start_writing(9)

💅 start_writing — NAME

okay so this is start_writing(9), and yes bestie it does exactly what it says on the tin: Begin the non-duplicate write path. that's the whole vibe. short, sweet, iconic. ✨

---

🎀 SYNOPSIS

void start_writing (struct hash_lock *lock , struct data_vio *agent );

that's it. that's the function. two pointers and a dream. 💖

---

🫶 ARGUMENTS

• lock — the hash lock. and listen, it's currently gotta be QUERYING — like, that's the state it needs to be in when you call this, no cap. don't come at it in any other state. 🙈
• agent — the data_vio that's currently acting as the agent for the lock. it's the main character of this lock rn, literally. 👑

---

🌈 DESCRIPTION

so here's the tea ☕: this kicks off the non-duplicate write path for a hash lock that had no advice — yep, no advice, it's out here making its own decisions.

if it needs to, it picks a data_vio that has an allocation and makes it the shiny new agent. if necessary, okay? only if necessary. 🦋

then — and this is the slay part — it resumes the agent on the data_vio write path. periodt. that's the whole function. she's efficient. 💅

---

⭐ SEE ALSO

okay this list is long long, but every single one of these is required reading, iykyk. also the kernel file lives at ./drivers/md/dm-vdo/dedupe.c — that's the home base, the mothership, the whole vibe. 🏠✨

• Introduction(9)
• return_hash_lock_to_pool(9)
• vdo_get_duplicate_lock(9)
• hash_lock_key(9)
• get_hash_lock_state_name(9)
• assert_hash_lock_agent(9)
• set_duplicate_lock(9)
• dequeue_lock_waiter(9)
• set_hash_lock(9)
• exit_hash_lock(9)
• set_duplicate_location(9)
• retire_lock_agent(9)
• wait_on_hash_lock(9)
• abort_waiter(9)
• start_bypassing(9)
• finish_unlocking(9)
• unlock_duplicate_pbn(9)
• start_unlocking(9)
• finish_updating(9)
• start_updating(9)
• finish_deduping(9)
• acquire_lock(9)
• enter_forked_lock(9)
• fork_hash_lock(9)
• launch_dedupe(9)
• start_deduping(9)
• increment_stat(9)
• finish_verifying(9)
• start_verifying(9)
• finish_locking(9)
• lock_duplicate_pbn(9)
• start_locking(9)
• finish_writing(9)
• select_writing_agent(9)
• finish_querying(9)
• start_querying(9)
• report_bogus_lock_state(9)
• vdo_continue_hash_lock(9)
• is_hash_collision(9)
• vdo_acquire_hash_lock(9)
• vdo_release_hash_lock(9)
• transfer_allocation_lock(9)
• vdo_share_compressed_write_lock(9)
• report_dedupe_timeouts(9)
• finish_index_operation(9)
• check_for_drain_complete(9)
• vdo_make_hash_zones(9)
• vdo_free_hash_zones(9)
• suspend_index(9)
• resume_index(9)
• vdo_resume_hash_zones(9)
• get_hash_zone_statistics(9)
• vdo_get_dedupe_statistics(9)
• vdo_select_hash_zone(9)
• dump_hash_lock(9)
• dump_hash_zone(9)
• vdo_dump_hash_zones(9)
• acquire_context(9)

fr fr, go read these. not me listing all 57 of them and you skipping to the bottom. 🔥

---

and that's the page!! mwah 💋 this one's from the Kernel API Manual, lives in ./drivers/md/dm-vdo, and it's dated October 2026. see u in the group chat bestie 🫶🍓💜