.\" $NetBSD: vnodeops.9,v 1.100.14.1 2023/06/21 16:50:21 martin Exp $ .\" .\" Copyright (c) 2001, 2005, 2006 The NetBSD Foundation, Inc. .\" All rights reserved. .\" .\" This code is derived from software contributed to The NetBSD Foundation .\" by Gregory McGarry. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS .\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED .\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .Dd June 15, 2023 .Dt VNODEOPS 9 .Os .Sh NAME .Nm vnodeops , .Nm VOP_LOOKUP , .Nm VOP_CREATE , .Nm VOP_MKNOD , .Nm VOP_OPEN , .Nm VOP_CLOSE , .Nm VOP_ACCESS , .Nm VOP_GETATTR , .Nm VOP_SETATTR , .Nm VOP_READ , .Nm VOP_WRITE , .Nm VOP_FALLOCATE , .Nm VOP_FDISCARD , .Nm VOP_IOCTL , .Nm VOP_FCNTL , .Nm VOP_POLL , .Nm VOP_KQFILTER , .Nm VOP_REVOKE , .Nm VOP_MMAP , .Nm VOP_FSYNC , .Nm VOP_SEEK , .Nm VOP_REMOVE , .Nm VOP_LINK , .Nm VOP_RENAME , .Nm VOP_MKDIR , .Nm VOP_RMDIR , .Nm VOP_SYMLINK , .Nm VOP_READDIR , .Nm VOP_READLINK , .Nm VOP_ABORTOP , .Nm VOP_INACTIVE , .Nm VOP_RECLAIM , .Nm VOP_LOCK , .Nm VOP_UNLOCK , .Nm VOP_ISLOCKED , .Nm VOP_BMAP , .Nm VOP_PRINT , .Nm VOP_PATHCONF , .Nm VOP_ADVLOCK , .Nm VOP_WHITEOUT , .Nm VOP_GETPAGES , .Nm VOP_PUTPAGES , .Nm VOP_STRATEGY , .Nm VOP_BWRITE , .Nm VOP_GETEXTATTR , .Nm VOP_SETEXTATTR , .Nm VOP_LISTEXTATTR , .Nm VOP_DELETEEXTATTR .Nd vnode operations .Sh SYNOPSIS .In sys/param.h .In sys/buf.h .In sys/dirent.h .In sys/vnode.h .In sys/mount.h .In sys/namei.h .In sys/unistd.h .In sys/fcntl.h .In sys/lockf.h .In sys/extattr.h .Ft int .Fn VOP_LOOKUP "struct vnode *dvp" "struct vnode **vpp" \ "struct componentname *cnp" .Ft int .Fn VOP_CREATE "struct vnode *dvp" "struct vnode **vpp" \ "struct componentname *cnp" "struct vattr *vap" .Ft int .Fn VOP_MKNOD "struct vnode *dvp" "struct vnode **vpp" \ "struct componentname *cnp" "struct vattr *vap" .Ft int .Fn VOP_OPEN "struct vnode *vp" "int mode" "kauth_cred_t cred" .Ft int .Fn VOP_CLOSE "struct vnode *vp" "int fflag" "kauth_cred_t cred" .Ft int .Fn VOP_ACCESS "struct vnode *vp" "int mode" "kauth_cred_t cred" .Ft int .Fn VOP_GETATTR "struct vnode *vp" "struct vattr *vap" "kauth_cred_t cred" .Ft int .Fn VOP_SETATTR "struct vnode *vp" "struct vattr *vap" "kauth_cred_t cred" .Ft int .Fn VOP_READ "struct vnode *vp" "struct uio *uio" "int ioflag" \ "kauth_cred_t cred" .Ft int .Fn VOP_WRITE "struct vnode *vp" "struct uio *uio" "int ioflag" \ "kauth_cred_t cred" .Ft int .Fn VOP_FALLOCATE "struct vnode *vp" "off_t pos" "off_t len" .Ft int .Fn VOP_FDISCARD "struct vnode *vp" "off_t pos" "off_t len" .Ft int .Fn VOP_IOCTL "struct vnode *vp" "u_long command" "void *data" \ "int fflag" "kauth_cred_t cred" .Ft int .Fn VOP_FCNTL "struct vnode *vp" "u_int command" "void *data" \ "int fflag" "kauth_cred_t cred" .Ft int .Fn VOP_POLL "struct vnode *vp" "int events" .Ft int .Fn VOP_KQFILTER "struct vnode *vp" "struct knote *kn" .Ft int .Fn VOP_REVOKE "struct vnode *vp" "int flags" .Ft int .Fn VOP_MMAP "struct vnode *vp" "vm_prot_t prot" "kauth_cred_t cred" .Ft int .Fn VOP_FSYNC "struct vnode *vp" "kauth_cred_t cred" "int flags" \ "off_t offlo" "off_t offhi" .Ft int .Fn VOP_SEEK "struct vnode *vp" "off_t oldoff" "off_t newoff" \ "kauth_cred_t cred" .Ft int .Fn VOP_REMOVE "struct vnode *dvp" "struct vnode *vp" \ "struct componentname *cnp" .Ft int .Fn VOP_LINK "struct vnode *dvp" "struct vnode *vp" \ "struct componentname *cnp" .Ft int .Fn VOP_RENAME "struct vnode *fdvp" "struct vnode *fvp" \ "struct componentname *fcnp" "struct vnode *tdvp" \ "struct vnode *tvp" "struct componentname *tcnp" .Ft int .Fn VOP_MKDIR "struct vnode *dvp" "struct vnode **vpp" \ "struct componentname *cnp" "struct vattr *vap" .Ft int .Fn VOP_RMDIR "struct vnode *dvp" "struct vnode *vp" \ "struct componentname *cnp" .Ft int .Fn VOP_SYMLINK "struct vnode *dvp" "struct vnode **vpp" \ "struct componentname *cnp" "struct vattr *vap" "char *target" .Ft int .Fn VOP_READDIR "struct vnode *vp" "struct uio *uio" \ "kauth_cred_t cred" "int *eofflag" "off_t **cookies" "int *ncookies" .Ft int .Fn VOP_READLINK "struct vnode *vp" "struct uio *uio" "kauth_cred_t cred" .Ft int .Fn VOP_ABORTOP "struct vnode *dvp" "struct componentname *cnp" .Ft int .Fn VOP_INACTIVE "struct vnode *vp" .Ft int .Fn VOP_RECLAIM "struct vnode *vp" .Ft int .Fn VOP_LOCK "struct vnode *vp" "int flags" .Ft int .Fn VOP_UNLOCK "struct vnode *vp" .Ft int .Fn VOP_ISLOCKED "struct vnode *vp" .Ft int .Fn VOP_BMAP "struct vnode *vp" "daddr_t bn" "struct vnode **vpp" \ "daddr_t *bnp" "int *runp" .Ft int .Fn VOP_PRINT "struct vnode *vp" .Ft int .Fn VOP_PATHCONF "struct vnode *vp" "int name" "register_t *retval" .Ft int .Fn VOP_ADVLOCK "struct vnode *vp" "void *id" "int op" \ "struct flock *fl" "int flags" .Ft int .Fn VOP_WHITEOUT "struct vnode *dvp" "struct componentname *cnp" \ "int flags" .Ft int .Fn VOP_GETPAGES "struct vnode *vp" "voff_t offset" "struct vm_page **m" \ "int *count" "int centeridx" "vm_prot_t access_type" "int advice" "int flags" .Ft int .Fn VOP_PUTPAGES "struct vnode *vp" "voff_t offlo" "voff_t offhi" \ "int flags" .Ft int .Fn VOP_STRATEGY "struct vnode *vp" "struct buf *bp" .Ft int .Fn VOP_BWRITE "struct vnode *vp" "struct buf *bp" .Ft int .Fn VOP_GETEXTATTR "struct vnode *vp" "int attrnamespace" "const char *name" \ "struct uio *uio" "size_t *size" "kauth_cred_t cred" .Ft int .Fn VOP_SETEXTATTR "struct vnode *vp" "int attrnamespace" "const char *name" \ "struct uio *uio" "kauth_cred_t cred" .Ft int .Fn VOP_LISTEXTATTR "struct vnode *vp" "int attrnamespace" "struct uio *uio" \ "size_t *size" "kauth_cred_t cred" .Ft int .Fn VOP_DELETEEXTATTR "struct vnode *vp" "int attrnamespace" \ "const char *name" "kauth_cred_t cred" .Pp Not all header files are required for each function. .Sh DESCRIPTION The vnode operations vector describes what operations can be done to the file associated with the vnode. The system maintains one vnode operations vector for each file system type configured into the kernel. The vnode operations vector contains a pointer to a function for each operation supported by the file system. Many of the functions described in the vnode operations vector are closely related to their corresponding system calls. In most cases, they are called as a result of the system call associated with the operation being invoked. .Pp Functions in the vnode operations vector are invoked using specialized macros. The following table gives a summary of the operations. .Pp .Bl -column "VOP_DELETEEXTATTR" "Wake up process sleeping on lock" -compact .It Sy Macro Ta Sy Description .It VOP_LOOKUP Lookup file name in name cache .It VOP_CREATE Create a new file .It VOP_MKNOD Make a new device .It VOP_OPEN Open a file .It VOP_CLOSE Close a file .It VOP_ACCESS Determine file accessibility .It VOP_GETATTR Get file attributes .It VOP_SETATTR Set file attributes .It VOP_READ Read from a file .It VOP_WRITE Write to a file .It VOP_FALLOCATE Allocate backing for a file .It VOP_FDISCARD Discard backing for a file .It VOP_IOCTL Perform device-specific I/O .It VOP_FCNTL Perform file control .It VOP_POLL Test if poll event has occurred .It VOP_KQFILTER Register a knote .It VOP_REVOKE Eliminate vnode activity .It VOP_MMAP Map file into user address space .It VOP_FSYNC Flush pending data to disk .It VOP_SEEK Test if file is seekable .It VOP_REMOVE Remove a file .It VOP_LINK Link a file .It VOP_RENAME Rename a file .It VOP_MKDIR Make a new directory .It VOP_RMDIR Remove a directory .It VOP_SYMLINK Create a symbolic link .It VOP_READDIR Read directory entry .It VOP_READLINK Read contents of a symlink .It VOP_ABORTOP Abort pending operation .It VOP_INACTIVE Release the inactive vnode .It VOP_RECLAIM Reclaim vnode for another file .It VOP_LOCK Sleep until vnode lock is free .It VOP_UNLOCK Wake up process sleeping on lock .It VOP_ISLOCKED Test if vnode is locked .It VOP_BMAP Logical block number conversion .It VOP_PRINT Print debugging information .It VOP_PATHCONF Return POSIX pathconf data .It VOP_ADVLOCK Advisory record locking .It VOP_WHITEOUT Whiteout vnode .It VOP_GETPAGES Read VM pages from file .It VOP_PUTPAGES Write VM pages to file .It VOP_STRATEGY Read/write a file system buffer .It VOP_BWRITE Write a file system buffer .It VOP_GETEXTATTR Get extended attribute .It VOP_SETEXTATTR Set extended attribute .It VOP_LISTEXTATTR List extended attributes .It VOP_DELETEEXTATTR Remove extended attribute .El .Pp The implementation details of the vnode operations vector are not quite what is described here. .Pp If the file system type does not support a specific operation, it must nevertheless assign an appropriate stub in the vnode operations vector to do the minimum required of it. In most cases, such functions either do nothing or return an error value to the effect that it is not supported. .Pp Many of the functions in the vnode operations vector take a componentname structure. It is used to encapsulate many parameters into a single function argument. It has the following structure: .Bd -literal struct componentname { /* * Arguments to lookup. */ uint32_t cn_nameiop; /* namei operation */ uint32_t cn_flags; /* flags to namei */ kauth_cred_t cn_cred; /* credentials */ /* * Shared between lookup and commit routines. */ const char *cn_nameptr; /* pointer to looked up name */ size_t cn_namelen; /* length of looked up component */ size_t cn_consume; /* chars to consume in lookup() */ }; .Ed .Pp The top half of the structure is used exclusively for the pathname lookups using .Fn VOP_LOOKUP and is initialized by the caller. The semantics of the lookup are affected by the lookup operation specified in .Em cn_nameiop and the flags specified in .Em cn_flags . Valid operations are: .Pp .Bl -tag -offset indent -width LOOKUP -compact .It LOOKUP perform name lookup only .It CREATE set up for file creation .It DELETE set up for file deletion .It RENAME set up for file renaming .It OPMASK mask for operation .El .Pp Valid values for .Em cn->cn_flags are: .Pp .Bl -tag -offset indent -width LOCKPARENT -compact .It LOCKLEAF lock inode on return .It LOCKPARENT want parent vnode returned locked .It NOCACHE name must not be left in name cache (see .Xr namecache 9 ) .It FOLLOW follow symbolic links .It NOFOLLOW do not follow symbolic links (pseudo) .It MODMASK mask of operational modifiers .El .Pp No vnode operations may be called from interrupt context. Most operations also require the vnode