spl_vfs.c

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    1 /*
    2  * Copyright (c) 2006-2007 Pawel Jakub Dawidek <pjd@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/types.h>
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/systm.h>
   34 #include <sys/malloc.h>
   35 #include <sys/mount.h>
   36 #include <sys/cred.h>
   37 #include <sys/vfs.h>
   38 #include <sys/priv.h>
   39 #include <sys/libkern.h>
   40 
   41 #include <sys/mutex.h>
   42 #include <sys/vnode.h>
   43 #include <sys/taskq.h>
   44 
   45 #include <sys/ccompat.h>
   46 
   47 MALLOC_DECLARE(M_MOUNT);
   48 
   49 void
   50 vfs_setmntopt(vfs_t *vfsp, const char *name, const char *arg,
   51     int flags __unused)
   52 {
   53         struct vfsopt *opt;
   54         size_t namesize;
   55         int locked;
   56 
   57         if (!(locked = mtx_owned(MNT_MTX(vfsp))))
   58                 MNT_ILOCK(vfsp);
   59 
   60         if (vfsp->mnt_opt == NULL) {
   61                 void *opts;
   62 
   63                 MNT_IUNLOCK(vfsp);
   64                 opts = malloc(sizeof (*vfsp->mnt_opt), M_MOUNT, M_WAITOK);
   65                 MNT_ILOCK(vfsp);
   66                 if (vfsp->mnt_opt == NULL) {
   67                         vfsp->mnt_opt = opts;
   68                         TAILQ_INIT(vfsp->mnt_opt);
   69                 } else {
   70                         free(opts, M_MOUNT);
   71                 }
   72         }
   73 
   74         MNT_IUNLOCK(vfsp);
   75 
   76         opt = malloc(sizeof (*opt), M_MOUNT, M_WAITOK);
   77         namesize = strlen(name) + 1;
   78         opt->name = malloc(namesize, M_MOUNT, M_WAITOK);
   79         strlcpy(opt->name, name, namesize);
   80         opt->pos = -1;
   81         opt->seen = 1;
   82         if (arg == NULL) {
   83                 opt->value = NULL;
   84                 opt->len = 0;
   85         } else {
   86                 opt->len = strlen(arg) + 1;
   87                 opt->value = malloc(opt->len, M_MOUNT, M_WAITOK);
   88                 memcpy(opt->value, arg, opt->len);
   89         }
   90 
   91         MNT_ILOCK(vfsp);
   92         TAILQ_INSERT_TAIL(vfsp->mnt_opt, opt, link);
   93         if (!locked)
   94                 MNT_IUNLOCK(vfsp);
   95 }
   96 
   97 void
   98 vfs_clearmntopt(vfs_t *vfsp, const char *name)
   99 {
  100         int locked;
  101 
  102         if (!(locked = mtx_owned(MNT_MTX(vfsp))))
  103                 MNT_ILOCK(vfsp);
  104         vfs_deleteopt(vfsp->mnt_opt, name);
  105         if (!locked)
  106                 MNT_IUNLOCK(vfsp);
  107 }
  108 
  109 int
  110 vfs_optionisset(const vfs_t *vfsp, const char *opt, char **argp)
  111 {
  112         struct vfsoptlist *opts = vfsp->mnt_optnew;
  113         int error;
  114 
  115         if (opts == NULL)
  116                 return (0);
  117         error = vfs_getopt(opts, opt, (void **)argp, NULL);
  118         return (error != 0 ? 0 : 1);
  119 }
  120 
  121 int
  122 mount_snapshot(kthread_t *td, vnode_t **vpp, const char *fstype, char *fspath,
  123     char *fspec, int fsflags)
  124 {
  125         struct vfsconf *vfsp;
  126         struct mount *mp;
  127         vnode_t *vp, *mvp;
  128         int error;
  129 
  130         ASSERT_VOP_ELOCKED(*vpp, "mount_snapshot");
  131 
  132         vp = *vpp;
  133         *vpp = NULL;
  134         error = 0;
  135 
  136         /*
  137          * Be ultra-paranoid about making sure the type and fspath
  138          * variables will fit in our mp buffers, including the
  139          * terminating NUL.
  140          */
  141         if (strlen(fstype) >= MFSNAMELEN || strlen(fspath) >= MNAMELEN)
  142                 error = ENAMETOOLONG;
  143         if (error == 0 && (vfsp = vfs_byname_kld(fstype, td, &error)) == NULL)
  144                 error = ENODEV;
  145         if (error == 0 && vp->v_type != VDIR)
  146                 error = ENOTDIR;
  147         /*
  148          * We need vnode lock to protect v_mountedhere and vnode interlock
  149          * to protect v_iflag.
  150          */
  151         if (error == 0) {
  152                 VI_LOCK(vp);
  153                 if ((vp->v_iflag & VI_MOUNT) == 0 && vp->v_mountedhere == NULL)
  154                         vp->v_iflag |= VI_MOUNT;
  155                 else
  156                         error = EBUSY;
  157                 VI_UNLOCK(vp);
  158         }
  159         if (error != 0) {
  160                 vput(vp);
  161                 return (error);
  162         }
  163         vn_seqc_write_begin(vp);
  164         VOP_UNLOCK1(vp);
  165 
  166         /*
  167          * Allocate and initialize the filesystem.
