bio_add_folio(9)

📦 version 7.3.1, in nixpkgs unstable

💅 bio_add_folio(9) — the Kernel API Manual, bestie edition

okay so this is bio_add_folio(9) from the Kernel API Manual, and honestly? it's a little cutie. let's get into it 🎀

✨ NAME ✨

bio_add_folio — attempt to add part of a folio to a bio. that's it. that's the whole vibe. 💖

🌸 SYNOPSIS 🌸

bool bio_add_folio (struct bio *bio , struct folio *folio , size_t len ,
size_t off );

like, look at her. four args, returns a bool. main character energy fr fr. 👑

🦋 ARGUMENTS 🦋

  • bio — the BIO to add to. she's the one receiving. 🫶
  • folio — the folio to add. the guest of honor ✨
  • len — how many bytes from the folio to add. like, a slice. 🍓
  • off — first byte in this folio to add. yes, we're starting from off, not zero, don't come for me 🙈

💜 DESCRIPTION 💜

so here's the tea ☕ — filesystems that use folios can call this function instead of calling bio_add_page for every single page in the folio. the way that saves you a whole loop... iconic. 😭💅

here's the little plot twist though: if off is bigger than PAGE_SIZE, this function can create a bio_vec that starts in a page after the bv_page. yeah. it do be like that. 🙈

💀 and this is the important bit, bestie — BIOs do not support folios that are 4GiB or larger. no cap. that's the limit. don't try it. ⭐

🔥 RETURN 🔥

whether the addition was successful. a simple bool, no drama, no hidden agenda. slay. ✨

🌈 SEE ALSO 🌈

kernel file ./block/bio.c plus the whole friend group:

iykyk 🧚💜

and that's the whole page!! this one lives under ./block and it's dated October 2026, page bio_add_folio(9) — go off, block layer. 🌸🦋⭐

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