ffs_suspend.c

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    1 /*-
    2  * Copyright (c) 2012 The FreeBSD Foundation
    3  * All rights reserved.
    4  *
    5  * This software was developed by Edward Tomasz Napierala under sponsorship
    6  * from the FreeBSD Foundation.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  * $FreeBSD: releng/10.1/sys/ufs/ffs/ffs_suspend.c 253106 2013-07-09 20:49:32Z kib $
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/10.1/sys/ufs/ffs/ffs_suspend.c 253106 2013-07-09 20:49:32Z kib $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/ioccom.h>
   38 #include <sys/mount.h>
   39 #include <sys/vnode.h>
   40 #include <sys/conf.h>
   41 #include <sys/jail.h>
   42 #include <sys/sx.h>
   43 
   44 #include <security/mac/mac_framework.h>
   45 
   46 #include <ufs/ufs/extattr.h>
   47 #include <ufs/ufs/quota.h>
   48 #include <ufs/ufs/ufsmount.h>
   49 #include <ufs/ufs/inode.h>
   50 
   51 #include <ufs/ffs/fs.h>
   52 #include <ufs/ffs/ffs_extern.h>
   53 
   54 static d_open_t ffs_susp_open;
   55 static d_write_t ffs_susp_rdwr;
   56 static d_ioctl_t ffs_susp_ioctl;
   57 
   58 static struct cdevsw ffs_susp_cdevsw = {
   59         .d_version =    D_VERSION,
   60         .d_open =       ffs_susp_open,
   61         .d_read =       ffs_susp_rdwr,
   62         .d_write =      ffs_susp_rdwr,
   63         .d_ioctl =      ffs_susp_ioctl,
   64         .d_name =       "ffs_susp",
   65 };
   66 
   67 static struct cdev *ffs_susp_dev;
   68 static struct sx ffs_susp_lock;
   69 
   70 static int
   71 ffs_susp_suspended(struct mount *mp)
   72 {
   73         struct ufsmount *ump;
   74 
   75         sx_assert(&ffs_susp_lock, SA_LOCKED);
   76 
   77         ump = VFSTOUFS(mp);
   78         if (ump->um_writesuspended)
   79                 return (1);
   80         return (0);
   81 }
   82 
   83 static int
   84 ffs_susp_open(struct cdev *dev __unused, int flags __unused,
   85     int fmt __unused, struct thread *td __unused)
   86 {
   87 
   88         return (0);
   89 }
   90 
   91 static int
   92 ffs_susp_rdwr(struct cdev *dev, struct uio *uio, int ioflag)
   93 {
   94         int error, i;
   95         struct vnode *devvp;
   96         struct mount *mp;
   97         struct ufsmount *ump;
   98         struct buf *bp;
   99         void *base;
  100         size_t len;
  101         ssize_t cnt;
  102         struct fs *fs;
  103 
  104         sx_slock(&ffs_susp_lock);
  105 
  106         error = devfs_get_cdevpriv((void **)&mp);
  107         if (error != 0) {
  108                 sx_sunlock(&ffs_susp_lock);
  109                 return (ENXIO);
  110         }
  111 
  112         ump = VFSTOUFS(mp);
  113         devvp = ump->um_devvp;
  114         fs = ump->um_fs;
  115 
  116         if (ffs_susp_suspended(mp) == 0) {
  117                 sx_sunlock(&ffs_susp_lock);
  118                 return (ENXIO);
  119         }
  120 
  121         KASSERT(uio->uio_rw == UIO_READ || uio->uio_rw == UIO_WRITE,
  122             ("neither UIO_READ or UIO_WRITE"));
  123         KASSERT(uio->uio_segflg == UIO_USERSPACE,
  124             ("uio->uio_segflg != UIO_USERSPACE"));
  125 
  126         cnt = uio->uio_resid;
  127 
  128         for (i = 0; i < uio->uio_iovcnt; i++) {
  129                 while (uio->uio_iov[i].iov_len) {
  130                         base = uio->uio_iov[i].iov_base;
  131                         len = uio->uio_iov[i].iov_len;
  132                         if (len > fs->fs_bsize)
  133                                 len = fs->fs_bsize;
  134                         if (fragoff(fs, uio->uio_offset) != 0 ||
  135                             fragoff(fs, len) != 0) {
  136                                 error = EINVAL;
  137                                 goto out;
  138                         }
  139                         error = bread(devvp, btodb(uio->uio_offset), len,
  140                             NOCRED, &bp);
  141                         if (error != 0)
  142                                 goto out;
  143                         if (uio->uio_rw == UIO_WRITE) {
  144                                 error = copyin(base, bp->b_data, len);
  145                                 if (error != 0) {
  146                                         bp->b_flags |= B_INVAL | B_NOCACHE;
  147                                         brelse(bp);
  148                                         goto out;
  149                                 }
  150                                 error = bwrite(bp);
  151                                 if (error != 0)
  152                                         goto out;
  153                         } else {
  154                                 error = copyout(bp->b_data, base, len);
  155                                 brelse(bp);
  156                                 if (error != 0)
  157                                         goto out;
  158                         }
  159                         uio->uio_iov[i].iov_base =
  160                             (char *)uio->uio_iov[i].iov_base + len;
  161                         uio->uio_iov[i].iov_len -= len;
  162                         uio->uio_resid -= len;
  163                         uio->uio_offset += len;
  164                 }
  165         }
  166 
  167 out:
  168         sx_sunlock(&ffs_susp_lock);
  169 
  170         if (uio->uio_resid < cnt)
  171                 return (0);
  172 
  173         return (error);
  174 }
  175 
  176 static int
  177 ffs_susp_suspend(struct mount *mp)
  178 {
  179         struct fs *fs;
  180         struct ufsmount *ump;
  181         int error;
  182 
  183         sx_assert(&ffs_susp_lock, SA_XLOCKED);
  184 
  185         if (!ffs_own_mount(mp))
  186                 return (EINVAL);
  187         if (ffs_susp_suspended(mp))
  188                 return (EBUSY);
  189 
  190         ump = VFSTOUFS(mp);
  191         fs = ump->um_fs;
  192 
  193         /*
  194          * Make sure the calling thread is permitted to access the mounted
  195          * device.  The permissions can change after we unlock the vnode;
  196          * it's harmless.
