Initial import

1 files changed, 1105 insertions, 0 deletions

diff --git a/fs/aufs/dentry.c b/fs/aufs/dentry.c
new file mode 100644
index 000000000..1191a6c93
--- /dev/null
+++ b/fs/aufs/dentry.c
@@ -0,0 +1,1105 @@
+/*
+ * Copyright (C) 2005-2015 Junjiro R. Okajima
+ *
+ * This program, aufs is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * lookup and dentry operations
+ */
+
+#include <linux/namei.h>
+#include "aufs.h"
+
+#define AuLkup_ALLOW_NEG	1
+#define AuLkup_IGNORE_PERM	(1 << 1)
+#define au_ftest_lkup(flags, name)	((flags) & AuLkup_##name)
+#define au_fset_lkup(flags, name) \
+	do { (flags) |= AuLkup_##name; } while (0)
+#define au_fclr_lkup(flags, name) \
+	do { (flags) &= ~AuLkup_##name; } while (0)
+
+struct au_do_lookup_args {
+	unsigned int		flags;
+	mode_t			type;
+};
+
+/*
+ * returns positive/negative dentry, NULL or an error.
+ * NULL means whiteout-ed or not-found.
+ */
+static struct dentry*
+au_do_lookup(struct dentry *h_parent, struct dentry *dentry,
+	     aufs_bindex_t bindex, struct qstr *wh_name,
+	     struct au_do_lookup_args *args)
+{
+	struct dentry *h_dentry;
+	struct inode *h_inode;
+	struct au_branch *br;
+	int wh_found, opq;
+	unsigned char wh_able;
+	const unsigned char allow_neg = !!au_ftest_lkup(args->flags, ALLOW_NEG);
+	const unsigned char ignore_perm = !!au_ftest_lkup(args->flags,
+							  IGNORE_PERM);
+
+	wh_found = 0;
+	br = au_sbr(dentry->d_sb, bindex);
+	wh_able = !!au_br_whable(br->br_perm);
+	if (wh_able)
+		wh_found = au_wh_test(h_parent, wh_name, /*try_sio*/0);
+	h_dentry = ERR_PTR(wh_found);
+	if (!wh_found)
+		goto real_lookup;
+	if (unlikely(wh_found < 0))
+		goto out;
+
+	/* We found a whiteout */
+	/* au_set_dbend(dentry, bindex); */
+	au_set_dbwh(dentry, bindex);
+	if (!allow_neg)
+		return NULL; /* success */
+
+real_lookup:
+	if (!ignore_perm)
+		h_dentry = vfsub_lkup_one(&dentry->d_name, h_parent);
+	else
+		h_dentry = au_sio_lkup_one(&dentry->d_name, h_parent);
+	if (IS_ERR(h_dentry)) {
+		if (PTR_ERR(h_dentry) == -ENAMETOOLONG
+		    && !allow_neg)
+			h_dentry = NULL;
+		goto out;
+	}
+
+	h_inode = d_inode(h_dentry);
+	if (d_is_negative(h_dentry)) {
+		if (!allow_neg)
+			goto out_neg;
+	} else if (wh_found
+		   || (args->type && args->type != (h_inode->i_mode & S_IFMT)))
+		goto out_neg;
+
+	if (au_dbend(dentry) <= bindex)
+		au_set_dbend(dentry, bindex);
+	if (au_dbstart(dentry) < 0 || bindex < au_dbstart(dentry))
+		au_set_dbstart(dentry, bindex);
+	au_set_h_dptr(dentry, bindex, h_dentry);
+
+	if (!d_is_dir(h_dentry)
+	    || !wh_able
+	    || (d_really_is_positive(dentry) && !d_is_dir(dentry)))
+		goto out; /* success */
+
+	mutex_lock_nested(&h_inode->i_mutex, AuLsc_I_CHILD);
+	opq = au_diropq_test(h_dentry);
+	mutex_unlock(&h_inode->i_mutex);
+	if (opq > 0)
+		au_set_dbdiropq(dentry, bindex);
+	else if (unlikely(opq < 0)) {
+		au_set_h_dptr(dentry, bindex, NULL);
+		h_dentry = ERR_PTR(opq);
+	}
+	goto out;
+
+out_neg:
+	dput(h_dentry);
+	h_dentry = NULL;
+out:
+	return h_dentry;
+}
+
+static int au_test_shwh(struct super_block *sb, const struct qstr *name)
+{
+	if (unlikely(!au_opt_test(au_mntflags(sb), SHWH)
+		     && !strncmp(name->name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)))
+		return -EPERM;
+	return 0;
+}
+
+/*
+ * returns the number of lower positive dentries,
+ * otherwise an error.
+ * can be called at unlinking with @type is zero.
