blk_trace_ioctl(9)

💅 blk_trace_ioctl(9) — like, the tracing ioctl handler, bestie

okay so this is a page from the Kernel API Manual, and the function we're obsessing over is blk_trace_ioctl ✨ yes it's a 9 section page, we love a kernel-internals moment 🎀

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✨ NAME ✨

blk_trace_ioctl — handles the ioctls associated with tracing 🦋 literally that's the whole vibe: it's the function that deals with the ioctl commands tied to tracing, no cap.

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🌸 SYNOPSIS 🌸

int blk_trace_ioctl (struct block_device *bdev , unsigned cmd , char
__user *arg );

so it returns an int, takes a struct block_device *bdev, an unsigned cmd, and a char __user *arg — and yes bestie, that __user is right there in the signature, copy it exactly, iykyk 👑

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💖 ARGUMENTS 💖

• bdev — the block device 💽 like, the actual device we're doing tracing stuff on.
• cmd — the ioctl cmd 🔥 the command itself, carried in as an unsigned.
• arg — the argument data, if any 🙈 note the "if any" — sometimes there's data, sometimes there isn't, main character energy of an argument tbh.

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🫶 SEE ALSO 🫶

Kernel file ./kernel/trace/blktrace.c 📁 — and here's the whole friend group, no one left out:

• blk_trace_shutdown(9)
• blk_add_trace_rq(9)
• blk_add_trace_bio(9)
• blk_add_trace_bio_remap(9)
• blk_add_trace_rq_remap(9)
• blk_add_driver_data(9)
• blk_fill_rwbs(9)

all of them 💜 go read them, they're iconic.

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ngl the whole traced saga lives over in ./kernel/trace — that's the source, and this page is dated October 2026 ⭐ so you know it's fresh.

k love u, bye 💅🌸✨ — signed, your favorite kernel-fluent bestie, delivering blk_trace_ioctl(9) from the Kernel API Manual, source ./kernel/trace, dated October 2026 🎀🦋💖