fscrypt_prepare_rename(9)

💅 fscrypt_prepare_rename(9) — kernel API manual, bestie edition ✨

okay so picture this: you're deep in the kernel, in fscrypt land, and somebody wants to rename a file where the source dir, the target dir, or honestly both of them, might be encrypted 🎀. That's literally what this function is for. It lives in the Kernel API Manual, and it's here to do the vibe check before the rename actually happens 🦋.

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✨ SYNOPSIS ✨

int fscrypt_prepare_rename (struct inode *old_dir , struct dentry
*old_dentry , struct inode *new_dir , struct dentry *new_dentry ,
unsigned int flags );

like, look at all those parameters. she's got range 💅

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🌸 ARGUMENTS 🌸

• old_dir — the source directory, aka where the file is right now 🏠
• old_dentry — the dentry for the source file, the actual thing being moved
• new_dir — the target directory, where it's headed 👀
• new_dentry — the dentry for the target location. quick note: this one may be negative unless you're exchanging (iykyk)
• flags — the rename flags. we care at least about RENAME_EXCHANGE, so don't be weird about it fr fr

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💖 DESCRIPTION 💖

so this is the prep step for ->rename, and the whole point is that the source and/or target directories may be encrypted 🔐. and here's the tea:

a new link can only be added to an encrypted directory if that directory's encryption key is available — because otherwise, bestie, we'd literally have no way to encrypt the filename 😭. that's just math.

but a rename to an existing name? that one is cryptographically possible without the key. yes, technically doable. and yet — we take the more conservative approach and just forbid all no-key renames. periodt. no key, no rename 🙅‍♀️

we also verify that the rename won't violate the constraint that all files in an encrypted directory tree use the same encryption policy. consistency is the moment 💅✨

ngl this one's strict on purpose — the whole point is not letting a rename sneak past the encryption rules 👑

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⭐ RETURN ⭐

• 0 on success — slay 🎉
• -ENOKEY if an encryption key is missing 🔑💀
• -EXDEV if the rename would cause inconsistent encryption policies 🚫
• or another -errno code, because sometimes life gives you surprises 🙈

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🦋 SEE ALSO 🦋

• Kernel file ./include/linux/fscrypt.h — the source of truth, go read it 🫶
• fscrypt_needs_contents_encryption(9)
• fscrypt_is_nokey_name(9)
• fscrypt_has_encryption_key(9)
• fscrypt_prepare_link(9)
• fscrypt_prepare_lookup(9)
• fscrypt_prepare_readdir(9)
• fscrypt_prepare_setattr(9)
• fscrypt_encrypt_symlink(9)

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that's the whole page, bestie, go forth and rename responsibly 🧚💜

source/version: ./include/linux · dated October 2026 · fscrypt_prepare_rename(9) — mwah, that's a wrap 🎀✨