}
EXPORT_SYMBOL(get_super);
+
+/**
+ * get_active_super - get an active reference to the superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device given. Returns the superblock with an active
+ * reference and s_umount held exclusively or %NULL if none was found.
+ */
+struct super_block *get_active_super(struct block_device *bdev)
+{
+ struct super_block *sb;
+
+ if (!bdev)
+ return NULL;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (sb->s_bdev != bdev)
+ continue;
+
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_write(&sb->s_umount);
+ if (sb->s_root) {
+ spin_lock(&sb_lock);
+ if (sb->s_count > S_BIAS) {
+ atomic_inc(&sb->s_active);
+ sb->s_count--;
+ spin_unlock(&sb_lock);
+ return sb;
+ }
+ spin_unlock(&sb_lock);
+ }
+ up_write(&sb->s_umount);
+ put_super(sb);
+ yield();
+ spin_lock(&sb_lock);
+ }
+ spin_unlock(&sb_lock);
+ return NULL;
+}
struct super_block * user_get_super(dev_t dev)
{
int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
{
int retval;
- int remount_rw;
-
+ int remount_rw, remount_ro;
+
+ if (sb->s_frozen != SB_UNFROZEN)
+ return -EBUSY;
+
#ifdef CONFIG_BLOCK
if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
return -EACCES;
#endif
+
if (flags & MS_RDONLY)
acct_auto_close(sb);
shrink_dcache_sb(sb);
sync_filesystem(sb);
+ remount_ro = (flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY);
+ remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
+
/* If we are remounting RDONLY and current sb is read/write,
make sure there are no rw files opened */
- if ((flags & MS_RDONLY) && !(sb->s_flags & MS_RDONLY)) {
+ if (remount_ro) {
if (force)
mark_files_ro(sb);
else if (!fs_may_remount_ro(sb))
if (retval < 0 && retval != -ENOSYS)
return -EBUSY;
}
- remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
if (sb->s_op->remount_fs) {
retval = sb->s_op->remount_fs(sb, &flags, data);
sb->s_flags = (sb->s_flags & ~MS_RMT_MASK) | (flags & MS_RMT_MASK);
if (remount_rw)
vfs_dq_quota_on_remount(sb);
+ /*
+ * Some filesystems modify their metadata via some other path than the
+ * bdev buffer cache (eg. use a private mapping, or directories in
+ * pagecache, etc). Also file data modifications go via their own
+ * mappings. So If we try to mount readonly then copy the filesystem
+ * from bdev, we could get stale data, so invalidate it to give a best
+ * effort at coherency.
+ */
+ if (remount_ro && sb->s_bdev)
+ invalidate_bdev(sb->s_bdev);
return 0;
}
return error;
}
s->s_flags |= MS_ACTIVE;
+ } else {
+ do_remount_sb(s, flags, data, 0);
}
- do_remount_sb(s, flags, data, 0);
simple_set_mnt(mnt, s);
return 0;
}
if (!mnt)
goto out;
+ if (flags & MS_KERNMOUNT)
+ mnt->mnt_flags = MNT_INTERNAL;
+
if (data && !(type->fs_flags & FS_BINARY_MOUNTDATA)) {
secdata = alloc_secdata();
if (!secdata)