aufs: virtual or vertical directory 2/2, body

It is hard to implement readdir(3) for aufs virtual directory.
It considers the every whiteout in a single direcotry, as well as the
(first) opaque marker (diropq).
This implementation consumes memory a lot, and I'd suggest you to try
RDU (readdir in userspace) in later commit.

See also the document in previous commit.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/dir.h

@@ -76,7 +76,15 @@ loff_t au_dir_size(struct file *file, struct dentry *dentry);
 void au_dir_ts(struct inode *dir, aufs_bindex_t bsrc);
 
 /* vdir.c */
+unsigned int au_rdhash_est(loff_t sz);
+int au_nhash_alloc(struct au_nhash *nhash, unsigned int num_hash, gfp_t gfp);
+void au_nhash_wh_free(struct au_nhash *whlist);
+int au_nhash_test_known_wh(struct au_nhash *whlist, char *name, int nlen);
+int au_nhash_append_wh(struct au_nhash *whlist, char *name, int nlen, ino_t ino,
+		       unsigned int d_type, aufs_bindex_t bindex);
 void au_vdir_free(struct au_vdir *vdir);
+int au_vdir_init(struct file *file);
+int au_vdir_fill_de(struct file *file, struct dir_context *ctx);
 
 #endif /* __KERNEL__ */
 #endif /* __AUFS_DIR_H__ */

fs/aufs/vdir.c

@@ -7,8 +7,308 @@
  * virtual or vertical directory
  */
 
+#include <linux/iversion.h>
 #include "aufs.h"
 
+static unsigned int calc_size(int nlen)
+{
+	return ALIGN(sizeof(struct au_vdir_de) + nlen, sizeof(ino_t));
+}
+
+static int set_deblk_end(union au_vdir_deblk_p *p,
+			 union au_vdir_deblk_p *deblk_end)
+{
+	if (calc_size(0) <= deblk_end->deblk - p->deblk) {
+		p->de->de_str.len = 0;
+		/* smp_mb(); */
+		return 0;
+	}
+	return -1; /* error */
+}
+
+/* returns true or false */
+static int is_deblk_end(union au_vdir_deblk_p *p,
+			union au_vdir_deblk_p *deblk_end)
+{
+	if (calc_size(0) <= deblk_end->deblk - p->deblk)
+		return !p->de->de_str.len;
+	return 1;
+}
+
+static unsigned char *last_deblk(struct au_vdir *vdir)
+{
+	return vdir->vd_deblk[vdir->vd_nblk - 1];
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* estimate the appropriate size for name hash table */
+unsigned int au_rdhash_est(loff_t sz)
+{
+	unsigned int n;
+
+	n = UINT_MAX;
+	sz >>= 10;
+	if (sz < n)
+		n = sz;
+	if (sz < AUFS_RDHASH_DEF)
+		n = AUFS_RDHASH_DEF;
+	/* pr_info("n %u\n", n); */
+	return n;
+}
+
+/*
+ * the allocated memory has to be freed by
+ * au_nhash_wh_free() or au_nhash_de_free().
