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zfs-builds-mm/zfs-2.0.0/module/os/freebsd/zfs/zfs_ctldir.c

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add_2.0.0
2020-12-02 17:25:31 +01:00
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2015 by Delphix. All rights reserved.
* Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
*/
/*
* ZFS control directory (a.k.a. ".zfs")
*
* This directory provides a common location for all ZFS meta-objects.
* Currently, this is only the 'snapshot' directory, but this may expand in the
* future. The elements are built using the GFS primitives, as the hierarchy
* does not actually exist on disk.
*
* For 'snapshot', we don't want to have all snapshots always mounted, because
* this would take up a huge amount of space in /etc/mnttab. We have three
* types of objects:
*
* ctldir ------> snapshotdir -------> snapshot
* |
* |
* V
* mounted fs
*
* The 'snapshot' node contains just enough information to lookup '..' and act
* as a mountpoint for the snapshot. Whenever we lookup a specific snapshot, we
* perform an automount of the underlying filesystem and return the
* corresponding vnode.
*
* All mounts are handled automatically by the kernel, but unmounts are
* (currently) handled from user land. The main reason is that there is no
* reliable way to auto-unmount the filesystem when it's "no longer in use".
* When the user unmounts a filesystem, we call zfsctl_unmount(), which
* unmounts any snapshots within the snapshot directory.
*
* The '.zfs', '.zfs/snapshot', and all directories created under
* '.zfs/snapshot' (ie: '.zfs/snapshot/<snapname>') are all GFS nodes and
* share the same vfs_t as the head filesystem (what '.zfs' lives under).
*
* File systems mounted ontop of the GFS nodes '.zfs/snapshot/<snapname>'
* (ie: snapshots) are ZFS nodes and have their own unique vfs_t.
* However, vnodes within these mounted on file systems have their v_vfsp
* fields set to the head filesystem to make NFS happy (see
* zfsctl_snapdir_lookup()). We VFS_HOLD the head filesystem's vfs_t
* so that it cannot be freed until all snapshots have been unmounted.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/libkern.h>
#include <sys/dirent.h>
#include <sys/zfs_context.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_vfsops.h>
#include <sys/namei.h>
#include <sys/stat.h>
#include <sys/dmu.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_destroy.h>
#include <sys/dsl_deleg.h>
#include <sys/mount.h>
#include <sys/zap.h>
#include <sys/sysproto.h>
#include "zfs_namecheck.h"
#include <sys/kernel.h>
#include <sys/ccompat.h>
/* Common access mode for all virtual directories under the ctldir */
const uint16_t zfsctl_ctldir_mode = S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP |
S_IROTH | S_IXOTH;
/*
* "Synthetic" filesystem implementation.
*/
/*
* Assert that A implies B.
*/
#define KASSERT_IMPLY(A, B, msg) KASSERT(!(A) || (B), (msg));
static MALLOC_DEFINE(M_SFSNODES, "sfs_nodes", "synthetic-fs nodes");
typedef struct sfs_node {
char sn_name[ZFS_MAX_DATASET_NAME_LEN];
uint64_t sn_parent_id;
uint64_t sn_id;
} sfs_node_t;
/*
* Check the parent's ID as well as the node's to account for a chance
* that IDs originating from different domains (snapshot IDs, artificial
* IDs, znode IDs) may clash.
*/
static int
sfs_compare_ids(struct vnode *vp, void *arg)
{
sfs_node_t *n1 = vp->v_data;
sfs_node_t *n2 = arg;
bool equal;
equal = n1->sn_id == n2->sn_id &&
n1->sn_parent_id == n2->sn_parent_id;
/* Zero means equality. */
return (!equal);
}
static int
sfs_vnode_get(const struct mount *mp, int flags, uint64_t parent_id,
uint64_t id, struct vnode **vpp)
{
sfs_node_t search;
int err;
search.sn_id = id;
search.sn_parent_id = parent_id;
err = vfs_hash_get(mp, (uint32_t)id, flags, curthread, vpp,
sfs_compare_ids, &search);
return (err);
}
static int
sfs_vnode_insert(struct vnode *vp, int flags, uint64_t parent_id,
uint64_t id, struct vnode **vpp)
{
int err;
KASSERT(vp->v_data != NULL, ("sfs_vnode_insert with NULL v_data"));
err = vfs_hash_insert(vp, (uint32_t)id, flags, curthread, vpp,
sfs_compare_ids, vp->v_data);
return (err);
}
static void
sfs_vnode_remove(struct vnode *vp)
{
vfs_hash_remove(vp);
}
typedef void sfs_vnode_setup_fn(vnode_t *vp, void *arg);
static int
sfs_vgetx(struct mount *mp, int flags, uint64_t parent_id, uint64_t id,
const char *tag, struct vop_vector *vops,
sfs_vnode_setup_fn setup, void *arg,
struct vnode **vpp)
{
struct vnode *vp;
int error;
error = sfs_vnode_get(mp, flags, parent_id, id, vpp);
if (error != 0 || *vpp != NULL) {
KASSERT_IMPLY(error == 0, (*vpp)->v_data != NULL,
"sfs vnode with no data");
return (error);
}
/* Allocate a new vnode/inode. */
error = getnewvnode(tag, mp, vops, &vp);
if (error != 0) {
*vpp = NULL;
return (error);
}
/*
* Exclusively lock the vnode vnode while it's being constructed.
