aufs: sysfs interface

The branch path can be much longer and it is not suitable to print via
/proc/mounts as a part of mount options. Aufs can show it either
separately via sysfs or /proc/mounts (as a part of mount options).
This approach affects the lifetime of aufs objects and sbinfo contains
kobject (in another commit). Theoretically user can disable
CONFIG_SYSFS, but the lifetime management is always necessary. So
supporting sysfs is split into two files, sysaufs.c and sysfs.c.
sysaufs.c is always compiled, but sysfs.c is compiled only when
CONFIG_SYSFS is enabled.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

Documentation/ABI/testing/sysfs-aufs

+What:		/sys/fs/aufs/si_<id>/
+Date:		March 2009
+Contact:	J. R. Okajima <hooanon05g@gmail.com>
+Description:
+		Under /sys/fs/aufs, a directory named si_<id> is created
+		per aufs mount, where <id> is a unique id generated
+		internally.
+
+What:		/sys/fs/aufs/si_<id>/br0, br1 ... brN
+Date:		March 2009
+Contact:	J. R. Okajima <hooanon05g@gmail.com>
+Description:
+		It shows the abolute path of a member directory (which
+		is called branch) in aufs, and its permission.
+
+What:		/sys/fs/aufs/si_<id>/brid0, brid1 ... bridN
+Date:		July 2013
+Contact:	J. R. Okajima <hooanon05g@gmail.com>
+Description:
+		It shows the id of a member directory (which is called
+		branch) in aufs.
+
+What:		/sys/fs/aufs/si_<id>/xi_path
+Date:		March 2009
+Contact:	J. R. Okajima <hooanon05g@gmail.com>
+Description:
+		It shows the abolute path of XINO (External Inode Number
+		Bitmap, Translation Table and Generation Table) file
+		even if it is the default path.
+		When the aufs mount option 'noxino' is specified, it
+		will be empty. About XINO files, see the aufs manual.

fs/aufs/Makefile

@@ -10,11 +10,12 @@ ccflags-y += -DDEBUG
 ccflags-y += -include ${srctree}/include/uapi/linux/aufs_type.h
 
 obj-$(CONFIG_AUFS_FS) += aufs.o
-aufs-y := module.o sbinfo.o super.o branch.o xino.o opts.o \
+aufs-y := module.o sbinfo.o super.o branch.o xino.o sysaufs.o opts.o \
 	wkq.o vfsub.o dcsub.o \
 	cpup.o \
 	dinfo.o \
 	iinfo.o inode.o
 
 # all are boolean
+aufs-$(CONFIG_SYSFS) += sysfs.o
 aufs-$(CONFIG_AUFS_DEBUG) += debug.o

fs/aufs/aufs.h

@@ -34,6 +34,7 @@
 #include "opts.h"
 #include "rwsem.h"
 #include "super.h"
+#include "sysaufs.h"
 #include "vfsub.h"
 #include "wkq.h"
 

fs/aufs/branch.c

@@ -223,6 +223,7 @@ static int au_br_init(struct au_branch *br, struct super_block *sb,
 		}
 	}
 
+	sysaufs_br_init(br);
 	path_get(&br->br_path);
 	goto out; /* success */
 

fs/aufs/branch.h

@@ -38,6 +38,18 @@ struct au_xino {
 	struct kref		xi_kref;
 };
 
+/* sysfs entries */
+struct au_brsysfs {
+	char			name[16];
+	struct attribute	attr;
+};
+
+enum {
+	AuBrSysfs_BR,
+	AuBrSysfs_BRID,
+	AuBrSysfs_Last
+};
+
 /* protected by superblock rwsem */
 struct au_branch {
 	struct au_xino		*br_xino;
@@ -47,6 +59,11 @@ struct au_branch {
 	int			br_perm;
 	struct path		br_path;
 	au_lcnt_t		br_count;	/* in-use for other */
+
+#ifdef CONFIG_SYSFS
+	/* entries under sysfs per mount-point */
+	struct au_brsysfs	br_sysfs[AuBrSysfs_Last];
+#endif
 };
 
