fixup_overlap_head(9)

✨ fixup_overlap_head ✨

okay so bestie, welcome to the fixup_overlap_head(9) glow-up 💅 this one lives in the Kernel API Manual and it's literally the head-overlap handler for cache keys. no cap, she's a little niche but she's iconic.

---

🌸 SYNOPSIS 🌸

int fixup_overlap_head (struct pcache_cache_key *key , struct
pcache_cache_key *key_tmp , struct pcache_cache_subtree_walk_ctx *ctx );

---

🎀 ARGUMENTS 🎀

• key — the brand-new cache key you're inserting, main character energy fr fr.
• key_tmp — the existing cache key that overlaps with your new key 👀 the one getting adjusted.
• ctx — context for the cache tree walk, iykyk.

---

💖 DESCRIPTION 💖

So here's the vibe: this function adjusts the existing key whenever the new key overlaps with the beginning of it 🫶

And here's the important part — if the key length ends up at zero after that adjustment, the key gets deleted. that's the tree telling you this key no longer holds valid data 😭 which means the tree has to be re-researched for a new insertion point. not me having to go find a fresh spot in the tree...

---

🔥 SEE ALSO 🔥

All of these live in the kernel file ./drivers/md/dm-pcache/cache_key.c — go say hi to the whole squad:

• cache_key_get(9)
• cache_key_destroy(9)
• cache_key_append(9)
• cache_subtree_walk(9)
• cache_subtree_search(9)
• fixup_overlap_tail(9)
• fixup_overlap_contain(9)
• fixup_overlap_contained(9)
• cache_key_insert(9)
• clean_fn(9)

---

🫶 friendly reminder bestie: zero-length key after adjustment = deleted = tree walk needs to happen again. don't skip that part 💀

---

aaaand that's the whole page, we ate and left zero crumbs 🍓 this lil' number comes to you from ./drivers/md/dm-pcache, dated October 2026 — mwah, see you in the next manpage 💜🧚✨