posix_lock_file(9)

💖 posix_lock_file(9) 💖

okay bestie, welcome to the Kernel API Manual entry for posix_lock_file — yes that's the manual name, yes it's giving very serious kernel energy, and yes i'm gonna make it make sense for you 🫶

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✨ NAME ✨

posix_lock_file — apply a POSIX-style lock to a file 🔒

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🌸 SYNOPSIS 🌸

int posix_lock_file (struct file *filp , struct file_lock *fl , struct file_lock *conflock );

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🎀 ARGUMENTS 🎀

• filp — the file you're applying the lock to, like your main character file 📁
• fl — the actual lock you want to apply, no cap ✨
• conflock — a spot to stash a copy of the conflicting lock, if one is found 👀

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🦋 DESCRIPTION 🦋

so the vibe here is: you're adding a POSIX style lock to a file. that's literally it, that's the whole thing 💅

the way this works, we merge adjacent & overlapping locks whenever possible — highkey efficient, we love to see it. and POSIX locks are sorted by owner task, then by starting address. iykyk 📚

🚨 important lil note bestie: if you call this with an FL_EXISTS argument, the caller may determine whether or not a lock was successfully freed by testing the return value for -ENOENT. so like, -ENOENT? that's your answer right there. write that down 🔥

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👑 SEE ALSO 👑

go be nosy, here's the whole friend group — Kernel file ./fs/locks.c and:

• locks_owner_has_blockers(9)
• lease_open_conflict(9)
• locks_delete_block(9)
• posix_lock_inode_wait(9)
• inode_lease_ignore_mask(9)
• __break_lease(9)
• lease_get_mtime(9)
• __fcntl_getlease(9)
• generic_setlease(9)
• vfs_setlease(9)
• fcntl_setlease(9)
• fcntl_setdeleg(9)
• flock_lock_inode_wait(9)
• locks_lock_inode_wait(9)
• sys_flock(9)
• vfs_test_lock(9)
• locks_translate_pid(9)
• vfs_lock_file(9)
• vfs_cancel_lock(9)
• vfs_inode_has_locks(9)

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and that's a wrap, bestie 🧚💜 this lil page came from ./fs and it's dated October 2026, still stamped posix_lock_file(9) — iconic, no notes 🌈⭐