file_modified_flags(9)

💅 file_modified_flags — Kernel API Manual (section 9, bestie)

okay so picture this: it's giving "official kernel API manual" energy, the page header says file_modified_flags(9), and today we're reading it together. grab a snack. 🍓

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✨ NAME ✨

file_modified_flags — the function that handles mandated vfs changes when you modify a file. yes, mandated. like, it's not optional, it's the law of the vfs. 👑

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🦋 SYNOPSIS 🦋

int file_modified_flags (struct file *file , int flags );

that's it. that's the whole call. two args, one int back. clean. iconic. 💅

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🎀 ARGUMENTS 🎀

• file — the file that was modified, bestie. the one we're out here modifying. 🫶
• flags — kiocb flags. that's the whole description, don't come for me, I'm just the messenger. 🌸

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💖 DESCRIPTION 💖

so when file has been modified, this function makes sure two things happen:

• special file privileges get removed 🧚
• time settings get updated ⭐

that's the whole job. slay.

but — and this is the part where you need to pay attention — if IOCB_NOWAIT is set, then:

• special file privileges will not be removed
• time settings will not be updated
• and it returns -EAGAIN

lowkey that's the whole vibe check of this function: IOCB_NOWAIT means "nope, not doing the privilege/timestamp work, try again later." no cap. 😭

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🔥 CONTEXT 🔥

the caller must hold the file's inode lock. not "should", not "ideally" — must. this is not a drill, this is a locking requirement, periodt. 💀

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🌈 RETURN 🌈

• 0 on success 🎉
• negative errno on failure 😔

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👑 SEE ALSO 👑

okay this list is LONG, so buckle up, we're going through all of it. every single one. no skipping, that's the rule. 💜

the Kernel file is ./fs/inode.c and here's the full squad:

inode_init_always_gfp(9), alloc_inode(9), drop_nlink(9), clear_nlink(9), set_nlink(9), inc_nlink(9), inode_sb_list_add(9), __insert_inode_hash(9), __remove_inode_hash(9), evict_inodes(9), new_inode(9), unlock_new_inode(9), lock_two_nondirectories(9), unlock_two_nondirectories(9), inode_insert5(9), iget5_locked(9), iget5_locked_rcu(9), iget_locked(9), iunique(9), ihold(9), ilookup5_nowait(9), ilookup5(9), ilookup(9), find_inode_nowait(9), find_inode_rcu(9), find_inode_by_ino_rcu(9), iput(9), iput_not_last(9), bmap(9), inode_update_time(9), generic_update_time(9), atime_needs_update(9), file_remove_privs(9), current_time(9), file_update_time(9), file_modified(9), kiocb_modified(9), inode_init_owner(9), inode_owner_or_capable(9), inode_dio_wait(9), timestamp_truncate(9), inode_set_ctime_current(9), inode_set_ctime_deleg(9), in_group_or_capable(9), mode_strip_sgid(9), dump_inode(9)

like I said. the whole squad. 🫡

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and that's the page, bestie!! we ate, we left no crumbs. this one's from ./fs, dated October 2026, and it's the file_modified_flags(9) kernel API manual page — go forth and modify your files responsibly, and please, for the love of everything, hold that inode lock. 💖✨🎀