*/
lockmgr(vp->v_vnlock, LK_EXCLUSIVE, NULL);
error = insmntque(vp, mp);
if (error != 0) {
*vpp = NULL;
return (error);
}
setup(vp, arg);
error = sfs_vnode_insert(vp, flags, parent_id, id, vpp);
if (error != 0 || *vpp != NULL) {
KASSERT_IMPLY(error == 0, (*vpp)->v_data != NULL,
"sfs vnode with no data");
return (error);
}
*vpp = vp;
return (0);
}
static void
sfs_print_node(sfs_node_t *node)
{
printf("\tname = %s\n", node->sn_name);
printf("\tparent_id = %ju\n", (uintmax_t)node->sn_parent_id);
printf("\tid = %ju\n", (uintmax_t)node->sn_id);
}
static sfs_node_t *
sfs_alloc_node(size_t size, const char *name, uint64_t parent_id, uint64_t id)
{
struct sfs_node *node;
KASSERT(strlen(name) < sizeof (node->sn_name),
("sfs node name is too long"));
KASSERT(size >= sizeof (*node), ("sfs node size is too small"));
node = malloc(size, M_SFSNODES, M_WAITOK | M_ZERO);
strlcpy(node->sn_name, name, sizeof (node->sn_name));
node->sn_parent_id = parent_id;
node->sn_id = id;
return (node);
}
static void
sfs_destroy_node(sfs_node_t *node)
{
free(node, M_SFSNODES);
}
static void *
sfs_reclaim_vnode(vnode_t *vp)
{
void *data;
sfs_vnode_remove(vp);
data = vp->v_data;
vp->v_data = NULL;
return (data);
}
static int
sfs_readdir_common(uint64_t parent_id, uint64_t id, struct vop_readdir_args *ap,
uio_t *uio, off_t *offp)
{
struct dirent entry;
int error;
/* Reset ncookies for subsequent use of vfs_read_dirent. */
if (ap->a_ncookies != NULL)
*ap->a_ncookies = 0;
if (uio->uio_resid < sizeof (entry))
return (SET_ERROR(EINVAL));
if (uio->uio_offset < 0)
return (SET_ERROR(EINVAL));
if (uio->uio_offset == 0) {
entry.d_fileno = id;
entry.d_type = DT_DIR;
entry.d_name[0] = '.';
entry.d_name[1] = '\0';
entry.d_namlen = 1;
entry.d_reclen = sizeof (entry);
error = vfs_read_dirent(ap, &entry, uio->uio_offset);
if (error != 0)
return (SET_ERROR(error));
}
if (uio->uio_offset < sizeof (entry))
return (SET_ERROR(EINVAL));
if (uio->uio_offset == sizeof (entry)) {
entry.d_fileno = parent_id;
entry.d_type = DT_DIR;
entry.d_name[0] = '.';
entry.d_name[1] = '.';
entry.d_name[2] = '\0';
entry.d_namlen = 2;
entry.d_reclen = sizeof (entry);
error = vfs_read_dirent(ap, &entry, uio->uio_offset);
if (error != 0)
return (SET_ERROR(error));
}
if (offp != NULL)
*offp = 2 * sizeof (entry);
return (0);
}
/*
* .zfs inode namespace
*
* We need to generate unique inode numbers for all files and directories
* within the .zfs pseudo-filesystem. We use the following scheme:
*
* ENTRY ZFSCTL_INODE
* .zfs 1
* .zfs/snapshot 2
* .zfs/snapshot/<snap> objectid(snap)
*/
#define ZFSCTL_INO_SNAP(id) (id)
static struct vop_vector zfsctl_ops_root;
static struct vop_vector zfsctl_ops_snapdir;
static struct vop_vector zfsctl_ops_snapshot;
void
zfsctl_init(void)
{
}
void
zfsctl_fini(void)
{
}
boolean_t
zfsctl_is_node(vnode_t *vp)
{
return (vn_matchops(vp, zfsctl_ops_root) ||
vn_matchops(vp, zfsctl_ops_snapdir) ||
vn_matchops(vp, zfsctl_ops_snapshot));
}
typedef struct zfsctl_root {
sfs_node_t node;
sfs_node_t *snapdir;
timestruc_t cmtime;
} zfsctl_root_t;
/*
* Create the '.zfs' directory.
*/
void
zfsctl_create(zfsvfs_t *zfsvfs)
{
zfsctl_root_t *dot_zfs;
sfs_node_t *snapdir;
vnode_t *rvp;
uint64_t crtime[2];
ASSERT(zfsvfs->z_ctldir == NULL);
snapdir = sfs_alloc_node(sizeof (*snapdir), "snapshot", ZFSCTL_INO_ROOT,
ZFSCTL_INO_SNAPDIR);
dot_zfs = (zfsctl_root_t *)sfs_alloc_node(sizeof (*dot_zfs), ".zfs", 0,
ZFSCTL_INO_ROOT);
dot_zfs->snapdir = snapdir;
VERIFY(VFS_ROOT(zfsvfs->z_vfs, LK_EXCLUSIVE, &rvp) == 0);
VERIFY(0 == sa_lookup(VTOZ(rvp)->z_sa_hdl, SA_ZPL_CRTIME(zfsvfs),
&crtime, sizeof (crtime)));
ZFS_TIME_DECODE(&dot_zfs->cmtime, crtime);
vput(rvp);
zfsvfs->z_ctldir = dot_zfs;
}
/*
* Destroy the '.zfs' directory. Only called when the filesystem is unmounted.
