STRUCT NILFS_BMAP_STORE(9)

💖 struct nilfs_bmap_store 💖

Kernel API Manual · section 9 · the shadow-copy glow-up you didn't know you needed ✨

okay bestie, so this is a kernel struct page, and yes it's a whole vibe. it lives in the kernel API manual (that's the manual name, iykyk) and it's literally just a lil snapshot container. no cap, it's giving "save state before you do something unhinged" 🫶

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🌸 NAME 🌸

struct nilfs_bmap_store — shadow copy of bmap state 💅

like… a photocopy of your bmap state. a spare. a little backup bestie. periodt.

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✨ SYNOPSIS ✨

struct nilfs_bmap_store {
    __le64 data[NILFS_BMAP_SIZE / sizeof(__le64)];
    __u64 last_allocated_key;
    __u64 last_allocated_ptr;
    int state;
 };

copy it exactly, don't be weird about it 🔥 (yes, the spacing is a little funky at the end, that's just how the original ate, leave it)

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🎀 Members 🎀

• data — the cached raw block mapping of the on-disk inode. literally the receipts, cached. 💾
• last_allocated_key — the cached value of the last allocated key for the data block. it remembers the last key so you don't have to 🗝️
• last_allocated_ptr — the cached value of the last allocated ptr for the data block. the matching pointer bestie, keeping last_allocated_key company 🫶
• state — the cached value of the state field of the bmap structure. a little photocopy of the state field, iconic behaviour 👑

so yeah, all four are cached values — that's the whole point of the struct. shadow copy energy only. no original claims, no improvisation 🌈

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🦋 SEE ALSO 🦋

• Kernel file ./fs/nilfs2/bmap.h — the source of truth, go read it if you're nosy (respectfully) 📖
• union nilfs_bmap_ptr_req(9)
• struct nilfs_bmap_stats(9)
• struct nilfs_bmap_operations(9)
• struct nilfs_bmap(9)

the whole friend group, fr fr 💜

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and that's the page!! source: ./fs/nilfs2, dated October 2026 — mwah, drink water, and go read bmap.h 💖🎀✨