Theodore Tso <tytso@xxxxxxx> wrote:
> bg_inode_table_hi doesn't exist on a small filesystem.
> You need to take a look at if INCOMPAT_64BIT is not set,
> or if INCOMPAT_64BIT is set and s_desc_size is 32, then
> only the first 32 bytes of struct ext4_group_desc are
> in use --- which look exactly the same as ext2_group_desc.
>
> So there is no problem here. Just a misunderstanding of
> the filesystem format.
>
> - Ted
Thanks a lot; and sorry, I should have guessed myself that
the field is not there when s_desc_size is too small,
whatever the value of INCOMPAT_64BIT.
May I ask confirmation of this 2 points on the list too:
- the array of inode in the inode_table is an array where
each inode has the size superblock->s_inode_size (or
EXT2_GOOD_OLD_INODE_SIZE) whatever s_min_extra_isize,
s_want_extra_isize, inode->i_extra_isize because
the "extra" size of an inode is not stored in the
inode_table.
- If I only access the ext4 filesystem readonly, I do not
have any difference considering the flags of the superblock:
EXT4_FEATURE_INCOMPAT_META_BG, EXT4_FEATURE_INCOMPAT_MMP,
EXT4_FEATURE_INCOMPAT_FLEX_BG. That is, I do not want to
allocate any block, so I should not refuse to "mount" an
ext4fs whatever the value of these flags.
I do not know anything about EXT4_FEATURE_INCOMPAT_MMP...
Thanks in advance,
Etienne.
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