+ */
+int au_lkup_dentry(struct dentry *dentry, aufs_bindex_t bstart, mode_t type)
+{
+	int npositive, err;
+	aufs_bindex_t bindex, btail, bdiropq;
+	unsigned char isdir, dirperm1;
+	struct qstr whname;
+	struct au_do_lookup_args args = {
+		.flags		= 0,
+		.type		= type
+	};
+	const struct qstr *name = &dentry->d_name;
+	struct dentry *parent;
+	struct super_block *sb;
+
+	sb = dentry->d_sb;
+	err = au_test_shwh(sb, name);
+	if (unlikely(err))
+		goto out;
+
+	err = au_wh_name_alloc(&whname, name);
+	if (unlikely(err))
+		goto out;
+
+	isdir = !!d_is_dir(dentry);
+	if (!type)
+		au_fset_lkup(args.flags, ALLOW_NEG);
+	dirperm1 = !!au_opt_test(au_mntflags(sb), DIRPERM1);
+
+	npositive = 0;
+	parent = dget_parent(dentry);
+	btail = au_dbtaildir(parent);
+	for (bindex = bstart; bindex <= btail; bindex++) {
+		struct dentry *h_parent, *h_dentry;
+		struct inode *h_inode, *h_dir;
+
+		h_dentry = au_h_dptr(dentry, bindex);
+		if (h_dentry) {
+			if (d_is_positive(h_dentry))
+				npositive++;
+			if (type != S_IFDIR)
+				break;
+			continue;
+		}
+		h_parent = au_h_dptr(parent, bindex);
+		if (!h_parent || !d_is_dir(h_parent))
+			continue;
+
+		h_dir = d_inode(h_parent);
+		mutex_lock_nested(&h_dir->i_mutex, AuLsc_I_PARENT);
+		h_dentry = au_do_lookup(h_parent, dentry, bindex, &whname,
+					&args);
+		mutex_unlock(&h_dir->i_mutex);
+		err = PTR_ERR(h_dentry);
+		if (IS_ERR(h_dentry))
+			goto out_parent;
+		if (h_dentry)
+			au_fclr_lkup(args.flags, ALLOW_NEG);
+		if (dirperm1)
+			au_fset_lkup(args.flags, IGNORE_PERM);
+
+		if (au_dbwh(dentry) >= 0)
+			break;
+		if (!h_dentry)
+			continue;
+		if (d_is_negative(h_dentry))
+			continue;
+		h_inode = d_inode(h_dentry);
+		npositive++;
+		if (!args.type)
+			args.type = h_inode->i_mode & S_IFMT;
+		if (args.type != S_IFDIR)
+			break;
+		else if (isdir) {
+			/* the type of lower may be different */
+			bdiropq = au_dbdiropq(dentry);
+			if (bdiropq >= 0 && bdiropq <= bindex)
+				break;
+		}
+	}
+
+	if (npositive) {
+		AuLabel(positive);
+		au_update_dbstart(dentry);
+	}
+	err = npositive;
+	if (unlikely(!au_opt_test(au_mntflags(sb), UDBA_NONE)
+		     && au_dbstart(dentry) < 0)) {
+		err = -EIO;
+		AuIOErr("both of real entry and whiteout found, %pd, err %d\n",
+			dentry, err);
+	}
+
+out_parent:
+	dput(parent);
+	kfree(whname.name);
+out:
+	return err;
+}
+
+struct dentry *au_sio_lkup_one(struct qstr *name, struct dentry *parent)
+{
+	struct dentry *dentry;
+	int wkq_err;
+
+	if (!au_test_h_perm_sio(d_inode(parent), MAY_EXEC))
+		dentry = vfsub_lkup_one(name, parent);
+	else {
+		struct vfsub_lkup_one_args args = {
+			.errp	= &dentry,
+			.name	= name,
+			.parent	= parent
+		};
+
+		wkq_err = au_wkq_wait(vfsub_call_lkup_one, &args);
+		if (unlikely(wkq_err))
+			dentry = ERR_PTR(wkq_err);
+	}
+
+	return dentry;
+}
+
+/*
+ * lookup @dentry on @bindex which should be negative.
