bdev_rw_virt(9)

🦋 bdev_rw_virt(9) — Kernel API Manual, but make it cute 🦋

okay so welcome to the bdev_rw_virt(9) page, bestie. This is the Kernel API Manual entry for synchronous read/write into kernel mappings, and we’re gonna make it make sense. No cap. ✨

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✨ NAME ✨

bdev_rw_virt - synchronously read into / write from kernel mapping. That’s the name, that’s the job, that’s the vibe check. 💅

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🌸 SYNOPSIS 🌸

       int bdev_rw_virt (struct block_device *bdev , sector_t sector , void
       *data , size_t len , enum req_op op );

Yep, that’s the whole signature. Keep it exactly like that — kernel API energy does not do “close enough,” fr fr. 😭

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🎀 ARGUMENTS 🎀

• bdev — block device to access. The block device bestie. 🫶
• sector — sector to access. Yes, sector, not sector-adjacent. 💀
• data — data to read/write. The payload of the operation. 🍓
• len — length in byte to read/write. Keep the unit exactly as the page says. 🌸
• op — operation (e.g. REQ_OP_READ/REQ_OP_WRITE). This tells it which direction the vibe is going. 🔥

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💅 DESCRIPTION 💅

Performs synchronous I/O to bdev for data/len. So it’s sync I/O, not “I’ll get back to you later” energy. 💖

🚨 Important caveat: data must be in the kernel direct mapping and not a vmalloc address. Do not ignore this, bestie — this is the “read the instructions before you touch the kernel” part. 😭

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🦋 SEE ALSO 🦋

Kernel file ./block/bio.c — and the whole bio friend group, in the order the page lists them:

• 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_bounce(9)
• bio_iov_iter_unbounce(9)
• bio_await(9)
• submit_bio_wait(9)
• bio_copy_data(9)
• bio_endio(9)
• bio_split(9)
• bio_trim(9)
• bioset_init(9)

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That’s the page, bestie! 💖 Source/version: ./block · Date: October 2026. Go forth and slay your synchronous I/O with the correct mapping energy. 🫶✨