+ */
+int au_nhash_alloc(struct au_nhash *nhash, unsigned int num_hash, gfp_t gfp)
+{
+	struct hlist_head *head;
+	unsigned int u;
+	size_t sz;
+
+	sz = sizeof(*nhash->nh_head) * num_hash;
+	head = kmalloc(sz, gfp);
+	if (head) {
+		nhash->nh_num = num_hash;
+		nhash->nh_head = head;
+		for (u = 0; u < num_hash; u++)
+			INIT_HLIST_HEAD(head++);
+		return 0; /* success */
+	}
+
+	return -ENOMEM;
+}
+
+static void nhash_count(struct hlist_head *head)
+{
+#if 0
+	unsigned long n;
+	struct hlist_node *pos;
+
+	n = 0;
+	hlist_for_each(pos, head)
+		n++;
+	pr_info("%lu\n", n);
+#endif
+}
+
+static void au_nhash_wh_do_free(struct hlist_head *head)
+{
+	struct au_vdir_wh *pos;
+	struct hlist_node *node;
+
+	hlist_for_each_entry_safe(pos, node, head, wh_hash)
+		au_kfree_rcu(pos);
+}
+
+static void au_nhash_de_do_free(struct hlist_head *head)
+{
+	struct au_vdir_dehstr *pos;
+	struct hlist_node *node;
+
+	hlist_for_each_entry_safe(pos, node, head, hash)
+		au_cache_free_vdir_dehstr(pos);
+}
+
+static void au_nhash_do_free(struct au_nhash *nhash,
+			     void (*free)(struct hlist_head *head))
+{
+	unsigned int n;
+	struct hlist_head *head;
+
+	n = nhash->nh_num;
+	if (!n)
+		return;
+
+	head = nhash->nh_head;
+	while (n-- > 0) {
+		nhash_count(head);
+		free(head++);
+	}
+	au_kfree_try_rcu(nhash->nh_head);
+}
+
+void au_nhash_wh_free(struct au_nhash *whlist)
+{
+	au_nhash_do_free(whlist, au_nhash_wh_do_free);
+}
+
+static void au_nhash_de_free(struct au_nhash *delist)
+{
+	au_nhash_do_free(delist, au_nhash_de_do_free);
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct hlist_head *au_name_hash(struct au_nhash *nhash,
+				       unsigned char *name,
+				       unsigned int len)
+{
+	unsigned int v;
+	/* const unsigned int magic_bit = 12; */
+
+	AuDebugOn(!nhash->nh_num || !nhash->nh_head);
+
+	v = 0;
+	if (len > 8)
+		len = 8;
+	while (len--)
+		v += *name++;
+	/* v = hash_long(v, magic_bit); */
+	v %= nhash->nh_num;
+	return nhash->nh_head + v;
+}
+
+static int au_nhash_test_name(struct au_vdir_destr *str, const char *name,
+			      int nlen)
+{
+	return str->len == nlen && !memcmp(str->name, name, nlen);
+}
+
+/* returns found or not */
+int au_nhash_test_known_wh(struct au_nhash *whlist, char *name, int nlen)
+{
+	struct hlist_head *head;
+	struct au_vdir_wh *pos;
+	struct au_vdir_destr *str;
+
+	head = au_name_hash(whlist, name, nlen);
+	hlist_for_each_entry(pos, head, wh_hash) {
+		str = &pos->wh_str;
+		AuDbg("%.*s\n", str->len, str->name);
+		if (au_nhash_test_name(str, name, nlen))
+			return 1;
+	}
+	return 0;
+}
+
+/* returns found(true) or not */
+static int test_known(struct au_nhash *delist, char *name, int nlen)
+{
+	struct hlist_head *head;
+	struct au_vdir_dehstr *pos;
+	struct au_vdir_destr *str;
+
+	head = au_name_hash(delist, name, nlen);
+	hlist_for_each_entry(pos, head, hash) {
