rwsem[READ]);
 
 	/*
 	 * Should wait end_io to count F2FS_WB_CP_DATA correctly by
@@ -2171,10 +2172,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		f2fs_warn(sbi, "Unexpected flush for atomic writes: ino=%lu, npages=%u",
 			  inode->i_ino, get_dirty_pages(inode));
 	ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
-	if (ret) {
-		f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
-		goto out;
-	}
+	if (ret)
+		goto out_unlock;
 
 	/* Check if the inode already has a COW inode */
 	if (fi->cow_inode == NULL) {
@@ -2183,10 +2182,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		struct inode *dir = d_inode(dentry->d_parent);
 
 		ret = f2fs_get_tmpfile(idmap, dir, &fi->cow_inode);
-		if (ret) {
-			f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
-			goto out;
-		}
+		if (ret)
+			goto out_unlock;
 
 		set_inode_flag(fi->cow_inode, FI_COW_FILE);
 		clear_inode_flag(fi->cow_inode, FI_INLINE_DATA);
@@ -2200,10 +2197,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		invalidate_mapping_pages(fi->cow_inode->i_mapping, 0, -1);
 
 		ret = f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
-		if (ret) {
-			f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
-			goto out;
-		}
+		if (ret)
+			goto out_unlock;
 	}
 
 	f2fs_write_inode(inode, NULL);
@@ -2222,7 +2217,11 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 	}
 	f2fs_i_size_write(fi->cow_inode, isize);
 
+out_unlock:
+	f2fs_up_write(&fi->i_gc_rwsem[READ]);
 	f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
+	if (ret)
+		goto out;
 
 	f2fs_update_time(sbi, REQ_TIME);
 	fi->atomic_write_task = current;
@@ -4570,6 +4569,13 @@ static ssize_t f2fs_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 		f2fs_down_read(&fi->i_gc_rwsem[READ]);
 	}
 
+	/* dio is not compatible w/ atomic file */
+	if (f2fs_is_atomic_file(inode)) {
+		f2fs_up_read(&fi->i_gc_rwsem[READ]);
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
 	/*
 	 * We have to use __iomap_dio_rw() and iomap_dio_complete() instead of
 	 * the higher-level function iomap_dio_rw() in order to ensure that the
@@ -4985,6 +4991,12 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	/* Determine whether we will do a direct write or a buffered write. */
 	dio = f2fs_should_use_dio(inode, iocb, from);
 
+	/* dio is not compatible w/ atomic write */
+	if (dio && f2fs_is_atomic_file(inode)) {
+		ret = -EOPNOTSUPP;
+		goto out_unlock;
+	}
+
 	/* Possibly preallocate the blocks for the write. */
 	target_size = iocb->ki_pos + iov_iter_count(from);
 	preallocated = f2fs_preallocate_blocks(iocb, from, dio);