iov_iter_extract_bvecs(9)

📦 version 7.3.1, in nixpkgs unstable

💅 iov_iter_extract_bvecs — Kernel API Manual ✨

okay so bestie, welcome to iov_iter_extract_bvecs(9), straight out of the Kernel API Manual — yes that manual, the one we all pretend we've read 🎀

This is the page for iov_iter_extract_bvecs, and it's literally about pulling bvecs out of an iterator. Slay. Let's get into it 🦋

🌸 NAME 🌸

iov_iter_extract_bvecs — Extract bvecs from an iterator. that's it, that's the whole vibe 💖

✨ SYNOPSIS ✨

ssize_t iov_iter_extract_bvecs (struct iov_iter *iter , struct bio_vec
*bv , size_t max_size , unsigned short *nr_vecs , unsigned short
max_vecs , unsigned mem_align_mask , iov_iter_extraction_t
extraction_flags );

no cap, that's a whole lot of parameters, but we're gonna go through every single one together 🫶

🎀 ARGUMENTS 🎀

  • iter — the iterator you're extracting from. your main character, if you will 👑
  • bv — the bvec return array. this is where the extracted goodies land 🍓
  • max_size — the maximum size to extract from iter. a lil boundary, respect it 💅
  • nr_vecs — number of vectors in bv, and heads up bestie, it's on in and output — it goes both ways 😭
  • max_vecs — the maximum vectors in bv, including those filled before calling. so like, count the ones already there, don't be out here acting like the array was empty 🙈
  • mem_align_mask — reject with -EINVAL if the source address or length is not aligned to this mask. alignment is not optional, it's a lifestyle ⭐
  • extraction_flags — flags to qualify the request. the little extra seasoning on top 🔥

💜 DESCRIPTION 💜

So think of it like iov_iter_extract_pages, but make it bvec 💅 — instead of returning multiple entries, it returns physically contiguous ranges contained in a single folio as a single bvec. fewer entries, same energy. iconic behaviour honestly 🌈

It returns the number of bytes extracted when successful, or a negative errno. and ngl, there's one lil quirk to know: if nr_vecs was non-zero on entry, the number of successfully extracted bytes can be 0. not a bug, just how it is, so don't come for it 😌

🧚 SEE ALSO 🧚

like a whole friend group of functions, fr fr — go say hi to all of them 🦋

lowkey important: that -EINVAL on misalignment in mem_align_mask is real, and that 0-bytes-extracted case when nr_vecs was non-zero on entry is real too. know them, love them, don't get surprised by them 💀

and that's the page babes 💖 this one lives in ./lib, dated October 2026, and it's filed under iov_iter_extract_bvecs(9) — periodt. go extract some bvecs, you're gonna eat 🎀✨🌸

📦 where this page comes from