is_last_write(9)

💅 is_last_write(9) — like, the Kernel API Manual page for is_last_write 🎀

okay so bestie, sit down, we're reading a kernel page together and honestly? it's a short one, we ate. ✨

---

🌸 NAME 🌸

is_last_write — literally figures out if some offset was chillin' in the last write to a LEB. that's it, that's the whole vibe check. 🦋

---

✨ SYNOPSIS ✨

int is_last_write (const struct ubifs_info *c , void *buf , int offs );

look at her go, three args, int out the other side. iconic. 💅

---

🍓 ARGUMENTS 🍓

• c — the UBIFS file-system description object, the main character of the story ngl 🫶
• buf — the buffer we're checking, like the little container of data we're snooping in 🔍
• offs — the offset we're checking, the specific spot bestie, the coords 📍

---

💖 DESCRIPTION 💖

so the way this works is: this function returns 1 if offs was in the last write to the LEB whose data lives in buf. otherwise you get 0. no cap, that's the whole deal. 😌

and how does it know? the determination is made by checking for subsequent empty space starting from the next c->max_write_size boundary. like, it peeks past that boundary looking for emptiness and goes "yeah, that was the last write" or "nope". detective behaviour fr fr 🔥

---

🌈 SEE ALSO 🌈

Kernel file ./fs/ubifs/recovery.c has a whole friend group, and they're all here — say hi besties 👋💜

• is_empty(9)
• first_non_ff(9)
• get_master_node(9)
• write_rcvrd_mst_node(9)
• ubifs_recover_master_node(9)
• ubifs_write_rcvrd_mst_node(9)
• clean_buf(9)
• no_more_nodes(9)
• fix_unclean_leb(9)
• drop_last_group(9)
• drop_last_node(9)
• ubifs_recover_leb(9)
• get_cs_sqnum(9)
• ubifs_recover_log_leb(9)
• recover_head(9)
• ubifs_recover_inl_heads(9)
• clean_an_unclean_leb(9)
• ubifs_clean_lebs(9)
• grab_empty_leb(9)
• ubifs_rcvry_gc_commit(9)
• struct size_entry(9)
• add_ino(9)
• find_ino(9)
• remove_ino(9)
• ubifs_destroy_size_tree(9)
• ubifs_recover_size_accum(9)
• fix_size_in_place(9)
• inode_fix_size(9)
• ubifs_recover_size(9)

---

k byeee, that's the page 🫶 this lil masterpiece comes from ./fs/ubifs, dated October 2026 — and this rewrite's filed under is_last_write(9) too, obviously, she contains multitudes 💀✨👑