 /* ---------------------------------------------------------------------- */
@@ -133,6 +150,8 @@ int au_xino_init_br(struct super_block *sb, struct au_branch *br, ino_t hino,
 ino_t au_xino_new_ino(struct super_block *sb);
 void au_xino_delete_inode(struct inode *inode, const int unlinked);
 
+int au_xino_path(struct seq_file *seq, struct file *file);
+
 /* ---------------------------------------------------------------------- */
 
 /* @idx is signed to accept -1 meaning the first file */

fs/aufs/module.c

@@ -8,6 +8,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/seq_file.h>
 #include "aufs.h"
 
 /* shrinkable realloc */
@@ -112,17 +113,51 @@ MODULE_DESCRIPTION(AUFS_NAME
 	" -- Advanced multi layered unification filesystem");
 MODULE_VERSION(AUFS_VERSION);
 
+/* this module parameter has no meaning when SYSFS is disabled */
+int sysaufs_brs = 1;
+MODULE_PARM_DESC(brs, "use <sysfs>/fs/aufs/si_*/brN");
+module_param_named(brs, sysaufs_brs, int, 0444);
+
 /* ---------------------------------------------------------------------- */
 
-static int __init aufs_init(void)
+static char au_esc_chars[0x20 + 3]; /* 0x01-0x20, backslash, del, and NULL */
+
+int au_seq_path(struct seq_file *seq, struct path *path)
 {
 	int err;
 
+	err = seq_path(seq, path, au_esc_chars);
+	if (err >= 0)
+		err = 0;
+	else
+		err = -ENOMEM;
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static int __init aufs_init(void)
+{
+	int err, i;
+	char *p;
+
+	p = au_esc_chars;
+	for (i = 1; i <= ' '; i++)
+		*p++ = i;
+	*p++ = '\\';
+	*p++ = '\x7f';
+	*p = 0;
+
 	memset(au_cache, 0, sizeof(au_cache));
 
-	err = au_wkq_init();
+	sysaufs_brs_init();
+	err = sysaufs_init();
 	if (unlikely(err))
 		goto out;
+	err = au_wkq_init();
+	if (unlikely(err))
+		goto out_sysaufs;
 	err = au_cache_init();
 	if (unlikely(err))
 		goto out_wkq;
@@ -133,6 +168,8 @@ static int __init aufs_init(void)
 
 out_wkq:
 	au_wkq_fin();
+out_sysaufs:
+	sysaufs_fin();
 out:
 	return err;
 }

fs/aufs/module.h

@@ -17,6 +17,14 @@
 #include "dentry.h"
 #include "inode.h"
 
+struct path;
+struct seq_file;
+
+/* module parameters */
+extern int sysaufs_brs;
+
+/* ---------------------------------------------------------------------- */
+
 void *au_krealloc(void *p, unsigned int new_sz, gfp_t gfp, int may_shrink);
 void *au_kzrealloc(void *p, unsigned int nused, unsigned int new_sz, gfp_t gfp,
 		   int may_shrink);
@@ -77,6 +85,8 @@ static inline int au_kmidx_sub(size_t sz, size_t new_sz)
 #endif
 }
 
+int au_seq_path(struct seq_file *seq, struct path *path);
+
 /* ---------------------------------------------------------------------- */
 
 /* kmem cache */

fs/aufs/sbinfo.c

@@ -46,6 +46,10 @@ int au_si_alloc(struct super_block *sb)
 	if (unlikely(!sbinfo->si_branch))
 		goto out_sbinfo;
 
+	err = sysaufs_si_init(sbinfo);
+	if (unlikely(err))
+		goto out_br;
+
 	au_nwt_init(&sbinfo->si_nowait);
 	au_rw_init_wlock(&sbinfo->si_rwsem);
 
@@ -58,9 +62,11 @@ int au_si_alloc(struct super_block *sb)
 	/* leave si_xib_last_pindex and si_xib_next_bit */
 
 	/* leave other members for sysaufs and si_mnt. */
+	sbinfo->si_sb = sb;
 	sb->s_fs_info = sbinfo;
 	return 0; /* success */
 
+out_br:
 	au_kfree_try_rcu(sbinfo->si_branch);
 out_sbinfo:
 	au_kfree_rcu(sbinfo);

fs/aufs/super.c

@@ -8,6 +8,7 @@
  */
 
 #include <linux/iversion.h>
+#include <linux/seq_file.h>
 #include "aufs.h"
 