+		str = pos->str;
+		AuDbg("%.*s\n", str->len, str->name);
+		if (au_nhash_test_name(str, name, nlen))
+			return 1;
+	}
+	return 0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int au_nhash_append_wh(struct au_nhash *whlist, char *name, int nlen, ino_t ino,
+		       unsigned int d_type, aufs_bindex_t bindex)
+{
+	int err;
+	struct au_vdir_destr *str;
+	struct au_vdir_wh *wh;
+
+	AuDbg("%.*s\n", nlen, name);
+	AuDebugOn(!whlist->nh_num || !whlist->nh_head);
+
+	err = -ENOMEM;
+	wh = kmalloc(sizeof(*wh) + nlen, GFP_NOFS);
+	if (unlikely(!wh))
+		goto out;
+
+	err = 0;
+	wh->wh_bindex = bindex;
+	str = &wh->wh_str;
+	str->len = nlen;
+	memcpy(str->name, name, nlen);
+	hlist_add_head(&wh->wh_hash, au_name_hash(whlist, name, nlen));
+	/* smp_mb(); */
+
+out:
+	return err;
+}
+
+static int append_deblk(struct au_vdir *vdir)
+{
+	int err;
+	unsigned long ul;
+	const unsigned int deblk_sz = vdir->vd_deblk_sz;
+	union au_vdir_deblk_p p, deblk_end;
+	unsigned char **o;
+
+	err = -ENOMEM;
+	o = au_krealloc(vdir->vd_deblk, sizeof(*o) * (vdir->vd_nblk + 1),
+			GFP_NOFS, /*may_shrink*/0);
+	if (unlikely(!o))
+		goto out;
+
+	vdir->vd_deblk = o;
+	p.deblk = kmalloc(deblk_sz, GFP_NOFS);
+	if (p.deblk) {
+		ul = vdir->vd_nblk++;
+		vdir->vd_deblk[ul] = p.deblk;
+		vdir->vd_last.ul = ul;
+		vdir->vd_last.p.deblk = p.deblk;
+		deblk_end.deblk = p.deblk + deblk_sz;
+		err = set_deblk_end(&p, &deblk_end);
+	}
+
+out:
+	return err;
+}
+
+static int append_de(struct au_vdir *vdir, char *name, int nlen, ino_t ino,
+		     unsigned int d_type, struct au_nhash *delist)
+{
+	int err;
+	unsigned int sz;
+	const unsigned int deblk_sz = vdir->vd_deblk_sz;
+	union au_vdir_deblk_p p, *room, deblk_end;
+	struct au_vdir_dehstr *dehstr;
+
+	p.deblk = last_deblk(vdir);
+	deblk_end.deblk = p.deblk + deblk_sz;
+	room = &vdir->vd_last.p;
+	AuDebugOn(room->deblk < p.deblk || deblk_end.deblk <= room->deblk
+		  || !is_deblk_end(room, &deblk_end));
+
+	sz = calc_size(nlen);
+	if (unlikely(sz > deblk_end.deblk - room->deblk)) {
+		err = append_deblk(vdir);
+		if (unlikely(err))
+			goto out;
+
+		p.deblk = last_deblk(vdir);
+		deblk_end.deblk = p.deblk + deblk_sz;
+		/* smp_mb(); */
+		AuDebugOn(room->deblk != p.deblk);
+	}
+
+	err = -ENOMEM;
+	dehstr = au_cache_alloc_vdir_dehstr();
+	if (unlikely(!dehstr))
+		goto out;
+
+	dehstr->str = &room->de->de_str;
+	hlist_add_head(&dehstr->hash, au_name_hash(delist, name, nlen));
+	room->de->de_ino = ino;
+	room->de->de_type = d_type;
+	room->de->de_str.len = nlen;
+	memcpy(room->de->de_str.name, name, nlen);
+
+	err = 0;
+	room->deblk += sz;
+	if (unlikely(set_deblk_end(room, &deblk_end)))
+		err = append_deblk(vdir);
+	/* smp_mb(); */
+
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
 void au_vdir_free(struct au_vdir *vdir)
 {
 	unsigned char **deblk;
@@ -19,3 +319,468 @@ void au_vdir_free(struct au_vdir *vdir)
