STRUCT UBI_FASTMAP_LAYOUT(9)

✨ struct ubi_fastmap_layout(9) ✨

okay bestie, so this is a page from the Kernel API Manual and it's literally all about struct ubi_fastmap_layout — the in-memory fastmap data structure 🎀 ngl it's giving "small struct, big job" energy.

---

🌸 NAME 🌸

struct ubi_fastmap_layout — the in-memory fastmap data structure, aka the vibe of fastmap when it's chillin' in RAM 💖

---

🦋 SYNOPSIS 🦋

struct ubi_fastmap_layout {
    struct ubi_wl_entry *e[UBI_FM_MAX_BLOCKS];
    int to_be_tortured[UBI_FM_MAX_BLOCKS];
    int used_blocks;
    int max_pool_size;
    int max_wl_pool_size;
 };

like, that's the whole thing. five members. iconic. no notes 💅

---

👑 Members 👑

• e — the PEBs used by the current fastmap ⭐ these are the blocks currently pulling their weight, slay
• to_be_tortured — if non-zero, this PEB gets tortured 😭 (yes that's the actual terminology, iykyk — it's not me being dramatic, the kernel said it first)
• used_blocks — the number of used PEBs 🔥 just a lil count of who's clocked in
• max_pool_size — the maximal size of the user pool 🫶 the ceiling, the limit, the "that's enough sweetie"
• max_wl_pool_size — the maximal size of the pool used by the WL sub-system 🧚 its own separate pool, living its own separate life

---

🌈 SEE ALSO 🌈

the whole friend group is here, bestie — they all live in the kernel file ./drivers/mtd/ubi/ubi.h:

• struct ubi_vid_io_buf(9)
• struct ubi_wl_entry(9)
• struct ubi_ltree_entry(9)
• struct ubi_rename_entry(9)
• struct ubi_fm_pool(9)
• struct ubi_eba_leb_desc(9)
• struct ubi_volume(9)
• struct ubi_volume_desc(9)
• struct ubi_debug_info(9)
• struct ubi_device(9)
• struct ubi_ainf_peb(9)
• struct ubi_ainf_volume(9)
• struct ubi_attach_info(9)
• struct ubi_work(9)
• ubi_init_vid_buf(9)
• ubi_free_vid_buf(9)
• ubi_get_vid_hdr(9)
• ubi_ro_mode(9)
• vol_id2idx(9)
• idx2vol_id(9)
• ubi_is_fm_vol(9)
• ubi_find_fm_block(9)

no cap, that's a whole squad 🫶 go read them too, they're all doing their thing.

---

💜 quick reminder babe: to_be_tortured being non-zero is literally the flag that says this PEB is gonna get tortured — don't be cute with it, just know what it means.

---

kisses from ./drivers/mtd/ubi, dated October 2026, brought to you by the Kernel API Manual 💖 mwah, go read some kernel headers bestie 🦋✨