bio_uncopy_user(9)

💅 bio_uncopy_user(9) — from the Kernel API Manual, bestie

okay so this is a kernel API page, it lives in the Kernel API Manual, and the whole vibe is "we mapped a bio earlier, now we gotta clean it up." it's literally the cleanup era. 🧹✨

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✨ NAME ✨

bio_uncopy_user — finish a bio that was previously mapped 🎀

like, the cool-down function. the "we're done here, undo the copy situation" moment. no cap.

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🌸 SYNOPSIS 🌸

int bio_uncopy_user (struct bio *bio );

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🦋 ARGUMENTS 🦋

• bio — the bio being terminated 💀 (not in a scary way!! in a "this request is wrapping up" way. it's the bio that's getting finished.)

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👑 DESCRIPTION 👑

so here's the tea, bestie 🍓: this frees the pages that were allocated from bio_copy_user_iov, and — important bit — it writes the data back to user space in case of a read. so if it was a read, the data makes its way home. iconic behavior honestly. 🫶

tl;dr: free the pages, and on a read, copy the goods back out to userspace. two jobs, one function, main character energy. ✨

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🌈 SEE ALSO 🌈

• Kernel file ./block/blk-map.c
• bio_copy_from_iter(9)
• bio_copy_to_iter(9)
• bio_copy_kern(9)
• blk_rq_map_user_iov(9)
• blk_rq_unmap_user(9)
• blk_rq_map_kern(9)

the whole friend group, fr fr. go read them, iykyk 💜

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lowkey reminder: this page is filed under ./block, and it's dated October 2026 — so yeah, mark your calendar, bestie. 🎀

that's the whole page!! mwah 💋 go finish that bio and slay ✨💅🦋