blkg_lookup(9)

💅 blkg_lookup(9) — Kernel API Manual, bestie edition 🎀

okay so hi bestie 💖 we're in the Kernel API Manual and this is the blkg_lookup(9) page. It's giving kernel-cgroup lookup realness, and yes, you're gonna understand it. 🦋

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🌸 NAME

blkg_lookup — lookup blkg for the specified blkcg - q pair. That's the whole name vibe: one lookup, one blkcg - q pair, no cap. ✨

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✨ SYNOPSIS

       struct blkcg_gq * blkg_lookup (struct blkcg *blkcg , struct
       request_queue *q );

That's the signature, bestie — copy it exactly if you're quoting it, because kernel signatures are not a choose-your-own-adventure. 💅

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🎀 ARGUMENTS

• blkcg — blkcg of interest. Like, the one you're curious about. 👀
• q — request_queue of interest. The queue in question, periodt. 🫶

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💖 DESCRIPTION

okay so this function looks up the blkg for the blkcg - q pair. That's the move. ✨

⚠️ Must be called in a RCU critical section. This is not optional, bestie — the manpage literally says must, so keep your lookup inside that RCU critical section. 😭

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🔥 SEE ALSO

The whole SEE ALSO squad, iykyk: 🌈

• Kernel file ./block/blk-cgroup.h
• bio_issue_as_root_blkg(9)
• blkg_to_pd(9)
• pd_to_blkg(9)
• blkg_get(9)
• blkg_tryget(9)
• blkg_put(9)
• blkg_for_each_descendant_pre(9)
• blkg_for_each_descendant_post(9)
• blkcg_set_delay(9)
• blkcg_clear_delay(9)
• blk_cgroup_mergeable(9)

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xoxo, your Kernel API Manual bestie 💖 source/version: ./block · date: October 2026 · page: blkg_lookup(9) ✨