ext2fs: Add uninit_bg feature support.

[fsu]

Test Plan

The next script{F1418349} and fstorture from: https://github.com/thedrgreenthumb/fstools

[pfg]

I don't know much about this feature but it is probably interesting enough to put all the new functionality in a different file.
ext2_alloc is already crowded.

[fsu]

Ok, you are right, I will try to add file like ext2_csum.c

[pfg]

In D11211#232008, @thisisadrgreenthumb_gmail.com wrote:

Ok, you are right, I will try to add file like ext2_csum.c

BTW, I think we might have code for CRCs in the kernel already. Not sure but ext2_crc16() may be redundant,

[fsu]

Move csum logic to own file.

[fsu]

BTW, I think we might have code for CRCs in the kernel already. Not sure but ext2_crc16() may be redundant,

Seems like, it is impossible. Because only one crc16 implementation in kernel exist, and it is incompatible with ext2 crc16.

[pfg]

Looks good to me.

sys/fs/ext2fs/ext2_alloc.c

755

We have some bitmap manipulation routines in ffs(3).
Maybe some can be of use here?

[fsu]

Learned this man pages, but it is more about bit-sequences finding. Here I should only fill first parts of bitmaps. So, can not find how it is possible to apply it here.

[pfg]

sys/fs/ext2fs/ext2_alloc.c

713

This looks strange:

X / Y / 8 = 8 * X / Y.

Also ... should cg be unsigned?

sys/fs/ext2fs/ext2_csum.c

96

offsetof(3) returns a size_t type: it could overflow int.

121

i should be unsigned as it is used to index an unsigned number.

141

Thia should be an unsigned int since e2fs_gcount is unsigned.

sys/fs/ext2fs/ext2_vfsops.c

397

Typo (Verify).

[pfg]

Note to self: I think this feature may work on ext3 so it can be tested with tune2fs.

[fsu]

Comments fixes.

sys/fs/ext2fs/ext2_alloc.c

713

Also ... should cg be unsigned?

cg is signed everywhere, I can try to change it to unsigned, but seems like, it should be another patch.

[pfg]

LGTM