Hello, On Thu 15-03-12 18:48:56, Akshay Nehe wrote: > 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). struct ext4_extent_header is just directly stored in the space occupied by i_block[EXT4_N_BLOCKS]. So for example ext_inode_hdr() does: (struct ext4_extent_header *)EXT4_I(inode)->i_data (where i_data is just one-to-one copy of i_blocks from on disk inode). And it's the same with struct ext4_extent. See for example macro EXT_FIRST_EXTENT. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
