__bio_split_to_limits(9)

💅 __bio_split_to_limits(9) — the Kernel API Manual, bestie edition 🎀

okay so real talk, this one lives in the Kernel API Manual (section 9, kernel girlies know) and it's literally the function that decides whether a bio is too much for the queue to handle and needs to be chopped down to size. it's giving responsible older sibling energy, honestly 🫶

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✨ SYNOPSIS ✨

struct bio * __bio_split_to_limits (struct bio *bio , const struct
       queue_limits *lim , unsigned int *nr_segs );

like, yes, that's the whole signature and yes you have to read it. it's fine. it's iconic. 🔥

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🌸 ARGUMENTS 🌸

• bio — the bio that's about to get split. this is the main character of the function, lowkey 💖
• lim — the queue limits we're doing the splitting based on. these are the rules, and we respect them fr fr
• nr_segs — this one returns the number of segments in the returned bio. it's an output, not an input, so don't come for it 🙈

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🦋 DESCRIPTION 🦋

so here's the vibe: we check if the bio needs splitting based on the queue limits, and if it does, we split off a bio that actually fits the limits — from the beginning of bio — and return it. slay ✨

then bio gets shortened to the remainder and re-submitted. the way that it just keeps going, honestly obsessed 😭

the split bio is allocated from q->bio_split, which is provided by the block layer. no cap, that's where it comes from 👑

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🧚 SEE ALSO 🧚

• Kernel file ./block/blk.h
• get_max_segment_size(9)

both of these are your little study buddies for this one, iykyk 💜

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ngl, if you skim this you WILL mess up which bio is the remainder and which one you're returning, and that's a whole situation. read it twice. 💀

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and that's the page, bestie!! 🍓 source is ./block, dated October 2026, and the title up top is __bio_split_to_limits(9) — mwah, bye, go split some bios responsibly 🌈⭐💅