allocate_and_lock_block(9)

💅 allocate_and_lock_block(9) — the kernel API manual, but make it make sense

okay so bestie, welcome to the allocate_and_lock_block(9) page from the Kernel API Manual ✨ this is a little function that lives in the kernel-adjacent world and honestly? it's giving "small but mighty" energy. let's get into it 🫶

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🌸 NAME 🌸

allocate_and_lock_block — literally just: attempt to allocate a block from this zone. that's the whole vibe. lowkey does what it says on the tin 💀

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✨ SYNOPSIS ✨

int allocate_and_lock_block (struct allocation *allocation );

that's it. that's the whole call. one argument, returns an int, no cap 🎀

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🎯 ARGUMENTS 🎯

• allocation — the struct allocation of the data_vio that's out here attempting to allocate. that's the thing you're passing in. it wants a block. be nice to it 💖

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🦋 DESCRIPTION 🦋

so here's the tea: if a block does get allocated, the recipient will also hold a lock on it. like, you don't just get the block, you get the block and the lock, packaged together, main character bundle deal 👑 no separate step, no "come back later for your lock", it's included.

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🔥 RETURN 🔥

• VDO_SUCCESS — yay!! a block was allocated, slay 🎉
• an error code — ok so it didn't work out, but you get an error code back so at least you know what happened 😭

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🌈 SEE ALSO 🌈

the whole friend group, fr fr:

• Kernel file ./drivers/md/dm-vdo/physical-zone.c
• vdo_is_pbn_read_lock(9)
• vdo_downgrade_pbn_write_lock(9)
• vdo_claim_pbn_lock_increment(9)
• vdo_assign_pbn_lock_provisional_reference(9)
• vdo_unassign_pbn_lock_provisional_reference(9)
• release_pbn_lock_provisional_reference(9)
• union idle_pbn_lock(9)
• struct pbn_lock_pool(9)
• return_pbn_lock_to_pool(9)
• make_pbn_lock_pool(9)
• free_pbn_lock_pool(9)
• borrow_pbn_lock_from_pool(9)
• initialize_zone(9)
• vdo_make_physical_zones(9)
• vdo_free_physical_zones(9)
• vdo_get_physical_zone_pbn_lock(9)
• vdo_attempt_physical_zone_pbn_lock(9)
• retry_allocation(9)
• continue_allocating(9)
• vdo_allocate_block_in_zone(9)
• vdo_release_physical_zone_pbn_lock(9)
• vdo_dump_physical_zone(9)

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bestie reminder: it's an attempt. allocate_and_lock_block does not promise you a block. check that return value, always 💅

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and that's the page!! brought to you by ./drivers/md/dm-vdo, dated October 2026 — mwah, go read the source, ily, bye 🧚‍♀️💜