 	au_kfree_try_rcu(vdir->vd_deblk);
 	au_cache_free_vdir(vdir);
 }
+
+static struct au_vdir *alloc_vdir(struct file *file)
+{
+	struct au_vdir *vdir;
+	struct super_block *sb;
+	int err;
+
+	sb = file->f_path.dentry->d_sb;
+	SiMustAnyLock(sb);
+
+	err = -ENOMEM;
+	vdir = au_cache_alloc_vdir();
+	if (unlikely(!vdir))
+		goto out;
+
+	vdir->vd_deblk = kzalloc(sizeof(*vdir->vd_deblk), GFP_NOFS);
+	if (unlikely(!vdir->vd_deblk))
+		goto out_free;
+
+	vdir->vd_deblk_sz = au_sbi(sb)->si_rdblk;
+	if (!vdir->vd_deblk_sz) {
+		/* estimate the appropriate size for deblk */
+		vdir->vd_deblk_sz = au_dir_size(file, /*dentry*/NULL);
+		/* pr_info("vd_deblk_sz %u\n", vdir->vd_deblk_sz); */
+	}
+	vdir->vd_nblk = 0;
+	vdir->vd_version = 0;
+	vdir->vd_jiffy = 0;
+	err = append_deblk(vdir);
+	if (!err)
+		return vdir; /* success */
+
+	au_kfree_try_rcu(vdir->vd_deblk);
+
+out_free:
+	au_cache_free_vdir(vdir);
+out:
+	vdir = ERR_PTR(err);
+	return vdir;
+}
+
+static int reinit_vdir(struct au_vdir *vdir)
+{
+	int err;
+	union au_vdir_deblk_p p, deblk_end;
+
+	while (vdir->vd_nblk > 1) {
+		au_kfree_try_rcu(vdir->vd_deblk[vdir->vd_nblk - 1]);
+		/* vdir->vd_deblk[vdir->vd_nblk - 1] = NULL; */
+		vdir->vd_nblk--;
+	}
+	p.deblk = vdir->vd_deblk[0];
+	deblk_end.deblk = p.deblk + vdir->vd_deblk_sz;
+	err = set_deblk_end(&p, &deblk_end);
+	/* keep vd_dblk_sz */
+	vdir->vd_last.ul = 0;
+	vdir->vd_last.p.deblk = vdir->vd_deblk[0];
+	vdir->vd_version = 0;
+	vdir->vd_jiffy = 0;
+	/* smp_mb(); */
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+#define AuFillVdir_CALLED	1
+#define AuFillVdir_WHABLE	(1 << 1)
+#define au_ftest_fillvdir(flags, name)	((flags) & AuFillVdir_##name)
+#define au_fset_fillvdir(flags, name) \
+	do { (flags) |= AuFillVdir_##name; } while (0)
+#define au_fclr_fillvdir(flags, name) \
+	do { (flags) &= ~AuFillVdir_##name; } while (0)
+
+struct fillvdir_arg {
+	struct dir_context	ctx;
+	struct file		*file;
+	struct au_vdir		*vdir;
+	struct au_nhash		delist;
+	struct au_nhash		whlist;
+	aufs_bindex_t		bindex;
+	unsigned int		flags;
+	int			err;
+};
+
+static int fillvdir(struct dir_context *ctx, const char *__name, int nlen,
+		    loff_t offset __maybe_unused, u64 h_ino,
+		    unsigned int d_type)
+{
+	struct fillvdir_arg *arg = container_of(ctx, struct fillvdir_arg, ctx);
+	char *name = (void *)__name;
+	struct super_block *sb;
+	ino_t ino;
+
+	arg->err = 0;
+	sb = arg->file->f_path.dentry->d_sb;
+	au_fset_fillvdir(arg->flags, CALLED);
+	/* smp_mb(); */
+	if (nlen <= AUFS_WH_PFX_LEN
+	    || memcmp(name, AUFS_WH_PFX, AUFS_WH_PFX_LEN)) {
+		if (test_known(&arg->delist, name, nlen)
+		    || au_nhash_test_known_wh(&arg->whlist, name, nlen))
+			goto out; /* already exists or whiteouted */
+
+		arg->err = au_ino(sb, arg->bindex, h_ino, d_type, &ino);
+		if (!arg->err) {
