find_inode_by_ino_rcu(9)

✨ find_inode_by_ino_rcu(9) ✨

okay so this is a page from the Kernel API Manual, section 9, and bestie it's literally called find_inode_by_ino_rcu — we're doing inode cache scavenger hunts today, lmk if you're seated 💅

---

🎀 NAME 🎀

find_inode_by_ino_rcu — Find an inode in the inode cache. that's it, that's the whole vibe: you go looking for an inode, it's in the cache, slay 🌸

---

🦋 SYNOPSIS 🦋

struct inode * find_inode_by_ino_rcu (struct super_block *sb , u64 ino );

like, you hand it a super block and an inode number, and it hands you back a struct inode *. iconic signature ngl 🫶

---

💖 ARGUMENTS 💖

• sb — Super block of file system to search. this is the neighborhood you're snooping around in, bestie 🏘️
• ino — The inode number to match. the exact number you're looking for, no substitutions, no "close enough" 🙅‍♀️

---

🔥 DESCRIPTION 🔥

okay so here's what's going down: it searches for the inode specified by hashval and data in the inode cache. and the helper function test is the one doing the judging — it returns 0 if the inode does not match, and 1 if it does. real binary queen behavior 👑

⚠️ and listen, the test function has responsibilities, okay? it must be responsible for taking the i_lock spin_lock and checking i_state for an inode being freed or being initialized. no cap, that's on test, not on this function 💀

If successful, this will return the inode for which the test function returned 1, and NULL otherwise. so like, 1 = you found your girl, NULL = she's not here, go home 😭

and here's the strict part — the test function is not permitted to take a ref on any inode presented. also not permitted to sleep. nope. not allowed. we don't do that here 🙈

💀 big one: the caller must hold the RCU read lock. like, must must. that's not a suggestion, that's the law of this function periodt.

---

🌈 SEE ALSO 🌈

Kernel file ./fs/inode.c — and honestly the whole inode squad is here, roll call bestie 📋:

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_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)

every single one, we don't skip the lineup 💜

---

and that's the page!! this one came from the source ./fs, dated October 2026 — bookmark it, screenshot it, send it to the group chat, whatever you gotta do 🎀💖✨ mwah, go find those inodes bestie 🦋