file_update_time(9)

file_update_time(9) 🌸

okay so this little icon is straight outta the Kernel API Manual, and it's lowkey doing a very specific timestamp glow-up. no cap, it's giving "tiny function, very particular job" energy. 💅

✨ NAME ✨

file_update_time — update mtime and ctime time. periodt. 🎀

🌈 SYNOPSIS 🌈

int file_update_time (struct file *file );

🎀 ARGUMENTS 🎀

• file — file accessed. that's the one in question, bestie. 🫶

💖 DESCRIPTION 💖

okay so file_update_time updates the mtime and ctime members of an inode and marks the inode for writeback. literally the timestamp update + writeback flag combo. ✨

bestie, read this part twice: this function is meant exclusively for usage in the file write path of filesystems, and filesystems may choose to explicitly ignore updates via this function with the _NOCMTIME inode flag, e.g. for network filesystem where these imestamps are handled by the server. 🫶

also highkey important: this can return an error for file systems who need to allocate space in order to update an inode. so yeah, it's not always a free little timestamp slay. 😭

⭐ RETURN ⭐

• 0 on success. slay. 💖
• negative errno on failure. not slay, but factual. 💀

👑 SEE ALSO 👑

the Kernel file ./fs/inode.c is the main character source here, and the whole linked crew is:

• 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_modified_flags(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)

---

and that's the whole vibe check, bestie — signed, sealed, timestamped from ./fs, October 2026 💌✨