aufs: inode op, rename 2/2, body

Implement i_op->rename().
This is a big monster and I don't like it.

In this version, the copy-up always happen.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/Makefile

@@ -17,7 +17,7 @@ aufs-y := module.o sbinfo.o super.o branch.o xino.o sysaufs.o opts.o \
 	dynop.o \
 	finfo.o file.o \
 	dir.o vdir.o \
-	iinfo.o inode.o i_op.o i_op_add.o i_op_del.o
+	iinfo.o inode.o i_op.o i_op_add.o i_op_del.o i_op_ren.o
 
 # all are boolean
 aufs-$(CONFIG_PROC_FS) += procfs.o plink.o

fs/aufs/i_op.c

@@ -652,6 +652,7 @@ struct inode_operations aufs_iop[] = {
 		.mkdir		= aufs_mkdir,
 		.rmdir		= aufs_rmdir,
 		.mknod		= aufs_mknod,
+		.rename		= aufs_rename,
 
 		.permission	= aufs_permission,
 

fs/aufs/i_op_ren.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * inode operation (rename entry)
+ * todo: this is crazy monster
+ */
+
+#include <linux/iversion.h>
+#include "aufs.h"
+
+enum { AuSRC, AuDST, AuSrcDst };
+enum { AuPARENT, AuCHILD, AuParentChild };
+
+#define AuRen_ISDIR_SRC		1
+#define AuRen_ISDIR_DST		(1 << 1)
+#define AuRen_ISSAMEDIR		(1 << 2)
+#define AuRen_WHSRC		(1 << 3)
+#define AuRen_WHDST		(1 << 4)
+#define AuRen_MNT_WRITE		(1 << 5)
+#define AuRen_DT_DSTDIR		(1 << 6)
+#define AuRen_DIROPQ_SRC	(1 << 7)
+#define AuRen_DIROPQ_DST	(1 << 8)
+#define au_ftest_ren(flags, name)	((flags) & AuRen_##name)
+#define au_fset_ren(flags, name) \
+	do { (flags) |= AuRen_##name; } while (0)
+#define au_fclr_ren(flags, name) \
+	do { (flags) &= ~AuRen_##name; } while (0)
+
+struct au_ren_args {
+	struct {
+		struct dentry *dentry, *h_dentry, *parent, *h_parent,
+			*wh_dentry;
+		struct inode *dir, *inode;
+		struct au_hinode *hdir, *hinode;
+		struct au_dtime dt[AuParentChild];
+		aufs_bindex_t btop, bdiropq;
+	} sd[AuSrcDst];
+
+#define src_dentry	sd[AuSRC].dentry
+#define src_dir		sd[AuSRC].dir
+#define src_inode	sd[AuSRC].inode
+#define src_h_dentry	sd[AuSRC].h_dentry
+#define src_parent	sd[AuSRC].parent
+#define src_h_parent	sd[AuSRC].h_parent
+#define src_wh_dentry	sd[AuSRC].wh_dentry
+#define src_hdir	sd[AuSRC].hdir
+#define src_hinode	sd[AuSRC].hinode
+#define src_h_dir	sd[AuSRC].hdir->hi_inode
+#define src_dt		sd[AuSRC].dt
+#define src_btop	sd[AuSRC].btop
+#define src_bdiropq	sd[AuSRC].bdiropq
+
+#define dst_dentry	sd[AuDST].dentry
+#define dst_dir		sd[AuDST].dir
+#define dst_inode	sd[AuDST].inode
+#define dst_h_dentry	sd[AuDST].h_dentry
+#define dst_parent	sd[AuDST].parent
+#define dst_h_parent	sd[AuDST].h_parent
+#define dst_wh_dentry	sd[AuDST].wh_dentry
+#define dst_hdir	sd[AuDST].hdir
+#define dst_hinode	sd[AuDST].hinode
+#define dst_h_dir	sd[AuDST].hdir->hi_inode
+#define dst_dt		sd[AuDST].dt
+#define dst_btop	sd[AuDST].btop
+#define dst_bdiropq	sd[AuDST].bdiropq
+
+	struct dentry *h_trap;
+	struct au_branch *br;
+	struct path h_path;
+	struct au_nhash whlist;
+	aufs_bindex_t btgt, src_bwh;
+
+	struct {
+		unsigned short auren_flags;
+		unsigned char flags;	/* syscall parameter */
+		unsigned char exchange;
+	} __packed;
+
+	struct au_whtmp_rmdir *thargs;
+	struct dentry *h_dst;
+};
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * functions for reverting.