* The nodes must not have any associated vnodes by now as they should be
* vflush-ed.
*/
void
zfsctl_destroy(zfsvfs_t *zfsvfs)
{
sfs_destroy_node(zfsvfs->z_ctldir->snapdir);
sfs_destroy_node((sfs_node_t *)zfsvfs->z_ctldir);
zfsvfs->z_ctldir = NULL;
}
static int
zfsctl_fs_root_vnode(struct mount *mp, void *arg __unused, int flags,
struct vnode **vpp)
{
return (VFS_ROOT(mp, flags, vpp));
}
static void
zfsctl_common_vnode_setup(vnode_t *vp, void *arg)
{
ASSERT_VOP_ELOCKED(vp, __func__);
/* We support shared locking. */
VN_LOCK_ASHARE(vp);
vp->v_type = VDIR;
vp->v_data = arg;
}
static int
zfsctl_root_vnode(struct mount *mp, void *arg __unused, int flags,
struct vnode **vpp)
{
void *node;
int err;
node = ((zfsvfs_t *)mp->mnt_data)->z_ctldir;
err = sfs_vgetx(mp, flags, 0, ZFSCTL_INO_ROOT, "zfs", &zfsctl_ops_root,
zfsctl_common_vnode_setup, node, vpp);
return (err);
}
static int
zfsctl_snapdir_vnode(struct mount *mp, void *arg __unused, int flags,
struct vnode **vpp)
{
void *node;
int err;
node = ((zfsvfs_t *)mp->mnt_data)->z_ctldir->snapdir;
err = sfs_vgetx(mp, flags, ZFSCTL_INO_ROOT, ZFSCTL_INO_SNAPDIR, "zfs",
&zfsctl_ops_snapdir, zfsctl_common_vnode_setup, node, vpp);
return (err);
}
/*
* Given a root znode, retrieve the associated .zfs directory.
* Add a hold to the vnode and return it.
*/
int
zfsctl_root(zfsvfs_t *zfsvfs, int flags, vnode_t **vpp)
{
int error;
error = zfsctl_root_vnode(zfsvfs->z_vfs, NULL, flags, vpp);
return (error);
}
/*
* Common open routine. Disallow any write access.
*/
static int
zfsctl_common_open(struct vop_open_args *ap)
{
int flags = ap->a_mode;
if (flags & FWRITE)
return (SET_ERROR(EACCES));
return (0);
}
/*
* Common close routine. Nothing to do here.
*/
/* ARGSUSED */
static int
zfsctl_common_close(struct vop_close_args *ap)
{
return (0);
}
/*
* Common access routine. Disallow writes.
*/
static int
zfsctl_common_access(struct vop_access_args *ap)
{
accmode_t accmode = ap->a_accmode;
if (accmode & VWRITE)
return (SET_ERROR(EACCES));
return (0);
}
/*
* Common getattr function. Fill in basic information.
*/
static void
zfsctl_common_getattr(vnode_t *vp, vattr_t *vap)
{
timestruc_t now;
sfs_node_t *node;
node = vp->v_data;
vap->va_uid = 0;
vap->va_gid = 0;
vap->va_rdev = 0;
/*
* We are a purely virtual object, so we have no
* blocksize or allocated blocks.
*/
vap->va_blksize = 0;
vap->va_nblocks = 0;
vap->va_seq = 0;
vn_fsid(vp, vap);
vap->va_mode = zfsctl_ctldir_mode;
vap->va_type = VDIR;
/*
* We live in the now (for atime).
*/
gethrestime(&now);
vap->va_atime = now;
/* FreeBSD: Reset chflags(2) flags. */
vap->va_flags = 0;
vap->va_nodeid = node->sn_id;
/* At least '.' and '..'. */
vap->va_nlink = 2;
}
#ifndef _OPENSOLARIS_SYS_VNODE_H_
struct vop_fid_args {
struct vnode *a_vp;
struct fid *a_fid;
};
#endif
static int
zfsctl_common_fid(struct vop_fid_args *ap)
{
vnode_t *vp = ap->a_vp;
fid_t *fidp = (void *)ap->a_fid;
sfs_node_t *node = vp->v_data;
uint64_t object = node->sn_id;
zfid_short_t *zfid;
int i;
zfid = (zfid_short_t *)fidp;
zfid->zf_len = SHORT_FID_LEN;
for (i = 0; i < sizeof (zfid->zf_object); i++)
zfid->zf_object[i] = (uint8_t)(object >> (8 * i));
/* .zfs nodes always have a generation number of 0 */
for (i = 0; i < sizeof (zfid->zf_gen); i++)
zfid->zf_gen[i] = 0;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct vop_reclaim_args {
struct vnode *a_vp;
struct thread *a_td;
};
#endif
static int
zfsctl_common_reclaim(struct vop_reclaim_args *ap)
{
vnode_t *vp = ap->a_vp;
(void) sfs_reclaim_vnode(vp);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct vop_print_args {
struct vnode *a_vp;
};
#endif
static int
zfsctl_common_print(struct vop_print_args *ap)
{
sfs_print_node(ap->a_vp->v_data);
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct vop_getattr_args {
struct vnode *a_vp;
struct vattr *a_vap;
struct ucred *a_cred;
};
#endif
/*
* Get root directory attributes.
