Module path 

Path-to-inode resolution.

Walk a slash-separated path — bytes, never decoded — from the root directory (inode 2) down to a target inode number. Used by every public-facing C API function that accepts a path (stat, dir_open, read_file, readlink).

Algorithm: start at EXT4_ROOT_INODE, read its inode, for each non-empty path component look up the entry by name in the current directory’s data blocks, then descend into the matching child inode.

An htree-indexed directory is searched through its index first (htree::lookup_leaf_with), and a name the index does not lead to is then found by a linear scan, which is always valid because the index is an acceleration over ordinary directory blocks, not a replacement for them. Other directories are scanned linearly.

Constants

EXT4_ROOT_INODE

Root directory inode number (always 2 on every ext[234] filesystem).

Functions

lookup

Resolve a slash-separated path to an inode number.

lookup_bytes_with_csum

lookup_with_csum of a path given as bytes, which is what a path is: the components are compared byte for byte against the directory entry names, which have no encoding. A path that is not UTF-8 names exactly the file whose name bytes it holds, and a path naming nothing is NotFound — never the root by accident (#418).

lookup_with_csum

Path → inode lookup with directory-block checksum verification.