fs/sdcardfs/super.c

   1 /*
   2  * fs/sdcardfs/super.c
   3  *
   4  * Copyright (c) 2013 Samsung Electronics Co. Ltd
   5  *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
   6  *               Sunghwan Yun, Sungjong Seo
   7  *
   8  * This program has been developed as a stackable file system based on
   9  * the WrapFS which written by
  10  *
  11  * Copyright (c) 1998-2011 Erez Zadok
  12  * Copyright (c) 2009     Shrikar Archak
  13  * Copyright (c) 2003-2011 Stony Brook University
  14  * Copyright (c) 2003-2011 The Research Foundation of SUNY
  15  *
  16  * This file is dual licensed.  It may be redistributed and/or modified
  17  * under the terms of the Apache 2.0 License OR version 2 of the GNU
  18  * General Public License.
  19  */
  20
  21 #include "sdcardfs.h"
  22
  23 /*
  24  * The inode cache is used with alloc_inode for both our inode info and the
  25  * vfs inode.
  26  */
  27 static struct kmem_cache *sdcardfs_inode_cachep;
  28
  29 /*
  30  * To support the top references, we must track some data separately.
  31  * An sdcardfs_inode_info always has a reference to its data, and once set up,
  32  * also has a reference to its top. The top may be itself, in which case it
  33  * holds two references to its data. When top is changed, it takes a ref to the
  34  * new data and then drops the ref to the old data.
  35  */
  36 static struct kmem_cache *sdcardfs_inode_data_cachep;
  37
  38 void data_release(struct kref *ref)
  39 {
  40         struct sdcardfs_inode_data *data =
  41                 container_of(ref, struct sdcardfs_inode_data, refcount);
  42
  43         kmem_cache_free(sdcardfs_inode_data_cachep, data);
  44 }
  45
  46 /* final actions when unmounting a file system */
  47 static void sdcardfs_put_super(struct super_block *sb)
  48 {
  49         struct sdcardfs_sb_info *spd;
  50         struct super_block *s;
  51
  52         spd = SDCARDFS_SB(sb);
  53         if (!spd)
  54                 return;
  55
  56         if (spd->obbpath_s) {
  57                 kfree(spd->obbpath_s);
  58                 path_put(&spd->obbpath);
  59         }
  60
  61         /* decrement lower super references */
  62         s = sdcardfs_lower_super(sb);
  63         sdcardfs_set_lower_super(sb, NULL);
  64         atomic_dec(&s->s_active);
  65
  66         kfree(spd);
  67         sb->s_fs_info = NULL;
  68 }
  69
  70 static int sdcardfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  71 {
  72         int err;
  73         struct path lower_path;
  74         u32 min_blocks;
  75         struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
  76
  77         sdcardfs_get_lower_path(dentry, &lower_path);
  78         err = vfs_statfs(&lower_path, buf);
  79         sdcardfs_put_lower_path(dentry, &lower_path);
  80
  81         if (sbi->options.reserved_mb) {
  82                 /* Invalid statfs informations. */
  83                 if (buf->f_bsize == 0) {
  84                         pr_err("Returned block size is zero.\n");
  85                         return -EINVAL;
  86                 }
  87
  88                 min_blocks = ((sbi->options.reserved_mb * 1024 * 1024)/buf->f_bsize);
  89                 buf->f_blocks -= min_blocks;
  90
  91                 if (buf->f_bavail > min_blocks)
  92                         buf->f_bavail -= min_blocks;
  93                 else
  94                         buf->f_bavail = 0;
  95
  96                 /* Make reserved blocks invisiable to media storage */
  97                 buf->f_bfree = buf->f_bavail;
  98         }
  99
 100         /* set return buf to our f/s to avoid confusing user-level utils */
 101         buf->f_type = SDCARDFS_SUPER_MAGIC;
 102
 103         return err;
 104 }
 105
 106 /*
 107  * @flags: numeric mount options
 108  * @options: mount options string
 109  */
 110 static int sdcardfs_remount_fs(struct super_block *sb, int *flags, char *options)
 111 {
 112         int err = 0;
 113
 114         /*
 115          * The VFS will take care of "ro" and "rw" flags among others.  We
 116          * can safely accept a few flags (RDONLY, MANDLOCK), and honor
 117          * SILENT, but anything else left over is an error.
