raid1_check_read_range(9)

✨ raid1_check_read_range ✨

ok so bestie, welcome to the Kernel API Manual 💅 — today we're looking at raid1_check_read_range(9), which is genuinely one of those little helper functions that eats and leaves no crumbs 🍓

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🌸 NAME 🌸

raid1_check_read_range — check a given read range for bad blocks, and the available read length gets returned ✨ (yes, it says "returned;" with a semicolon, she's quirky like that, we love her)

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🎀 SYNOPSIS 🎀

int raid1_check_read_range (struct md_rdev *rdev , sector_t this_sector
, int *len );

like… look at that signature. iconic. no notes. 👑

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💖 ARGUMENTS 💖

• rdev — the rdev to read 🫶 this is the device we're checking babe
• this_sector — read position 📍 where we're at, sector-wise
• len — read length 📏 how much we're tryna read

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🦋 DESCRIPTION 🦋

okay so this is a helper function for read_balance — she's not the main character, she's the bestie behind the main character, and honestly? that's main character energy too 💅

here's the vibe check on what she returns 👇

1. If there are no bad blocks in the range, len is returned ✨ clean range, clean return, no drama
2. If the range is all bad blocks, 0 is returned 💀 nothing good in there, sorry bestie
3. If there are partial bad blocks, we gotta get specific:
   • If the bad block range starts after this_sector, the length of the first good region is returned 🌈 yay, we found the good part
   • If the bad block range starts before this_sector, 0 is returned and len is updated to the offset into the region before we get to the good blocks 🧚 so like, len gets rewritten to tell you how far you gotta skip before the good stuff starts

no cap, case 3 is the one where you actually gotta pay attention — len is an int *, she gets modified, so don't be surprised when she comes back different 🙈

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🔥 SEE ALSO 🔥

Kernel file ./drivers/md/raid1-10.c — go read the source, iykyk ⭐

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and that's the whole page bestie, fr fr 🎀 this one lives under ./drivers/md, and the page itself is dated October 2026 — so yeah, she's from the future and she's still slaying 💜✨👑