bio_iov_iter_bounce(9)

💖 bio_iov_iter_bounce(9) 💖

Okay bestie, this page is bio_iov_iter_bounce(9) from the Kernel API Manual, and it’s lowkey all about bouncing buffer data from an iter into a bio. Let’s get into it. ✨

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🌸 NAME 🌸

bio_iov_iter_bounce — bounce buffer data from an iter into a bio. That’s the whole name vibe, periodt.

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🎀 SYNOPSIS 🎀

int bio_iov_iter_bounce (struct bio *bio , struct iov_iter *iter ,
size_t maxlen , size_t minsize );

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🦋 ARGUMENTS 🦋

• bio — bio to send. This is the bio bestie.
• iter — iter to read from / write into.
• maxlen — maximum size to bounce.
• minsize — minimum folio allocation size.

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✨ DESCRIPTION ✨

Okay so picture this: it’s a helper for direct I/O implementations that need to bounce buffer because we need to checksum the data or perform other operations that require consistency. Very “we need things to match” energy. 💅

It allocates folios to back the bounce buffer, and for writes copies the data into it. So writes get their data copied in, no cap.

🫶 It needs to be paired with bio_iov_iter_unbounce called on completion. That pairing is not optional, bestie — the original says it needs to be paired, so don’t ghost it.

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🌈 SEE ALSO 🌈

Kernel file ./block/bio.c is where the neighborhood starts. Here’s the full friend group, exactly as listed:

• bio_reset(9)
• bio_reuse(9)
• bio_chain(9)
• bio_chain_and_submit(9)
• bio_alloc_bioset(9)
• bio_kmalloc(9)
• bio_truncate(9)
• guard_bio_eod(9)
• bio_put(9)
• bio_alloc_clone(9)
• bio_init_clone(9)
• bio_full(9)
• __bio_add_page(9)
• bio_add_virt_nofail(9)
• bio_add_page(9)
• bio_add_folio(9)
• bio_add_vmalloc_chunk(9)
• bio_add_vmalloc(9)
• bio_iov_iter_get_pages(9)
• bio_iov_iter_unbounce(9)
• bio_await(9)
• submit_bio_wait(9)
• bdev_rw_virt(9)
• bio_copy_data(9)
• bio_endio(9)
• bio_split(9)
• bio_trim(9)
• bioset_init(9)

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And that’s the page, bestie! It’s filed under the Kernel API Manual, source ./block, dated October 2026. Stay iconic, and don’t forget the bio_iov_iter_unbounce pairing 🎀💜✨