/* final actions when unmounting a file system */
static void wrapfs_put_super(struct super_block *sb)
{
struct wrapfs_sb_info *spd;
struct super_block *s;
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG;
#endif
spd = WRAPFS_SB(sb);
if (!spd)
return;
/* decrement lower super references */
s = wrapfs_lower_super(sb);
wrapfs_set_lower_super(sb, NULL);
atomic_dec(&s->s_active);
kfree(spd);
sb->s_fs_info = NULL;
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG_EXIT(0);
#endif
}
/* final actions when unmounting a file system */
static void wrapfs_put_super(struct super_block *sb)
{
struct wrapfs_sb_info *spd;
struct super_block *s;
spd = WRAPFS_SB(sb);
if (!spd)
return;
/* decrement lower super references */
s = wrapfs_lower_super(sb);
wrapfs_set_lower_super(sb, NULL);
atomic_dec(&s->s_active);
kfree(spd);
sb->s_fs_info = NULL;
}
/*
* There is no need to lock the wrapfs_super_info's rwsem as there is no
* way anyone can have a reference to the superblock at this point in time.
*/
static int wrapfs_read_super(struct super_block *sb, void *raw_data, int silent)
{
int err = 0;
struct super_block *lower_sb;
struct path lower_path;
char *dev_name = (char *) raw_data;
struct inode *inode;
if (!dev_name) {
printk(KERN_ERR
"wrapfs: read_super: missing dev_name argument\n");
err = -EINVAL;
goto out;
}
/* parse lower path */
err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
&lower_path);
if (err) {
printk(KERN_ERR "wrapfs: error accessing "
"lower directory '%s'\n", dev_name);
goto out;
}
/* allocate superblock private data */
sb->s_fs_info = kzalloc(sizeof(struct wrapfs_sb_info), GFP_KERNEL);
if (!WRAPFS_SB(sb)) {
printk(KERN_CRIT "wrapfs: read_super: out of memory\n");
err = -ENOMEM;
goto out_free;
}
/* set the lower superblock field of upper superblock */
lower_sb = lower_path.dentry->d_sb;
atomic_inc(&lower_sb->s_active);
wrapfs_set_lower_super(sb, lower_sb);
/* inherit maxbytes from lower file system */
sb->s_maxbytes = lower_sb->s_maxbytes;
/*
* Our c/m/atime granularity is 1 ns because we may stack on file
* systems whose granularity is as good.
*/
sb->s_time_gran = 1;
sb->s_op = &wrapfs_sops;
/* get a new inode and allocate our root dentry */
inode = wrapfs_iget(sb, lower_path.dentry->d_inode);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_sput;
}
sb->s_root = d_alloc_root(inode);
if (!sb->s_root) {
err = -ENOMEM;
goto out_iput;
}
d_set_d_op(sb->s_root, &wrapfs_dops);
/* link the upper and lower dentries */
sb->s_root->d_fsdata = NULL;
err = new_dentry_private_data(sb->s_root);
if (err)
goto out_freeroot;
/* if get here: cannot have error */
/* set the lower dentries for s_root */
wrapfs_set_lower_path(sb->s_root, &lower_path);
/*
* No need to call interpose because we already have a positive
* dentry, which was instantiated by d_alloc_root. Just need to
* d_rehash it.
*/
d_rehash(sb->s_root);
if (!silent)
printk(KERN_INFO
"wrapfs: mounted on top of %s type %s\n",
dev_name, lower_sb->s_type->name);
goto out; /* all is well */
/* no longer needed: free_dentry_private_data(sb->s_root); */
out_freeroot:
dput(sb->s_root);
out_iput:
iput(inode);
out_sput:
/* drop refs we took earlier */
atomic_dec(&lower_sb->s_active);
kfree(WRAPFS_SB(sb));
sb->s_fs_info = NULL;
out_free:
path_put(&lower_path);
out:
return err;
}