to be locked on entry. To prevent deadlocks, when acquiring locks on multiple vnodes, the lock of parent directory must be acquired before the lock on the child directory. .Pp Vnode operations for a file system type generally should not be called directly from the kernel, but accessed indirectly through the high-level convenience functions discussed in .Xr vnsubr 9 . .Sh FUNCTIONS .Bl -tag -width compact .It Fn VOP_LOOKUP "dvp" "vpp" "cnp" Lookup a single pathname component in a given directory. The argument .Fa dvp is the locked vnode of the directory to search and .Fa cnp is the pathname component to be searched for. If the pathname component is found, the address of the resulting unlocked vnode is returned in .Fa vpp . The operation specified in .Em cnp->cn_nameiop indicates .Fn VOP_LOOKUP the reason for requesting the lookup and uses it to cache file system type specific information in the vnode for subsequent operations. .Pp There are three types of lookups: ".", ".." (ISDOTDOT), and regular. If the pathname component being searched for is ".", then .Fa dvp has an extra reference added to it and it is returned in .Fa *vpp . For other pathname components, .Fn VOP_LOOKUP checks the accessibility of the directory and searches the name cache for the pathname component. See .Xr namecache 9 . If the pathname is not found in the name cache, the directory is searched for the pathname. The resulting unlocked vnode is returned in .Fa vpp . .Fa dvp is always returned locked. .Pp On failure .Fa *vpp is .Dv NULL , and .Fa *dvp is left locked. If the operation is successful .Fa *vpp is unlocked and zero is returned. Typically, if .Fa *vpp and .Fa dvp are the same vnode the caller will need to release twice (decrement the reference count) and unlock once. .It Fn VOP_CREATE "dvp" "vpp" "cnp" "vap" Create a new file in a given directory. The argument .Fa dvp is the locked vnode of the directory to create the new file in and .Fa cnp is the pathname component of the new file. The argument .Fa vap specifies the attributes that the new file should be created with. If the file is successfully created, the address of the resulting unlocked vnode is returned in .Fa vpp and zero is returned. .Pp This function is called after .Fn VOP_LOOKUP when a file is being created. Normally, .Fn VOP_LOOKUP will have set the SAVENAME flag in .Em cnp->cn_flags to keep the memory pointed to by .Em cnp->cn_pnbuf valid. If an error is detected when creating the file, this memory is released. If the file is created successfully it will be released unless the SAVESTART flags in specified in .Em cnp->cn_flags . .It Fn VOP_MKNOD "dvp" "vpp" "cnp" "vap" Make a new device-special file in a given directory. The argument .Fa dvp is the locked vnode of the directory to create the new device-special file in and .Fa cnp is the pathname component of the new device-special file. The argument .Fa vap specifies the attributes that the new device-special file should be created with. If the file is successfully created, the address of the resulting unlocked vnode is returned in .Fa vpp and zero is returned. .Pp This function is called after .Fn VOP_LOOKUP when a device-special file is being created. Normally, .Fn VOP_LOOKUP will have set the SAVENAME flag in .Em cnp->cn_flags to keep the memory pointed to by .Em cnp->cn_pnbuf valid. If an error is detected when creating the device-special file, this memory is released. If the device-special file is created successfully it will be released unless the SAVESTART flags in specified in .Em cnp->cn_flags . .It Fn VOP_OPEN "vp" "mode" "cred" Open a file. The argument .Fa vp is the vnode of the file to open and .Fa mode specifies the access mode required by the calling process. The calling credentials are specified by .Fa cred . The access mode is a set of flags, including FREAD, FWRITE, O_NONBLOCK, O_APPEND, etc. .Fn VOP_OPEN must be called before a file can be accessed by a thread. The vnode reference count is incremented. .Pp .Fn VOP_OPEN expects the vnode .Fa vp to be locked on entry and will leave it locked on return. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .It Fn VOP_CLOSE "vp" "fflag" "cred" Close a file. The argument .Fa vp is the vnode of the file to close and .Fa fflag specifies the access mode by the calling process. The possible flags are .Dv FREAD , .Dv FWRITE and .Dv FNONBLOCK . The calling credentials are specified by .Fa cred . .Fn VOP_CLOSE frees resources allocated by .Fn VOP_OPEN . .Pp The vnode .Fa vp will be locked on entry and should remain locked on return. .It Fn VOP_ACCESS "vp" "mode" "cred" Determine the accessibility (permissions) of the file against the specified credentials. The argument .Fa vp is the vnode of the file to check, .Fa mode is the type of access required and .Fa cred contains the user credentials to check. The argument .Fa mode is a mask which can contain VREAD, VWRITE or VEXEC. If the file is accessible in the specified way, zero is returned, otherwise an appropriate error code is returned. .Pp The vnode .Fa vp will be locked on entry and should remain locked on return. .It Fn VOP_GETATTR "vp" "vap" "cred" Get specific vnode attributes on a file. The argument .Fa vp is the vnode of the file to get the attributes for. The argument .Fa cred specifies the calling credentials. .Fn VOP_GETATTR uses the file system type specific data object .Em vp->v_data to reference the underlying file attributes. .