*/
static int
zfsctl_root_getattr(struct vop_getattr_args *ap)
{
struct vnode *vp = ap->a_vp;
struct vattr *vap = ap->a_vap;
zfsctl_root_t *node = vp->v_data;
zfsctl_common_getattr(vp, vap);
vap->va_ctime = node->cmtime;
vap->va_mtime = vap->va_ctime;
vap->va_birthtime = vap->va_ctime;
vap->va_nlink += 1; /* snapdir */
vap->va_size = vap->va_nlink;
return (0);
}
/*
* When we lookup "." we still can be asked to lock it
* differently, can't we?
*/
static int
zfsctl_relock_dot(vnode_t *dvp, int ltype)
{
vref(dvp);
if (ltype != VOP_ISLOCKED(dvp)) {
if (ltype == LK_EXCLUSIVE)
vn_lock(dvp, LK_UPGRADE | LK_RETRY);
else /* if (ltype == LK_SHARED) */
vn_lock(dvp, LK_DOWNGRADE | LK_RETRY);
/* Relock for the "." case may left us with reclaimed vnode. */
if (VN_IS_DOOMED(dvp)) {
vrele(dvp);
return (SET_ERROR(ENOENT));
}
}
return (0);
}
/*
* Special case the handling of "..".
*/
static int
zfsctl_root_lookup(struct vop_lookup_args *ap)
{
struct componentname *cnp = ap->a_cnp;
vnode_t *dvp = ap->a_dvp;
vnode_t **vpp = ap->a_vpp;
int flags = ap->a_cnp->cn_flags;
int lkflags = ap->a_cnp->cn_lkflags;
int nameiop = ap->a_cnp->cn_nameiop;
int err;
ASSERT(dvp->v_type == VDIR);
if ((flags & ISLASTCN) != 0 && nameiop != LOOKUP)
return (SET_ERROR(ENOTSUP));
if (cnp->cn_namelen == 1 && *cnp->cn_nameptr == '.') {
err = zfsctl_relock_dot(dvp, lkflags & LK_TYPE_MASK);
if (err == 0)
*vpp = dvp;
} else if ((flags & ISDOTDOT) != 0) {
err = vn_vget_ino_gen(dvp, zfsctl_fs_root_vnode, NULL,
lkflags, vpp);
} else if (strncmp(cnp->cn_nameptr, "snapshot", cnp->cn_namelen) == 0) {
err = zfsctl_snapdir_vnode(dvp->v_mount, NULL, lkflags, vpp);
} else {
err = SET_ERROR(ENOENT);
}
if (err != 0)
*vpp = NULL;
return (err);
}
static int
zfsctl_root_readdir(struct vop_readdir_args *ap)
{
struct dirent entry;
vnode_t *vp = ap->a_vp;
zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
zfsctl_root_t *node = vp->v_data;
uio_t *uio = ap->a_uio;
int *eofp = ap->a_eofflag;
off_t dots_offset;
int error;
ASSERT(vp->v_type == VDIR);
error = sfs_readdir_common(zfsvfs->z_root, ZFSCTL_INO_ROOT, ap, uio,
&dots_offset);
if (error != 0) {
if (error == ENAMETOOLONG) /* ran out of destination space */
error = 0;
return (error);
}
if (uio->uio_offset != dots_offset)
return (SET_ERROR(EINVAL));
CTASSERT(sizeof (node->snapdir->sn_name) <= sizeof (entry.d_name));
entry.d_fileno = node->snapdir->sn_id;
entry.d_type = DT_DIR;
strcpy(entry.d_name, node->snapdir->sn_name);
entry.d_namlen = strlen(entry.d_name);
entry.d_reclen = sizeof (entry);
error = vfs_read_dirent(ap, &entry, uio->uio_offset);
if (error != 0) {
if (error == ENAMETOOLONG)
error = 0;
return (SET_ERROR(error));
}
if (eofp != NULL)
*eofp = 1;
return (0);
}
static int
zfsctl_root_vptocnp(struct vop_vptocnp_args *ap)
{
static const char dotzfs_name[4] = ".zfs";
vnode_t *dvp;
int error;
if (*ap->a_buflen < sizeof (dotzfs_name))
return (SET_ERROR(ENOMEM));
error = vn_vget_ino_gen(ap->a_vp, zfsctl_fs_root_vnode, NULL,
LK_SHARED, &dvp);
if (error != 0)
return (SET_ERROR(error));
VOP_UNLOCK1(dvp);
*ap->a_vpp = dvp;
*ap->a_buflen -= sizeof (dotzfs_name);
bcopy(dotzfs_name, ap->a_buf + *ap->a_buflen, sizeof (dotzfs_name));
return (0);
}
static int
zfsctl_common_pathconf(struct vop_pathconf_args *ap)
{
/*
* We care about ACL variables so that user land utilities like ls
* can display them correctly. Since the ctldir's st_dev is set to be
* the same as the parent dataset, we must support all variables that
* it supports.
