get_anon_bdev(9)

💅 get_anon_bdev 💅

okay so bestie, welcome to the Kernel API Manual ✨ — today's main character is get_anon_bdev(9), and she's literally the friend who hooks you up when you don't have your own block device. let's get into it 🫶

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✨ NAME ✨

get_anon_bdev — allocate a block device for filesystems which don't have one. no cap, that's the whole job 💖

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🎀 SYNOPSIS 🎀

int get_anon_bdev (dev_t *p );

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🦋 ARGUMENTS 🦋

• p — a pointer to a dev_t. that's it, that's the argument. she takes one (1) pointer and she takes it seriously ✨

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🌸 DESCRIPTION 🌸

so like, some filesystems don't use real block devices — they're doing their own thing, living their truth 💅 — and those filesystems can call this function to allocate a virtual block device.

that's the vibe. no physical hardware required, just a cute little virtual bdev to call your own 🎀

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💜 CONTEXT 💜

Any context. literally any. she's flexible like that 🧚

though highkey, she's frequently called while holding sb_lock — so like, know that going in, iykyk 😌

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⭐ RETURN ⭐

here's the vibe check on what you get back:

• 0 — slay, success 💖
• -EMFILE — no anonymous bdevs left 😭 they're all taken, the shelf is empty
• -ENOMEM — memory allocation failed 💀 the malloc said no

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🌈 SEE ALSO 🌈

buckle up bestie, this is a whole friend group — all from the kernel file ./fs/super.c:

super_lock(9), alloc_super(9), deactivate_locked_super(9), deactivate_super(9), grab_super(9), retire_super(9), generic_shutdown_super(9), sget_fc(9), iterate_supers_type(9), reconfigure_super(9), emergency_thaw_all(9), sget_dev(9), fs_bdev_freeze(9), fs_bdev_thaw(9), fs_bdev_file_open_by_dev(9), fs_bdev_file_open_by_path(9), fs_bdev_unregister(9), fs_bdev_file_release(9), get_tree_bdev_flags(9), get_tree_bdev(9), vfs_get_tree(9), sb_wait_write(9), freeze_super(9), thaw_super(9)

like i said. a whole friend group. go say hi 👋💜

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remembe: virtual bdevs are a limited resource, so when -EMFILE hits, that's your sign to actually clean up after yourself. be the friend who returns the tupperware 🍓

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okay that's the page!! this one lives in ./fs and it's dated October 2026 — so like, mark your calendar, she's a whole era 👑✨ bye bestie, go allocate responsibly 💅🎀