+ */
+int au_lkup_neg(struct dentry *dentry, aufs_bindex_t bindex, int wh)
+{
+	int err;
+	struct dentry *parent, *h_parent, *h_dentry;
+	struct au_branch *br;
+
+	parent = dget_parent(dentry);
+	h_parent = au_h_dptr(parent, bindex);
+	br = au_sbr(dentry->d_sb, bindex);
+	if (wh)
+		h_dentry = au_whtmp_lkup(h_parent, br, &dentry->d_name);
+	else
+		h_dentry = au_sio_lkup_one(&dentry->d_name, h_parent);
+	err = PTR_ERR(h_dentry);
+	if (IS_ERR(h_dentry))
+		goto out;
+	if (unlikely(d_is_positive(h_dentry))) {
+		err = -EIO;
+		AuIOErr("%pd should be negative on b%d.\n", h_dentry, bindex);
+		dput(h_dentry);
+		goto out;
+	}
+
+	err = 0;
+	if (bindex < au_dbstart(dentry))
+		au_set_dbstart(dentry, bindex);
+	if (au_dbend(dentry) < bindex)
+		au_set_dbend(dentry, bindex);
+	au_set_h_dptr(dentry, bindex, h_dentry);
+
+out:
+	dput(parent);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* subset of struct inode */
+struct au_iattr {
+	unsigned long		i_ino;
+	/* unsigned int		i_nlink; */
+	kuid_t			i_uid;
+	kgid_t			i_gid;
+	u64			i_version;
+/*
+	loff_t			i_size;
+	blkcnt_t		i_blocks;
+*/
+	umode_t			i_mode;
+};
+
+static void au_iattr_save(struct au_iattr *ia, struct inode *h_inode)
+{
+	ia->i_ino = h_inode->i_ino;
+	/* ia->i_nlink = h_inode->i_nlink; */
+	ia->i_uid = h_inode->i_uid;
+	ia->i_gid = h_inode->i_gid;
+	ia->i_version = h_inode->i_version;
+/*
+	ia->i_size = h_inode->i_size;
+	ia->i_blocks = h_inode->i_blocks;
+*/
+	ia->i_mode = (h_inode->i_mode & S_IFMT);
+}
+
+static int au_iattr_test(struct au_iattr *ia, struct inode *h_inode)
+{
+	return ia->i_ino != h_inode->i_ino
+		/* || ia->i_nlink != h_inode->i_nlink */
+		|| !uid_eq(ia->i_uid, h_inode->i_uid)
+		|| !gid_eq(ia->i_gid, h_inode->i_gid)
+		|| ia->i_version != h_inode->i_version
+/*
+		|| ia->i_size != h_inode->i_size
+		|| ia->i_blocks != h_inode->i_blocks
+*/
+		|| ia->i_mode != (h_inode->i_mode & S_IFMT);
+}
+
+static int au_h_verify_dentry(struct dentry *h_dentry, struct dentry *h_parent,
+			      struct au_branch *br)
+{
+	int err;
+	struct au_iattr ia;
+	struct inode *h_inode;
+	struct dentry *h_d;
+	struct super_block *h_sb;
+
+	err = 0;
+	memset(&ia, -1, sizeof(ia));
+	h_sb = h_dentry->d_sb;
+	h_inode = NULL;
+	if (d_is_positive(h_dentry)) {
+		h_inode = d_inode(h_dentry);
+		au_iattr_save(&ia, h_inode);
+	} else if (au_test_nfs(h_sb) || au_test_fuse(h_sb))
+		/* nfs d_revalidate may return 0 for negative dentry */
+		/* fuse d_revalidate always return 0 for negative dentry */
+		goto out;
+
+	/* main purpose is namei.c:cached_lookup() and d_revalidate */
+	h_d = vfsub_lkup_one(&h_dentry->d_name, h_parent);
+	err = PTR_ERR(h_d);
+	if (IS_ERR(h_d))
+		goto out;
+
+	err = 0;
+	if (unlikely(h_d != h_dentry
+		     || d_inode(h_d) != h_inode
+		     || (h_inode && au_iattr_test(&ia, h_inode))))
+		err = au_busy_or_stale();
+	dput(h_d);
+
+out:
+	AuTraceErr(err);
+	return err;
+}
+
+int au_h_verify(struct dentry *h_dentry, unsigned int udba, struct inode *h_dir,
+		struct dentry *h_parent, struct au_branch *br)
+{
+	int err;
+
+	err = 0;
+	if (udba == AuOpt_UDBA_REVAL
+	    && !au_test_fs_remote(h_dentry->d_sb)) {
+		IMustLock(h_dir);
+		err = (d_inode(h_dentry->d_parent) != h_dir);
+	} else if (udba != AuOpt_UDBA_NONE)