+			if (unlikely(nlen > AUFS_MAX_NAMELEN))
+				d_type = DT_UNKNOWN;
+			arg->err = append_de(arg->vdir, name, nlen, ino,
+					     d_type, &arg->delist);
+		}
+	} else if (au_ftest_fillvdir(arg->flags, WHABLE)) {
+		name += AUFS_WH_PFX_LEN;
+		nlen -= AUFS_WH_PFX_LEN;
+		if (au_nhash_test_known_wh(&arg->whlist, name, nlen))
+			goto out; /* already whiteouted */
+
+		if (!arg->err) {
+			if (nlen <= AUFS_MAX_NAMELEN + AUFS_WH_PFX_LEN)
+				d_type = DT_UNKNOWN;
+			arg->err = au_nhash_append_wh
+				(&arg->whlist, name, nlen, ino, d_type,
+				 arg->bindex);
+		}
+	}
+
+out:
+	if (!arg->err)
+		arg->vdir->vd_jiffy = jiffies;
+	/* smp_mb(); */
+	AuTraceErr(arg->err);
+	return arg->err;
+}
+
+static int au_do_read_vdir(struct fillvdir_arg *arg)
+{
+	int err;
+	unsigned int rdhash;
+	loff_t offset;
+	aufs_bindex_t bbot, bindex, btop;
+	struct file *hf, *file;
+	struct super_block *sb;
+
+	file = arg->file;
+	sb = file->f_path.dentry->d_sb;
+	SiMustAnyLock(sb);
+
+	rdhash = au_sbi(sb)->si_rdhash;
+	if (!rdhash)
+		rdhash = au_rdhash_est(au_dir_size(file, /*dentry*/NULL));
+	err = au_nhash_alloc(&arg->delist, rdhash, GFP_NOFS);
+	if (unlikely(err))
+		goto out;
+	err = au_nhash_alloc(&arg->whlist, rdhash, GFP_NOFS);
+	if (unlikely(err))
+		goto out_delist;
+
+	err = 0;
+	arg->flags = 0;
+	btop = au_fbtop(file);
+	bbot = au_fbbot_dir(file);
+	for (bindex = btop; !err && bindex <= bbot; bindex++) {
+		hf = au_hf_dir(file, bindex);
+		if (!hf)
+			continue;
+
+		offset = vfsub_llseek(hf, 0, SEEK_SET);
+		err = offset;
+		if (unlikely(offset))
+			break;
+
+		arg->bindex = bindex;
+		au_fclr_fillvdir(arg->flags, WHABLE);
+		if (bindex != bbot
+		    && au_br_whable(au_sbr_perm(sb, bindex)))
+			au_fset_fillvdir(arg->flags, WHABLE);
+		do {
+			arg->err = 0;
+			au_fclr_fillvdir(arg->flags, CALLED);
+			/* smp_mb(); */
+			err = vfsub_iterate_dir(hf, &arg->ctx);
+			if (err >= 0)
+				err = arg->err;
+		} while (!err && au_ftest_fillvdir(arg->flags, CALLED));
+
+		/*
+		 * dir_relax() may be good for concurrency, but aufs should not
+		 * use it since it will cause a lockdep problem.
+		 */
+	}
+	au_nhash_wh_free(&arg->whlist);
+
+out_delist:
+	au_nhash_de_free(&arg->delist);
+out:
+	return err;
+}
+
+static int read_vdir(struct file *file, int may_read)
+{
+	int err;
+	unsigned long expire;
+	unsigned char do_read;
+	struct fillvdir_arg arg = {
+		.ctx = {
+			.actor = fillvdir
+		}
+	};
+	struct inode *inode;
+	struct au_vdir *vdir, *allocated;
+
+	err = 0;
+	inode = file_inode(file);
+	IMustLock(inode);
+	IiMustWriteLock(inode);
+	SiMustAnyLock(inode->i_sb);
+
+	allocated = NULL;
+	do_read = 0;
+	expire = au_sbi(inode->i_sb)->si_rdcache;
+	vdir = au_ivdir(inode);
+	if (!vdir) {
+		do_read = 1;
+		vdir = alloc_vdir(file);
+		err = PTR_ERR(vdir);
+		if (IS_ERR(vdir))
+			goto out;
+		err = 0;
+		allocated = vdir;
