VOP_ALLOCATE(9)

📦 version 15.1, in freebsd 14.5, freebsd 15.1, nixpkgs unstable

okay bestie, welcome to the VOP_ALLOCATE(9) glow-up 💅 this page is from the Kernel Developer's Manual, section 9, and it's giving “allocate storage for a file” energy. no cap, we're gonna go through every lil detail together. 🫶

✨ NAME ✨

VOP_ALLOCATE — allocate storage for a file 💾✨

🌸 SYNOPSIS 🌸

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

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

💖 DESCRIPTION 💖

This call allocates storage for a range of offsets in a file. It is used to implement the posix_fallocate(2) system call. literally the whole vibe is reserving space in a file, and the file's contents are not changed. 🎀

Its arguments are:

  • vp — The vnode of the file. the main character vnode, honestly. 👑
  • offset — The start of the range to allocate storage for in the file. where the storage party begins. 📍
  • len — The length of the range to allocate storage for in the file. how long the storage party goes. 📏
  • ioflag — Directives and hints to be given to the file system. lil instructions for the fs bestie. 🫡
  • cred — The credentials of the caller. who's asking, basically. 🪪

The offset and len arguments are updated to reflect the portion of the range that still needs to be allocated on return. A partial allocation is considered a successful operation. The file's contents are not changed. periodt. 💅

🔒 LOCKS 🔒

The file should be exclusively locked on entry and will still be locked on exit. no sneaky lock drops here, bestie. 🔐

🫶 RETURN VALUES 🫶

Zero is returned if the call is successful, otherwise an appropriate error code is returned. slay if it's zero; if not, bestie check the error. 😭

💀 ERRORS 💀

  • [EFBIG] — An attempt was made to write a file that exceeds the process's file size limit or the maximum file size. 💀
  • [ENOSPC] — The file system is full. no room, no vibes. 😭
  • [EPERM] — An append-only flag is set on the file, but the caller is attempting to write before the current end of file. permission said absolutely not. 🙈

🌈 SEE ALSO 🌈

go read these next, iykyk. 📚✨

💖 that's the whole page, bestie. it's from Debian, dated November 8, 2021, and it's the VOP_ALLOCATE(9) manual page. mwah 💋

📦 where this page comes from