 /*
@@ -69,6 +70,84 @@ out:
 	return inode;
 }
 
+/* lock free root dinfo */
+/* re-commit later */ __maybe_unused
+static int au_show_brs(struct seq_file *seq, struct super_block *sb)
+{
+	int err;
+	aufs_bindex_t bindex, bbot;
+	struct path path;
+	struct au_hdentry *hdp;
+	struct au_branch *br;
+	au_br_perm_str_t perm;
+
+	err = 0;
+	bbot = au_sbbot(sb);
+	bindex = 0;
+	hdp = au_hdentry(au_di(sb->s_root), bindex);
+	for (; !err && bindex <= bbot; bindex++, hdp++) {
+		br = au_sbr(sb, bindex);
+		path.mnt = au_br_mnt(br);
+		path.dentry = hdp->hd_dentry;
+		err = au_seq_path(seq, &path);
+		if (!err) {
+			au_optstr_br_perm(&perm, br->br_perm);
+			seq_printf(seq, "=%s", perm.a);
+			if (bindex != bbot)
+				seq_putc(seq, ':');
+		}
+	}
+	if (unlikely(err || seq_has_overflowed(seq)))
+		err = -E2BIG;
+
+	return err;
+}
+
+/* re-commit later */ __maybe_unused
+static int au_show_xino(struct seq_file *seq, struct super_block *sb)
+{
+#ifdef CONFIG_SYSFS
+	return 0;
+#else
+	int err;
+	const int len = sizeof(AUFS_XINO_FNAME) - 1;
+	aufs_bindex_t bindex, brid;
+	struct qstr *name;
+	struct file *f;
+	struct dentry *d, *h_root;
+	struct au_branch *br;
+
+	AuRwMustAnyLock(&sbinfo->si_rwsem);
+
+	err = 0;
+	f = au_sbi(sb)->si_xib;
+	if (!f)
+		goto out;
+
+	/* stop printing the default xino path on the first writable branch */
+	h_root = NULL;
+	bindex = au_xi_root(sb, f->f_path.dentry);
+	if (bindex >= 0) {
+		br = au_sbr_sb(sb, bindex);
+		h_root = au_br_dentry(br);
+	}
+
+	d = f->f_path.dentry;
+	name = &d->d_name;
+	/* safe ->d_parent because the file is unlinked */
+	if (d->d_parent == h_root
+	    && name->len == len
+	    && !memcmp(name->name, AUFS_XINO_FNAME, len))
+		goto out;
+
+	seq_puts(seq, ",xino=");
+	err = au_xino_path(seq, f);
+
+out:
+	return err;
+#endif
+}
+
 /* ---------------------------------------------------------------------- */
 
 /* final actions when unmounting a file system */

fs/aufs/super.h

@@ -63,6 +63,9 @@ struct au_sbinfo {
 	 * but using sysfs is majority.
 	 */
 	struct kobject		si_kobj;
+
+	/* dirty, necessary for unmounting, sysfs and sysrq */
+	struct super_block	*si_sb;
 };
 