\" Attributes associated with the file are collected by setting the .\" required attribute bits in .\" .Em vap->va_mask . The attributes are returned in .Fa vap . Attributes which are not available are set to the value VNOVAL. .Pp For more information on vnode attributes see .Xr vattr 9 . Historically it was considered acceptable to call .Fn VOP_GETATTR without first locking the vnode. This usage is deprecated. .Pp The vnode .Fa vp will be locked on entry and should remain locked on return. .It Fn VOP_SETATTR "vp" "vap" "cred" Set specific vnode attributes on a file. The argument .Fa vp is the locked vnode of the file to set the attributes for. The argument .Fa cred specifies the calling credentials. .Fn VOP_SETATTR uses the file system type specific data object .Em vp->v_data to reference the underlying file attributes. The new attributes are defined in .Fa vap . .\" Attributes associated with the file are set by setting the required .\" attribute bits in .\" .Em vap->va_mask . Attributes which are not being modified by .Fn VOP_SETATTR should be set to the value VNOVAL. If the operation is successful zero is returned, otherwise an appropriate error is returned. .Pp For more information on vnode attributes see .Xr vattr 9 . .It Fn VOP_READ "vp" "uio" "ioflag" "cred" Read the contents of a file. The argument .Fa vp is the vnode of the file to read from, .Fa uio is the location to read the data into, .Fa ioflag is a set of flags and .Fa cred are the credentials of the calling process. .Pp The .Fa ioflag argument is used to give directives and hints to the file system. When attempting a read, the high 16 bits are used to provide a read-ahead hint (in unit of file system blocks) that the file system should attempt. The low 16 bits are a bit mask which can contain the following flags: .Pp .Bl -tag -offset indent -width IO_ALTSEMANTICS -compact .It IO_UNIT do I/O as atomic unit .It IO_APPEND append write to end .It IO_SYNC sync I/O file integrity completion .It IO_NODELOCKED underlying node already locked .It IO_NDELAY FNDELAY flag set in file table .It IO_DSYNC sync I/O data integrity completion .It IO_ALTSEMANTICS use alternate I/O semantics .It IO_NORMAL operate on regular data .It IO_EXT operate on extended attributes .It IO_DIRECT do not buffer data in the kernel .El .Pp Zero is returned on success, otherwise an error is returned. The vnode should be locked on entry and remains locked on exit. .It Fn VOP_WRITE "vp" "uio" "ioflag" "cred" Write to a file. The argument .Fa vp is the vnode of the file to write to, .Fa uio is the location of the data to write, .Fa ioflag is a set of flags and .Fa cred are the credentials of the calling process. .Pp The .Fa ioflag argument is used to give directives and hints to the file system. The low 16 bits are a bit mask which can contain the same flags as .Fn VOP_READ . .Pp Zero is returned on success, otherwise an error is returned. The vnode should be locked on entry and remains locked on exit. .It Fn VOP_FALLOCATE "vp" "pos" "len" Allocate backing store. The argument .Fa vp is the vnode for the file. The .Fa pos and .Fa len arguments (specified in bytes) name an extent within the file. The blocks underlying this range, rounding up at the top and down at the bottom if needed, are checked; if no physical storage is allocated, a physical block is allocated and zeroed. This operation removes .Dq holes from files. .It Fn VOP_FDISCARD "vp" "pos" "len" Discard backing store. The argument .Fa vp is the vnode for the file. The .Fa pos and .Fa len arguments (specified in bytes) name an extent within the file. The blocks underlying this range, rounding down at the top and up at the bottom if needed, are checked. If any physical storage is used, it is deallocated. This operation creates .Dq holes in files. Discarded blocks of regular files read back afterwards as zeroes. On devices, the underlying discard-block operation if any (e.g. ATA TRIM) is issued. The device handles this as it sees fit. In particular it is .Em not guaranteed that discarded blocks on devices will be zeroed; reading a discarded block might produce zeros, or ones, or the previously existing data, or some other data, or trash. .\" XXX: if you discard part of a block in a regular file, should that .\" part be explicitly zeroed? Also, how do you find the underlying .