VFSSUBR(9) | Kernel Developer's Manual | VFSSUBR(9)

# NAME

`vfssubr`, `vfs_getnewfsid`, `vfs_getvfs`, `vfs_export`, `vfs_showexport`, `vfs_export_lookup`, `vfs_setpublicfs`, `vfs_mountedon`, `vfs_mountroot`, `vfs_unmountall`, `vfs_busy`, `vfs_unbusy`, `vfs_mountalloc`, `vfs_rootmountalloc`, `vfs_shutdown`, `vfs_attach`, `vfs_detach`, `vfs_reinit`, `vfs_getopsbyname`, `vfs_suspend`, `vfs_resume`, `vfs_vnode_iterator_init`, `vfs_vnode_iterator_destroy`, `vfs_vnode_iterator_next` —
high-level interface to kernel file system interface

# SYNOPSIS

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

void
`vfs_getnewfsid`(struct mount *mp);

struct mount *
`vfs_getvfs`(fsid_t *fsid);

int
`vfs_export_lookup`(struct mount *mp, struct netexport *nep, struct export_args *argp);

int
`vfs_setpublicfs`(struct mount *mp, struct netexport *nep, struct export_args *argp);

int
`vfs_mountedon`(struct vnode *vp);

int
`vfs_mountroot`(void);

void
`vfs_unmountall`(struct lwp *l);

int
`vfs_busy`(struct mount *mp);

void
`vfs_unbusy`(struct mount *mp);

struct mount *
`vfs_mountalloc`(struct vfsops *vfs, struct vnode *vp);

int
`vfs_rootmountalloc`(char *fstypename, char *devname, struct mount **mpp);

void
`vfs_shutdown`(void);

int
`vfs_attach`(struct vfsops *vfs);

int
`vfs_detach`(struct vfsops *vfs);

void
`vfs_reinit`(void);

struct vfsops *
`vfs_getopsbyname`(const char *name);

int
`vfs_suspend`(struct mount *mp, int nowait);

void
`vfs_resume`(struct mount *mp);

void
`vfs_vnode_iterator_init`(struct mount *mp, struct vnode_iterator **vip);

void
`vfs_vnode_iterator_destroy`(struct vnode_iterator *vi);

struct vnode *
`vfs_vnode_iterator_next`(struct vnode_iterator *vi, bool (*selector)(void *context, struct vnode *vpp), void *context);

# DESCRIPTION

The high-level functions described in this page are the interface to the kernel file system interface (VFS).

# FUNCTIONS

`vfs_getnewfsid`(mp)
  Get a new unique file system id type for the file system specified by the mount structure mp. The file system id type is stored in mp->mnt_stat.f_fsidx.
`vfs_getvfs`(fsid)
  Lookup a mount point with the file system identifier fsid.
`vfs_export_lookup`(mp, nep, argp)
  Check client permission on the exportable file system specified by the mount structure mp. The argument nam is the address of the networked client. This function is used by file system type specific functions to verify that the client can access the file system.
`vfs_setpublicfs`(mp, nep, argp)
  Set the publicly exported file system specified by the mount structure mp.
`vfs_mountedon`(vp)
  Check to see if a file system is mounted on a block device specified by the vnode vp.
`vfs_mountroot`(void)
  Mount the root file system.
`vfs_unmountall`(l)
  Unmount all file systems.
`vfs_busy`(mp)
  Mark the mount point specified by mp as busy and get a reference to it. This function is used to synchronize access and to delay unmounting. The caller must hold a pre-existing reference to the mount.
`vfs_unbusy`(mp)
  Undo a `vfs_busy`() on the mount point specified by mp.
`vfs_mountalloc`(vfsops, vp)
  Allocate and initialise a mount structure, setting mnt_vnodecovered to vp and mnt_op to vfsops. On success return the address of the mount structure. Otherwise, return `NULL`.
`vfs_rootmountalloc`(fstypename, devname, mpp)
  Lookup a file system type specified by the name fstypename and if found allocate and initialise a mount structure for it. The allocated mount structure is marked as busy and returned in the address specified by mpp. The device the root file system was mounted from is specified by the argument devname and is recorded in the new mount structure.
`vfs_shutdown`()
  Sync and unmount all file systems before shutting down. Invoked by cpu_reboot(9).
`vfs_attach`(vfs)
  Establish file system vfs and initialise it.
`vfs_detach`(vfs)
  Remove file system vfs from the kernel.
`vfs_reinit`(void)
  Reinitialises all file systems within the kernel through file system-specific vfs operation (see vfsops(9)).
`vfs_getopsbyname`(name)
  Given a file system name specified by name, look up the vfs operations for that file system (see vfsops(9)), or return `NULL` if file system isn't present in the kernel.
`vfs_suspend`(mp, nowait)
  Request a mounted file system to suspend all operations. All new operations to the file system are stopped. After all operations in progress have completed, the file system is synced to disk and the function returns. If a file system suspension is currently in progress and nowait is set `EWOULDBLOCK` is returned. If the operation is successful, zero is returned, otherwise an appropriate error code is returned.
`vfs_resume`(mp)
  Request a mounted file system to resume operations.
`vfs_vnode_iterator_init`(mp, vip)
  Allocate and initialize an iterator vip over all vnodes attached to mount point mp.
`vfs_vnode_iterator_destroy`(vi)
  Free all resources associated with an iterator vi.
`vfs_vnode_iterator_next`(vi, selector, context)
  Return the next vnode from iterator vi. If the operation is successful the vnode has a reference added to it and it is returned. If the iterator is exhausted the function returns `NULL`. If an optional selector function is provided, then this function is called with the context provided and the candidate vnode to be returned. If the selector returns `false`, then the vnode is skipped; if it returns `true`, the vnode is referenced and then returned.

# CODE REFERENCES

The vfs interface functions are implemented within the files sys/kern/vfs_mount.c, sys/kern/vfs_subr.c and sys/kern/vfs_init.c.

# SEE ALSO

intro(9), namei(9), vfs(9), vfsops(9), vnode(9), vnodeops(9)

April 17, 2017 | NetBSD 9.2