+ * when an error happened in a single rename systemcall, we should revert
+ * everything as if nothing happened.
+ * we don't need to revert the copied-up/down the parent dir since they are
+ * harmless.
+ */
+
+#define RevertFailure(fmt, ...) do { \
+	AuIOErr("revert failure: " fmt " (%d, %d)\n", \
+		##__VA_ARGS__, err, rerr); \
+	err = -EIO; \
+} while (0)
+
+static void au_ren_do_rev_diropq(int err, struct au_ren_args *a, int idx)
+{
+	int rerr;
+	struct dentry *d;
+#define src_or_dst(member) a->sd[idx].member
+
+	d = src_or_dst(dentry); /* {src,dst}_dentry */
+	au_hn_inode_lock_nested(src_or_dst(hinode), AuLsc_I_CHILD);
+	rerr = au_diropq_remove(d, a->btgt);
+	au_hn_inode_unlock(src_or_dst(hinode));
+	au_set_dbdiropq(d, src_or_dst(bdiropq));
+	if (rerr)
+		RevertFailure("remove diropq %pd", d);
+
+#undef src_or_dst_
+}
+
+static void au_ren_rev_diropq(int err, struct au_ren_args *a)
+{
+	if (au_ftest_ren(a->auren_flags, DIROPQ_SRC))
+		au_ren_do_rev_diropq(err, a, AuSRC);
+	if (au_ftest_ren(a->auren_flags, DIROPQ_DST))
+		au_ren_do_rev_diropq(err, a, AuDST);
+}
+
+static void au_ren_rev_rename(int err, struct au_ren_args *a)
+{
+	int rerr;
+	struct inode *delegated;
+
+	a->h_path.dentry = vfsub_lkup_one(&a->src_dentry->d_name,
+					  a->src_h_parent);
+	rerr = PTR_ERR(a->h_path.dentry);
+	if (IS_ERR(a->h_path.dentry)) {
+		RevertFailure("lkup one %pd", a->src_dentry);
+		return;
+	}
+
+	delegated = NULL;
+	rerr = vfsub_rename(a->dst_h_dir,
+			    au_h_dptr(a->src_dentry, a->btgt),
+			    a->src_h_dir, &a->h_path, &delegated, a->flags);
+	if (unlikely(rerr == -EWOULDBLOCK)) {
+		pr_warn("cannot retry for NFSv4 delegation"
+			" for an internal rename\n");
+		iput(delegated);
+	}
+	d_drop(a->h_path.dentry);
+	dput(a->h_path.dentry);
+	/* au_set_h_dptr(a->src_dentry, a->btgt, NULL); */
+	if (rerr)
+		RevertFailure("rename %pd", a->src_dentry);
+}
+
+static void au_ren_rev_whtmp(int err, struct au_ren_args *a)
+{
+	int rerr;
+	struct inode *delegated;
+
+	a->h_path.dentry = vfsub_lkup_one(&a->dst_dentry->d_name,
+					  a->dst_h_parent);
+	rerr = PTR_ERR(a->h_path.dentry);
+	if (IS_ERR(a->h_path.dentry)) {
+		RevertFailure("lkup one %pd", a->dst_dentry);
+		return;
+	}
+	if (d_is_positive(a->h_path.dentry)) {
+		d_drop(a->h_path.dentry);
+		dput(a->h_path.dentry);
+		return;
+	}
+
+	delegated = NULL;
+	rerr = vfsub_rename(a->dst_h_dir, a->h_dst, a->dst_h_dir, &a->h_path,
+			    &delegated, a->flags);
+	if (unlikely(rerr == -EWOULDBLOCK)) {
+		pr_warn("cannot retry for NFSv4 delegation"
+			" for an internal rename\n");
+		iput(delegated);
+	}
+	d_drop(a->h_path.dentry);
+	dput(a->h_path.dentry);
