debugfs: fixup the hard-coded buffer length in dump_file

Allocate the block buffer in dump_file() instead of assuming that the
block size is no more than 8k.

CC: George Spelvin <linux@horizon.com>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
1 file changed