module/os/linux/zfs/zpl_super.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or https://opensource.org/licenses/CDDL-1.0.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2011, Lawrence Livermore National Security, LLC.
  23  */
  24
  25
  26 #include <sys/zfs_znode.h>
  27 #include <sys/zfs_vfsops.h>
  28 #include <sys/zfs_vnops.h>
  29 #include <sys/zfs_ctldir.h>
  30 #include <sys/zpl.h>
  31
  32
  33 static struct inode *
  34 zpl_inode_alloc(struct super_block *sb)
  35 {
  36         struct inode *ip;
  37
  38         VERIFY3S(zfs_inode_alloc(sb, &ip), ==, 0);
  39         inode_set_iversion(ip, 1);
  40
  41         return (ip);
  42 }
  43
  44 static void
  45 zpl_inode_destroy(struct inode *ip)
  46 {
  47         ASSERT(atomic_read(&ip->i_count) == 0);
  48         zfs_inode_destroy(ip);
  49 }
  50
  51 /*
  52  * Called from __mark_inode_dirty() to reflect that something in the
  53  * inode has changed.  We use it to ensure the znode system attributes
  54  * are always strictly update to date with respect to the inode.
  55  */
  56 #ifdef HAVE_DIRTY_INODE_WITH_FLAGS
  57 static void
  58 zpl_dirty_inode(struct inode *ip, int flags)
  59 {
  60         fstrans_cookie_t cookie;
  61
  62         cookie = spl_fstrans_mark();
  63         zfs_dirty_inode(ip, flags);
  64         spl_fstrans_unmark(cookie);
  65 }
  66 #else
  67 static void
  68 zpl_dirty_inode(struct inode *ip)
  69 {
  70         fstrans_cookie_t cookie;
  71
  72         cookie = spl_fstrans_mark();
  73         zfs_dirty_inode(ip, 0);
  74         spl_fstrans_unmark(cookie);
  75 }
  76 #endif /* HAVE_DIRTY_INODE_WITH_FLAGS */
  77
  78 /*
  79  * When ->drop_inode() is called its return value indicates if the
  80  * inode should be evicted from the inode cache.  If the inode is
  81  * unhashed and has no links the default policy is to evict it
  82  * immediately.
  83  *
  84  * The ->evict_inode() callback must minimally truncate the inode pages,
  85  * and call clear_inode().  For 2.6.35 and later kernels this will
  86  * simply update the inode state, with the sync occurring before the
  87  * truncate in evict().  For earlier kernels clear_inode() maps to
  88  * end_writeback() which is responsible for completing all outstanding
  89  * write back.  In either case, once this is done it is safe to cleanup
  90  * any remaining inode specific data via zfs_inactive().
  91  * remaining filesystem specific data.
  92  */
  93 static void
  94 zpl_evict_inode(struct inode *ip)
  95 {
  96         fstrans_cookie_t cookie;
  97
  98         cookie = spl_fstrans_mark();
  99         truncate_setsize(ip, 0);
 100         clear_inode(ip);
 101         zfs_inactive(ip);
 102         spl_fstrans_unmark(cookie);
 103 }
 104
 105 static void
 106 zpl_put_super(struct super_block *sb)
 107 {
 108         fstrans_cookie_t cookie;
 109         int error;
 110
 111         cookie = spl_fstrans_mark();
 112         error = -zfs_umount(sb);
 113         spl_fstrans_unmark(cookie);
 114         ASSERT3S(error, <=, 0);
 115 }
 116
 117 static int
 118 zpl_sync_fs(struct super_block *sb, int wait)
 119 {
 120         fstrans_cookie_t cookie;
 121         cred_t *cr = CRED();
 122         int error;
 123
 124         crhold(cr);
 125         cookie = spl_fstrans_mark();
 126         error = -zfs_sync(sb, wait, cr);
 127         spl_fstrans_unmark(cookie);
 128         crfree(cr);
 129         ASSERT3S(error, <=, 0);
 130
 131         return (error);
 132 }
 133
 134 static int
 135 zpl_statfs(struct dentry *dentry, struct kstatfs *statp)
 136 {
 137         fstrans_cookie_t cookie;
 138         int error;
 139
 140         cookie = spl_fstrans_mark();
 141         error = -zfs_statvfs(dentry->d_inode, statp);
 142         spl_fstrans_unmark(cookie);
 143         ASSERT3S(error, <=, 0);
 144
 145         /*
 146          * If required by a 32-bit system call, dynamically scale the
 147          * block size up to 16MiB and decrease the block counts.  This
 148          * allows for a maximum size of 64EiB to be reported.  The file
 149          * counts must be artificially capped at 2^32-1.
