lookup_level0_dirty(9)

💖 NAME 💖

Okay bestie, welcome to lookup_level0_dirty(9) from the Kernel API Manual — yes, we're doing a search for zero-level znode dirtying, and it's kinda iconic 💅.

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🌸 SYNOPSIS 🌸

int lookup_level0_dirty (struct ubifs_info *c , const union ubifs_key
*key , struct ubifs_znode **zn , int *n );

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✨ ARGUMENTS ✨

• c — UBIFS file-system description object — the context baddie you pass in.
• key — key to lookup — the key we're hunting for, no cap.
• zn — znode is returned here — the found zero-level znode gets dropped right into this pointer.
• n — znode branch slot number is returned here — the slot number comes back through this one.

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🦋 DESCRIPTION 🦋

So this function looks up the TNC tree and searches for the zero-level znode that refers to key key ✨. The found zero-level znode is returned in zn, bestie.

There are 3 cases, keep up 👑:

1. Exact match — the found zero-level znode contains key key. Then 1 is returned, and the slot number of the matched branch is stored in n 💖.
2. Not exact match — meaning the zero-level znode does not contain the key. Then 0 is returned, and the slot number of the closed branch is stored in n 🫶.
3. Key is tiny — so small that it's even less than the lowest key of the leftmost zero-level node. Then 0 is returned, and -1 is stored in n 😭.

Additionally, all znodes in the path from the root to the located zero-level znode are marked as dirty 🎀.

Note, when the TNC tree is traversed, some znodes may be absent, then this function reads corresponding indexing nodes and inserts them to TNC. In case of failure, a negative error code is returned 💀.

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🎀 SEE ALSO 🎀

Kernel file ./fs/ubifs/tnc.c and the whole crew, in order:

• insert_old_idx(9), insert_old_idx_znode(9), ins_clr_old_idx_znode(9), destroy_old_idx(9), copy_znode(9), add_idx_dirt(9)
• replace_znode(9), dirty_cow_znode(9), lnc_add(9), lnc_free(9), tnc_read_hashed_node(9), try_read_node(9)
• fallible_read_node(9), matches_name(9), get_znode(9), tnc_next(9), tnc_prev(9), resolve_collision(9)
• fallible_matches_name(9), fallible_resolve_collision(9), matches_position(9), resolve_collision_directly(9), dirty_cow_bottom_up(9), ubifs_lookup_level0(9)
• maybe_leb_gced(9), ubifs_tnc_locate(9), ubifs_tnc_get_bu_keys(9), read_wbuf(9), validate_data_node(9), ubifs_tnc_bulk_read(9)
• do_lookup_nm(9), ubifs_tnc_lookup_nm(9), ubifs_tnc_lookup_dh(9), correct_parent_keys(9), insert_zbranch(9), tnc_insert(9)
• ubifs_tnc_add(9), ubifs_tnc_replace(9), ubifs_tnc_add_nm(9), tnc_delete(9), ubifs_tnc_remove(9), ubifs_tnc_remove_nm(9)
• ubifs_tnc_remove_dh(9), key_in_range(9), ubifs_tnc_remove_range(9), ubifs_tnc_remove_ino(9), ubifs_tnc_next_ent(9), tnc_destroy_cnext(9)
• ubifs_tnc_close(9), left_znode(9), right_znode(9), lookup_znode(9), is_idx_node_in_tnc(9), is_leaf_node_in_tnc(9)
• ubifs_tnc_has_node(9), ubifs_dirty_idx_node(9), dbg_check_inode_size(9)

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Signed with love from the ./fs/ubifs girlies, October 2026 — catch you in lookup_level0_dirty(9) 💜🫶