module/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 http://www.opensolaris.org/os/licensing.
  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_vfsops.h>
  27 #include <sys/zfs_vnops.h>
  28 #include <sys/zfs_znode.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         ip->i_version = 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  * When ->drop_inode() is called its return value indicates if the
  53  * inode should be evicted from the inode cache.  If the inode is
  54  * unhashed and has no links the default policy is to evict it
  55  * immediately.
  56  *
  57  * Prior to 2.6.36 this eviction was accomplished by the vfs calling
  58  * ->delete_inode().  It was ->delete_inode()'s responsibility to
  59  * truncate the inode pages and call clear_inode().  The call to
  60  * clear_inode() synchronously invalidates all the buffers and
  61  * calls ->clear_inode().  It was ->clear_inode()'s responsibility
  62  * to cleanup and filesystem specific data before freeing the inode.
  63  *
  64  * This elaborate mechanism was replaced by ->evict_inode() which
  65  * does the job of both ->delete_inode() and ->clear_inode().  It
  66  * will be called exactly once, and when it returns the inode must
  67  * be in a state where it can simply be freed.i
  68  *
  69  * The ->evict_inode() callback must minimally truncate the inode pages,
  70  * and call clear_inode().  For 2.6.35 and later kernels this will
  71  * simply update the inode state, with the sync occurring before the
  72  * truncate in evict().  For earlier kernels clear_inode() maps to
  73  * end_writeback() which is responsible for completing all outstanding
  74  * write back.  In either case, once this is done it is safe to cleanup
  75  * any remaining inode specific data via zfs_inactive().
  76  * remaining filesystem specific data.
  77  */
  78 #ifdef HAVE_EVICT_INODE
  79 static void
  80 zpl_evict_inode(struct inode *ip)
  81 {
  82         truncate_setsize(ip, 0);
  83         clear_inode(ip);
  84         zfs_inactive(ip);
  85 }
  86
  87 #else
  88
  89 static void
  90 zpl_clear_inode(struct inode *ip)
  91 {
  92         zfs_inactive(ip);
  93 }
  94
  95 static void
  96 zpl_inode_delete(struct inode *ip)
  97 {
  98         truncate_setsize(ip, 0);
  99         clear_inode(ip);
 100 }
 101
 102 #endif /* HAVE_EVICT_INODE */
 103
 104 static void
 105 zpl_put_super(struct super_block *sb)
 106 {
 107         int error;
 108
 109         error = -zfs_umount(sb);
 110         ASSERT3S(error, <=, 0);
 111 }
 112
 113 static int
 114 zpl_sync_fs(struct super_block *sb, int wait)
 115 {
 116         cred_t *cr = CRED();
 117         int error;
 118
 119         crhold(cr);
 120         error = -zfs_sync(sb, wait, cr);
 121         crfree(cr);
 122         ASSERT3S(error, <=, 0);
 123
 124         return (error);
 125 }
 126
 127 static int
 128 zpl_statfs(struct dentry *dentry, struct kstatfs *statp)
 129 {
 130         int error;
 131
 132         error = -zfs_statvfs(dentry, statp);
 133         ASSERT3S(error, <=, 0);
 134
 135         return (error);
 136 }
 137
 138 static int
 139 zpl_remount_fs(struct super_block *sb, int *flags, char *data)
 140 {
 141         int error;
 142         error = -zfs_remount(sb, flags, data);
 143         ASSERT3S(error, <=, 0);
 144
 145         return (error);
 146 }
 147
 148 static void
 149 zpl_umount_begin(struct super_block *sb)
 150 {
 151         zfs_sb_t *zsb = sb->s_fs_info;
 152         int count;
 153
 154         /*
 155          * Best effort to unmount snapshots in .zfs/snapshot/.  Normally this
 156          * isn't required because snapshots have the MNT_SHRINKABLE flag set.
 157          */
 158         if (zsb->z_ctldir)
 159                 (void) zfsctl_unmount_snapshots(zsb, MNT_FORCE, &count);
 160 }
 161
 162 /*
 163  * The Linux VFS automatically handles the following flags:
 164  * MNT_NOSUID, MNT_NODEV, MNT_NOEXEC, MNT_NOATIME, MNT_READONLY
 165  */
 166 #ifdef HAVE_SHOW_OPTIONS_WITH_DENTRY
 167 static int
 168 zpl_show_options(struct seq_file *seq, struct dentry *root)
 169 {
 170         zfs_sb_t *zsb = root->d_sb->s_fs_info;
 171
 172         seq_printf(seq, ",%s", zsb->z_flags & ZSB_XATTR ? "xattr" : "noxattr");
 173
 174         return (0);
 175 }
 176 #else
 177 static int
 178 zpl_show_options(struct seq_file *seq, struct vfsmount *vfsp)
 179 {
 180         zfs_sb_t *zsb = vfsp->mnt_sb->s_fs_info;
 181
 182         seq_printf(seq, ",%s", zsb->z_flags & ZSB_XATTR ? "xattr" : "noxattr");
 183
 184         return (0);
 185 }
 186 #endif /* HAVE_SHOW_OPTIONS_WITH_DENTRY */
 187
 188 static int
 189 zpl_fill_super(struct super_block *sb, void *data, int silent)
 190 {
 191         int error;
 192
 193         error = -zfs_domount(sb, data, silent);
 194         ASSERT3S(error, <=, 0);
 195
 196         return (error);
 197 }
 198
 199 #ifdef HAVE_MOUNT_NODEV
 200 static struct dentry *
 201 zpl_mount(struct file_system_type *fs_type, int flags,
 202     const char *osname, void *data)
 203 {
 204         zpl_mount_data_t zmd = { osname, data };
 205
 206         return mount_nodev(fs_type, flags, &zmd, zpl_fill_super);
 207 }
 208 #else
 209 static int
 210 zpl_get_sb(struct file_system_type *fs_type, int flags,
 211     const char *osname, void *data, struct vfsmount *mnt)
 212 {
 213         zpl_mount_data_t zmd = { osname, data };
 214
 215         return get_sb_nodev(fs_type, flags, &zmd, zpl_fill_super, mnt);
 216 }
 217 #endif /* HAVE_MOUNT_NODEV */
 218
 219 static void
 220 zpl_kill_sb(struct super_block *sb)
 221 {
 222         zfs_preumount(sb);
 223         kill_anon_super(sb);
 224 }
 225
 226 #ifdef HAVE_SHRINK
 227 /*
 228  * Linux 3.1 - 3.x API
 229  *
 230  * The Linux 3.1 API introduced per-sb cache shrinkers to replace the
 231  * global ones.  This allows us a mechanism to cleanly target a specific
 232  * zfs file system when the dnode and inode caches grow too large.