*/
switch (ap->a_name) {
case _PC_LINK_MAX:
*ap->a_retval = MIN(LONG_MAX, ZFS_LINK_MAX);
return (0);
case _PC_FILESIZEBITS:
*ap->a_retval = 64;
return (0);
case _PC_MIN_HOLE_SIZE:
*ap->a_retval = (int)SPA_MINBLOCKSIZE;
return (0);
case _PC_ACL_EXTENDED:
*ap->a_retval = 0;
return (0);
case _PC_ACL_NFS4:
*ap->a_retval = 1;
return (0);
case _PC_ACL_PATH_MAX:
*ap->a_retval = ACL_MAX_ENTRIES;
return (0);
case _PC_NAME_MAX:
*ap->a_retval = NAME_MAX;
return (0);
default:
return (vop_stdpathconf(ap));
}
}
/*
* Returns a trivial ACL
*/
static int
zfsctl_common_getacl(struct vop_getacl_args *ap)
{
int i;
if (ap->a_type != ACL_TYPE_NFS4)
return (EINVAL);
acl_nfs4_sync_acl_from_mode(ap->a_aclp, zfsctl_ctldir_mode, 0);
/*
* acl_nfs4_sync_acl_from_mode assumes that the owner can always modify
* attributes. That is not the case for the ctldir, so we must clear
* those bits. We also must clear ACL_READ_NAMED_ATTRS, because xattrs
* aren't supported by the ctldir.
*/
for (i = 0; i < ap->a_aclp->acl_cnt; i++) {
struct acl_entry *entry;
entry = &(ap->a_aclp->acl_entry[i]);
entry->ae_perm &= ~(ACL_WRITE_ACL | ACL_WRITE_OWNER |
ACL_WRITE_ATTRIBUTES | ACL_WRITE_NAMED_ATTRS |
ACL_READ_NAMED_ATTRS);
}
return (0);
}
static struct vop_vector zfsctl_ops_root = {
.vop_default = &default_vnodeops,
#if __FreeBSD_version >= 1300121
.vop_fplookup_vexec = VOP_EAGAIN,
#endif
.vop_open = zfsctl_common_open,
.vop_close = zfsctl_common_close,
.vop_ioctl = VOP_EINVAL,
.vop_getattr = zfsctl_root_getattr,
.vop_access = zfsctl_common_access,
.vop_readdir = zfsctl_root_readdir,
.vop_lookup = zfsctl_root_lookup,
.vop_inactive = VOP_NULL,
.vop_reclaim = zfsctl_common_reclaim,
.vop_fid = zfsctl_common_fid,
.vop_print = zfsctl_common_print,
.vop_vptocnp = zfsctl_root_vptocnp,
.vop_pathconf = zfsctl_common_pathconf,
.vop_getacl = zfsctl_common_getacl,
};
VFS_VOP_VECTOR_REGISTER(zfsctl_ops_root);
static int
zfsctl_snapshot_zname(vnode_t *vp, const char *name, int len, char *zname)
{
objset_t *os = ((zfsvfs_t *)((vp)->v_vfsp->vfs_data))->z_os;
dmu_objset_name(os, zname);
if (strlen(zname) + 1 + strlen(name) >= len)
return (SET_ERROR(ENAMETOOLONG));
(void) strcat(zname, "@");
(void) strcat(zname, name);
return (0);
}
static int
zfsctl_snapshot_lookup(vnode_t *vp, const char *name, uint64_t *id)
{
objset_t *os = ((zfsvfs_t *)((vp)->v_vfsp->vfs_data))->z_os;
int err;
err = dsl_dataset_snap_lookup(dmu_objset_ds(os), name, id);
return (err);
}
/*
* Given a vnode get a root vnode of a filesystem mounted on top of
* the vnode, if any. The root vnode is referenced and locked.
* If no filesystem is mounted then the orinal vnode remains referenced
* and locked. If any error happens the orinal vnode is unlocked and
* released.
*/
static int
zfsctl_mounted_here(vnode_t **vpp, int flags)
{
struct mount *mp;
int err;
ASSERT_VOP_LOCKED(*vpp, __func__);
ASSERT3S((*vpp)->v_type, ==, VDIR);
if ((mp = (*vpp)->v_mountedhere) != NULL) {
err = vfs_busy(mp, 0);
KASSERT(err == 0, ("vfs_busy(mp, 0) failed with %d", err));
KASSERT(vrefcnt(*vpp) > 1, ("unreferenced mountpoint"));
vput(*vpp);
err = VFS_ROOT(mp, flags, vpp);
vfs_unbusy(mp);
return (err);
}
return (EJUSTRETURN);
}
typedef struct {
const char *snap_name;
uint64_t snap_id;
} snapshot_setup_arg_t;
static void
zfsctl_snapshot_vnode_setup(vnode_t *vp, void *arg)
{
snapshot_setup_arg_t *ssa = arg;
sfs_node_t *node;
ASSERT_VOP_ELOCKED(vp, __func__);
node = sfs_alloc_node(sizeof (sfs_node_t),
ssa->snap_name, ZFSCTL_INO_SNAPDIR, ssa->snap_id);
zfsctl_common_vnode_setup(vp, node);
/* We have to support recursive locking. */
VN_LOCK_AREC(vp);
}
/*
* Lookup entry point for the 'snapshot' directory. Try to open the
* snapshot if it exist, creating the pseudo filesystem vnode as necessary.
