STRUCT NILFS_SEGSUM_INFO(9)

💖 struct nilfs_segsum_info(9) 💖

okay bestie so this is a page straight out of the Kernel API Manual, and honestly? it's giving "receipt for a segment" — this struct is the on-memory segment summary for nilfs2, and it holds literally every little number the kernel needs to remember about a chunk of stuff it just wrote. no cap, it's the main character of segment bookkeeping. 🎀

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✨ NAME ✨

struct nilfs_segsum_info — the on-memory segment summary. that's it, that's the whole vibe. it lives in memory and it summarises segments. periodt. 💅

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🦋 SYNOPSIS 🦋

struct nilfs_segsum_info {
    unsigned int            flags;
    unsigned long           nfinfo;
    unsigned long           nblocks;
    unsigned long           nsumblk;
    unsigned long           sumbytes;
    unsigned long           nfileblk;
    u64 seg_seq;
    __u64 cno;
    time64_t ctime;
    sector_t next;
 };

look at that field list. ten members. all of them slaying in their own lane, all of them copied here exactly, not one of them renamed. 🫶

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👑 Members 👑

here's the tea on every single field, in order, no skipping, we don't do skipping here:

• flags — the flags. yes bestie, that's genuinely all it says, and we're not out here inventing lore. 🚩
• nfinfo — number of file information structures. that's how many file info structs are in the building.
• nblocks — number of blocks included in the partial segment. note the partial — this is not the whole segment, it's the partial one, tyvm.
• nsumblk — number of summary blocks. so many summary blocks. an icon.
• sumbytes — the byte count of the segment summary. bytes is bytes and she counts them all.
• nfileblk — the total number of file blocks. total total. 🌈
• seg_seq — the segment sequence number, u64 and proud of it.
• cno — the checkpoint number, a __u64. checkpoints are lowkey the heart of nilfs2 and you will respect them. ⭐
• ctime — creation time, and she's a time64_t. she was born at a moment and she remembers exactly which one. 🕰️
• next — the block number of the next full segment, typed sector_t. the sequel. the next chapter. the cliffhanger. 🔥

fr fr, every type in that list matters — unsigned int, unsigned long, u64, __u64, time64_t and sector_t are all doing different jobs and none of them are interchangeable. pls don't swap them around, bestie, the compiler will simply pass away. 💀

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💜 SEE ALSO 💜

• Kernel file ./fs/nilfs2/segbuf.h — that's the header you actually want to go read.
• struct nilfs_segment_buffer(9) — her sister struct. same folder energy. go say hi. 🧚

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and that's the whole page bestie!! 🌸 written from ./fs/nilfs2, dated October 2026, and honestly? iconic of that directory to serve this to us. mwah 💋 ✨ slay responsibly and keep your types exactly as typed 🍓