 150          */
 151         if (unlikely(zpl_is_32bit_api())) {
 152                 while (statp->f_blocks > UINT32_MAX &&
 153                     statp->f_bsize < SPA_MAXBLOCKSIZE) {
 154                         statp->f_frsize <<= 1;
 155                         statp->f_bsize <<= 1;
 156
 157                         statp->f_blocks >>= 1;
 158                         statp->f_bfree >>= 1;
 159                         statp->f_bavail >>= 1;
 160                 }
 161
 162                 uint64_t usedobjs = statp->f_files - statp->f_ffree;
 163                 statp->f_ffree = MIN(statp->f_ffree, UINT32_MAX - usedobjs);
 164                 statp->f_files = statp->f_ffree + usedobjs;
 165         }
 166
 167         return (error);
 168 }
 169
 170 static int
 171 zpl_remount_fs(struct super_block *sb, int *flags, char *data)
 172 {
 173         zfs_mnt_t zm = { .mnt_osname = NULL, .mnt_data = data };
 174         fstrans_cookie_t cookie;
 175         int error;
 176
 177         cookie = spl_fstrans_mark();
 178         error = -zfs_remount(sb, flags, &zm);
 179         spl_fstrans_unmark(cookie);
 180         ASSERT3S(error, <=, 0);
 181
 182         return (error);
 183 }
 184
 185 static int
 186 __zpl_show_devname(struct seq_file *seq, zfsvfs_t *zfsvfs)
 187 {
 188         int error;
 189         if ((error = zpl_enter(zfsvfs, FTAG)) != 0)
 190                 return (error);
 191
 192         char *fsname = kmem_alloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP);
 193         dmu_objset_name(zfsvfs->z_os, fsname);
 194
 195         for (int i = 0; fsname[i] != 0; i++) {
 196                 /*
 197                  * Spaces in the dataset name must be converted to their
 198                  * octal escape sequence for getmntent(3) to correctly
 199                  * parse then fsname portion of /proc/self/mounts.
 200                  */
 201                 if (fsname[i] == ' ') {
 202                         seq_puts(seq, "\\040");
 203                 } else {
 204                         seq_putc(seq, fsname[i]);
 205                 }
 206         }
 207
 208         kmem_free(fsname, ZFS_MAX_DATASET_NAME_LEN);
 209
 210         zpl_exit(zfsvfs, FTAG);
 211
 212         return (0);
 213 }
 214
 215 static int
 216 zpl_show_devname(struct seq_file *seq, struct dentry *root)
 217 {
 218         return (__zpl_show_devname(seq, root->d_sb->s_fs_info));
 219 }
 220
 221 static int
 222 __zpl_show_options(struct seq_file *seq, zfsvfs_t *zfsvfs)
 223 {
 224         seq_printf(seq, ",%s",
 225             zfsvfs->z_flags & ZSB_XATTR ? "xattr" : "noxattr");
 226
 227 #ifdef CONFIG_FS_POSIX_ACL
 228         switch (zfsvfs->z_acl_type) {
 229         case ZFS_ACLTYPE_POSIX:
 230                 seq_puts(seq, ",posixacl");
 231                 break;
 232         default:
 233                 seq_puts(seq, ",noacl");
 234                 break;
 235         }
 236 #endif /* CONFIG_FS_POSIX_ACL */
 237
 238         switch (zfsvfs->z_case) {
 239         case ZFS_CASE_SENSITIVE:
 240                 seq_puts(seq, ",casesensitive");
 241                 break;
 242         case ZFS_CASE_INSENSITIVE:
 243                 seq_puts(seq, ",caseinsensitive");
 244                 break;
 245         default:
 246                 seq_puts(seq, ",casemixed");
 247                 break;
 248         }
 249
 250         return (0);
 251 }
 252
 253 static int
 254 zpl_show_options(struct seq_file *seq, struct dentry *root)
 255 {
 256         return (__zpl_show_options(seq, root->d_sb->s_fs_info));
 257 }
 258
 259 static int
 260 zpl_fill_super(struct super_block *sb, void *data, int silent)
 261 {
 262         zfs_mnt_t *zm = (zfs_mnt_t *)data;
 263         fstrans_cookie_t cookie;
 264         int error;
 265
 266         cookie = spl_fstrans_mark();
 267         error = -zfs_domount(sb, zm, silent);
 268         spl_fstrans_unmark(cookie);
 269         ASSERT3S(error, <=, 0);
 270
 271         return (error);
 272 }
 273
 274 static int
 275 zpl_test_super(struct super_block *s, void *data)
 276 {
 277         zfsvfs_t *zfsvfs = s->s_fs_info;
 278         objset_t *os = data;
 279
 280         if (zfsvfs == NULL)
 281                 return (0);
 282
 283         return (os == zfsvfs->z_os);
 284 }
 285
 286 static struct super_block *
 287 zpl_mount_impl(struct file_system_type *fs_type, int flags, zfs_mnt_t *zm)
 288 {
 289         struct super_block *s;
 290         objset_t *os;
 291         int err;
 292
 293         err = dmu_objset_hold(zm->mnt_osname, FTAG, &os);
 294         if (err)
 295                 return (ERR_PTR(-err));
 296
 297         /*
 298          * The dsl pool lock must be released prior to calling sget().