* Perform a mount of the associated dataset on top of the vnode.
* There are four possibilities:
* - the snapshot node and vnode do not exist
* - the snapshot vnode is covered by the mounted snapshot
* - the snapshot vnode is not covered yet, the mount operation is in progress
* - the snapshot vnode is not covered, because the snapshot has been unmounted
* The last two states are transient and should be relatively short-lived.
*/
static int
zfsctl_snapdir_lookup(struct vop_lookup_args *ap)
{
vnode_t *dvp = ap->a_dvp;
vnode_t **vpp = ap->a_vpp;
struct componentname *cnp = ap->a_cnp;
char name[NAME_MAX + 1];
char fullname[ZFS_MAX_DATASET_NAME_LEN];
char *mountpoint;
size_t mountpoint_len;
zfsvfs_t *zfsvfs = dvp->v_vfsp->vfs_data;
uint64_t snap_id;
int nameiop = cnp->cn_nameiop;
int lkflags = cnp->cn_lkflags;
int flags = cnp->cn_flags;
int err;
ASSERT(dvp->v_type == VDIR);
if ((flags & ISLASTCN) != 0 && nameiop != LOOKUP)
return (SET_ERROR(ENOTSUP));
if (cnp->cn_namelen == 1 && *cnp->cn_nameptr == '.') {
err = zfsctl_relock_dot(dvp, lkflags & LK_TYPE_MASK);
if (err == 0)
*vpp = dvp;
return (err);
}
if (flags & ISDOTDOT) {
err = vn_vget_ino_gen(dvp, zfsctl_root_vnode, NULL, lkflags,
vpp);
return (err);
}
if (cnp->cn_namelen >= sizeof (name))
return (SET_ERROR(ENAMETOOLONG));
strlcpy(name, ap->a_cnp->cn_nameptr, ap->a_cnp->cn_namelen + 1);
err = zfsctl_snapshot_lookup(dvp, name, &snap_id);
if (err != 0)
return (SET_ERROR(ENOENT));
for (;;) {
snapshot_setup_arg_t ssa;
ssa.snap_name = name;
ssa.snap_id = snap_id;
err = sfs_vgetx(dvp->v_mount, LK_SHARED, ZFSCTL_INO_SNAPDIR,
snap_id, "zfs", &zfsctl_ops_snapshot,
zfsctl_snapshot_vnode_setup, &ssa, vpp);
if (err != 0)
return (err);
/* Check if a new vnode has just been created. */
if (VOP_ISLOCKED(*vpp) == LK_EXCLUSIVE)
break;
/*
* Check if a snapshot is already mounted on top of the vnode.
*/
err = zfsctl_mounted_here(vpp, lkflags);
if (err != EJUSTRETURN)
return (err);
/*
* If the vnode is not covered, then either the mount operation
* is in progress or the snapshot has already been unmounted
* but the vnode hasn't been inactivated and reclaimed yet.
* We can try to re-use the vnode in the latter case.
*/
VI_LOCK(*vpp);
if (((*vpp)->v_iflag & VI_MOUNT) == 0) {
/*
* Upgrade to exclusive lock in order to:
* - avoid race conditions
* - satisfy the contract of mount_snapshot()
*/
err = VOP_LOCK(*vpp, LK_TRYUPGRADE | LK_INTERLOCK);
if (err == 0)
break;
} else {
VI_UNLOCK(*vpp);
}
/*
* In this state we can loop on uncontested locks and starve
* the thread doing the lengthy, non-trivial mount operation.
* So, yield to prevent that from happening.
*/
vput(*vpp);
kern_yield(PRI_USER);
}
VERIFY0(zfsctl_snapshot_zname(dvp, name, sizeof (fullname), fullname));
mountpoint_len = strlen(dvp->v_vfsp->mnt_stat.f_mntonname) +
strlen("/" ZFS_CTLDIR_NAME "/snapshot/") + strlen(name) + 1;
mountpoint = kmem_alloc(mountpoint_len, KM_SLEEP);
(void) snprintf(mountpoint, mountpoint_len,
"%s/" ZFS_CTLDIR_NAME "/snapshot/%s",
dvp->v_vfsp->mnt_stat.f_mntonname, name);
err = mount_snapshot(curthread, vpp, "zfs", mountpoint, fullname, 0);
kmem_free(mountpoint, mountpoint_len);
if (err == 0) {
/*
* Fix up the root vnode mounted on .zfs/snapshot/<snapname>.
*
* This is where we lie about our v_vfsp in order to
* make .zfs/snapshot/<snapname> accessible over NFS
* without requiring manual mounts of <snapname>.
