ext4: enforce bigalloc restrictions (e.g., no online resizing, etc.)

At least initially if the bigalloc feature is enabled, we will not
support non-extent mapped inodes, online resizing, online defrag, or
the FITRIM ioctl.  This simplifies the initial implementation.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --cc fs/ext4/indirect.c
Simple merge

diff --cc fs/ext4/inode.c
Simple merge

diff --cc fs/ext4/ioctl.c
Simple merge

diff --cc fs/ext4/super.c
Simple merge