tune2fs: zero inode table when removing checksums

tune2fs: zero inode table when removing checksums

When disabling group checksums, we have to initialize the inode table.  Right
now tune2fs doesn't do this; it merely punts to e2fsck to clean up the mess.
Unfortunately, if the "uninitialized" inode table contains things that look
like inodes (i_link_count > 0, specifically), the e2fsck tries to recover these
inodes.  This leads to it misinterpreting i_blocks as a block map, at which
point it needlessly resurrects phantom inodes and crosslinked file repairs.  As
part of initializing the block bitmaps, we must also mark block group metadata
blocks in use.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>