is_subdir(9)

🦋 is_subdir(9) — Kernel API Manual, but make it cute 🦋

🌸 NAME 🌸

is_subdir — is new dentry a subdirectory of old_dentry? That's the whole question, bestie. 🕵️‍♀️

✨ SYNOPSIS ✨

bool is_subdir (struct dentry *new_dentry , struct dentry *old_dentry );

🎀 ARGUMENTS 🎀

• new_dentry — the new dentry, the fresh little entry we're checking. 🫶
• old_dentry — the old dentry, the one it's being checked against. 💅

💖 DESCRIPTION 💖

Okay so here's the tea: is_subdir returns true if new_dentry is a subdirectory of the parent (at any depth). It returns false otherwise. No cap. ✨

⚠️ caller responsibility, bestie: the caller must ensure that "new_dentry" is pinned before calling is_subdir. Like, do not skip this. 💀

🔥 SEE ALSO 🔥

Kernel file ./fs/dcache.c is the home base, and the whole friend group is:

• d_drop(9)
• dentry_kill(9)
• __move_to_shrink_list(9)
• d_find_any_alias(9)
• d_find_alias(9)
• prune_dcache_sb(9)
• shrink_dcache_sb(9)
• enum d_walk_ret(9)
• d_walk(9)
• path_has_submounts(9)
• shrink_dcache_tree(9)
• d_invalidate(9)
• __d_alloc(9)
• d_alloc(9)
• d_alloc_pseudo(9)
• d_instantiate(9)
• d_obtain_alias(9)
• d_obtain_root(9)
• d_add_ci(9)
• d_same_name(9)
• __d_lookup_rcu(9)
• d_lookup(9)
• __d_lookup(9)
• d_hash_and_lookup(9)
• d_delete(9)
• d_rehash(9)
• d_add(9)
• d_ancestor(9)
• d_splice_alias(9)

okay bye bestie 💅 this page's source/version is ./fs, dated October 2026, and it's still is_subdir(9) — mwah! 🫶