fscrypt_prepare_new_inode(9)

📦 version 7.3.1, in nixpkgs unstable

💫 fscrypt_prepare_new_inode — like, the kernel API manual, bestie

okay so this is fscrypt_prepare_new_inode(9) from the Kernel API Manual and it's literally the glow-up routine you run before a brand-new inode gets created inside a directory. think of it as the pre-game. the vibe check before the main character (the inode) walks in. 🎀

✨ SYNOPSIS ✨

int fscrypt_prepare_new_inode (struct inode *dir , struct inode *inode ,
bool *encrypt_ret );

that's it. that's the whole aesthetic. three args, one int back. slay. 💅

🌸 ARGUMENTS 🌸

  • dir — a possibly-encrypted directory. maybe it's encrypted, maybe it's not, we don't judge, we just check. 🦋
  • inode — the new inode, the fresh baby, the new addition to the group chat. heads up tho: its ->i_mode and ->i_blkbits must be set already. like, non-negotiable, already done. but ->i_ino? doesn't need to be set yet. no pressure, it'll come later. 🙈
  • encrypt_ret — this one's an output (yes, a pointer, she writes back 💖) and it gets set to true if the new inode will be encrypted.

💜 DESCRIPTION 💜

so here's the tea. if the directory is encrypted, this function sets up its encryption key in preparation for encrypting the name of the new file. got it? the directory's name-encrypting situation gets handled.

and also — if the new inode itself will be encrypted, it sets up its encryption key too, and sets *encrypt_ret=true. two keys, two setups, one function call. iconic behavior honestly. ✨

⚠️ important caveat time, do not skip this: this isn't GFP_NOFS-safe. so because of that, you gotta call it before starting any filesystem transaction to create the inode. that's literally the reason ->i_ino isn't required to be set yet — the filesystem may not have set it at that point. the ordering is the whole point, bestie. no cap. 🔥

one more thing, and this is lowkey a big deal: this does not persist the new inode's encryption context. nope. nada. that part still needs to be done later by calling fscrypt_set_context. so don't be out here thinking you're done, because you are not done. 🙈

⭐ RETURN ⭐

  • 0 on success — we love a clean win, periodt. 👑
  • -ENOKEY if a key needs to be set up for dir or inode but the needed master key is absent. that's the "where's the key, we can't find the key" situation. 💀
  • or another -errno code — because life is full of surprises. 🌈

🫶 SEE ALSO 🫶

kernel file ./fs/crypto/keysetup.c, and these absolute icons:

iykyk. go read them, they're all part of the same lore. 🧚

and that's the page!! mwah 💋 this whole thing lives in ./fs/crypto, dated October 2026, and it's the fscrypt_prepare_new_inode(9) page — hope that cleared everything up for you bestie, now go set up those keys before you start any transactions, mwah 💖🎀🦋

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