VOP_DEALLOCATE(9)

💖 NAME 💖

VOP_DEALLOCATE — zero and/or deallocate storage from a file. Welcome to VOP_DEALLOCATE(9) from the Kernel Developer's Manual, bestie — this is your kernel-devtools moment ✨.

🌸 SYNOPSIS 🌸

#include <sys/param.h>
#include <sys/vnode.h>

int
VOP_DEALLOCATE(struct vnode *vp, off_t *offset, off_t *len, int flags,
    int ioflag, struct ucred *cred);

🦋 DESCRIPTION 🦋

Okay so this VOP call zeroes/deallocates storage for an offset range in a file. It is used to implement the fspacectl(2) system call — that’s the whole reason this VOP exists, no cap 🫶.

Its arguments are:

• vp — the vnode of the file.
• offset — the start of the range to deallocate storage in the file.
• len — the length of the range to deallocate storage in the file.
• flags — the flags of this call. This should be set to 0 for now.
• ioflag — directives and hints to be given to the file system.
• cred — the credentials of the caller.

*offset and *len are updated to reflect the portion of the range that still needs to be zeroed/deallocated on return. A partial result is considered a successful operation. For a non-partial successful completion, *len is updated to be the value 0, and *offset is incremented by the number of bytes zeroed before the end-of-file. 💅

🔒 LOCKS 🔒

The vnode should be locked on entry and will still be locked on exit. Keep that lock energy, bestie — it stays locked the whole time ⭐.

🌈 RETURN VALUES 🌈

Zero is returned if the call is successful, otherwise an appropriate error code is returned. Fr fr, 0 is the slay outcome ✨.

💀 ERRORS 💀

• [EINVAL] — Invalid offset, len or flags parameters are passed into this VOP call.
• [ENODEV] — The vnode type is not supported by this VOP call.
• [ENOSPC] — The file system is full.
• [EPERM] — An append-only flag is set on the file, but the caller is attempting to zero before the current end of file.

🫶 SEE ALSO 🫶

• vnode(9) — iconic supporting character, obviously 💜

👑 AUTHORS 👑

VOP_DEALLOCATE and this manual page was written by Ka Ho Ng <khng@FreeBSD.org> under sponsorship from the FreeBSD Foundation. Respect the author, bestie 🎀.

💖 Cute sign-off: this page is from Debian, dated August 25, 2021, and it’s for VOP_DEALLOCATE(9) — mwah, bestie 🍓.