*/
ASSERT(VTOZ(*vpp)->z_zfsvfs != zfsvfs);
VTOZ(*vpp)->z_zfsvfs->z_parent = zfsvfs;
/* Clear the root flag (set via VFS_ROOT) as well. */
(*vpp)->v_vflag &= ~VV_ROOT;
}
if (err != 0)
*vpp = NULL;
return (err);
}
static int
zfsctl_snapdir_readdir(struct vop_readdir_args *ap)
{
char snapname[ZFS_MAX_DATASET_NAME_LEN];
struct dirent entry;
vnode_t *vp = ap->a_vp;
zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
uio_t *uio = ap->a_uio;
int *eofp = ap->a_eofflag;
off_t dots_offset;
int error;
ASSERT(vp->v_type == VDIR);
error = sfs_readdir_common(ZFSCTL_INO_ROOT, ZFSCTL_INO_SNAPDIR, ap, uio,
&dots_offset);
if (error != 0) {
if (error == ENAMETOOLONG) /* ran out of destination space */
error = 0;
return (error);
}
ZFS_ENTER(zfsvfs);
for (;;) {
uint64_t cookie;
uint64_t id;
cookie = uio->uio_offset - dots_offset;
dsl_pool_config_enter(dmu_objset_pool(zfsvfs->z_os), FTAG);
error = dmu_snapshot_list_next(zfsvfs->z_os, sizeof (snapname),
snapname, &id, &cookie, NULL);
dsl_pool_config_exit(dmu_objset_pool(zfsvfs->z_os), FTAG);
if (error != 0) {
if (error == ENOENT) {
if (eofp != NULL)
*eofp = 1;
error = 0;
}
ZFS_EXIT(zfsvfs);
return (error);
}
entry.d_fileno = id;
entry.d_type = DT_DIR;
strcpy(entry.d_name, snapname);
entry.d_namlen = strlen(entry.d_name);
entry.d_reclen = sizeof (entry);
error = vfs_read_dirent(ap, &entry, uio->uio_offset);
if (error != 0) {
if (error == ENAMETOOLONG)
error = 0;
ZFS_EXIT(zfsvfs);
return (SET_ERROR(error));
}
uio->uio_offset = cookie + dots_offset;
}
/* NOTREACHED */
}
static int
zfsctl_snapdir_getattr(struct vop_getattr_args *ap)
{
vnode_t *vp = ap->a_vp;
vattr_t *vap = ap->a_vap;
zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
dsl_dataset_t *ds;
uint64_t snap_count;
int err;
ZFS_ENTER(zfsvfs);
ds = dmu_objset_ds(zfsvfs->z_os);
zfsctl_common_getattr(vp, vap);
vap->va_ctime = dmu_objset_snap_cmtime(zfsvfs->z_os);
vap->va_mtime = vap->va_ctime;
vap->va_birthtime = vap->va_ctime;
if (dsl_dataset_phys(ds)->ds_snapnames_zapobj != 0) {
err = zap_count(dmu_objset_pool(ds->ds_objset)->dp_meta_objset,
dsl_dataset_phys(ds)->ds_snapnames_zapobj, &snap_count);
if (err != 0) {
ZFS_EXIT(zfsvfs);
return (err);
}
vap->va_nlink += snap_count;
}
vap->va_size = vap->va_nlink;
ZFS_EXIT(zfsvfs);
return (0);
}
static struct vop_vector zfsctl_ops_snapdir = {
.vop_default = &default_vnodeops,
#if __FreeBSD_version >= 1300121
.vop_fplookup_vexec = VOP_EAGAIN,
#endif
.vop_open = zfsctl_common_open,
.vop_close = zfsctl_common_close,
.vop_getattr = zfsctl_snapdir_getattr,
.vop_access = zfsctl_common_access,
.vop_readdir = zfsctl_snapdir_readdir,
.vop_lookup = zfsctl_snapdir_lookup,
.vop_reclaim = zfsctl_common_reclaim,
.vop_fid = zfsctl_common_fid,
.vop_print = zfsctl_common_print,
.vop_pathconf = zfsctl_common_pathconf,
.vop_getacl = zfsctl_common_getacl,
};
VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapdir);
static int
zfsctl_snapshot_inactive(struct vop_inactive_args *ap)
{
vnode_t *vp = ap->a_vp;
VERIFY(vrecycle(vp) == 1);
return (0);
}
static int
zfsctl_snapshot_reclaim(struct vop_reclaim_args *ap)
{
vnode_t *vp = ap->a_vp;
void *data = vp->v_data;
sfs_reclaim_vnode(vp);
sfs_destroy_node(data);
return (0);
}
static int
zfsctl_snapshot_vptocnp(struct vop_vptocnp_args *ap)
{
struct mount *mp;
vnode_t *dvp;
vnode_t *vp;
sfs_node_t *node;
size_t len;
int locked;
int error;
vp = ap->a_vp;
node = vp->v_data;
len = strlen(node->sn_name);
if (*ap->a_buflen < len)
return (SET_ERROR(ENOMEM));
/*
* Prevent unmounting of the snapshot while the vnode lock
* is not held. That is not strictly required, but allows
* us to assert that an uncovered snapshot vnode is never
* "leaked".
*/
mp = vp->v_mountedhere;
if (mp == NULL)
return (SET_ERROR(ENOENT));
error = vfs_busy(mp, 0);
KASSERT(error == 0, ("vfs_busy(mp, 0) failed with %d", error));
/*
* We can vput the vnode as we can now depend on the reference owned
* by the busied mp. But we also need to hold the vnode, because
* the reference may go after vfs_unbusy() which has to be called
* before we can lock the vnode again.