+		err = au_h_verify_dentry(h_dentry, h_parent, br);
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int au_do_refresh_hdentry(struct dentry *dentry, struct dentry *parent)
+{
+	int err;
+	aufs_bindex_t new_bindex, bindex, bend, bwh, bdiropq;
+	struct au_hdentry tmp, *p, *q;
+	struct au_dinfo *dinfo;
+	struct super_block *sb;
+
+	DiMustWriteLock(dentry);
+
+	sb = dentry->d_sb;
+	dinfo = au_di(dentry);
+	bend = dinfo->di_bend;
+	bwh = dinfo->di_bwh;
+	bdiropq = dinfo->di_bdiropq;
+	p = dinfo->di_hdentry + dinfo->di_bstart;
+	for (bindex = dinfo->di_bstart; bindex <= bend; bindex++, p++) {
+		if (!p->hd_dentry)
+			continue;
+
+		new_bindex = au_br_index(sb, p->hd_id);
+		if (new_bindex == bindex)
+			continue;
+
+		if (dinfo->di_bwh == bindex)
+			bwh = new_bindex;
+		if (dinfo->di_bdiropq == bindex)
+			bdiropq = new_bindex;
+		if (new_bindex < 0) {
+			au_hdput(p);
+			p->hd_dentry = NULL;
+			continue;
+		}
+
+		/* swap two lower dentries, and loop again */
+		q = dinfo->di_hdentry + new_bindex;
+		tmp = *q;
+		*q = *p;
+		*p = tmp;
+		if (tmp.hd_dentry) {
+			bindex--;
+			p--;
+		}
+	}
+
+	dinfo->di_bwh = -1;
+	if (bwh >= 0 && bwh <= au_sbend(sb) && au_sbr_whable(sb, bwh))
+		dinfo->di_bwh = bwh;
+
+	dinfo->di_bdiropq = -1;
+	if (bdiropq >= 0
+	    && bdiropq <= au_sbend(sb)
+	    && au_sbr_whable(sb, bdiropq))
+		dinfo->di_bdiropq = bdiropq;
+
+	err = -EIO;
+	dinfo->di_bstart = -1;
+	dinfo->di_bend = -1;
+	bend = au_dbend(parent);
+	p = dinfo->di_hdentry;
+	for (bindex = 0; bindex <= bend; bindex++, p++)
+		if (p->hd_dentry) {
+			dinfo->di_bstart = bindex;
+			break;
+		}
+
+	if (dinfo->di_bstart >= 0) {
+		p = dinfo->di_hdentry + bend;
+		for (bindex = bend; bindex >= 0; bindex--, p--)
+			if (p->hd_dentry) {
+				dinfo->di_bend = bindex;
+				err = 0;
+				break;
+			}
+	}
+
+	return err;
+}
+
+static void au_do_hide(struct dentry *dentry)
+{
+	struct inode *inode;
+
+	if (d_really_is_positive(dentry)) {
+		inode = d_inode(dentry);
+		if (!d_is_dir(dentry)) {
+			if (inode->i_nlink && !d_unhashed(dentry))
+				drop_nlink(inode);
+		} else {
+			clear_nlink(inode);
+			/* stop next lookup */
+			inode->i_flags |= S_DEAD;
+		}
+		smp_mb(); /* necessary? */
+	}
+	d_drop(dentry);
+}
+
+static int au_hide_children(struct dentry *parent)
+{
+	int err, i, j, ndentry;
+	struct au_dcsub_pages dpages;
+	struct au_dpage *dpage;
+	struct dentry *dentry;
+
+	err = au_dpages_init(&dpages, GFP_NOFS);
+	if (unlikely(err))
+		goto out;
+	err = au_dcsub_pages(&dpages, parent, NULL, NULL);
+	if (unlikely(err))
+		goto out_dpages;
+
+	/* in reverse order */
+	for (i = dpages.ndpage - 1; i >= 0; i--) {
+		dpage = dpages.dpages + i;
+		ndentry = dpage->ndentry;
+		for (j = ndentry - 1; j >= 0; j--) {
+			dentry = dpage->dentries[j];
+			if (dentry != parent)
+				au_do_hide(dentry);
+		}
+	}
+
+out_dpages:
+	au_dpages_free(&dpages);
+out:
+	return err;
+}
+
+static void au_hide(struct dentry *dentry)
+{
+	int err;
+
+	AuDbgDentry(dentry);
+	if (d_is_dir(dentry)) {
+		/* shrink_dcache_parent(dentry); */
+		err = au_hide_children(dentry);
+		if (unlikely(err))
+			AuIOErr("%pd, failed hiding children, ignored %d\n",
+				dentry, err);
+	}
+	au_do_hide(dentry);
+}
+
+/*
+ * By adding a dirty branch, a cached dentry may be affected in various ways.