\" block size? .It Fn VOP_IOCTL "vp" "command" "data" "fflag" "cred" Perform device-specific I/O. The argument .Fa vp is the vnode of the file, normally representing a device. The argument .Fa command specifies the device-specific operation to perform and .Fa cnp provides extra data for the specified operation. The argument .Fa fflags is a set of flags. The argument .Fa cred is the caller's credentials. If the operation is successful, zero is returned, otherwise an appropriate error code is returned. .Pp Most file systems do not supply a function for .Fn VOP_IOCTL . This function implements the .Xr ioctl 2 system call. .It Fn VOP_FCNTL "vp" "command" "data" "fflag" "cred" Perform file control. The argument .Fa vp is the locked vnode of the file. The argument .Fa command specifies the operation to perform and .Fa cnp provides extra data for the specified operation. The argument .Fa fflags is a set of flags. The argument .Fa cred is the caller's credentials. If the operation is successful, zero is returned, otherwise an appropriate error code is returned. .It Fn VOP_POLL "vp" "events" Test if a poll event has occurred. The argument .Fa vp is the vnode of the file to poll. It returns any events of interest as specified by .Fa events that may have occurred for the file. The argument .Fa events is a set of flags as specified by .Xr poll 2 . .Pp The vnode .Fa vp remains unlocked throughout the whole operation. .It Fn VOP_KQFILTER "vp" "kn" Register a knote .Fa kn with the vnode .Fa vn . If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Pp The vnode .Fa vp remains unlocked throughout the whole operation. .It Fn VOP_REVOKE "vp" "flags" Eliminate all activity associated with the vnode .Fa vp . The argument .Fa flags is a set of flags. If REVOKEALL is set in .Fa flags all vnodes aliased to the vnode .Fa vp are also eliminated. If the operation is successful zero is returned, otherwise an appropriate error is returned. .Pp The vnode .Fa vp remains unlocked throughout the whole operation. .It Fn VOP_MMAP "vp" "prot" "cred" Inform file system that .Fa vp is in the process of being memory mapped. The argument .Fa prot specifies the vm access protection the vnode is going to be mapped with. The argument .Fa cred is the caller's credentials. If the file system allows the memory mapping, zero is returned, otherwise an appropriate error code is returned. .Pp Most file systems do not supply a function for .Fn VOP_MMAP and use .Fn genfs_mmap to default for success. Only file systems which do not integrate with the page cache at all typically want to disallow memory mapping. .It Fn VOP_FSYNC "vp" "cred" "flags" "offlo" "offhi" Flush pending data buffers for a file to disk. The argument .Fa vp is the locked vnode of the file for flush. The argument .Fa cred is the caller's credentials. The argument .Fa flags is a set of flags. If FSYNC_WAIT is specified in .Fa flags , the function should wait for I/O to complete before returning. The argument .Fa offlo and .Fa offhi specify the range of file to flush. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Pp This function implements the .Xr sync 2 and .Xr fsync 2 system calls. .It Fn VOP_SEEK "vp" "oldoff" "newoff" "cred" Test if the file is seekable for the specified offset .Fa newoff . The argument .Fa vp is the locked vnode of the file to test. For most file systems this function simply tests if .Fa newoff is valid. If the specified .Fa newoff is less than zero, the function returns error code EINVAL. .It Fn VOP_REMOVE "dvp" "vp" "cnp" Remove a file. The argument .Fa dvp is the locked vnode of the directory to remove the file from and .Fa vp is the locked vnode of the file to remove. The argument .Fa cnp is the pathname component about the file to remove. If the operation is successful zero is returned, otherwise an appropriate error code is returned. Both .Fa dvp and .Fa vp are locked on entry and are to be unlocked before returning. .It Fn VOP_LINK "dvp" "vp" "cnp" Link to a file. The argument .Fa dvp is the locked node of the directory to create the new link and .Fa vp is the vnode of the file to be linked. The argument .Fa cnp is the pathname component of the new link. If the operation is successful zero is returned, otherwise an error code is returned. The directory vnode .Fa dvp should be locked on entry and will be released and unlocked on return. The vnode .Fa vp should not be locked on entry and will remain unlocked on return. .It Fn VOP_RENAME "fdvp" "fvp" "fcnp" "tdvp" "tvp" "tcnp" Rename a file. The argument .Fa fdvp is the vnode of the old parent directory containing in the file to be renamed and .Fa fvp is the vnode of the file to be renamed. The argument .Fa fcnp is the pathname component about the file to be renamed. The argument .Fa tdvp is the vnode of the new directory of the target file and .Fa tvp is the vnode of the target file (if it exists). The argument .Fa tcnp is the pathname component about the file's new name. If the operation is successful zero is returned, otherwise an error code is returned. .Pp The caller must hold the target file system's rename lock. The source directory and file vnodes should be unlocked and their reference counts should be incremented before entry. The target directory and file vnodes should both be locked on entry. .Fn VOP_RENAME updates the reference counts prior to returning. .Pp Because of the complexity and nastiness of the interface, please do not write new code that calls .Fn VOP_RENAME directly until such time as ongoing cleanup work reaches a point where the interface has been rendered halfway sane. .It Fn VOP_MKDIR "dvp" "vpp" "cnp" "vap" Make a new directory in a given directory. The argument .Fa dvp is the locked vnode of the directory to create the new directory