cache_subtree_search(9)

✨ cache_subtree_search(9) ✨

okay bestie so we're diving into the Kernel API Manual today — this one's cache_subtree_search(9) and it's literally the little function that goes hunting through the cache tree for your key 🔍💖

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🌸 NAME 🌸

cache_subtree_search — Search for a key in the cache tree.

like... it searches, babes. that's the whole gig 💅

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🦋 SYNOPSIS 🦋

struct rb_node * cache_subtree_search (struct pcache_cache_subtree
*cache_subtree , struct pcache_cache_key *key , struct rb_node **parentp
, struct rb_node ***newp , struct list_head *delete_key_list );

not me presenting you with five parameters, but honestly she ate 🎀

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🎀 ARGUMENTS 🎀

• cache_subtree — Pointer to the cache tree structure. your main character tree, the one we're searching ✨
• key — Pointer to the cache key to search for. the thing we're looking for, bestie, like when you can't find your airpods but they're literally in your pocket 🙈
• parentp — Pointer to store the parent node of the found node. this is where the parent of the found node goes 💖
• newp — Pointer to store the location where the new node should be inserted. yes it's a triple pointer. yes we're both going through it 😭 but she's storing where the new node should be inserted, slay
• delete_key_list — List to collect invalid keys for deletion. the ✨cleanup committee✨ — anything invalid found along the way gets tossed in here

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💅 DESCRIPTION 💅

so here's the vibe 🌈 this function searches the cache tree for a specific key and returns the node that is the predecessor of the key — or the first node if the key is less than all keys in the tree. lowkey iconic behavior honestly 👑

and if any invalid keys are found during the search, they get added to the delete_key_list for later cleanup. no cap, we clean as we go 🧹✨

and like, the whole point: it returns a pointer to the previous node. struct rb_node * out the door, periodt 💀

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🔥 SEE ALSO 🔥

• Kernel file ./drivers/md/dm-pcache/cache_key.c
• cache_key_get(9)
• cache_key_destroy(9)
• cache_key_append(9)
• cache_subtree_walk(9)
• fixup_overlap_tail(9)
• fixup_overlap_contain(9)
• fixup_overlap_contained(9)
• fixup_overlap_head(9)
• cache_key_insert(9)
• clean_fn(9)

iykyk, go read all of them, they're a whole friend group fr fr 🫶🦋

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💜 okay that's the page!! this little manual lives in ./drivers/md/dm-pcache and it's dated October 2026 — shoutout to the kernel docs from the future, we love to see it ⭐🌸 mwah, go search some trees bestie 🎀💖