+ *
+ * a dirty branch is added
+ * - on the top of layers
+ * - in the middle of layers
+ * - to the bottom of layers
+ *
+ * on the added branch there exists
+ * - a whiteout
+ * - a diropq
+ * - a same named entry
+ *   + exist
+ *     * negative --> positive
+ *     * positive --> positive
+ *	 - type is unchanged
+ *	 - type is changed
+ *   + doesn't exist
+ *     * negative --> negative
+ *     * positive --> negative (rejected by au_br_del() for non-dir case)
+ * - none
+ */
+static int au_refresh_by_dinfo(struct dentry *dentry, struct au_dinfo *dinfo,
+			       struct au_dinfo *tmp)
+{
+	int err;
+	aufs_bindex_t bindex, bend;
+	struct {
+		struct dentry *dentry;
+		struct inode *inode;
+		mode_t mode;
+	} orig_h, tmp_h;
+	struct au_hdentry *hd;
+	struct inode *inode, *h_inode;
+	struct dentry *h_dentry;
+
+	err = 0;
+	AuDebugOn(dinfo->di_bstart < 0);
+	orig_h.mode = 0;
+	orig_h.dentry = dinfo->di_hdentry[dinfo->di_bstart].hd_dentry;
+	orig_h.inode = NULL;
+	if (d_is_positive(orig_h.dentry)) {
+		orig_h.inode = d_inode(orig_h.dentry);
+		orig_h.mode = orig_h.inode->i_mode & S_IFMT;
+	}
+	memset(&tmp_h, 0, sizeof(tmp_h));
+	if (tmp->di_bstart >= 0) {
+		tmp_h.dentry = tmp->di_hdentry[tmp->di_bstart].hd_dentry;
+		tmp_h.inode = NULL;
+		if (d_is_positive(tmp_h.dentry)) {
+			tmp_h.inode = d_inode(tmp_h.dentry);
+			tmp_h.mode = tmp_h.inode->i_mode & S_IFMT;
+		}
+	}
+
+	inode = NULL;
+	if (d_really_is_positive(dentry))
+		inode = d_inode(dentry);
+	if (!orig_h.inode) {
+		AuDbg("nagative originally\n");
+		if (inode) {
+			au_hide(dentry);
+			goto out;
+		}
+		AuDebugOn(inode);
+		AuDebugOn(dinfo->di_bstart != dinfo->di_bend);
+		AuDebugOn(dinfo->di_bdiropq != -1);
+
+		if (!tmp_h.inode) {
+			AuDbg("negative --> negative\n");
+			/* should have only one negative lower */
+			if (tmp->di_bstart >= 0
+			    && tmp->di_bstart < dinfo->di_bstart) {
+				AuDebugOn(tmp->di_bstart != tmp->di_bend);
+				AuDebugOn(dinfo->di_bstart != dinfo->di_bend);
+				au_set_h_dptr(dentry, dinfo->di_bstart, NULL);
+				au_di_cp(dinfo, tmp);
+				hd = tmp->di_hdentry + tmp->di_bstart;
+				au_set_h_dptr(dentry, tmp->di_bstart,
+					      dget(hd->hd_dentry));
+			}
+			au_dbg_verify_dinode(dentry);
+		} else {
+			AuDbg("negative --> positive\n");
+			/*
+			 * similar to the behaviour of creating with bypassing
+			 * aufs.
+			 * unhash it in order to force an error in the
+			 * succeeding create operation.
+			 * we should not set S_DEAD here.
+			 */
+			d_drop(dentry);
+			/* au_di_swap(tmp, dinfo); */
+			au_dbg_verify_dinode(dentry);
+		}
+	} else {
+		AuDbg("positive originally\n");
+		/* inode may be NULL */
+		AuDebugOn(inode && (inode->i_mode & S_IFMT) != orig_h.mode);
+		if (!tmp_h.inode) {
+			AuDbg("positive --> negative\n");
+			/* or bypassing aufs */
+			au_hide(dentry);
+			if (tmp->di_bwh >= 0 && tmp->di_bwh <= dinfo->di_bstart)
+				dinfo->di_bwh = tmp->di_bwh;
+			if (inode)
+				err = au_refresh_hinode_self(inode);
+			au_dbg_verify_dinode(dentry);
+		} else if (orig_h.mode == tmp_h.mode) {
+			AuDbg("positive --> positive, same type\n");
+			if (!S_ISDIR(orig_h.mode)
+			    && dinfo->di_bstart > tmp->di_bstart) {
+				/*
+				 * similar to the behaviour of removing and
+				 * creating.
