Showing posts from March, 2014

How incore inodes are allocated ?

Hello friends I am beginning this discussion by assuming that you knows the few basics of OS (UNIX) especially about kernel and its working, so let’s start the discussion. The kernel identifies particular inodes by their file system and inode number and allocated incore inode at the request of higher level algorithms, here higher level algorithms means we are considering some abstract levels so higher level means above the current abstract level. The OS kernel uses algorithm  iget  to allocate incore copy of inode, the kernel maps device number and inode number into hash queue and searches the queue for the inode if it cannot find the inode, it allocates one from the free list and locks it. After that kernel prepares, read the disk copy of the newly accessed inode into incore copy. It already knows the inode number and logical device and computes the logical disk block that contains the inode according to how many disk inodes that fits into the disk block. The computation is followed b