 /* ---------------------------------------------------------------------- */

fs/aufs/sysaufs.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * sysfs interface and lifetime management
+ * they are necessary regardless sysfs is disabled.
+ */
+
+#include <linux/random.h>
+#include "aufs.h"
+
+unsigned long sysaufs_si_mask;
+struct kset *sysaufs_kset;
+
+#define AuSiAttr(_name) { \
+	.attr   = { .name = __stringify(_name), .mode = 0444 },	\
+	.show   = sysaufs_si_##_name,				\
+}
+
+static struct sysaufs_si_attr sysaufs_si_attr_xi_path = AuSiAttr(xi_path);
+struct attribute *sysaufs_si_attrs[] = {
+	&sysaufs_si_attr_xi_path.attr,
+	NULL,
+};
+
+static const struct sysfs_ops au_sbi_ops = {
+	.show   = sysaufs_si_show
+};
+
+static struct kobj_type au_sbi_ktype = {
+	.release	= au_si_free,
+	.sysfs_ops	= &au_sbi_ops,
+	.default_attrs	= sysaufs_si_attrs
+};
+
+/* ---------------------------------------------------------------------- */
+
+int sysaufs_si_init(struct au_sbinfo *sbinfo)
+{
+	int err;
+
+	sbinfo->si_kobj.kset = sysaufs_kset;
+	/* cf. sysaufs_name() */
+	err = kobject_init_and_add
+		(&sbinfo->si_kobj, &au_sbi_ktype, /*&sysaufs_kset->kobj*/NULL,
+		 SysaufsSiNamePrefix "%lx", sysaufs_si_id(sbinfo));
+
+	return err;
+}
+
+void sysaufs_fin(void)
+{
+	sysfs_remove_group(&sysaufs_kset->kobj, sysaufs_attr_group);
+	kset_unregister(sysaufs_kset);
+}
+
+int __init sysaufs_init(void)
+{
+	int err;
+
+	do {
+		get_random_bytes(&sysaufs_si_mask, sizeof(sysaufs_si_mask));
+	} while (!sysaufs_si_mask);
+
+	err = -EINVAL;
+	sysaufs_kset = kset_create_and_add(AUFS_NAME, NULL, fs_kobj);
+	if (unlikely(!sysaufs_kset))
+		goto out;
+	err = PTR_ERR(sysaufs_kset);
+	if (IS_ERR(sysaufs_kset))
+		goto out;
+	err = sysfs_create_group(&sysaufs_kset->kobj, sysaufs_attr_group);
+	if (unlikely(err))
+		kset_unregister(sysaufs_kset);
+
+out:
+	return err;
+}

fs/aufs/sysaufs.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * sysfs interface and mount lifetime management
+ */
+
+#ifndef __SYSAUFS_H__
+#define __SYSAUFS_H__
+
+#ifdef __KERNEL__
+
+#include <linux/sysfs.h>
+#include "module.h"
+
+struct super_block;
+struct au_sbinfo;
+
+struct sysaufs_si_attr {
+	struct attribute attr;
+	int (*show)(struct seq_file *seq, struct super_block *sb);
+};
+
+/* ---------------------------------------------------------------------- */
+
+/* sysaufs.c */
+extern unsigned long sysaufs_si_mask;
+extern struct kset *sysaufs_kset;
+extern struct attribute *sysaufs_si_attrs[];
+int sysaufs_si_init(struct au_sbinfo *sbinfo);
+int __init sysaufs_init(void);
+void sysaufs_fin(void);
+
+/* ---------------------------------------------------------------------- */
+
+/* some people doesn't like to show a pointer in kernel */
+static inline unsigned long sysaufs_si_id(struct au_sbinfo *sbinfo)
+{
+	return sysaufs_si_mask ^ (unsigned long)sbinfo;
+}
+
+#define SysaufsSiNamePrefix	"si_"
+#define SysaufsSiNameLen	(sizeof(SysaufsSiNamePrefix) + 16)
+static inline void sysaufs_name(struct au_sbinfo *sbinfo, char *name)
+{
+	snprintf(name, SysaufsSiNameLen, SysaufsSiNamePrefix "%lx",
+		 sysaufs_si_id(sbinfo));
+}
+
+struct au_branch;
+#ifdef CONFIG_SYSFS
+/* sysfs.c */
+extern struct attribute_group *sysaufs_attr_group;
+
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb);
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+			 char *buf);
+
+void sysaufs_br_init(struct au_branch *br);
+void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex);
+
+#define sysaufs_brs_init()	do {} while (0)
+
+#else
+#define sysaufs_attr_group	NULL
+
+AuStubInt0(sysaufs_si_xi_path, struct seq_file *seq, struct super_block *sb)
+AuStub(ssize_t, sysaufs_si_show, return 0, struct kobject *kobj,
+       struct attribute *attr, char *buf)
+AuStubVoid(sysaufs_br_init, struct au_branch *br)
+AuStubVoid(sysaufs_brs_add, struct super_block *sb, aufs_bindex_t bindex)
+
+static inline void sysaufs_brs_init(void)
+{
+	sysaufs_brs = 0;
+}
+
+#endif /* CONFIG_SYSFS */
+
+#endif /* __KERNEL__ */
+#endif /* __SYSAUFS_H__ */

