find_inode_rcu(9)

💖 find_inode_rcu(9) — Kernel API Manual 💖

hey bestie 🫶 welcome to the Kernel API Manual page for find_inode_rcu(9). this is the inode-cache search function, and yes, it’s giving “find the matching inode and don’t do anything cursed” energy. let’s go. ✨

✨ NAME ✨

find_inode_rcu — find an inode in the inode cache. that’s it, that’s the assignment, and it ate. 💅

🌸 SYNOPSIS 🌸

struct inode * find_inode_rcu (struct super_block *sb , u64 hashval ,
       int (*test)(struct inode *, void *) , void *data );

🎀 ARGUMENTS 🎀

okay so here’s who’s who in this function’s group chat:

• sb — Super block of file system to search. it’s the super block of the file system you’re searching, bestie. 🦋
• hashval — Key to hash. the hash key for the search. 🔑
• test — Function to test match on an inode. this is the matchmaker. 💅
• data — Data for test function. the lil extra data that gets handed to test. 🎀

💜 DESCRIPTION 💜

Search for the inode specified by hashval and data in the inode cache, where the helper function test will return 0 if the inode does not match and 1 if it does. so test is basically doing the vibe check: 0 = nope, 1 = yes bestie. 💅

the test function must be responsible for taking the i_lock spin_lock and checking i_state for an inode being freed or being initialized. that responsibility is literally on test, no cap. 🫶

If successful, this will return the inode for which the test function returned 1 and NULL otherwise. no extra little treats, just the matching inode or NULL. ✨

The test function is not permitted to take a ref on any inode presented. It is also not permitted to sleep. and the caller must hold the RCU read lock. this is highkey not optional, bestie. 🚨

🔎 SEE ALSO 🔎

Kernel file ./fs/inode.c — plus the whole friend group:

• inode_init_always_gfp(9), alloc_inode(9), drop_nlink(9), clear_nlink(9), set_nlink(9), inc_nlink(9), inode_sb_list_add(9), __insert_inode_hash(9), __remove_inode_hash(9), evict_inodes(9)
• new_inode(9), unlock_new_inode(9), lock_two_nondirectories(9), unlock_two_nondirectories(9), inode_insert5(9), iget5_locked(9), iget5_locked_rcu(9), iget_locked(9), iunique(9), ihold(9)
• ilookup5_nowait(9), ilookup5(9), ilookup(9), find_inode_nowait(9), find_inode_by_ino_rcu(9), iput(9), iput_not_last(9), bmap(9), inode_update_time(9), generic_update_time(9)
• atime_needs_update(9), file_remove_privs(9), current_time(9), file_update_time(9), file_modified_flags(9), file_modified(9), kiocb_modified(9), inode_init_owner(9), inode_owner_or_capable(9), inode_dio_wait(9)
• timestamp_truncate(9), inode_set_ctime_current(9), inode_set_ctime_deleg(9), in_group_or_capable(9), mode_strip_sgid(9), dump_inode(9)

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made with 💖 by ./fs, October 2026 — find_inode_rcu(9), out. mwah 💋