d_obtain_root(9)

✨ NAME ✨ — d_obtain_root(9)

okay bestie, welcome to d_obtain_root(9) from the Kernel API Manual 💅 — the function that finds or allocates a dentry for a given inode, and honestly it's giving “root of the filesystem main character energy” 👑✨

🎀 SYNOPSIS 🎀

struct dentry * d_obtain_root (struct inode *inode );

🦋 ARGUMENTS 🦋

• inode — the inode you're allocating the dentry for, no cap 🫶

💖 DESCRIPTION 💖

So the goal is: obtain an IS_ROOT dentry for the root of a filesystem. Slay 🌈.

We must ensure that directory inodes only ever have one dentry — literally one, bestie. If a dentry is found, that one is returned instead of allocating a new one. Not me allocating a whole new dentry when one already exists 💀.

On successful return, the reference to the inode has been transferred to the dentry. In case of an error, the reference on the inode is released 🫶.

A NULL or IS_ERR inode may be passed in, and the error will propagate to the return value — with a NULL inode replaced by ERR_PTR(-ESTALE). Yep, that's the plot twist 🙈✨.

🔥 SEE ALSO 🔥

Kernel file ./fs/dcache.c and this whole friend group 🧚:

• 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_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)
• is_subdir(9)

Cute sign-off bestie 💜: this page comes from source/version ./fs, dated October 2026, and it's d_obtain_root(9) — byeee, drink water and check your dentries 💅🫶