  197          */
  198         vn_lock(ump->um_devvp, LK_EXCLUSIVE | LK_RETRY);
  199         error = VOP_ACCESS(ump->um_devvp, VREAD | VWRITE,
  200             curthread->td_ucred, curthread);
  201         VOP_UNLOCK(ump->um_devvp, 0);
  202         if (error != 0)
  203                 return (error);
  204 #ifdef MAC
  205         if (mac_mount_check_stat(curthread->td_ucred, mp) != 0)
  206                 return (EPERM);
  207 #endif
  208 
  209         if ((error = vfs_write_suspend(mp, VS_SKIP_UNMOUNT)) != 0)
  210                 return (error);
  211 
  212         ump->um_writesuspended = 1;
  213 
  214         return (0);
  215 }
  216 
  217 static void
  218 ffs_susp_dtor(void *data)
  219 {
  220         struct fs *fs;
  221         struct ufsmount *ump;
  222         struct mount *mp;
  223         int error;
  224 
  225         sx_xlock(&ffs_susp_lock);
  226 
  227         mp = (struct mount *)data;
  228         ump = VFSTOUFS(mp);
  229         fs = ump->um_fs;
  230 
  231         if (ffs_susp_suspended(mp) == 0) {
  232                 sx_xunlock(&ffs_susp_lock);
  233                 return;
  234         }
  235 
  236         KASSERT((mp->mnt_kern_flag & MNTK_SUSPEND) != 0,
  237             ("MNTK_SUSPEND not set"));
  238 
  239         error = ffs_reload(mp, curthread, 1);
  240         if (error != 0)
  241                 panic("failed to unsuspend writes on %s", fs->fs_fsmnt);
  242 
  243         /*
  244          * XXX: The status is kept per-process; the vfs_write_resume() routine
  245          *      asserts that the resuming thread is the same one that called
  246          *      vfs_write_suspend().  The cdevpriv data, however, is attached
  247          *      to the file descriptor, e.g. is inherited during fork.  Thus,
  248          *      it's possible that the resuming process will be different from
  249          *      the one that started the suspension.
  250          *
  251          *      Work around by fooling the check in vfs_write_resume().
  252          */
  253         mp->mnt_susp_owner = curthread;
  254 
  255         vfs_write_resume(mp, 0);
  256         vfs_unbusy(mp);
  257         ump->um_writesuspended = 0;
  258 
  259         sx_xunlock(&ffs_susp_lock);
  260 }
  261 
  262 static int
  263 ffs_susp_ioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flags,
  264     struct thread *td)
  265 {
  266         struct mount *mp;
  267         fsid_t *fsidp;
  268         int error;
  269 
  270         /*
  271          * No suspend inside the jail.  Allowing it would require making
  272          * sure that e.g. the devfs ruleset for that jail permits access
  273          * to the devvp.
  274          */
  275         if (jailed(td->td_ucred))
  276                 return (EPERM);
  277 
  278         sx_xlock(&ffs_susp_lock);
  279 
  280         switch (cmd) {
  281         case UFSSUSPEND:
  282                 fsidp = (fsid_t *)addr;
  283                 mp = vfs_getvfs(fsidp);
  284                 if (mp == NULL) {
  285                         error = ENOENT;
  286                         break;
  287                 }
  288                 error = vfs_busy(mp, 0);
  289                 vfs_rel(mp);
  290                 if (error != 0)
  291                         break;
  292                 error = ffs_susp_suspend(mp);
  293                 if (error != 0) {
  294                         vfs_unbusy(mp);
  295                         break;
  296                 }
  297                 error = devfs_set_cdevpriv(mp, ffs_susp_dtor);
  298                 KASSERT(error == 0, ("devfs_set_cdevpriv failed"));
  299                 break;
  300         case UFSRESUME:
  301                 error = devfs_get_cdevpriv((void **)&mp);
  302                 if (error != 0)
  303                         break;
  304                 /*
  305                  * This calls ffs_susp_dtor, which in turn unsuspends the fs.
  306                  * The dtor expects to be called without lock held, because
  307                  * sometimes it's called from here, and sometimes due to the
  308                  * file being closed or process exiting.
  309                  */
  310                 sx_xunlock(&ffs_susp_lock);
  311                 devfs_clear_cdevpriv();
  312                 return (0);
  313         default:
  314                 error = ENXIO;
  315                 break;
  316         }
  317 
  318         sx_xunlock(&ffs_susp_lock);
  319 
  320         return (error);
  321 }
  322 
  323 void
  324 ffs_susp_initialize(void)
  325 {
  326 
  327         sx_init(&ffs_susp_lock, "ffs_susp");
  328         ffs_susp_dev = make_dev(&ffs_susp_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600,
  329             "ufssuspend");
  330 }
  331 
  332 void
  333 ffs_susp_uninitialize(void)
  334 {
  335 
  336         destroy_dev(ffs_susp_dev);
  337         sx_destroy(&ffs_susp_lock);
  338 }
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FreeBSD/Linux Kernel Cross Reference sys/ufs/ffs/ffs_suspend.c

FreeBSD/Linux Kernel Cross Reference
sys/ufs/ffs/ffs_suspend.c
