read_old_block_mapping(9)

💅 read_old_block_mapping(9) — like, the previous block mapping, bestie 💅

okay so first things first, hi, welcome to the Kernel API Manual 🎀 — yes this is that read_old_block_mapping(9) page, the one you keep opening in a tab and never reading. not anymore. we're doing this together, hand in hand, 🫶.

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✨ NAME ✨

read_old_block_mapping — no cap, all this does is Get the previous PBN/LBN mapping of an in-progress write. that's it. that's the whole vibe. 💖

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🌸 SYNOPSIS 🌸

void read_old_block_mapping (struct vdo_completion *completion );

literally one argument. one. we love a low-effort icon ✨

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🦋 ARGUMENTS 🦋

• completion — the data_vio doing the read. that's the one. the main character of this whole operation 👑

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💜 DESCRIPTION 💜

okay so picture this: we're mid-write, right? and this function — bestie, it Gets the previous PBN mapped to this LBN from the block map, so as to make an appropriate journal entry referencing the removal of this LBN->PBN mapping.

so like. we need to know what used to be there 👀 so the journal can say "yeah, this mapping? we're removing it" and everything stays consistent. it's giving ✨bookkeeping but make it iconic✨. the old mapping gets read out of the block map, boom, journal entry gets made, no notes. 🌈

evergreen reminder: the only thing this does is fetch that previous mapping — it's not out here doing the removal itself, iykyk. keep the facts safe, keep the vibes immaculate 💅

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🔥 SEE ALSO 🔥

the group chat, basically. every single one of these, no skips, no ✂️:

• Kernel file ./drivers/md/dm-vdo/data-vio.c
• Bio flags.(9)
• Introduction(9)
• check_for_drain_complete_locked(9)
• pack_status(9)
• set_data_vio_compression_status(9)
• cancel_data_vio_compression(9)
• attempt_logical_block_lock(9)
• launch_data_vio(9)
• schedule_releases(9)
• process_release_callback(9)
• initialize_data_vio(9)
• make_data_vio_pool(9)
• free_data_vio_pool(9)
• vdo_launch_bio(9)
• drain_data_vio_pool(9)
• resume_data_vio_pool(9)
• dump_data_vio_pool(9)
• release_allocated_lock(9)
• release_logical_lock(9)
• finish_cleanup(9)
• get_data_vio_operation_name(9)
• data_vio_allocate_data_block(9)
• release_data_vio_allocation_lock(9)
• uncompress_data_vio(9)
• modify_for_partial_write(9)
• read_block(9)
• update_block_map(9)
• pack_compressed_data(9)
• compress_data_vio(9)
• launch_compress_data_vio(9)
• hash_data_vio(9)
• write_bio_finished(9)
• acknowledge_write_callback(9)
• allocate_block(9)
• handle_allocation_error(9)
• continue_data_vio_with_block_map_slot(9)

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k bye, this page lives in ./drivers/md/dm-vdo, it's dated October 2026, and yes the header up top really does say read_old_block_mapping(9) twice because manpages are extra like that. go read update_block_map(9) next, you're gonna slay 🧚‍♀️💖