+				 */
+				au_hide(dentry);
+				if (inode)
+					err = au_refresh_hinode_self(inode);
+				au_dbg_verify_dinode(dentry);
+			} else {
+				/* fill empty slots */
+				if (dinfo->di_bstart > tmp->di_bstart)
+					dinfo->di_bstart = tmp->di_bstart;
+				if (dinfo->di_bend < tmp->di_bend)
+					dinfo->di_bend = tmp->di_bend;
+				dinfo->di_bwh = tmp->di_bwh;
+				dinfo->di_bdiropq = tmp->di_bdiropq;
+				hd = tmp->di_hdentry;
+				bend = dinfo->di_bend;
+				for (bindex = tmp->di_bstart; bindex <= bend;
+				     bindex++) {
+					if (au_h_dptr(dentry, bindex))
+						continue;
+					h_dentry = hd[bindex].hd_dentry;
+					if (!h_dentry)
+						continue;
+					AuDebugOn(d_is_negative(h_dentry));
+					h_inode = d_inode(h_dentry);
+					AuDebugOn(orig_h.mode
+						  != (h_inode->i_mode
+						      & S_IFMT));
+					au_set_h_dptr(dentry, bindex,
+						      dget(h_dentry));
+				}
+				err = au_refresh_hinode(inode, dentry);
+				au_dbg_verify_dinode(dentry);
+			}
+		} else {
+			AuDbg("positive --> positive, different type\n");
+			/* similar to the behaviour of removing and creating */
+			au_hide(dentry);
+			if (inode)
+				err = au_refresh_hinode_self(inode);
+			au_dbg_verify_dinode(dentry);
+		}
+	}
+
+out:
+	return err;
+}
+
+int au_refresh_dentry(struct dentry *dentry, struct dentry *parent)
+{
+	int err, ebrange;
+	unsigned int sigen;
+	struct au_dinfo *dinfo, *tmp;
+	struct super_block *sb;
+	struct inode *inode;
+
+	DiMustWriteLock(dentry);
+	AuDebugOn(IS_ROOT(dentry));
+	AuDebugOn(d_really_is_negative(parent));
+
+	sb = dentry->d_sb;
+	sigen = au_sigen(sb);
+	err = au_digen_test(parent, sigen);
+	if (unlikely(err))
+		goto out;
+
+	dinfo = au_di(dentry);
+	err = au_di_realloc(dinfo, au_sbend(sb) + 1);
+	if (unlikely(err))
+		goto out;
+	ebrange = au_dbrange_test(dentry);
+	if (!ebrange)
+		ebrange = au_do_refresh_hdentry(dentry, parent);
+
+	if (d_unhashed(dentry) || ebrange /* || dinfo->di_tmpfile */) {
+		AuDebugOn(au_dbstart(dentry) < 0 && au_dbend(dentry) >= 0);
+		if (d_really_is_positive(dentry)) {
+			inode = d_inode(dentry);
+			err = au_refresh_hinode_self(inode);
+		}
+		au_dbg_verify_dinode(dentry);
+		if (!err)
+			goto out_dgen; /* success */
+		goto out;
+	}
+
+	/* temporary dinfo */
+	AuDbgDentry(dentry);
+	err = -ENOMEM;
+	tmp = au_di_alloc(sb, AuLsc_DI_TMP);
+	if (unlikely(!tmp))
+		goto out;
+	au_di_swap(tmp, dinfo);
+	/* returns the number of positive dentries */
+	/*
+	 * if current working dir is removed, it returns an error.
+	 * but the dentry is legal.
+	 */
+	err = au_lkup_dentry(dentry, /*bstart*/0, /*type*/0);
+	AuDbgDentry(dentry);
+	au_di_swap(tmp, dinfo);
+	if (err == -ENOENT)
+		err = 0;
+	if (err >= 0) {
+		/* compare/refresh by dinfo */
+		AuDbgDentry(dentry);
+		err = au_refresh_by_dinfo(dentry, dinfo, tmp);
+		au_dbg_verify_dinode(dentry);
+		AuTraceErr(err);
+	}
+	au_rw_write_unlock(&tmp->di_rwsem);
+	au_di_free(tmp);
+	if (unlikely(err))
+		goto out;
+
+out_dgen:
+	au_update_digen(dentry);
+out:
+	if (unlikely(err && !(dentry->d_flags & DCACHE_NFSFS_RENAMED))) {
+		AuIOErr("failed refreshing %pd, %d\n", dentry, err);
+		AuDbgDentry(dentry);
+	}
+	AuTraceErr(err);
+	return err;
+}
+
+static int au_do_h_d_reval(struct dentry *h_dentry, unsigned int flags,
+			   struct dentry *dentry, aufs_bindex_t bindex)
+{
+	int err, valid;
+
+	err = 0;
+	if (!(h_dentry->d_flags & DCACHE_OP_REVALIDATE))
+		goto out;
+
+	AuDbg("b%d\n", bindex);
+	/*
+	 * gave up supporting LOOKUP_CREATE/OPEN for lower fs,
+	 * due to whiteout and branch permission.
+	 */
+	flags &= ~(/*LOOKUP_PARENT |*/ LOOKUP_OPEN | LOOKUP_CREATE
+		   | LOOKUP_FOLLOW | LOOKUP_EXCL);
+	/* it may return tri-state */
+	valid = h_dentry->d_op->d_revalidate(h_dentry, flags);
+
+	if (unlikely(valid < 0))
+		err = valid;
+	else if (!valid)
+		err = -EINVAL;
+
+out:
+	AuTraceErr(err);
+	return err;
+}
+
+/* todo: remove this */
+static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
+			  unsigned int flags, int do_udba)
+{
+	int err;
+	umode_t mode, h_mode;
+	aufs_bindex_t bindex, btail, bstart, ibs, ibe;
+	unsigned char plus, unhashed, is_root, h_plus, h_nfs, tmpfile;
+	struct inode *h_inode, *h_cached_inode;
+	struct dentry *h_dentry;
+	struct qstr *name, *h_name;
+
+	err = 0;
+	plus = 0;
+	mode = 0;
+	ibs = -1;
+	ibe = -1;
+	unhashed = !!d_unhashed(dentry);
+	is_root = !!IS_ROOT(dentry);
+	name = &dentry->d_name;
+	tmpfile = au_di(dentry)->di_tmpfile;
+
+	/*
+	 * Theoretically, REVAL test should be unnecessary in case of
+	 * {FS,I}NOTIFY.