 233  *
 234  * In addition, the 3.0 kernel added the iterate_supers_type() helper
 235  * function which is used to safely walk all of the zfs file systems.
 236  */
 237 static void
 238 zpl_prune_sb(struct super_block *sb, void *arg)
 239 {
 240         int objects = 0;
 241         int error;
 242
 243         error = -zfs_sb_prune(sb, *(unsigned long *)arg, &objects);
 244         ASSERT3S(error, <=, 0);
 245
 246         return;
 247 }
 248
 249 void
 250 zpl_prune_sbs(int64_t bytes_to_scan, void *private)
 251 {
 252         unsigned long nr_to_scan = (bytes_to_scan / sizeof(znode_t));
 253
 254         iterate_supers_type(&zpl_fs_type, zpl_prune_sb, &nr_to_scan);
 255         kmem_reap();
 256 }
 257 #else
 258 /*
 259  * Linux 2.6.x - 3.0 API
 260  *
 261  * These are best effort interfaces are provided by the SPL to induce
 262  * the Linux VM subsystem to reclaim a fraction of the both dnode and
 263  * inode caches.  Ideally, we want to just target the zfs file systems
 264  * however our only option is to reclaim from them all.
 265  */
 266 void
 267 zpl_prune_sbs(int64_t bytes_to_scan, void *private)
 268 {
 269         unsigned long nr_to_scan = (bytes_to_scan / sizeof(znode_t));
 270
 271         shrink_dcache_memory(nr_to_scan, GFP_KERNEL);
 272         shrink_icache_memory(nr_to_scan, GFP_KERNEL);
 273         kmem_reap();
 274 }
 275 #endif /* HAVE_SHRINK */
 276
 277 #ifdef HAVE_NR_CACHED_OBJECTS
 278 static int
 279 zpl_nr_cached_objects(struct super_block *sb)
 280 {
 281         zfs_sb_t *zsb = sb->s_fs_info;
 282         int nr;
 283
 284         mutex_enter(&zsb->z_znodes_lock);
 285         nr = zsb->z_nr_znodes;
 286         mutex_exit(&zsb->z_znodes_lock);
 287
 288         return (nr);
 289 }
 290 #endif /* HAVE_NR_CACHED_OBJECTS */
 291
 292 #ifdef HAVE_FREE_CACHED_OBJECTS
 293 /*
 294  * Attempt to evict some meta data from the cache.  The ARC operates in
 295  * terms of bytes while the Linux VFS uses objects.  Now because this is
 296  * just a best effort eviction and the exact values aren't critical so we
 297  * extrapolate from an object count to a byte size using the znode_t size.
 298  */
 299 static void
 300 zpl_free_cached_objects(struct super_block *sb, int nr_to_scan)
 301 {
 302         arc_adjust_meta(nr_to_scan * sizeof(znode_t), B_FALSE);
 303 }
 304 #endif /* HAVE_FREE_CACHED_OBJECTS */
 305
 306 const struct super_operations zpl_super_operations = {
 307         .alloc_inode            = zpl_inode_alloc,
 308         .destroy_inode          = zpl_inode_destroy,
 309         .dirty_inode            = NULL,
 310         .write_inode            = NULL,
 311         .drop_inode             = NULL,
 312 #ifdef HAVE_EVICT_INODE
 313         .evict_inode            = zpl_evict_inode,
 314 #else
 315         .clear_inode            = zpl_clear_inode,
 316         .delete_inode           = zpl_inode_delete,
 317 #endif /* HAVE_EVICT_INODE */
 318         .put_super              = zpl_put_super,
 319         .write_super            = NULL,
 320         .sync_fs                = zpl_sync_fs,
 321         .statfs                 = zpl_statfs,
 322         .remount_fs             = zpl_remount_fs,
 323         .umount_begin           = zpl_umount_begin,
 324         .show_options           = zpl_show_options,
 325         .show_stats             = NULL,
 326 #ifdef HAVE_NR_CACHED_OBJECTS
 327         .nr_cached_objects      = zpl_nr_cached_objects,
 328 #endif /* HAVE_NR_CACHED_OBJECTS */
 329 #ifdef HAVE_FREE_CACHED_OBJECTS
 330         .free_cached_objects    = zpl_free_cached_objects,
 331 #endif /* HAVE_FREE_CACHED_OBJECTS */
 332 };
 333
 334 struct file_system_type zpl_fs_type = {
 335         .owner                  = THIS_MODULE,
 336         .name                   = ZFS_DRIVER,
 337 #ifdef HAVE_MOUNT_NODEV
 338         .mount                  = zpl_mount,
 339 #else
 340         .get_sb                 = zpl_get_sb,
 341 #endif /* HAVE_MOUNT_NODEV */
 342         .kill_sb                = zpl_kill_sb,
 343 };