+	if (!rerr)
+		au_set_h_dptr(a->dst_dentry, a->btgt, dget(a->h_dst));
+	else
+		RevertFailure("rename %pd", a->h_dst);
+}
+
+static void au_ren_rev_whsrc(int err, struct au_ren_args *a)
+{
+	int rerr;
+
+	a->h_path.dentry = a->src_wh_dentry;
+	rerr = au_wh_unlink_dentry(a->src_h_dir, &a->h_path, a->src_dentry);
+	au_set_dbwh(a->src_dentry, a->src_bwh);
+	if (rerr)
+		RevertFailure("unlink %pd", a->src_wh_dentry);
+}
+#undef RevertFailure
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * when we have to copyup the renaming entry, do it with the rename-target name
+ * in order to minimize the cost (the later actual rename is unnecessary).
+ * otherwise rename it on the target branch.
+ */
+static int au_ren_or_cpup(struct au_ren_args *a)
+{
+	int err;
+	struct dentry *d;
+	struct inode *delegated;
+
+	d = a->src_dentry;
+	if (au_dbtop(d) == a->btgt) {
+		a->h_path.dentry = a->dst_h_dentry;
+		AuDebugOn(au_dbtop(d) != a->btgt);
+		delegated = NULL;
+		err = vfsub_rename(a->src_h_dir, au_h_dptr(d, a->btgt),
+				   a->dst_h_dir, &a->h_path, &delegated,
+				   a->flags);
+		if (unlikely(err == -EWOULDBLOCK)) {
+			pr_warn("cannot retry for NFSv4 delegation"
+				" for an internal rename\n");
+			iput(delegated);
+		}
+	} else
+		BUG();
+
+	if (!err && a->h_dst)
+		/* it will be set to dinfo later */
+		dget(a->h_dst);
+
+	return err;
+}
+
+/* cf. aufs_rmdir() */
+static int au_ren_del_whtmp(struct au_ren_args *a)
+{
+	struct inode *dir;
+
+	dir = a->dst_dir;
+	SiMustAnyLock(dir->i_sb);
+	au_nhash_wh_free(&a->thargs->whlist);
+	a->thargs->whlist = a->whlist;
+	a->whlist.nh_num = 0;
+	au_whtmp_kick_rmdir(dir, a->btgt, a->h_dst, a->thargs);
+	dput(a->h_dst);
+	a->thargs = NULL;
+
+	return 0;
+}
+
+/* make it 'opaque' dir. */
+static int au_ren_do_diropq(struct au_ren_args *a, int idx)
+{
+	int err;
+	struct dentry *d, *diropq;
+#define src_or_dst(member) a->sd[idx].member
+
+	err = 0;
+	d = src_or_dst(dentry); /* {src,dst}_dentry */
+	src_or_dst(bdiropq) = au_dbdiropq(d);
+	src_or_dst(hinode) = au_hi(src_or_dst(inode), a->btgt);
+	au_hn_inode_lock_nested(src_or_dst(hinode), AuLsc_I_CHILD);
+	diropq = au_diropq_create(d, a->btgt);
+	au_hn_inode_unlock(src_or_dst(hinode));
+	if (IS_ERR(diropq))
+		err = PTR_ERR(diropq);
+	else
+		dput(diropq);
+
+#undef src_or_dst_
+	return err;
+}
+
+static int au_ren_diropq(struct au_ren_args *a)
+{
+	int err;
+	struct dentry *d;
+
+	err = 0;
+	d = a->dst_dentry; /* already renamed on the branch */
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC)
+	    && a->btgt != au_dbdiropq(a->src_dentry)
+	    && (a->dst_wh_dentry
+		|| a->btgt <= au_dbdiropq(d)