+	 * But {fs,i}notify doesn't fire some necessary events,
+	 *	IN_ATTRIB for atime/nlink/pageio
+	 * Let's do REVAL test too.
+	 */
+	if (do_udba && inode) {
+		mode = (inode->i_mode & S_IFMT);
+		plus = (inode->i_nlink > 0);
+		ibs = au_ibstart(inode);
+		ibe = au_ibend(inode);
+	}
+
+	bstart = au_dbstart(dentry);
+	btail = bstart;
+	if (inode && S_ISDIR(inode->i_mode))
+		btail = au_dbtaildir(dentry);
+	for (bindex = bstart; bindex <= btail; bindex++) {
+		h_dentry = au_h_dptr(dentry, bindex);
+		if (!h_dentry)
+			continue;
+
+		AuDbg("b%d, %pd\n", bindex, h_dentry);
+		h_nfs = !!au_test_nfs(h_dentry->d_sb);
+		spin_lock(&h_dentry->d_lock);
+		h_name = &h_dentry->d_name;
+		if (unlikely(do_udba
+			     && !is_root
+			     && ((!h_nfs
+				  && (unhashed != !!d_unhashed(h_dentry)
+				      || (!tmpfile
+					  && !au_qstreq(name, h_name))
+					  ))
+				 || (h_nfs
+				     && !(flags & LOOKUP_OPEN)
+				     && (h_dentry->d_flags
+					 & DCACHE_NFSFS_RENAMED)))
+			    )) {
+			int h_unhashed;
+
+			h_unhashed = d_unhashed(h_dentry);
+			spin_unlock(&h_dentry->d_lock);
+			AuDbg("unhash 0x%x 0x%x, %pd %pd\n",
+			      unhashed, h_unhashed, dentry, h_dentry);
+			goto err;
+		}
+		spin_unlock(&h_dentry->d_lock);
+
+		err = au_do_h_d_reval(h_dentry, flags, dentry, bindex);
+		if (unlikely(err))
+			/* do not goto err, to keep the errno */
+			break;
+
+		/* todo: plink too? */
+		if (!do_udba)
+			continue;
+
+		/* UDBA tests */
+		if (unlikely(!!inode != d_is_positive(h_dentry)))
+			goto err;
+
+		h_inode = NULL;
+		if (d_is_positive(h_dentry))
+			h_inode = d_inode(h_dentry);
+		h_plus = plus;
+		h_mode = mode;
+		h_cached_inode = h_inode;
+		if (h_inode) {
+			h_mode = (h_inode->i_mode & S_IFMT);
+			h_plus = (h_inode->i_nlink > 0);
+		}
+		if (inode && ibs <= bindex && bindex <= ibe)
+			h_cached_inode = au_h_iptr(inode, bindex);
+
+		if (!h_nfs) {
+			if (unlikely(plus != h_plus && !tmpfile))
+				goto err;
+		} else {
+			if (unlikely(!(h_dentry->d_flags & DCACHE_NFSFS_RENAMED)
+				     && !is_root
+				     && !IS_ROOT(h_dentry)
+				     && unhashed != d_unhashed(h_dentry)))
+				goto err;
+		}
+		if (unlikely(mode != h_mode
+			     || h_cached_inode != h_inode))
+			goto err;
+		continue;
+
+err:
+		err = -EINVAL;
+		break;
+	}
+
+	AuTraceErr(err);
+	return err;
+}
+
+/* todo: consolidate with do_refresh() and au_reval_for_attr() */
+static int simple_reval_dpath(struct dentry *dentry, unsigned int sigen)
+{
+	int err;
+	struct dentry *parent;
+
+	if (!au_digen_test(dentry, sigen))
+		return 0;
+
+	parent = dget_parent(dentry);
+	di_read_lock_parent(parent, AuLock_IR);
+	AuDebugOn(au_digen_test(parent, sigen));
+	au_dbg_verify_gen(parent, sigen);
+	err = au_refresh_dentry(dentry, parent);
+	di_read_unlock(parent, AuLock_IR);
+	dput(parent);
+	AuTraceErr(err);
+	return err;
+}
+
+int au_reval_dpath(struct dentry *dentry, unsigned int sigen)
+{
+	int err;
+	struct dentry *d, *parent;
+
+	if (!au_ftest_si(au_sbi(dentry->d_sb), FAILED_REFRESH_DIR))
+		return simple_reval_dpath(dentry, sigen);
+
+	/* slow loop, keep it simple and stupid */
+	/* cf: au_cpup_dirs() */
+	err = 0;
+	parent = NULL;
+	while (au_digen_test(dentry, sigen)) {
+		d = dentry;
+		while (1) {
+			dput(parent);
+			parent = dget_parent(d);
+			if (!au_digen_test(parent, sigen))
+				break;
+			d = parent;
+		}
+
+		if (d != dentry)
+			di_write_lock_child2(d);
+
+		/* someone might update our dentry while we were sleeping */
+		if (au_digen_test(d, sigen)) {
+			/*
+			 * todo: consolidate with simple_reval_dpath(),
+			 * do_refresh() and au_reval_for_attr().