fs/aufs/sysfs.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * sysfs interface
+ */
+
+#include <linux/seq_file.h>
+#include "aufs.h"
+
+static struct attribute *au_attr[] = {
+	NULL,	/* need to NULL terminate the list of attributes */
+};
+
+static struct attribute_group sysaufs_attr_group_body = {
+	.attrs = au_attr
+};
+
+struct attribute_group *sysaufs_attr_group = &sysaufs_attr_group_body;
+
+/* ---------------------------------------------------------------------- */
+
+int sysaufs_si_xi_path(struct seq_file *seq, struct super_block *sb)
+{
+	int err;
+
+	SiMustAnyLock(sb);
+
+	err = 0;
+	if (au_opt_test(au_mntflags(sb), XINO)) {
+		err = au_xino_path(seq, au_sbi(sb)->si_xib);
+		seq_putc(seq, '\n');
+	}
+	return err;
+}
+
+/*
+ * the lifetime of branch is independent from the entry under sysfs.
+ * sysfs handles the lifetime of the entry, and never call ->show() after it is
+ * unlinked.
+ */
+static int sysaufs_si_br(struct seq_file *seq, struct super_block *sb,
+			 aufs_bindex_t bindex, int idx)
+{
+	int err;
+	struct path path;
+	struct dentry *root;
+	struct au_branch *br;
+	au_br_perm_str_t perm;
+
+	AuDbg("b%d\n", bindex);
+
+	err = 0;
+	root = sb->s_root;
+	di_read_lock_parent(root, !AuLock_IR);
+	br = au_sbr(sb, bindex);
+
+	switch (idx) {
+	case AuBrSysfs_BR:
+		path.mnt = au_br_mnt(br);
+		path.dentry = au_h_dptr(root, bindex);
+		err = au_seq_path(seq, &path);
+		if (!err) {
+			au_optstr_br_perm(&perm, br->br_perm);
+			seq_printf(seq, "=%s\n", perm.a);
+		}
+		break;
+	case AuBrSysfs_BRID:
+		seq_printf(seq, "%d\n", br->br_id);
+		break;
+	}
+	di_read_unlock(root, !AuLock_IR);
+	if (unlikely(err || seq_has_overflowed(seq)))
+		err = -E2BIG;
+
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static struct seq_file *au_seq(char *p, ssize_t len)
+{
+	struct seq_file *seq;
+
+	seq = kzalloc(sizeof(*seq), GFP_NOFS);
+	if (seq) {
+		/* mutex_init(&seq.lock); */
+		seq->buf = p;
+		seq->size = len;
+		return seq; /* success */
+	}
+
+	seq = ERR_PTR(-ENOMEM);
+	return seq;
+}
+
+#define SysaufsBr_PREFIX	"br"
+#define SysaufsBrid_PREFIX	"brid"
+
+/* todo: file size may exceed PAGE_SIZE */
+ssize_t sysaufs_si_show(struct kobject *kobj, struct attribute *attr,
+			char *buf)
+{
+	ssize_t err;
+	int idx;
+	long l;
+	aufs_bindex_t bbot;
+	struct au_sbinfo *sbinfo;
+	struct super_block *sb;
+	struct seq_file *seq;
+	char *name;
+	struct attribute **cattr;
+
+	sbinfo = container_of(kobj, struct au_sbinfo, si_kobj);
+	sb = sbinfo->si_sb;
+
+	/*
+	 * prevent a race condition between sysfs and aufs.
+	 * for instance, sysfs_file_read() calls sysfs_get_active_two() which
+	 * prohibits maintaining the sysfs entries.
+	 * hew we acquire read lock after sysfs_get_active_two().
+	 * on the other hand, the remount process may maintain the sysfs/aufs
+	 * entries after acquiring write lock.
+	 * it can cause a deadlock.
+	 * simply we gave up processing read here.
+	 */
+	err = -EBUSY;
+	if (unlikely(!si_noflush_read_trylock(sb)))
