linux/fs/statfs.c
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   1#include <linux/syscalls.h>
   2#include <linux/module.h>
   3#include <linux/fs.h>
   4#include <linux/file.h>
   5#include <linux/mount.h>
   6#include <linux/namei.h>
   7#include <linux/statfs.h>
   8#include <linux/security.h>
   9#include <linux/uaccess.h>
  10
  11static int flags_by_mnt(int mnt_flags)
  12{
  13        int flags = 0;
  14
  15        if (mnt_flags & MNT_READONLY)
  16                flags |= ST_RDONLY;
  17        if (mnt_flags & MNT_NOSUID)
  18                flags |= ST_NOSUID;
  19        if (mnt_flags & MNT_NODEV)
  20                flags |= ST_NODEV;
  21        if (mnt_flags & MNT_NOEXEC)
  22                flags |= ST_NOEXEC;
  23        if (mnt_flags & MNT_NOATIME)
  24                flags |= ST_NOATIME;
  25        if (mnt_flags & MNT_NODIRATIME)
  26                flags |= ST_NODIRATIME;
  27        if (mnt_flags & MNT_RELATIME)
  28                flags |= ST_RELATIME;
  29        return flags;
  30}
  31
  32static int flags_by_sb(int s_flags)
  33{
  34        int flags = 0;
  35        if (s_flags & MS_SYNCHRONOUS)
  36                flags |= ST_SYNCHRONOUS;
  37        if (s_flags & MS_MANDLOCK)
  38                flags |= ST_MANDLOCK;
  39        return flags;
  40}
  41
  42static int calculate_f_flags(struct vfsmount *mnt)
  43{
  44        return ST_VALID | flags_by_mnt(mnt->mnt_flags) |
  45                flags_by_sb(mnt->mnt_sb->s_flags);
  46}
  47
  48int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf)
  49{
  50        int retval;
  51
  52        if (!dentry->d_sb->s_op->statfs)
  53                return -ENOSYS;
  54
  55        memset(buf, 0, sizeof(*buf));
  56        retval = security_sb_statfs(dentry);
  57        if (retval)
  58                return retval;
  59        retval = dentry->d_sb->s_op->statfs(dentry, buf);
  60        if (retval == 0 && buf->f_frsize == 0)
  61                buf->f_frsize = buf->f_bsize;
  62        return retval;
  63}
  64
  65int vfs_statfs(struct path *path, struct kstatfs *buf)
  66{
  67        int error;
  68
  69        error = statfs_by_dentry(path->dentry, buf);
  70        if (!error)
  71                buf->f_flags = calculate_f_flags(path->mnt);
  72        return error;
  73}
  74EXPORT_SYMBOL(vfs_statfs);
  75
  76int user_statfs(const char __user *pathname, struct kstatfs *st)
  77{
  78        struct path path;
  79        int error = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
  80        if (!error) {
  81                error = vfs_statfs(&path, st);
  82                path_put(&path);
  83        }
  84        return error;
  85}
  86
  87int fd_statfs(int fd, struct kstatfs *st)
  88{
  89        struct file *file = fget(fd);
  90        int error = -EBADF;
  91        if (file) {
  92                error = vfs_statfs(&file->f_path, st);
  93                fput(file);
  94        }
  95        return error;
  96}
  97
  98static int do_statfs_native(struct kstatfs *st, struct statfs __user *p)
  99{
 100        struct statfs buf;
 101
 102        if (sizeof(buf) == sizeof(*st))
 103                memcpy(&buf, st, sizeof(*st));
 104        else {
 105                if (sizeof buf.f_blocks == 4) {
 106                        if ((st->f_blocks | st->f_bfree | st->f_bavail |
 107                             st->f_bsize | st->f_frsize) &
 108                            0xffffffff00000000ULL)
 109                                return -EOVERFLOW;
 110                        /*
 111                         * f_files and f_ffree may be -1; it's okay to stuff
 112                         * that into 32 bits
 113                         */
 114                        if (st->f_files != -1 &&
 115                            (st->f_files & 0xffffffff00000000ULL))
 116                                return -EOVERFLOW;