 118          */
 119         if ((*flags & ~(MS_RDONLY | MS_MANDLOCK | MS_SILENT)) != 0) {
 120                 pr_err("sdcardfs: remount flags 0x%x unsupported\n", *flags);
 121                 err = -EINVAL;
 122         }
 123
 124         return err;
 125 }
 126
 127 /*
 128  * @mnt: mount point we are remounting
 129  * @sb: superblock we are remounting
 130  * @flags: numeric mount options
 131  * @options: mount options string
 132  */
 133 static int sdcardfs_remount_fs2(struct vfsmount *mnt, struct super_block *sb,
 134                                                 int *flags, char *options)
 135 {
 136         int err = 0;
 137
 138         /*
 139          * The VFS will take care of "ro" and "rw" flags among others.  We
 140          * can safely accept a few flags (RDONLY, MANDLOCK), and honor
 141          * SILENT, but anything else left over is an error.
 142          */
 143         if ((*flags & ~(MS_RDONLY | MS_MANDLOCK | MS_SILENT | MS_REMOUNT)) != 0) {
 144                 pr_err("sdcardfs: remount flags 0x%x unsupported\n", *flags);
 145                 err = -EINVAL;
 146         }
 147         pr_info("Remount options were %s for vfsmnt %p.\n", options, mnt);
 148         err = parse_options_remount(sb, options, *flags & ~MS_SILENT, mnt->data);
 149
 150
 151         return err;
 152 }
 153
 154 static void *sdcardfs_clone_mnt_data(void *data)
 155 {
 156         struct sdcardfs_vfsmount_options *opt = kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
 157         struct sdcardfs_vfsmount_options *old = data;
 158
 159         if (!opt)
 160                 return NULL;
 161         opt->gid = old->gid;
 162         opt->mask = old->mask;
 163         return opt;
 164 }
 165
 166 static void sdcardfs_copy_mnt_data(void *data, void *newdata)
 167 {
 168         struct sdcardfs_vfsmount_options *old = data;
 169         struct sdcardfs_vfsmount_options *new = newdata;
 170
 171         old->gid = new->gid;
 172         old->mask = new->mask;
 173 }
 174
 175 /*
 176  * Called by iput() when the inode reference count reached zero
 177  * and the inode is not hashed anywhere.  Used to clear anything
 178  * that needs to be, before the inode is completely destroyed and put
 179  * on the inode free list.
 180  */
 181 static void sdcardfs_evict_inode(struct inode *inode)
 182 {
 183         struct inode *lower_inode;
 184
 185         truncate_inode_pages_final(&inode->i_data);
 186         set_top(SDCARDFS_I(inode), NULL);
 187         clear_inode(inode);
 188         /*
 189          * Decrement a reference to a lower_inode, which was incremented
 190          * by our read_inode when it was created initially.
 191          */
 192         lower_inode = sdcardfs_lower_inode(inode);
 193         sdcardfs_set_lower_inode(inode, NULL);
 194         iput(lower_inode);
 195 }
 196
 197 static struct inode *sdcardfs_alloc_inode(struct super_block *sb)
 198 {
 199         struct sdcardfs_inode_info *i;
 200         struct sdcardfs_inode_data *d;
 201
 202         i = kmem_cache_alloc(sdcardfs_inode_cachep, GFP_KERNEL);
 203         if (!i)
 204                 return NULL;
 205
 206         /* memset everything up to the inode to 0 */
 207         memset(i, 0, offsetof(struct sdcardfs_inode_info, vfs_inode));
 208
 209         d = kmem_cache_alloc(sdcardfs_inode_data_cachep,
 210                                         GFP_KERNEL | __GFP_ZERO);
 211         if (!d) {
 212                 kmem_cache_free(sdcardfs_inode_cachep, i);
 213                 return NULL;
 214         }
 215
 216         i->data = d;
 217         kref_init(&d->refcount);
 218
 219         i->vfs_inode.i_version = 1;
 220         return &i->vfs_inode;
 221 }
 222
 223 static void i_callback(struct rcu_head *head)
 224 {
 225         struct inode *inode = container_of(head, struct inode, i_rcu);
 226
 227         release_own_data(SDCARDFS_I(inode));
