Add TODO about moving version depend code into separate header.
simplefs_write(): use generic_write_checks()
sb: use s_maxbytes field instead of hardcoded check in simplefs_write()

generic_write_checks() will do this for us now, using s_maxbytes field
from sb.
simplefs_create_fs_object(): release mutexes when we can't acquire sb_lock

We need more pretty code for this.
Add new helper simplefs_inode_search()
Start implementing verbose logging depends on macros. (SIMPLEFS_DEBUG)

In many cases we don't need such verbose loggin, just add macros to
print loggin only if SIMPLEFS_DEBUG isset.
And it will be installed by default. (in Makefile)
Add new helper - simplefs_inode_save()

And use it next functions:
- simplefs_write()
- simplefs_create_fs_object()
test: add some read operations after unmount/mount
test: read file after truncate it to more smaller size.

Just write less bytes.
read: drop static "done" variable, we already have file_size in inode.