+			 */
+			di_read_lock_parent(parent, AuLock_IR);
+			err = au_refresh_dentry(d, parent);
+			di_read_unlock(parent, AuLock_IR);
+		}
+
+		if (d != dentry)
+			di_write_unlock(d);
+		dput(parent);
+		if (unlikely(err))
+			break;
+	}
+
+	return err;
+}
+
+/*
+ * if valid returns 1, otherwise 0.
+ */
+static int aufs_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	int valid, err;
+	unsigned int sigen;
+	unsigned char do_udba;
+	struct super_block *sb;
+	struct inode *inode;
+
+	/* todo: support rcu-walk? */
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	valid = 0;
+	if (unlikely(!au_di(dentry)))
+		goto out;
+
+	valid = 1;
+	sb = dentry->d_sb;
+	/*
+	 * todo: very ugly
+	 * i_mutex of parent dir may be held,
+	 * but we should not return 'invalid' due to busy.
+	 */
+	err = aufs_read_lock(dentry, AuLock_FLUSH | AuLock_DW | AuLock_NOPLM);
+	if (unlikely(err)) {
+		valid = err;
+		AuTraceErr(err);
+		goto out;
+	}
+	inode = NULL;
+	if (d_really_is_positive(dentry))
+		inode = d_inode(dentry);
+	if (unlikely(inode && is_bad_inode(inode))) {
+		err = -EINVAL;
+		AuTraceErr(err);
+		goto out_dgrade;
+	}
+	if (unlikely(au_dbrange_test(dentry))) {
+		err = -EINVAL;
+		AuTraceErr(err);
+		goto out_dgrade;
+	}
+
+	sigen = au_sigen(sb);
+	if (au_digen_test(dentry, sigen)) {
+		AuDebugOn(IS_ROOT(dentry));
+		err = au_reval_dpath(dentry, sigen);
+		if (unlikely(err)) {
+			AuTraceErr(err);
+			goto out_dgrade;
+		}
+	}
+	di_downgrade_lock(dentry, AuLock_IR);
+
+	err = -EINVAL;
+	if (!(flags & (LOOKUP_OPEN | LOOKUP_EMPTY))
+	    && inode
+	    && !(inode->i_state && I_LINKABLE)
+	    && (IS_DEADDIR(inode) || !inode->i_nlink))
+		goto out_inval;
+
+	do_udba = !au_opt_test(au_mntflags(sb), UDBA_NONE);
+	if (do_udba && inode) {
+		aufs_bindex_t bstart = au_ibstart(inode);
+		struct inode *h_inode;
+
+		if (bstart >= 0) {
+			h_inode = au_h_iptr(inode, bstart);
+			if (h_inode && au_test_higen(inode, h_inode))
+				goto out_inval;
+		}
+	}
+
+	err = h_d_revalidate(dentry, inode, flags, do_udba);
+	if (unlikely(!err && do_udba && au_dbstart(dentry) < 0)) {
+		err = -EIO;
+		AuDbg("both of real entry and whiteout found, %p, err %d\n",
+		      dentry, err);
+	}
+	goto out_inval;
+
+out_dgrade:
+	di_downgrade_lock(dentry, AuLock_IR);
+out_inval:
+	aufs_read_unlock(dentry, AuLock_IR);
+	AuTraceErr(err);
+	valid = !err;
+out:
+	if (!valid) {
+		AuDbg("%pd invalid, %d\n", dentry, valid);
+		d_drop(dentry);
+	}
+	return valid;
+}
+
+static void aufs_d_release(struct dentry *dentry)
+{
+	if (au_di(dentry)) {
+		au_di_fin(dentry);
+		au_hn_di_reinit(dentry);
+	}
+}
+
+const struct dentry_operations aufs_dop = {
+	.d_revalidate		= aufs_d_revalidate,
+	.d_weak_revalidate	= aufs_d_revalidate,
+	.d_release		= aufs_d_release
+};