 299          * It is possible sget() may block on the lock in grab_super()
 300          * while deactivate_super() holds that same lock and waits for
 301          * a txg sync.  If the dsl_pool lock is held over sget()
 302          * this can prevent the pool sync and cause a deadlock.
 303          */
 304         dsl_dataset_long_hold(dmu_objset_ds(os), FTAG);
 305         dsl_pool_rele(dmu_objset_pool(os), FTAG);
 306
 307         s = sget(fs_type, zpl_test_super, set_anon_super, flags, os);
 308
 309         dsl_dataset_long_rele(dmu_objset_ds(os), FTAG);
 310         dsl_dataset_rele(dmu_objset_ds(os), FTAG);
 311
 312         if (IS_ERR(s))
 313                 return (ERR_CAST(s));
 314
 315         if (s->s_root == NULL) {
 316                 err = zpl_fill_super(s, zm, flags & SB_SILENT ? 1 : 0);
 317                 if (err) {
 318                         deactivate_locked_super(s);
 319                         return (ERR_PTR(err));
 320                 }
 321                 s->s_flags |= SB_ACTIVE;
 322         } else if ((flags ^ s->s_flags) & SB_RDONLY) {
 323                 deactivate_locked_super(s);
 324                 return (ERR_PTR(-EBUSY));
 325         }
 326
 327         return (s);
 328 }
 329
 330 static struct dentry *
 331 zpl_mount(struct file_system_type *fs_type, int flags,
 332     const char *osname, void *data)
 333 {
 334         zfs_mnt_t zm = { .mnt_osname = osname, .mnt_data = data };
 335
 336         struct super_block *sb = zpl_mount_impl(fs_type, flags, &zm);
 337         if (IS_ERR(sb))
 338                 return (ERR_CAST(sb));
 339
 340         return (dget(sb->s_root));
 341 }
 342
 343 static void
 344 zpl_kill_sb(struct super_block *sb)
 345 {
 346         zfs_preumount(sb);
 347         kill_anon_super(sb);
 348 }
 349
 350 void
 351 zpl_prune_sb(int64_t nr_to_scan, void *arg)
 352 {
 353         struct super_block *sb = (struct super_block *)arg;
 354         int objects = 0;
 355
 356         (void) -zfs_prune(sb, nr_to_scan, &objects);
 357 }
 358
 359 const struct super_operations zpl_super_operations = {
 360         .alloc_inode            = zpl_inode_alloc,
 361         .destroy_inode          = zpl_inode_destroy,
 362         .dirty_inode            = zpl_dirty_inode,
 363         .write_inode            = NULL,
 364         .evict_inode            = zpl_evict_inode,
 365         .put_super              = zpl_put_super,
 366         .sync_fs                = zpl_sync_fs,
 367         .statfs                 = zpl_statfs,
 368         .remount_fs             = zpl_remount_fs,
 369         .show_devname           = zpl_show_devname,
 370         .show_options           = zpl_show_options,
 371         .show_stats             = NULL,
 372 };
 373
 374 struct file_system_type zpl_fs_type = {
 375         .owner                  = THIS_MODULE,
 376         .name                   = ZFS_DRIVER,
 377         .fs_flags               = FS_USERNS_MOUNT,
 378         .mount                  = zpl_mount,
 379         .kill_sb                = zpl_kill_sb,
 380 };