nilfs_sufile_warn_on_error(9)

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

okay so this is a page from the Kernel API Manual, and it's about nilfs_sufile_warn_on_error — which literally does what it says on the tin: it warns you when a sufile error is unexpected. like, girl, the audacity of this error. 💀

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✨ NAME ✨

nilfs_sufile_warn_on_error — warn on unexpected sufile error 🌸

🫶 SYNOPSIS 🫶

nilfs_sufile_warn_on_error (sufile , err );

💖 ARGUMENTS 💖

• sufile — the inode of the segment usage file. yes bestie, that's the sufile, the main character of this whole page 👑
• err — the status code that some sufile function handed back to you, and now you're like "hmm, should I be worried?" 🙈

🌈 DESCRIPTION 🌈

so here's the situation, and hear me out.

Even if buffer heads of blocks containing segment usage entries have been dirtied in advance by calling functions such as nilfs_sufile_mark_dirty or nilfs_sufile_{alloc,free}(), those buffers can still get discarded from memory 🫠 — this happens after the file system detects corruption and degrades to read-only mode. and the way that this absolutely wrecks things is that it may cause sufile operations, including cancel operations, to return errors. not cute, not iconic, lowkey a mess.

so that's the whole reason nilfs_sufile_warn_on_error exists: it's used to detect unexpected errors — like, errors that are anything other than the ones during read-only degradation. it's giving vibe check for your error codes 💅

ngl, this is the "is this error serious or is it just the read-only thing again" detector. don't sleep on it. 🔥

⭐ RETURN ⭐

• 0 if err is 0 — all good, we slay 💜
• -EROFS if in read-only degraded mode — fr fr, that one's expected
• -EIO otherwise — bestie, this is the unexpected one 😭

🦋 SEE ALSO 🦋

Kernel file ./fs/nilfs2/sufile.h plus these iconic little functions:

• nilfs_sufile_scrap(9)
• nilfs_sufile_free(9)
• nilfs_sufile_freev(9)
• nilfs_sufile_cancel_freev(9)
• nilfs_sufile_set_error(9)

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✨ and that's the page! brought to you by the fine folks in ./fs/nilfs2, dated October 2026, all about nilfs_sufile_warn_on_error(9). go forth and read your error codes, queen. 💅👑🌸