 228         kmem_cache_free(sdcardfs_inode_cachep, SDCARDFS_I(inode));
 229 }
 230
 231 static void sdcardfs_destroy_inode(struct inode *inode)
 232 {
 233         call_rcu(&inode->i_rcu, i_callback);
 234 }
 235
 236 /* sdcardfs inode cache constructor */
 237 static void init_once(void *obj)
 238 {
 239         struct sdcardfs_inode_info *i = obj;
 240
 241         inode_init_once(&i->vfs_inode);
 242 }
 243
 244 int sdcardfs_init_inode_cache(void)
 245 {
 246         sdcardfs_inode_cachep =
 247                 kmem_cache_create("sdcardfs_inode_cache",
 248                                   sizeof(struct sdcardfs_inode_info), 0,
 249                                   SLAB_RECLAIM_ACCOUNT, init_once);
 250
 251         if (!sdcardfs_inode_cachep)
 252                 return -ENOMEM;
 253
 254         sdcardfs_inode_data_cachep =
 255                 kmem_cache_create("sdcardfs_inode_data_cache",
 256                                   sizeof(struct sdcardfs_inode_data), 0,
 257                                   SLAB_RECLAIM_ACCOUNT, NULL);
 258         if (!sdcardfs_inode_data_cachep) {
 259                 kmem_cache_destroy(sdcardfs_inode_cachep);
 260                 return -ENOMEM;
 261         }
 262
 263         return 0;
 264 }
 265
 266 /* sdcardfs inode cache destructor */
 267 void sdcardfs_destroy_inode_cache(void)
 268 {
 269         kmem_cache_destroy(sdcardfs_inode_data_cachep);
 270         kmem_cache_destroy(sdcardfs_inode_cachep);
 271 }
 272
 273 /*
 274  * Used only in nfs, to kill any pending RPC tasks, so that subsequent
 275  * code can actually succeed and won't leave tasks that need handling.
 276  */
 277 static void sdcardfs_umount_begin(struct super_block *sb)
 278 {
 279         struct super_block *lower_sb;
 280
 281         lower_sb = sdcardfs_lower_super(sb);
 282         if (lower_sb && lower_sb->s_op && lower_sb->s_op->umount_begin)
 283                 lower_sb->s_op->umount_begin(lower_sb);
 284 }
 285
 286 static int sdcardfs_show_options(struct vfsmount *mnt, struct seq_file *m,
 287                         struct dentry *root)
 288 {
 289         struct sdcardfs_sb_info *sbi = SDCARDFS_SB(root->d_sb);
 290         struct sdcardfs_mount_options *opts = &sbi->options;
 291         struct sdcardfs_vfsmount_options *vfsopts = mnt->data;
 292
 293         if (opts->fs_low_uid != 0)
 294                 seq_printf(m, ",fsuid=%u", opts->fs_low_uid);
 295         if (opts->fs_low_gid != 0)
 296                 seq_printf(m, ",fsgid=%u", opts->fs_low_gid);
 297         if (vfsopts->gid != 0)
 298                 seq_printf(m, ",gid=%u", vfsopts->gid);
 299         if (opts->multiuser)
 300                 seq_puts(m, ",multiuser");
 301         if (vfsopts->mask)
 302                 seq_printf(m, ",mask=%u", vfsopts->mask);
 303         if (opts->fs_user_id)
 304                 seq_printf(m, ",userid=%u", opts->fs_user_id);
 305         if (opts->gid_derivation)
 306                 seq_puts(m, ",derive_gid");
 307         if (vfsopts->default_normal)
 308                 seq_puts(m, ",default_normal");
 309         if (opts->reserved_mb != 0)
 310                 seq_printf(m, ",reserved=%uMB", opts->reserved_mb);
 311
 312         return 0;
 313 };
 314
 315 const struct super_operations sdcardfs_sops = {
 316         .put_super      = sdcardfs_put_super,
 317         .statfs         = sdcardfs_statfs,
 318         .remount_fs     = sdcardfs_remount_fs,
 319         .remount_fs2    = sdcardfs_remount_fs2,
 320         .clone_mnt_data = sdcardfs_clone_mnt_data,
 321         .copy_mnt_data  = sdcardfs_copy_mnt_data,
 322         .evict_inode    = sdcardfs_evict_inode,
 323         .umount_begin   = sdcardfs_umount_begin,
 324         .show_options2  = sdcardfs_show_options,
 325         .alloc_inode    = sdcardfs_alloc_inode,
 326         .destroy_inode  = sdcardfs_destroy_inode,
 327         .drop_inode     = generic_delete_inode,
 328 };