kernfs_drain(9)

💅 NAME 💅

okay so this page is all about kernfs_drain — the function that literally drains a kernfs_node. that's it, that's the whole name, no cap. it's giving "short and iconic", and honestly? we love that for it. ✨

this one lives in section 9 of the Kernel API Manual, so yeah, it's kernel-dev territory, bestie — grab your fave beverage and let's go 🫶

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🌸 SYNOPSIS 🌸

void kernfs_drain (struct kernfs_node *kn , bool drop_supers );

literally the whole signature right there. two args, one void return because this function does the work and doesn't hand you a result back — main character energy, honestly. 👑

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🎀 ARGUMENTS 🎀

• kn — the kernfs_node you're about to drain. this is the girl you're working on. 💅
• drop_supers — set this to true if this function is called with the kernfs_supers_rwsem locked. yes bestie, that kernfs_supers_rwsem. read the room (and your locking context) before you flip this one, ok? 🙈

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🦋 DESCRIPTION 🦋

so what does it actually do. two things, and they're both kinda fierce:

• it drains existing usages of kn — like, politely but firmly showing everyone the door 🚪
• it nukes all existing mmaps of kn. yes. nukes. that's the actual word. violent but iconic 💀🔥

and here's the part that lowkey slays: multiple removers may invoke this function concurrently on kn, and all of them will return after draining is complete. so no weird "who goes first" drama — everybody waits, everybody returns, everybody's fine. synchronized queen behavior, fr fr 👑

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⭐ SEE ALSO ⭐

the kernel file in question is ./fs/kernfs/dir.c, and it comes with a whole friend group of related functions — here's the full squad, no one gets left behind 🫶:

kernfs_path_from_node_locked(9), kernfs_name(9), kernfs_path_from_node(9), pr_cont_kernfs_name(9), pr_cont_kernfs_path(9), kernfs_get_parent(9), kernfs_name_hash(9), kernfs_link_sibling(9), kernfs_unlink_sibling(9), kernfs_get_active(9), kernfs_put_active(9), kernfs_get(9), kernfs_put(9), kernfs_node_from_dentry(9), kernfs_add_one(9), kernfs_find_ns(9), kernfs_find_and_get_ns(9), kernfs_walk_and_get_ns(9), kernfs_create_root(9), kernfs_destroy_root(9), kernfs_root_to_node(9), kernfs_create_dir_ns(9), kernfs_create_empty_dir(9), kernfs_next_descendant_post(9), kernfs_activate(9), kernfs_show(9), kernfs_remove(9), kernfs_break_active_protection(9), kernfs_unbreak_active_protection(9), kernfs_remove_self(9), kernfs_remove_by_name_ns(9), kernfs_rename_ns(9)

like, that's a lot of friends. go read them too, iykyk 🌈

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okay that's the page!! this beauty came from ./fs/kernfs and it's dated October 2026 — so mark your calendar bestie, and slay your kernel work responsibly 💖🎀✨