fscrypt_set_bio_crypt_ctx(9)

💅 fscrypt_set_bio_crypt_ctx

okay so bestie, we're in the Kernel API Manual today and the star of the show is fscrypt_set_bio_crypt_ctx(9) — literally the function that gets a file contents bio all dressed up for inline crypto ✨

🌸 NAME 🌸

fscrypt_set_bio_crypt_ctx — prep a file contents bio for inline crypto 🎀

✨ SYNOPSIS ✨

void fscrypt_set_bio_crypt_ctx (struct bio *bio , const struct inode
*inode , loff_t pos , gfp_t gfp_mask );

🫶 ARGUMENTS 🫶

• bio — a bio that's eventually gonna get submitted to the file 🌈
• inode — the file's inode, yep that one
• pos — the first file position (in bytes) in the I/O 📍
• gfp_mask — memory allocation flags. and listen, these must be a waiting mask so that bio_crypt_set_ctx can't fail. no cap, that's a hard requirement 💀

🦋 DESCRIPTION 🦋

So like — if the contents of the file should be encrypted (or decrypted), then you assign the appropriate encryption context to the bio. that's the whole vibe 💜

Normally the bio should be newly allocated (i.e. no pages added yet), because otherwise fscrypt_mergeable_bio won't work as intended. so don't be out here adding pages first and then acting surprised 🙈

Good news tho: the encryption context will be freed automatically when the bio is freed. self-cleaning, iconic, main character energy 👑

🔥 SEE ALSO 🔥

• Kernel file ./fs/crypto/block.c
• fscrypt_mergeable_bio(9)
• fscrypt_limit_io_blocks(9)
• fscrypt_zeroout_range(9)

okay that's the whole page bestie, go forth and encrypt responsibly 💖

shoutout to the source ./fs/crypto, dated October 2026 — mwah, we love a documented kernel 🫶✨