blkcg_print_blkgs(9)

💖 blkcg_print_blkgs(9) 💖

okay so welcome to the Kernel API Manual, bestie — today's main character is blkcg_print_blkgs(9), and honestly? she's a helper. a little printing helper. a per-blkg data princess. let's get into it 🎀

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✨ NAME ✨

blkcg_print_blkgs — the helper for printing per-blkg data, periodt 💅

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🌸 SYNOPSIS 🌸

void blkcg_print_blkgs (struct seq_file *sf , struct blkcg *blkcg , u64
(*prfill)(struct seq_file *, struct blkg_policy_data *, int) , const
struct blkcg_policy *pol , int data , bool show_total );

like yes she takes six whole arguments, she's highkey booked and busy 🦋

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🧚 ARGUMENTS 🧚

• sf — the seq_file we're printing into. the canvas. the vibe recipient ✨
• blkcg — the blkcg of interest. the one we care about. the main character 💅
• prfill — the fill function, aka the thing that actually prints out a blkg. she's the talent 🎀
• pol — the policy in question. iykyk 👑
• data — the data being handed off to prfill. a little gift 🎁
• show_total — whether to print out the sum of prfill's return values or not. yes or no, bestie 🫶

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💜 DESCRIPTION 💜

so here's the tea: this function invokes prfill on each blkg of blkcg — but only if the pd for the policy specified by pol exists. no pd, no party 🙈

prfill gets invoked with sf, the policy data, and data, and all of that happens under RCU read lock. noted. respected. ⭐

and if show_total is true, the sum of the return values from prfill gets printed with a "Total" label at the end. slay, a little summation moment 🔥

real talk: this is to be used to construct print functions for cftype->read_seq_string. that's the whole point. that's her job 🧚

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🌈 SEE ALSO 🌈

Kernel file ./block/blk-cgroup.c

the whole friend group, no cap:

• blkcg_css(9)
• blkg_free(9)
• bio_blkcg_css(9)
• blkcg_parent(9)
• blkg_alloc(9)
• blkg_lookup_create(9)
• __blkg_prfill_u64(9)
• blkg_conf_init(9)
• blkg_conf_open_bdev(9)
• blkg_conf_prep(9)
• blkg_conf_unprep(9)
• blkg_conf_close_bdev(9)
• blkcg_destroy_blkgs(9)
• blkcg_pin_online(9)
• blkcg_unpin_online(9)
• blkcg_css_offline(9)
• blkcg_activate_policy(9)
• blkcg_deactivate_policy(9)
• blkcg_policy_register(9)
• blkcg_policy_unregister(9)
• blkcg_maybe_throttle_current(9)
• blkcg_schedule_throttle(9)
• blkcg_add_delay(9)
• blkg_tryget_closest(9)
• bio_associate_blkg_from_css(9)
• bio_associate_blkg(9)
• bio_clone_blkg_association(9)

like, that's the entire group chat and every single one of them is iconic 💖

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and that's the page, bestie!! 🫶 this one came to you from the ./block corner of the kernel, dated October 2026 — go forth, print your per-blkg data, and remember: RCU read lock is not a suggestion 💀✨