iomap_iter_next(9)

💜 iomap_iter_next(9) — the kernel API manual, bestie edition 💜

okay so this is iomap_iter_next(9) from the Kernel API Manual and honestly? it's lowkey the glue holding your ->iomap_next callback together. let's get into it ✨

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🎀 NAME 🎀

iomap_iter_next — finish the previous mapping and produce the next one. that's it, that's the whole vibe. closing one door, opening the next 🚪✨

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🌸 SYNOPSIS 🌸

int iomap_iter_next (const struct iomap_iter *iter , struct iomap *iomap
, struct iomap *srcmap , iomap_iter_begin_fn begin , iomap_iter_end_fn
end );

like, five parameters, no cap. very demure, very mindful signature 💅

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🦋 ARGUMENTS 🦋

• iter — the iteration structure, your main character of the hour 👑
• iomap — the mapping that gets finished and then repopulated. glow-up arc fr 🔥
• srcmap — the source mapping, also finished and then repopulated. matching set with the one above 🫶
• begin — the callback that produces a mapping for the current position. the glow-up artist 🎨
• end — an optional callback that finishes the previous mapping, or NULL. optional icon behavior, we respect it 🙈

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✨ DESCRIPTION ✨

so iomap_iter_next is an inline helper that implements the common body of an ->iomap_next callback. it's giving "shared code so nobody copies and pastes the same five lines" energy 🧚

here's the little routine it runs, in order:

1. finishes the previous mapping via end — but only if present 💫
2. decides via iomap_iter_continue whether to keep going 🤔
3. obtains the next mapping via begin 🌈

and here's the iconic part: this helper is marked __always_inline so that when a caller passes compile-time-constant begin and end callbacks, the compiler can call them directly — avoiding the indirect-call overhead. literally optimizing at compile time, she's so smart 😭👑

Returns

• 1 to continue iterating 🔁
• 0 once the range is fully consumed ✅
• a negative errno on error 💀

bestie pls double-check which of the three you got — negative errno is not the same vibe as "we're done here" and you do NOT want to mix them up 🙏

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🌺 SEE ALSO 🌺

• Kernel file ./include/linux/iomap.h struct iomap_iter(9) 📄
• iomap_length_trim(9)
• iomap_length(9)
• iomap_iter_advance_full(9)
• `iomap_iter_srcmap(9)

go read the whole friend group, they all hang out together 🫶💖

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and that's the page!! brought to you from ./include/linux, stamped October 2026 — mwah, slay, periodt, go write some mappings 💅🎀✨