int au_digen_test(struct dentry *dentry, unsigned int sigen)
{
int err;
err = 0;
if (unlikely(au_digen(dentry) != sigen
|| au_iigen_test(dentry->d_inode, sigen)))
err = -EIO;
return err;
}
static int aufs_permission(struct inode *inode, int mask)
{
int err;
aufs_bindex_t bindex, bend;
const unsigned char isdir = !!S_ISDIR(inode->i_mode),
write_mask = !!(mask & (MAY_WRITE | MAY_APPEND));
struct inode *h_inode;
struct super_block *sb;
struct au_branch *br;
/* todo: support rcu-walk? */
if (mask & MAY_NOT_BLOCK)
return -ECHILD;
sb = inode->i_sb;
si_read_lock(sb, AuLock_FLUSH);
ii_read_lock_child(inode);
#if 0
err = au_iigen_test(inode, au_sigen(sb));
if (unlikely(err))
goto out;
#endif
if (!isdir || write_mask) {
err = au_busy_or_stale();
h_inode = au_h_iptr(inode, au_ibstart(inode));
if (unlikely(!h_inode
|| (h_inode->i_mode & S_IFMT)
!= (inode->i_mode & S_IFMT)))
goto out;
err = 0;
bindex = au_ibstart(inode);
br = au_sbr(sb, bindex);
err = h_permission(h_inode, mask, br->br_mnt, br->br_perm);
if (write_mask
&& !err
&& !special_file(h_inode->i_mode)) {
/* test whether the upper writable branch exists */
err = -EROFS;
for (; bindex >= 0; bindex--)
if (!au_br_rdonly(au_sbr(sb, bindex))) {
err = 0;
break;
}
}
goto out;
}
/* non-write to dir */
err = 0;
bend = au_ibend(inode);
for (bindex = au_ibstart(inode); !err && bindex <= bend; bindex++) {
h_inode = au_h_iptr(inode, bindex);
if (h_inode) {
err = au_busy_or_stale();
if (unlikely(!S_ISDIR(h_inode->i_mode)))
break;
br = au_sbr(sb, bindex);
err = h_permission(h_inode, mask, br->br_mnt,
br->br_perm);
}
}
out:
ii_read_unlock(inode);
si_read_unlock(sb);
return err;
}
