vdo_convert_maximum_age(9)

💫 vdo_convert_maximum_age(9) 💫

okay bestie, welcome to the Kernel API Manual page for vdo_convert_maximum_age</p> — yes the whole page is literally named that, it's a whole vibe 🎀

---

✨ NAME ✨

vdo_convert_maximum_age — converts the maximum age so it reflects the new recovery journal format 🦋

---

🌸 SYNOPSIS 🌸

block_count_t vdo_convert_maximum_age (block_count_t age );

like, yes, that's the whole signature, no cap 💅

---

🎀 ARGUMENTS 🎀

• age — the configured maximum age, bestie. that's the one you're feeding in 🫶

---

⭐ RETURN ⭐

the converted age. that's it, that's the return value ✨

---

💖 DESCRIPTION 💖

okay so this is actually so interesting, let me set the scene for you 🌈

in the old recovery journal format, each journal block held 311 entries, and every write bio made two entries. and the old maximum age was half the usable journal length. periodt.

now in the new format, each block holds only 217 entries — yeah, fewer, I know 😭 — but each bio only makes one entry. so it kinda balances out.

so what this function does is convert the configured age so that the number of writes in a block map era is, like, the same in the old and the new formats 👑

and why do we care? two reasons, and they're both iconic:

• it keeps the bound on the amount of work required to recover the block map from the recovery journal the same across the format change 🧚
• it also keeps the amortization of block map page writes to write bios the same 💜

fr fr, that's the whole point. the vibes are preserved across the format change 💅

---

🔥 SEE ALSO 🔥

• Kernel file ./drivers/md/dm-vdo/block-map.h
• vdo_entry_callback_fn(9)

---

okay that's the page!! go off bestie, you understood all of it, i'm obsessed 🫶💖

signing off from ./drivers/md/dm-vdo — dated October 2026 — catch you in the next manpage, mwah 💋✨