in and .Fa cnp is the pathname component of the new directory. The argument .Fa vap specifies the attributes that the new directory should be created with. If the file is successfully created, the address of the resulting unlocked vnode is returned in .Fa vpp and zero is returned. .Pp This function is called after .Fn VOP_LOOKUP when a directory is being created. Normally, .Fn VOP_LOOKUP will have set the SAVENAME flag in .Em cnp->cn_flags to keep the memory pointed to by .Em cnp->cn_pnbuf valid. If an error is detected when creating the directory, this memory is released. If the directory is created successfully it will be released unless the SAVESTART flags in specified in .Em cnp->cn_flags . .It Fn VOP_RMDIR "dvp" "vp" "cnp" Remove a directory in a given directory. The argument .Fa dvp is the locked vnode of the directory to remove the directory from and .Fa vp is the locked vnode of the directory to remove. The argument .Fa cnp is the pathname component of the directory. Zero is returned on success, otherwise an error code is returned. Both .Fa dvp and .Fa vp should be locked on entry and will be released and unlocked on return. .It Fn VOP_SYMLINK "dvp" "vpp" "cnp" "vap" "target" Create a symbolic link in a given directory. The argument .Fa dvp is the locked vnode of the directory to create the symbolic link in and .Fa cnp is the pathname component of the symbolic link. The argument .Fa vap specifies the attributes that the symbolic link should be created with and .Fa target specifies the pathname of the target of the symbolic link. If the symbolic link is successfully created, the address of the resulting unlocked vnode is returned in .Fa vpp and zero is returned. .Pp This function is called after .Fn VOP_LOOKUP when a symbolic link is being created. Normally, .Fn VOP_LOOKUP will have set the SAVENAME flag in .Em cnp->cn_flags to keep the memory pointed to by .Em cnp->cn_pnbuf valid. If an error is detected when creating the symbolic link, this memory is released. If the symbolic link is created successfully it will be released unless the SAVESTART flags in specified in .Em cnp->cn_flags . .It Fn VOP_READDIR "vp" "uio" "cred" "eofflag" "cookies" "ncookies" Read directory entry. The argument .Fa vp is the vnode of the directory to read the contents of and .Fa uio is the destination location to read the contents into. The argument .Fa cred is the caller's credentials. The argument .Fa eofflag is the pointer to a flag which is set by .Fn VOP_READDIR to indicate an end-of-file condition. If .Fa eofflag is .Dv NULL , the end-of-file condition is not returned. The arguments .Fa cookies and .Fa ncookies specify the addresses for the list and number of directory seek cookies generated for NFS. Both .Fa cookies and .Fa ncookies should be .Dv NULL if they aren't required to be returned by .Fn VOP_READDIR . The directory contents are read into struct dirent structures and .Fa uio->uio_offset is set to the offset of the next unread directory entry. This offset may be used in a following invocation to continue a sequential read of the directory contents. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Pp The directory should be locked on entry and will remain locked on return. .Pp In case .Fa ncookies and .Fa cookies are supplied, one cookie should be returned per directory entry. The value of the cookie for each directory entry should be the offset within the directory where the on-disk version of the following directory entry starts. That is, for each directory entry .Fa i , the corresponding cookie should refer to the offset of directory entry .Fa i + 1 . .Pp Note that the .Fa cookies array must be allocated by the callee using the M_TEMP malloc type as callers of .Fn VOP_READDIR must be able to free the allocation. .It Fn VOP_READLINK "vp" "uio" "cred" Read the contents of a symbolic link. The argument .Fa vp is the locked vnode of the symlink and .Fa uio is the destination location to read the contents into. The argument .Fa cred is the credentials of the caller. If the operation is successful zero is returned, otherwise an error code is returned. .Pp The vnode should be locked on entry and will remain locked on return. .It Fn VOP_ABORTOP "dvp" "cnp" Abort pending operation on vnode .Fa dvp and free resources allocated in .Fa cnp . .Pp This operation is rarely implemented in file systems and .Fn genfs_abortop is typically used instead. .It Fn VOP_INACTIVE "vp" Release the inactive vnode. .Fn VOP_INACTIVE is called when the kernel is no longer using the vnode. This may be because the reference count reaches zero or it may be that the file system is being forcibly unmounted while there are open files. It can be used to reclaim space for open but deleted files. The argument .Fa vp is the locked vnode to be released. If the operation is successful zero is returned, otherwise an appropriate error code is returned. The vnode .Fa vp must be locked on entry, and will remain locked on return. .It Fn VOP_RECLAIM "vp" Reclaim the vnode for another file system. .Fn VOP_RECLAIM is called when a vnode is being reused for a different file system. Any file system specific resources associated with the vnode should be freed. The argument .Fa vp is the vnode to be reclaimed. If the operation is successful zero is returned, otherwise an appropriate error code is returned. The vnode .Fa vp should be locked on entry, and will be returned unlocked. .It Fn VOP_LOCK "vp" "flags" Sleep until vnode lock is free. The argument .Fa vp is the vnode of the file to be locked. The argument .Fa flags is .Dv LK_EXCLUSIVE to take the lock exclusively or .Dv LK_SHARED to take a shared lock. If .Fa flags contains .Dv LK_NOWAIT and the lock is busy, the operation will return immediately with an error code. If .Fa flags contains .Dv LK_RETRY this is a hint the caller wants the lock on dead vnodes too. