inode_insert5(9)

💅 inode_insert5(9) — like, the Kernel API Manual one, bestie

okay so picture this: it's the kernel, it's the inode cache, and you've already got an inode pre-made in your hand like a little 🎀 gift 🎀 and you just need to know — is this thing already in the cache, or do we slide it in? That's the whole vibe of inode_insert5(9). Let's get into it. ✨

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✨ NAME ✨

inode_insert5 — obtain an inode from a mounted file system 🦋

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✨ SYNOPSIS ✨

struct inode * inode_insert5 (struct inode *inode , u64 hashval , int
(*test)(struct inode *, void *) , int (*set)(struct inode *, void *) ,
void *data );

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✨ ARGUMENTS ✨

• inode — the pre-allocated inode you're gonna use for the insert into the cache 🫶 it's already yours, you're just deciding if it goes in.
• hashval — the hash value (usually the inode number, ngl) that you're trying to get 💫
• test — the callback used for comparisons between inodes, i.e. the "are these two the same actually" checker 👀
• set — the callback used to initialize a new struct inode 🌱 (this is how the fresh one gets its glow-up)
• data — an opaque data pointer that gets passed to both test and set 🎁 iykyk

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🌸 DESCRIPTION 🌸

So what it does: it searches the inode cache for the inode specified by hashval and data, and if it's already there — iconic — it returns it with an increased reference count 💖

It's basically a variant of iget5_locked that doesn't allocate an inode. no cap, that's the whole difference. the allocation part? not her problem. 🙅‍♀️

But if the inode is not present in the cache? Then bestie, you insert the pre-allocated inode and return it locked, hashed, and with the I_NEW flag set 🔥 The file system gets to fill it in before unlocking it via unlock_new_inode. That's the whole plan. ⭐

⚠️ important caveat, don't skip this one: both test and set are called with the inode_hash_lock held, so they can't sleep 😴🚫 like literally cannot. do not try it. 💀

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💜 SEE ALSO 💜

Kernel file ./fs/inode.c — and the whole extended 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)
• 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)
• 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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okay that's the whole page, you ate that 🍓 this one came from ./fs in the October 2026 era of the Kernel API Manual, so go forth and insert those inodes correctly, bestie 💅👑