*/
locked = VOP_ISLOCKED(vp);
#if __FreeBSD_version >= 1300045
enum vgetstate vs = vget_prep(vp);
#else
vhold(vp);
#endif
vput(vp);
/* Look up .zfs/snapshot, our parent. */
error = zfsctl_snapdir_vnode(vp->v_mount, NULL, LK_SHARED, &dvp);
if (error == 0) {
VOP_UNLOCK1(dvp);
*ap->a_vpp = dvp;
*ap->a_buflen -= len;
bcopy(node->sn_name, ap->a_buf + *ap->a_buflen, len);
}
vfs_unbusy(mp);
#if __FreeBSD_version >= 1300045
vget_finish(vp, locked | LK_RETRY, vs);
#else
vget(vp, locked | LK_VNHELD | LK_RETRY, curthread);
#endif
return (error);
}
/*
* These VP's should never see the light of day. They should always
* be covered.
*/
static struct vop_vector zfsctl_ops_snapshot = {
.vop_default = NULL, /* ensure very restricted access */
#if __FreeBSD_version >= 1300121
.vop_fplookup_vexec = VOP_EAGAIN,
#endif
.vop_inactive = zfsctl_snapshot_inactive,
#if __FreeBSD_version >= 1300045
.vop_need_inactive = vop_stdneed_inactive,
#endif
.vop_reclaim = zfsctl_snapshot_reclaim,
.vop_vptocnp = zfsctl_snapshot_vptocnp,
.vop_lock1 = vop_stdlock,
.vop_unlock = vop_stdunlock,
.vop_islocked = vop_stdislocked,
.vop_advlockpurge = vop_stdadvlockpurge, /* called by vgone */
.vop_print = zfsctl_common_print,
};
VFS_VOP_VECTOR_REGISTER(zfsctl_ops_snapshot);
int
zfsctl_lookup_objset(vfs_t *vfsp, uint64_t objsetid, zfsvfs_t **zfsvfsp)
{
zfsvfs_t *zfsvfs __unused = vfsp->vfs_data;
vnode_t *vp;
int error;
ASSERT(zfsvfs->z_ctldir != NULL);
*zfsvfsp = NULL;
error = sfs_vnode_get(vfsp, LK_EXCLUSIVE,
ZFSCTL_INO_SNAPDIR, objsetid, &vp);
if (error == 0 && vp != NULL) {
/*
* XXX Probably need to at least reference, if not busy, the mp.
*/
if (vp->v_mountedhere != NULL)
*zfsvfsp = vp->v_mountedhere->mnt_data;
vput(vp);
}
if (*zfsvfsp == NULL)
return (SET_ERROR(EINVAL));
return (0);
}
/*
* Unmount any snapshots for the given filesystem. This is called from
* zfs_umount() - if we have a ctldir, then go through and unmount all the
* snapshots.
*/
int
zfsctl_umount_snapshots(vfs_t *vfsp, int fflags, cred_t *cr)
{
char snapname[ZFS_MAX_DATASET_NAME_LEN];
zfsvfs_t *zfsvfs = vfsp->vfs_data;
struct mount *mp;
vnode_t *vp;
uint64_t cookie;
int error;
ASSERT(zfsvfs->z_ctldir != NULL);
cookie = 0;
for (;;) {
uint64_t id;
dsl_pool_config_enter(dmu_objset_pool(zfsvfs->z_os), FTAG);
error = dmu_snapshot_list_next(zfsvfs->z_os, sizeof (snapname),
snapname, &id, &cookie, NULL);
dsl_pool_config_exit(dmu_objset_pool(zfsvfs->z_os), FTAG);
if (error != 0) {
if (error == ENOENT)
error = 0;
break;
}
for (;;) {
error = sfs_vnode_get(vfsp, LK_EXCLUSIVE,
ZFSCTL_INO_SNAPDIR, id, &vp);
if (error != 0 || vp == NULL)
break;
mp = vp->v_mountedhere;
/*
* v_mountedhere being NULL means that the
* (uncovered) vnode is in a transient state
* (mounting or unmounting), so loop until it
* settles down.
*/
if (mp != NULL)
break;
vput(vp);
}
if (error != 0)
break;
if (vp == NULL)
continue; /* no mountpoint, nothing to do */
/*
* The mount-point vnode is kept locked to avoid spurious EBUSY
* from a concurrent umount.
* The vnode lock must have recursive locking enabled.
*/
vfs_ref(mp);
error = dounmount(mp, fflags, curthread);
KASSERT_IMPLY(error == 0, vrefcnt(vp) == 1,
("extra references after unmount"));
vput(vp);
if (error != 0)
break;
}
KASSERT_IMPLY((fflags & MS_FORCE) != 0, error == 0,
("force unmounting failed"));
return (error);
}
int
zfsctl_snapshot_unmount(const char *snapname, int flags __unused)
{
vfs_t *vfsp = NULL;
zfsvfs_t *zfsvfs = NULL;
if (strchr(snapname, '@') == NULL)
return (0);
int err = getzfsvfs(snapname, &zfsvfs);
if (err != 0) {
ASSERT3P(zfsvfs, ==, NULL);
return (0);
}
vfsp = zfsvfs->z_vfs;
ASSERT(!dsl_pool_config_held(dmu_objset_pool(zfsvfs->z_os)));
vfs_ref(vfsp);
vfs_unbusy(vfsp);
return (dounmount(vfsp, MS_FORCE, curthread));
}
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