+		goto out;
+
+	seq = au_seq(buf, PAGE_SIZE);
+	err = PTR_ERR(seq);
+	if (IS_ERR(seq))
+		goto out_unlock;
+
+	name = (void *)attr->name;
+	cattr = sysaufs_si_attrs;
+	while (*cattr) {
+		if (!strcmp(name, (*cattr)->name)) {
+			err = container_of(*cattr, struct sysaufs_si_attr, attr)
+				->show(seq, sb);
+			goto out_seq;
+		}
+		cattr++;
+	}
+
+	if (!strncmp(name, SysaufsBrid_PREFIX,
+		     sizeof(SysaufsBrid_PREFIX) - 1)) {
+		idx = AuBrSysfs_BRID;
+		name += sizeof(SysaufsBrid_PREFIX) - 1;
+	} else if (!strncmp(name, SysaufsBr_PREFIX,
+			    sizeof(SysaufsBr_PREFIX) - 1)) {
+		idx = AuBrSysfs_BR;
+		name += sizeof(SysaufsBr_PREFIX) - 1;
+	} else
+		  BUG();
+
+	err = kstrtol(name, 10, &l);
+	if (!err) {
+		bbot = au_sbbot(sb);
+		if (l <= bbot)
+			err = sysaufs_si_br(seq, sb, (aufs_bindex_t)l, idx);
+		else
+			err = -ENOENT;
+	}
+
+out_seq:
+	if (!err) {
+		err = seq->count;
+		/* sysfs limit */
+		if (unlikely(err == PAGE_SIZE))
+			err = -EFBIG;
+	}
+	au_kfree_rcu(seq);
+out_unlock:
+	si_read_unlock(sb);
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void sysaufs_br_init(struct au_branch *br)
+{
+	int i;
+	struct au_brsysfs *br_sysfs;
+	struct attribute *attr;
+
+	br_sysfs = br->br_sysfs;
+	for (i = 0; i < ARRAY_SIZE(br->br_sysfs); i++) {
+		attr = &br_sysfs->attr;
+		sysfs_attr_init(attr);
+		attr->name = br_sysfs->name;
+		attr->mode = 0444;
+		br_sysfs++;
+	}
+}
+
+void sysaufs_brs_add(struct super_block *sb, aufs_bindex_t bindex)
+{
+	int err, i;
+	aufs_bindex_t bbot;
+	struct kobject *kobj;
+	struct au_branch *br;
+	struct au_brsysfs *br_sysfs;
+
+	if (!sysaufs_brs)
+		return;
+
+	kobj = &au_sbi(sb)->si_kobj;
+	bbot = au_sbbot(sb);
+	for (; bindex <= bbot; bindex++) {
+		br = au_sbr(sb, bindex);
+		br_sysfs = br->br_sysfs;
+		snprintf(br_sysfs[AuBrSysfs_BR].name, sizeof(br_sysfs->name),
+			 SysaufsBr_PREFIX "%d", bindex);
+		snprintf(br_sysfs[AuBrSysfs_BRID].name, sizeof(br_sysfs->name),
+			 SysaufsBrid_PREFIX "%d", bindex);
+		for (i = 0; i < ARRAY_SIZE(br->br_sysfs); i++) {
+			err = sysfs_create_file(kobj, &br_sysfs->attr);
+			if (unlikely(err))
+				pr_warn("failed %s under sysfs(%d)\n",
+					br_sysfs->name, err);
+			br_sysfs++;
+		}
+	}
+}

fs/aufs/xino.c

@@ -24,6 +24,7 @@
 
 #include <linux/file.h>
 #include <linux/sched/signal.h>
+#include <linux/seq_file.h>
 #include <linux/statfs.h>
 #include <linux/uaccess.h>
 #include "aufs.h"
@@ -1454,3 +1455,23 @@ void au_xino_delete_inode(struct inode *inode, const int unlinked)
 		err = au_xino_do_write(xwrite, file, &calc, /*ino*/0);
 	}
 }
+
+/* ---------------------------------------------------------------------- */
+
+int au_xino_path(struct seq_file *seq, struct file *file)
+{
+	int err;
+
+	err = au_seq_path(seq, &file->f_path);
+	if (unlikely(err))
+		goto out;
+
+#define Deleted "\\040(deleted)"
+	seq->count -= sizeof(Deleted) - 1;
+	AuDebugOn(memcmp(seq->buf + seq->count, Deleted,
+			 sizeof(Deleted) - 1));
+#undef Deleted
+
+out:
+	return err;
+}