+		/* hide the lower to keep xino */
+		/* the lowers may not be a dir, but we hide them anyway */
+		|| a->btgt < au_dbbot(d))) {
+		AuDbg("here\n");
+		err = au_ren_do_diropq(a, AuSRC);
+		if (unlikely(err))
+			goto out;
+		au_fset_ren(a->auren_flags, DIROPQ_SRC);
+	}
+	if (!a->exchange)
+		goto out; /* success */
+
+	d = a->src_dentry; /* already renamed on the branch */
+	if (au_ftest_ren(a->auren_flags, ISDIR_DST)
+	    && a->btgt != au_dbdiropq(a->dst_dentry)
+	    && (a->btgt < au_dbdiropq(d)
+		|| a->btgt < au_dbbot(d))) {
+		AuDbgDentry(a->src_dentry);
+		AuDbgDentry(a->dst_dentry);
+		err = au_ren_do_diropq(a, AuDST);
+		if (unlikely(err))
+			goto out_rev_src;
+		au_fset_ren(a->auren_flags, DIROPQ_DST);
+	}
+	goto out; /* success */
+
+out_rev_src:
+	AuDbg("err %d, reverting src\n", err);
+	au_ren_rev_diropq(err, a);
+out:
+	return err;
+}
+
+static int do_rename(struct au_ren_args *a)
+{
+	int err;
+	struct dentry *d, *h_d;
+
+	if (!a->exchange) {
+		/* prepare workqueue args for asynchronous rmdir */
+		h_d = a->dst_h_dentry;
+		if (au_ftest_ren(a->auren_flags, ISDIR_DST)
+		    && d_is_positive(h_d)) {
+			err = -ENOMEM;
+			a->thargs = au_whtmp_rmdir_alloc(a->src_dentry->d_sb,
+							 GFP_NOFS);
+			if (unlikely(!a->thargs))
+				goto out;
+			a->h_dst = dget(h_d);
+		}
+
+		/* create whiteout for src_dentry */
+		if (au_ftest_ren(a->auren_flags, WHSRC)) {
+			a->src_bwh = au_dbwh(a->src_dentry);
+			AuDebugOn(a->src_bwh >= 0);
+			a->src_wh_dentry = au_wh_create(a->src_dentry, a->btgt,
+							a->src_h_parent);
+			err = PTR_ERR(a->src_wh_dentry);
+			if (IS_ERR(a->src_wh_dentry))
+				goto out_thargs;
+		}
+
+		/* lookup whiteout for dentry */
+		if (au_ftest_ren(a->auren_flags, WHDST)) {
+			h_d = au_wh_lkup(a->dst_h_parent,
+					 &a->dst_dentry->d_name, a->br);
+			err = PTR_ERR(h_d);
+			if (IS_ERR(h_d))
+				goto out_whsrc;
+			if (d_is_negative(h_d))
+				dput(h_d);
+			else
+				a->dst_wh_dentry = h_d;
+		}
+
+		/* rename dentry to tmpwh */
+		if (a->thargs) {
+			err = au_whtmp_ren(a->dst_h_dentry, a->br);
+			if (unlikely(err))
+				goto out_whdst;
+
+			d = a->dst_dentry;
+			au_set_h_dptr(d, a->btgt, NULL);
+			err = au_lkup_neg(d, a->btgt, /*wh*/0);
+			if (unlikely(err))
+				goto out_whtmp;
+			a->dst_h_dentry = au_h_dptr(d, a->btgt);
+		}
+	}
+
+	BUG_ON(d_is_positive(a->dst_h_dentry) && a->src_btop != a->btgt);
+#if 0
+	BUG_ON(!au_ftest_ren(a->auren_flags, DIRREN)
+	       && d_is_positive(a->dst_h_dentry)
+	       && a->src_btop != a->btgt);
+#endif
+
+	/* rename by vfs_rename or cpup */
+	err = au_ren_or_cpup(a);
+	if (unlikely(err))
+		/* leave the copied-up one */
+		goto out_whtmp;