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Fn VOP_LOCK is used to serialize access to the file system such as to prevent two writes to the same file from happening at the same time. Kernel code should use .Xr vn_lock 9 to lock a vnode rather than calling .Fn VOP_LOCK directly. .It Fn VOP_UNLOCK "vp" Wake up process sleeping on lock. The argument .Fa vp is the vnode of the file to be unlocked. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Fn VOP_UNLOCK is used to serialize access to the file system such as to prevent two writes to the same file from happening at the same time. .It Fn VOP_ISLOCKED "vp" Test if the vnode .Fa vp is locked. Possible return values are .Dv LK_EXCLUSIVE , .Dv LK_SHARED or 0 for lock held exclusively by the calling thread, shared lock held by anyone or unlocked, respectively. .Pp This function must never be used to make locking decisions at run time: it is provided only for diagnostic purposes. .It Fn VOP_BMAP "vp" "bn" "vpp" "bnp" "runp" Convert the logical block number .Fa bn of a file specified by vnode .Fa vp to its physical block number on the disk. The physical block is returned in .Fa bnp . In case the logical block is not allocated, \-1 is used. .Pp If .Fa vpp is not .Dv NULL , the vnode of the device vnode for the file system is returned in the address specified by .Fa vpp . If .Fa runp is not .Dv NULL , the number of contiguous blocks starting from the next block after the queried block will be returned in .Fa runp . .It Fn VOP_PRINT "vp" Print debugging information. The argument .Fa vp is the vnode to print. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .It Fn VOP_PATHCONF "vp" "name" "retval" Implement POSIX .Xr pathconf 2 and .Xr fpathconf 2 support. The argument .Fa vp is the locked vnode to get information about. The argument .Fa name specified the type of information to return. The information is returned in the address specified by .Fa retval . Valid values for .Fa name are: .Pp .Bl -tag -offset indent -width _PC_CHOWN_RESTRICTED -compact .It _PC_LINK_MAX return the maximum number of links to a file .It _PC_NAME_MAX return the maximum number of bytes in a file name .It _PC_PATH_MAX return the maximum number of bytes in a pathname .It _PC_PIPE_BUF return the maximum number of bytes which will be written atomically to a pipe .It _PC_CHOWN_RESTRICTED return 1 if appropriate privileges are required for the .Xr chown 2 system call, otherwise zero .It _PC_NO_TRUNC return 0 if file names longer than .Brq Dv NAME_MAX are silently truncated .El .Pp If .Fa name is recognized, .Fa *retval is set to the specified value and zero is returned, otherwise an appropriate error is returned. .It Fn VOP_ADVLOCK "vp" "id" "op" "fl" "flags" Manipulate Advisory record locks on a vnode. The argument .Fa vp is the vnode on which locks are manipulated. The argument .Fa id is the id token which is changing the lock and .Fa op is the .Xr fcntl 2 operation to perform. Valid values are: .Pp .Bl -tag -offset indent -width F_UNLCK -compact .It F_SETLK set lock .It F_GETLK get the first conflicted lock .It F_UNLCK clear lock .El .Pp The argument .Fa fl is a description of the lock. In the case of .Dv SEEK_CUR , The caller should add the current file offset to fl->l_start beforehand. .Fn VOP_ADVLOCK treats .Dv SEEK_CUR as .Dv SEEK_SET . .Pp The argument .Fa flags is the set of flags. Valid values are: .Pp .Bl -tag -offset indent -width F_FLOCK -compact .It F_WAIT wait until lock is granted .It F_FLOCK use .Xr flock 2 semantics for lock .It F_POSIX use POSIX semantics for lock .El .Pp If the operation is successful zero is returned, otherwise an appropriate error is returned. .It Fn VOP_WHITEOUT "dvp" "cnp" "flags" Whiteout pathname component in directory with vnode .Fa dvp . The argument .Fa cnp specifies the pathname component to whiteout. .Pp The vnode .Fa dvp should be locked on entry and will remain locked on return. .It Fn VOP_GETPAGES "vp" "offset" "m" "count" "centeridx" "access_type" "advice" "flags" Read VM pages from file. The argument .Fa vp is the locked vnode to read the VM pages from. The argument .Fa offset is offset in the file to start accessing and .Fa m is an array of VM pages. The argument .Fa count points a variable that specifies the number of pages to read. If the operation is successful zero is returned, otherwise an appropriate error code is returned. If PGO_LOCKED is specified in .Em flags , .Fn VOP_GETPAGES might return less pages than requested. In that