STRUCT CEPH_SUBVOL_METRIC_RB_ENTRY(9)

💅 struct ceph_subvol_metric_rb_entry(9) 💅

okay so bestie, we're in the Kernel API Manual today and this page is literally about struct ceph_subvol_metric_rb_entry — say that five times fast, i dare you — the per-subvolume I/O metrics node. yes. it's giving "one little node in a red-black tree but she's tracking EVERYTHING." 🎀

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✨ NAME ✨

struct ceph_subvol_metric_rb_entry — the per-subvolume I/O metrics node. that's her. that's the whole vibe. 🦋

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✨ SYNOPSIS ✨

like, here's exactly what she looks like, no notes:

struct ceph_subvol_metric_rb_entry {
    struct rb_node node;
    u64 subvolume_id;
    u64 read_ops;
    u64 write_ops;
    u64 read_bytes;
    u64 write_bytes;
    u64 read_latency_us;
    u64 write_latency_us;
 };

(yeah there's a lil extra space before that closing brace, leave it alone, it's part of the outfit 💅)

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✨ Members ✨

time for the roll call, everyone say hi 👑

• node — the red-black tree linkage, pointing at tracker->tree. she's literally the reason this struct can hang out in the tree at all. main character energy, fr fr. 🌳
• subvolume_id — the subvolume identifier, and also the key for rb-tree lookup. iykyk — this is the one you search by. 🔑
• read_ops — accumulated read operation count since the last snapshot. she's been counting. respectfully. 👀
• write_ops — accumulated write operation count since the last snapshot. same energy, different direction. ✍️
• read_bytes — accumulated bytes read since the last snapshot. big number vibes. 📖
• write_bytes — accumulated bytes written since the last snapshot. the other half of the byte story. 📝
• read_latency_us — the sum of read latencies in microseconds. not an average, bestie — a sum. do not come for me. ⏱️
• write_latency_us — the sum of write latencies in microseconds. again: sum. microseconds. periodt. ⏱️

💀 gentle reminder that the snapshot thing keeps showing up — read_ops, write_ops, read_bytes, and write_bytes are all counted since last snapshot, so don't be weird about it.

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🌈 SEE ALSO 🌈

• Kernel file ./fs/ceph/subvolume_metrics.c — go read the source, she ate. 🔥

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and that's the page!! 🫶 this came to you courtesy of ./fs/ceph, dated October 2026, in the iconic struct ceph_...ric_rb_entry(9) format (yes the title gets truncated in the header, that's just how the kernel rolls, we don't make the rules 💜). mwah, go track some metrics responsibly ✨🌸