  168          * We don't want regular user that triggered snapshot mount to be able
  169          * to unmount it, so pass credentials of the parent mount.
  170          */
  171         mp = vfs_mount_alloc(vp, vfsp, fspath, vp->v_mount->mnt_cred);
  172 
  173         mp->mnt_optnew = NULL;
  174         vfs_setmntopt(mp, "from", fspec, 0);
  175         mp->mnt_optnew = mp->mnt_opt;
  176         mp->mnt_opt = NULL;
  177 
  178         /*
  179          * Set the mount level flags.
  180          */
  181         mp->mnt_flag = fsflags & MNT_UPDATEMASK;
  182         /*
  183          * Snapshots are always read-only.
  184          */
  185         mp->mnt_flag |= MNT_RDONLY;
  186         /*
  187          * We don't want snapshots to allow access to vulnerable setuid
  188          * programs, so we turn off setuid when mounting snapshots.
  189          */
  190         mp->mnt_flag |= MNT_NOSUID;
  191         /*
  192          * We don't want snapshots to be visible in regular
  193          * mount(8) and df(1) output.
  194          */
  195         mp->mnt_flag |= MNT_IGNORE;
  196 
  197         error = VFS_MOUNT(mp);
  198         if (error != 0) {
  199                 /*
  200                  * Clear VI_MOUNT and decrement the use count "atomically",
  201                  * under the vnode lock.  This is not strictly required,
  202                  * but makes it easier to reason about the life-cycle and
  203                  * ownership of the covered vnode.
  204                  */
  205                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  206                 VI_LOCK(vp);
  207                 vp->v_iflag &= ~VI_MOUNT;
  208                 VI_UNLOCK(vp);
  209                 vn_seqc_write_end(vp);
  210                 vput(vp);
  211                 vfs_unbusy(mp);
  212                 vfs_freeopts(mp->mnt_optnew);
  213                 mp->mnt_vnodecovered = NULL;
  214                 vfs_mount_destroy(mp);
  215                 return (error);
  216         }
  217 
  218         if (mp->mnt_opt != NULL)
  219                 vfs_freeopts(mp->mnt_opt);
  220         mp->mnt_opt = mp->mnt_optnew;
  221         (void) VFS_STATFS(mp, &mp->mnt_stat);
  222 
  223         /*
  224          * Prevent external consumers of mount options from reading
  225          * mnt_optnew.
  226          */
  227         mp->mnt_optnew = NULL;
  228 
  229         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  230 #ifdef FREEBSD_NAMECACHE
  231         cache_purge(vp);
  232 #endif
  233         VI_LOCK(vp);
  234         vp->v_iflag &= ~VI_MOUNT;
  235 #ifdef VIRF_MOUNTPOINT
  236         vn_irflag_set_locked(vp, VIRF_MOUNTPOINT);
  237 #endif
  238         vp->v_mountedhere = mp;
  239         VI_UNLOCK(vp);
  240         /* Put the new filesystem on the mount list. */
  241         mtx_lock(&mountlist_mtx);
  242         TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
  243         mtx_unlock(&mountlist_mtx);
  244         vfs_event_signal(NULL, VQ_MOUNT, 0);
  245         if (VFS_ROOT(mp, LK_EXCLUSIVE, &mvp))
  246                 panic("mount: lost mount");
  247         vn_seqc_write_end(vp);
  248         VOP_UNLOCK1(vp);
  249 #if __FreeBSD_version >= 1300048
  250         vfs_op_exit(mp);
  251 #endif
  252         vfs_unbusy(mp);
  253         *vpp = mvp;
  254         return (0);
  255 }
  256 
  257 /*
  258  * Like vn_rele() except if we are going to call VOP_INACTIVE() then do it
  259  * asynchronously using a taskq. This can avoid deadlocks caused by re-entering
  260  * the file system as a result of releasing the vnode. Note, file systems
  261  * already have to handle the race where the vnode is incremented before the
  262  * inactive routine is called and does its locking.
  263  *
  264  * Warning: Excessive use of this routine can lead to performance problems.
  265  * This is because taskqs throttle back allocation if too many are created.
  266  */
  267 void
  268 vn_rele_async(vnode_t *vp, taskq_t *taskq)
  269 {
  270         VERIFY3U(vp->v_usecount, >, 0);
  271         if (refcount_release_if_not_last(&vp->v_usecount)) {
  272 #if __FreeBSD_version < 1300045
  273                 vdrop(vp);
  274 #endif
  275                 return;
  276         }
  277         VERIFY3U(taskq_dispatch((taskq_t *)taskq,
  278             (task_func_t *)vrele, vp, TQ_SLEEP), !=, 0);
  279 }

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FreeBSD/Linux Kernel Cross Reference sys/contrib/openzfs/module/os/freebsd/spl/spl_vfs.c

FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/os/freebsd/spl/spl_vfs.c