key_mask_hash(9)

💖 key_mask_hash(9) 💖

okay bestie, welcome to the Kernel API Manual page for key_mask_hash(9). It’s a tiny function with main character energy: it keeps the reserved hash values out of your directory offsets. ✨

🎀 NAME 🎀

key_mask_hash — mask a valid hash value. 💅

✨ SYNOPSIS ✨

uint32_t key_mask_hash (uint32_t hash );

🫶 ARGUMENTS 🫶

• hash — the value to be masked. 🎀

💅 DESCRIPTION 💅

So here’s the situation, bestie: we use hash values as offsets in directories, which means values 0 and 1 are reserved for "." and "..". The value 2 is reserved for the "end of readdir" marker. 😭

This function makes sure those reserved values are not used. Periodt. 🔥

🌈 SEE ALSO 🌈

Kernel file ./fs/ubifs/key.h — the whole friend group:

• key_r5_hash(9)
• key_test_hash(9)
• ino_key_init(9)
• ino_key_init_flash(9)
• lowest_ino_key(9)
• highest_ino_key(9)
• dent_key_init(9)
• dent_key_init_hash(9)
• dent_key_init_flash(9)
• lowest_dent_key(9)
• xent_key_init(9)
• xent_key_init_flash(9)
• lowest_xent_key(9)
• data_key_init(9)
• highest_data_key(9)
• trun_key_init(9)
• invalid_key_init(9)
• key_type(9)
• key_type_flash(9)
• key_inum(9)
• key_inum_flash(9)
• key_hash(9)
• key_hash_flash(9)
• key_block(9)
• key_block_flash(9)
• key_read(9)
• key_write(9)
• key_write_idx(9)
• key_copy(9)
• keys_cmp(9)
• keys_eq(9)
• is_hash_key(9)
• key_max_inode_size(9)

— source/version ./fs/ubifs, dated October 2026; that’s the whole page, bestie. 💅🫶