fscrypt_enc...lock_inplace(9)

📦 version 7.3.1, in nixpkgs unstable

🌸 fscrypt_encrypt_block_inplace — the Kernel API Manual, bestie edition 🌸

okay so this is a page from the Kernel API Manual (yes, that one) and it's about fscrypt_encrypt_block_inplace(9), which is giving "encrypt one filesystem block right where it already lives" energy. no copying, no moving, just glow-up in place. 💅

✨ NAME ✨

fscrypt_encrypt_block_inplace — Encrypt a filesystem block in-place

like, literally in-place. the block stays exactly where it is and just gets encrypted on the spot. iconic behavior, no cap. 🔥

🎀 SYNOPSIS 🎀

int fscrypt_encrypt_block_inplace (const struct inode *inode , struct
page *page , unsigned int len , unsigned int offs , u64 lblk_num );

she takes five arguments and returns an int. that's the whole vibe. ✨

🦋 ARGUMENTS 🦋

  • inode — The inode to which this block belongs. yes she needs to know whose block this is, it's giving "who's your mother" energy. 👑
  • page — The page containing the block to encrypt. this is the actual vessel, the main character page, the one holding the block. 🫶
  • len — Size of block to encrypt. This must be a multiple of FSCRYPT_CONTENTS_ALIGNMENT. not "should", not "ideally" — must. don't test her. 💀
  • offs — Byte offset within page at which the block to encrypt begins. so like, where in the page the block actually starts. 🎯
  • lblk_num — Filesystem logical block number of the block, i.e. the 0-based number of the block within the file. zero-based, so the first one is 0, not 1, yes really, that's just how it is. 🌈

💖 DESCRIPTION 💖

so the whole point: this encrypts a possibly-compressed filesystem block that lives in an arbitrary page — and like, key detail — not necessarily in the original pagecache page. so she's flexible, she's versatile, she's not gonna gatekeep which page the block is chilling in. 🧚

because of that flexibility, you must specify inode and lblk_num, since they literally cannot be determined from page alone. the page doesn't know its own lore. 😭

heads up bestie: this function only supports non-block-based filesystems that don't support sub-block data units (as indicated by the fscrypt_operations fields). so if your fs is block-based or does sub-block data units, this is not the function for you, sorry, next. 🙈

🌟 RETURN 🌟

  • 0 on success 🎉
  • -errno on failure 😔

she's simple like that. love that for her. 💜

🔮 SEE ALSO 🔮

Kernel file ./fs/crypto/crypto.c — and the whole friend group:

the squad, fr fr. 🫶✨

and that's the page!! source lives at ./fs/crypto, from October 2026, in the Kernel API Manual — so like, bookmark it, screenshot it, send it to the group chat, whatever you gotta do. mwah 💋🎀

📦 where this page comes from