 117                        if (st->f_ffree != -1 &&
 118                            (st->f_ffree & 0xffffffff00000000ULL))
 119                                return -EOVERFLOW;
 120                }
 121
 122                buf.f_type = st->f_type;
 123                buf.f_bsize = st->f_bsize;
 124                buf.f_blocks = st->f_blocks;
 125                buf.f_bfree = st->f_bfree;
 126                buf.f_bavail = st->f_bavail;
 127                buf.f_files = st->f_files;
 128                buf.f_ffree = st->f_ffree;
 129                buf.f_fsid = st->f_fsid;
 130                buf.f_namelen = st->f_namelen;
 131                buf.f_frsize = st->f_frsize;
 132                buf.f_flags = st->f_flags;
 133                memset(buf.f_spare, 0, sizeof(buf.f_spare));
 134        }
 135        if (copy_to_user(p, &buf, sizeof(buf)))
 136                return -EFAULT;
 137        return 0;
 138}
 139
 140static int do_statfs64(struct kstatfs *st, struct statfs64 __user *p)
 141{
 142        struct statfs64 buf;
 143        if (sizeof(buf) == sizeof(*st))
 144                memcpy(&buf, st, sizeof(*st));
 145        else {
 146                buf.f_type = st->f_type;
 147                buf.f_bsize = st->f_bsize;
 148                buf.f_blocks = st->f_blocks;
 149                buf.f_bfree = st->f_bfree;
 150                buf.f_bavail = st->f_bavail;
 151                buf.f_files = st->f_files;
 152                buf.f_ffree = st->f_ffree;
 153                buf.f_fsid = st->f_fsid;
 154                buf.f_namelen = st->f_namelen;
 155                buf.f_frsize = st->f_frsize;
 156                buf.f_flags = st->f_flags;
 157                memset(buf.f_spare, 0, sizeof(buf.f_spare));
 158        }
 159        if (copy_to_user(p, &buf, sizeof(buf)))
 160                return -EFAULT;
 161        return 0;
 162}
 163
 164SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
 165{
 166        struct kstatfs st;
 167        int error = user_statfs(pathname, &st);
 168        if (!error)
 169                error = do_statfs_native(&st, buf);
 170        return error;
 171}
 172
 173SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
 174{
 175        struct kstatfs st;
 176        int error;
 177        if (sz != sizeof(*buf))
 178                return -EINVAL;
 179        error = user_statfs(pathname, &st);
 180        if (!error)
 181                error = do_statfs64(&st, buf);
 182        return error;
 183}
 184
 185SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
 186{
 187        struct kstatfs st;
 188        int error = fd_statfs(fd, &st);
 189        if (!error)
 190                error = do_statfs_native(&st, buf);
 191        return error;
 192}
 193
 194SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
 195{
 196        struct kstatfs st;
 197        int error;
 198
 199        if (sz != sizeof(*buf))
 200                return -EINVAL;
 201
 202        error = fd_statfs(fd, &st);
 203        if (!error)
 204                error = do_statfs64(&st, buf);
 205        return error;
 206}
 207
 208SYSCALL_DEFINE2(ustat, unsigned, dev, struct ustat __user *, ubuf)
 209{
 210        struct super_block *s;
 211        struct ustat tmp;
 212        struct kstatfs sbuf;
 213        int err;
 214
 215        s = user_get_super(new_decode_dev(dev));
 216        if (!s)
 217                return -EINVAL;
 218
 219        err = statfs_by_dentry(s->s_root, &sbuf);
 220        drop_super(s);
 221        if (err)
 222                return err;
 223
 224        memset(&tmp,0,sizeof(struct ustat));
 225        tmp.f_tfree = sbuf.f_bfree;
 226        tmp.f_tinode = sbuf.f_ffree;
 227
 228        return copy_to_user(ubuf, &tmp, sizeof(struct ustat)) ? -EFAULT : 0;
 229}
 230
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