case, the variable pointed to by .Em count will be updated. .Pp This function is primarily used by the page-fault handing mechanism. .It Fn VOP_PUTPAGES "vp" "offlo" "offhi" "flags" Write modified (dirty) VM pages to file. The argument .Fa vp is the vnode to write the VM pages to. The vnode's vm object lock .Va ( v_uobj.vmobjlock ) must be held by the caller and will be released upon return. The arguments .Fa offlo and .Fa offhi specify the range of VM pages to write. In case .Fa offhi is given as 0, all pages at and after the start offset .Fa offlo belonging the vnode .Fa vp will be written. The argument .Fa flags controls the behavior of the routine and takes the vm pager's flags .Dv ( PGO_ -prefixed ) . If the operation is successful zero is returned, otherwise an appropriate error code is returned. .Pp The function is primarily used by the pageout handling mechanism and is commonly implemented indirectly by .Fn genfs_putpages with the help of .Fn VOP_STRATEGY and .Fn VOP_BMAP . .It Fn VOP_STRATEGY "vp" "bp" Read/write a file system buffer. The argument .Fa vp is the vnode to read/write to. The argument .Fa bp is the buffer to be read or written. .Fn VOP_STRATEGY will either read or write data to the file depending on the value of .Em bp->b_flags . If the operation is successful zero is returned, otherwise an appropriate error code is returned. .It Fn VOP_BWRITE "vp" "bp" Write a file system buffer. The argument .Fa vp is the vnode to write to. The argument .Fa bp specifies the buffer to be written. If the operation is successful zero is returned, otherwise an appropriate error code is returned. .It Fn VOP_GETEXTATTR "vp" "attrnamespace" "name" "uio" "size" "cred" Get an extended attribute. The argument .Fa vp is the locked vnode of the file or directory from which to retrieve the attribute. The argument .Fa attrnamespace specifies the extended attribute namespace. The argument .Fa name is a nul-terminated character string naming the attribute to retrieve. The argument .Fa uio , if not .Dv NULL , specifies where the extended attribute value is to be written. The argument .Fa size , if not .Dv NULL , will contain the number of bytes required to read all of the attribute data upon return. In most cases, .Fa uio will be .Dv NULL when .Fa size is not, and vice versa. The argument .Fa cred specifies the user credentials to use when authorizing the request. .It Fn VOP_SETEXTATTR "vp" "attrnamespace" "name" "uio" "cred" Set an extended attribute. The argument .Fa vp is the locked vnode of the file or directory to which to store the attribute. The argument .Fa namespace specifies the extended attribute namespace. The argument .Fa name is a nul-terminated character string naming the attribute to store. The argument .Fa uio specifies the source of the extended attribute data. The argument .Fa cred specifies the user credentials to use when authorizing the request. .It Fn VOP_LISTEXTATTR "vp" "attrnamespace" "uio" "size" "cred" Retrieve the list of extended attributes. The argument .Fa vp is the locked vnode of the file or directory whose attributes are to be listed. The argument .Fa attrnamespace specifies the extended attribute namespace. The argument .Fa uio , if not .Dv NULL , specifies where the extended attribute list is to be written. The argument .Fa size , if not .Dv NULL , will contain the number of bytes required to read all of the attribute names upon return. In most cases, .Fa uio will be .Dv NULL when .Fa size is not, and vice versa. The argument .Fa cred specifies the user credentials to use when authorizing the request. .It Fn VOP_DELETEEXTATTR "vp" "attrnamespace" "name" "cred" Remove attribute .Fa name from file associated with .Fa vp . The argument .Fa attrnamespace specifies the extended attribute namespace. If full removal is not supported, the file system should return .Er EOPNOTSUPP to allow the caller to zero out the value with .Fn VOP_SETEXTATTR . .Pp The vnode .Fa vp should be locked on entry and will remain locked on return. .El .Sh FILES .Pa src/sys/kern/vnode_if.src contains the list of vnode functions, their definitions and an exact locking protocol. .Sh ERRORS .Bl -tag -width Er .It Bq Er EACCES Access for the specified operation is denied. .It Bq Er EDQUOT Quota exceeded. .It Bq Er EINVAL attempt to read from an illegal offset in the directory; unrecognized input .It Bq Er EIO a read error occurred while reading the directory or reading the contents of a symbolic link .It Bq Er EJUSTRETURN A CREATE or RENAME operation would be successful. .It Bq Er ENOATTR The requested attribute is not defined for this vnode. .It Bq Er ENOENT The component was not found in the directory. .It Bq Er ENOSPC The file system is full. .It Bq Er ENOTDIR The vnode does not represent a directory. .It Bq Er ENOTEMPTY attempt to remove a directory which is not empty .It Bq Er EPERM an attempt was made to change an immutable file .It Bq Er EROFS the file system is read-only .El .Sh SEE ALSO .Xr extattr 9 , .Xr intro 9 , .Xr namei 9 , .Xr vattr 9 , .Xr vfs 9 , .Xr vfsops 9 , .Xr vnode 9 .Sh HISTORY The vnode operations vector, its functions and the corresponding macros appeared in .Bx 4.3 .