VOP_FSYNC(9)

💅 VOP_FSYNC(9) 💅

okay so bestie, this is the Kernel Developer's Manual page for VOP_FSYNC(9), and it’s literally about flushing file system buffers for a file. it’s giving “make sure your crash recovery is cute” energy, no cap. 💖

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🌸 NAME 🌸

VOP_FDATASYNC, VOP_FSYNC — flush file system buffers for a file ✨

✨ SYNOPSIS ✨

bestie, here’s the exact shape of it:

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

int
VOP_FDATASYNC(struct vnode *vp, struct thread *td);

int
VOP_FSYNC(struct vnode *vp, int waitfor, struct thread *td);

💖 DESCRIPTION 💖

VOP_FSYNC() makes sure a file can be recovered to its current state following a crash. that typically means flushing the file’s dirty buffers, its inode, and possibly other filesystem metadata to persistent media. VOP_FSYNC() is used to implement the sync(2) and fsync(2) system calls. slay.

Its arguments are:

• vp — the vnode of the file. iconic.
• waitfor — whether the function should wait for I/O to complete. possible values are:
  • MNT_WAIT — synchronously wait for I/O to complete.
  • MNT_NOWAIT — start all I/O, but do not wait for it.
  • MNT_LAZY — push data not written by file system syncer.
• td — the calling thread. hi bestie 👋

VOP_FDATASYNC() is similar, but it does not require that all of the file’s metadata be flushed. it only requires that the file’s data be recoverable after a crash. that implies the data itself must be flushed to disk, as well as some metadata such as the file’s size but not necessarily its attributes. VOP_FDATASYNC() should always wait for I/O to complete, as if called with MNT_WAIT. VOP_FDATASYNC() is used to implement fdatasync(2). periodt. 💅

🔒 LOCKS 🔒

the vnode should be exclusively locked on entry, and it stays locked on return. no sneaky unlocking, bestie — that’s the rule. 🔐

🎀 RETURN VALUES 🎀

Zero is returned if the call is successful; otherwise an appropriate error code is returned. that’s it, that’s the vibe check. ✅

🚨 ERRORS 🚨

• [ENOSPC] — The file system is full. 😭
• [EDQUOT] — Quota exceeded. 💀

👀 SEE ALSO 👀

• vnode(9) — go read that one too, iykyk. 🦋

🫶 AUTHORS 🫶

This manual page was written by Doug Rabson. shoutout, king. 👑

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okay that’s the whole page, bestie! this one is from Debian, dated March 22, 2019, and it’s the VOP_FSYNC(9) manual page. mwah 💋✨