+	} else if (may_read
+		   && (!inode_eq_iversion(inode, vdir->vd_version)
+		       || time_after(jiffies, vdir->vd_jiffy + expire))) {
+		do_read = 1;
+		err = reinit_vdir(vdir);
+		if (unlikely(err))
+			goto out;
+	}
+
+	if (!do_read)
+		return 0; /* success */
+
+	arg.file = file;
+	arg.vdir = vdir;
+	err = au_do_read_vdir(&arg);
+	if (!err) {
+		/* file->f_pos = 0; */ /* todo: ctx->pos? */
+		vdir->vd_version = inode_query_iversion(inode);
+		vdir->vd_last.ul = 0;
+		vdir->vd_last.p.deblk = vdir->vd_deblk[0];
+		if (allocated)
+			au_set_ivdir(inode, allocated);
+	} else if (allocated)
+		au_vdir_free(allocated);
+
+out:
+	return err;
+}
+
+static int copy_vdir(struct au_vdir *tgt, struct au_vdir *src)
+{
+	int err, rerr;
+	unsigned long ul, n;
+	const unsigned int deblk_sz = src->vd_deblk_sz;
+
+	AuDebugOn(tgt->vd_nblk != 1);
+
+	err = -ENOMEM;
+	if (tgt->vd_nblk < src->vd_nblk) {
+		unsigned char **p;
+
+		p = au_krealloc(tgt->vd_deblk, sizeof(*p) * src->vd_nblk,
+				GFP_NOFS, /*may_shrink*/0);
+		if (unlikely(!p))
+			goto out;
+		tgt->vd_deblk = p;
+	}
+
+	if (tgt->vd_deblk_sz != deblk_sz) {
+		unsigned char *p;
+
+		tgt->vd_deblk_sz = deblk_sz;
+		p = au_krealloc(tgt->vd_deblk[0], deblk_sz, GFP_NOFS,
+				/*may_shrink*/1);
+		if (unlikely(!p))
+			goto out;
+		tgt->vd_deblk[0] = p;
+	}
+	memcpy(tgt->vd_deblk[0], src->vd_deblk[0], deblk_sz);
+	tgt->vd_version = src->vd_version;
+	tgt->vd_jiffy = src->vd_jiffy;
+
+	n = src->vd_nblk;
+	for (ul = 1; ul < n; ul++) {
+		tgt->vd_deblk[ul] = kmemdup(src->vd_deblk[ul], deblk_sz,
+					    GFP_NOFS);
+		if (unlikely(!tgt->vd_deblk[ul]))
+			goto out;
+		tgt->vd_nblk++;
+	}
+	tgt->vd_nblk = n;
+	tgt->vd_last.ul = tgt->vd_last.ul;
+	tgt->vd_last.p.deblk = tgt->vd_deblk[tgt->vd_last.ul];
+	tgt->vd_last.p.deblk += src->vd_last.p.deblk
+		- src->vd_deblk[src->vd_last.ul];
+	/* smp_mb(); */
+	return 0; /* success */
+
+out:
+	rerr = reinit_vdir(tgt);
+	BUG_ON(rerr);
+	return err;
+}
+
+int au_vdir_init(struct file *file)
+{
+	int err;
+	struct inode *inode;
+	struct au_vdir *vdir_cache, *allocated;
+
+	/* test file->f_pos here instead of ctx->pos */
+	err = read_vdir(file, !file->f_pos);
+	if (unlikely(err))
+		goto out;
+
+	allocated = NULL;
+	vdir_cache = au_fvdir_cache(file);
+	if (!vdir_cache) {
+		vdir_cache = alloc_vdir(file);
+		err = PTR_ERR(vdir_cache);
+		if (IS_ERR(vdir_cache))
+			goto out;
+		allocated = vdir_cache;
+	} else if (!file->f_pos && vdir_cache->vd_version != file->f_version) {
+		/* test file->f_pos here instead of ctx->pos */
+		err = reinit_vdir(vdir_cache);
+		if (unlikely(err))
+			goto out;
+	} else
+		return 0; /* success */
+
+	inode = file_inode(file);
+	err = copy_vdir(vdir_cache, au_ivdir(inode));
+	if (!err) {
+		file->f_version = inode_query_iversion(inode);
+		if (allocated)
+			au_set_fvdir_cache(file, allocated);
