file_write_not_started(9)

💅 file_write_not_started(9) — the Kernel API Manual, bestie edition ✨

Okay so real talk: this is a page from the Kernel API Manual (file_write_not_started(9)), and it's a tiny one but it's got lore. Buckle up 🎀

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✨ NAME ✨

file_write_not_started — the little vibe check that asks "is SB_FREEZE_WRITE not held rn?" 🦋

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✨ SYNOPSIS ✨

bool file_write_not_started (const struct file *file );

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✨ ARGUMENTS ✨

• file — the file we write to 💖 (yes that's the whole argument, she's low maintenance)

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✨ DESCRIPTION ✨

So what does it actually do? It checks whether SB_FREEZE_WRITE is not held. That's it. That's the whole gig 👑

But listen, there are two caveats and I need you to hear me on these, because they're both about false positives and nobody wants to get caught out 🙈

May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN. So if you're running without CONFIG_LOCKDEP, or the lock state is LOCK_STATE_UNKNOWN, it might come back and lie to you a little. Not her fault, it's the config, okay? 😭

May be false positive with !S_ISREG, because file_start_write has no effect on !S_ISREG. So non-regular files? The check just doesn't bite. Giving nothing, honestly 💀

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✨ SEE ALSO ✨

Kernel file ./include/linux/fs.h — and the whole friend group 🫶

• enum positive_aop_returns(9)
• struct address_space(9)
• struct file_ra_state(9)
• struct file(9)
• i_uid_into_vfsuid(9)
• i_uid_needs_update(9)
• i_uid_update(9)
• i_gid_into_vfsgid(9)
• i_gid_needs_update(9)
• i_gid_update(9)
• inode_fsuid_set(9)
• inode_fsgid_set(9)
• fsuidgid_has_mapping(9)
• inode_set_ctime(9)
• file_write_started(9)
• struct renamedata(9)
• is_mgtime(9)
• iput_if_not_last(9)
• is_idmapped_mnt(9)
• file_start_write(9)
• file_end_write(9)
• kiocb_start_write(9)
• kiocb_end_write(9)
• name_is_dot_dotdot(9)
• name_contains_dotdot(9)
• inode_dio_begin(9)
• inode_dio_end(9)
• generic_ci_validate_strict_name(9)

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That's the whole page, bestie, go forth and check your write-freeze status responsibly 🌸

mwah — this masterpiece came out of the ./include/linux source tree, October 2026 edition, and she ate 💅✨👑