fcntl_setlease(9)

💅 NAME 💅

fcntl_setlease — bestie, this is the one that sets a lease on an open file ✨ (yes, like a lil' rental agreement but for your file, no cap)

So this whole page lives in the Kernel API Manual section 9, and the page itself is called fcntl_setlease(9) — that's the vibe check you're working with 🫶

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🎀 SYNOPSIS 🎀

int fcntl_setlease (unsigned int fd , struct file *filp , int arg );

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🦋 ARGUMENTS 🦋

• fd — the open file descriptor, aka the lil' number that says "this file right here" 💖
• filp — the file pointer, the actual struct file handle to the thing 👑
• arg — the type of lease you're trying to obtain, like picking which flavour at the ice cream place 🍓

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✨ DESCRIPTION ✨

Okay so listen 👀 — you call this fcntl to establish a lease on the file. That's the whole mission. Establishing. A lease. Slay 💅

But wait, bestie, hear me out 🚨 — you also need to call F_SETSIG if you want to actually receive a signal when that lease gets broken. Not me forgetting that and then wondering why no signal ever showed up 😭 literally the most important plot point. Set your signal, or you're just standing there with a lease and no notifications. Periodt.

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🌈 SEE ALSO 🌈

The kernel file ./fs/locks.c is the main character here, and it's bringing its whole friend group 🫶 — every single one of these is linked and invited:

• locks_owner_has_blockers(9)
• lease_open_conflict(9)
• locks_delete_block(9)
• posix_lock_file(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_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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That's the whole page, bestie, you ate that 🍓✨ — this lil' gem comes to you from ./fs, dated October 2026 in the Kernel API Manual, and honestly? Iconic. Go forth and lease responsibly 💜🦋