Required help for understanding ext4 block allocation

Akshay Nehe
2012-03-15T13:18:58Z

Hello,

I am trying to understand the block allocation in ext4 file sytem, I
have gone through all basic theory and browsing code to do it.

I am writing a module in which i got ext4 on disk inode, now according
to theory first 12 bytes of i_block points to ext4_extent_header, so
can i use this array of i_block[EXT4_N_BLOCKS].

Means how to fill objects of struct ext4_extent_header (using first
12 byte of i_block) and struct ext4_extent (using reminder bytes of
i_block).

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Regards,
Akshay Nehe.