+	} else if (allocated)
+		au_vdir_free(allocated);
+
+out:
+	return err;
+}
+
+static loff_t calc_offset(struct au_vdir *vdir)
+{
+	loff_t offset;
+	union au_vdir_deblk_p p;
+
+	p.deblk = vdir->vd_deblk[vdir->vd_last.ul];
+	offset = vdir->vd_last.p.deblk - p.deblk;
+	offset += vdir->vd_deblk_sz * vdir->vd_last.ul;
+	return offset;
+}
+
+/* returns true or false */
+static int seek_vdir(struct file *file, struct dir_context *ctx)
+{
+	int valid;
+	unsigned int deblk_sz;
+	unsigned long ul, n;
+	loff_t offset;
+	union au_vdir_deblk_p p, deblk_end;
+	struct au_vdir *vdir_cache;
+
+	valid = 1;
+	vdir_cache = au_fvdir_cache(file);
+	offset = calc_offset(vdir_cache);
+	AuDbg("offset %lld\n", offset);
+	if (ctx->pos == offset)
+		goto out;
+
+	vdir_cache->vd_last.ul = 0;
+	vdir_cache->vd_last.p.deblk = vdir_cache->vd_deblk[0];
+	if (!ctx->pos)
+		goto out;
+
+	valid = 0;
+	deblk_sz = vdir_cache->vd_deblk_sz;
+	ul = div64_u64(ctx->pos, deblk_sz);
+	AuDbg("ul %lu\n", ul);
+	if (ul >= vdir_cache->vd_nblk)
+		goto out;
+
+	n = vdir_cache->vd_nblk;
+	for (; ul < n; ul++) {
+		p.deblk = vdir_cache->vd_deblk[ul];
+		deblk_end.deblk = p.deblk + deblk_sz;
+		offset = ul;
+		offset *= deblk_sz;
+		while (!is_deblk_end(&p, &deblk_end) && offset < ctx->pos) {
+			unsigned int l;
+
+			l = calc_size(p.de->de_str.len);
+			offset += l;
+			p.deblk += l;
+		}
+		if (!is_deblk_end(&p, &deblk_end)) {
+			valid = 1;
+			vdir_cache->vd_last.ul = ul;
+			vdir_cache->vd_last.p = p;
+			break;
+		}
+	}
+
+out:
+	/* smp_mb(); */
+	if (!valid)
+		AuDbg("valid %d\n", !valid);
+	return valid;
+}
+
+int au_vdir_fill_de(struct file *file, struct dir_context *ctx)
+{
+	unsigned int l, deblk_sz;
+	union au_vdir_deblk_p deblk_end;
+	struct au_vdir *vdir_cache;
+	struct au_vdir_de *de;
+
+	if (!seek_vdir(file, ctx))
+		return 0;
+
+	vdir_cache = au_fvdir_cache(file);
+	deblk_sz = vdir_cache->vd_deblk_sz;
+	while (1) {
+		deblk_end.deblk = vdir_cache->vd_deblk[vdir_cache->vd_last.ul];
+		deblk_end.deblk += deblk_sz;
+		while (!is_deblk_end(&vdir_cache->vd_last.p, &deblk_end)) {
+			de = vdir_cache->vd_last.p.de;
+			AuDbg("%.*s, off%lld, i%lu, dt%d\n",
+			      de->de_str.len, de->de_str.name, ctx->pos,
+			      (unsigned long)de->de_ino, de->de_type);
+			if (unlikely(!dir_emit(ctx, de->de_str.name,
+					       de->de_str.len, de->de_ino,
+					       de->de_type))) {
+				/* todo: ignore the error caused by udba? */
+				/* return err; */
+				return 0;
+			}
+
+			l = calc_size(de->de_str.len);
+			vdir_cache->vd_last.p.deblk += l;
+			ctx->pos += l;
+		}
+		if (vdir_cache->vd_last.ul < vdir_cache->vd_nblk - 1) {
+			vdir_cache->vd_last.ul++;
+			vdir_cache->vd_last.p.deblk
+				= vdir_cache->vd_deblk[vdir_cache->vd_last.ul];
+			ctx->pos = deblk_sz * vdir_cache->vd_last.ul;
+			continue;
+		}
+		break;
+	}
+
+	/* smp_mb(); */
+	return 0;
+}