+
+	/* make dir opaque */
+	err = au_ren_diropq(a);
+	if (unlikely(err))
+		goto out_rename;
+
+	/* update target timestamps */
+	AuDebugOn(au_dbtop(a->src_dentry) != a->btgt);
+	a->h_path.dentry = au_h_dptr(a->src_dentry, a->btgt);
+	a->src_inode->i_ctime = d_inode(a->h_path.dentry)->i_ctime;
+
+	if (!a->exchange) {
+		/* remove whiteout for dentry */
+		if (a->dst_wh_dentry) {
+			a->h_path.dentry = a->dst_wh_dentry;
+			err = au_wh_unlink_dentry(a->dst_h_dir, &a->h_path,
+						  a->dst_dentry);
+			if (unlikely(err))
+				goto out_diropq;
+		}
+
+		/* remove whtmp */
+		if (a->thargs)
+			au_ren_del_whtmp(a); /* ignore this error */
+	}
+	err = 0;
+	goto out_success;
+
+out_diropq:
+	au_ren_rev_diropq(err, a);
+out_rename:
+	au_ren_rev_rename(err, a);
+	dput(a->h_dst);
+out_whtmp:
+	if (a->thargs)
+		au_ren_rev_whtmp(err, a);
+out_whdst:
+	dput(a->dst_wh_dentry);
+	a->dst_wh_dentry = NULL;
+out_whsrc:
+	if (a->src_wh_dentry)
+		au_ren_rev_whsrc(err, a);
+out_success:
+	dput(a->src_wh_dentry);
+	dput(a->dst_wh_dentry);
+out_thargs:
+	if (a->thargs) {
+		dput(a->h_dst);
+		au_whtmp_rmdir_free(a->thargs);
+		a->thargs = NULL;
+	}
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * test if @dentry dir can be rename destination or not.
+ * success means, it is a logically empty dir.
+ */
+static int may_rename_dstdir(struct dentry *dentry, struct au_nhash *whlist)
+{
+	return au_test_empty(dentry, whlist);
+}
+
+/*
+ * test if @dentry dir can be rename source or not.
+ * if it can, return 0.
+ * success means,
+ * - it is a logically empty dir.
+ * - or, it exists on writable branch and has no children including whiteouts
+ *   on the lower branch.
+ */
+static int may_rename_srcdir(struct dentry *dentry, aufs_bindex_t btgt)
+{
+	int err;
+	unsigned int rdhash;
+	aufs_bindex_t btop;
+	struct super_block *sb;
+
+	sb = dentry->d_sb;
+	btop = au_dbtop(dentry);
+	if (btop != btgt) {
+		struct au_nhash whlist;
+
+		SiMustAnyLock(sb);
+		rdhash = au_sbi(sb)->si_rdhash;
+		if (!rdhash)
+			rdhash = au_rdhash_est(au_dir_size(/*file*/NULL,
+							   dentry));
+		err = au_nhash_alloc(&whlist, rdhash, GFP_NOFS);
+		if (unlikely(err))
+			goto out;
+		err = au_test_empty(dentry, &whlist);
+		au_nhash_wh_free(&whlist);
+		goto out;
+	}
+
+	if (btop == au_dbtaildir(dentry))
+		return 0; /* success */
+
+	err = au_test_empty_lower(dentry);
+
+out:
+	if (err == -ENOTEMPTY) {
+		AuWarn1("renaming dir who has child(ren) on multiple branches,"
+			" is not supported\n");
+		err = -EXDEV;
+	}
+	return err;
+}
+
+/* side effect: sets whlist and h_dentry */
+static int au_ren_may_dir(struct au_ren_args *a)
+{
+	int err;
+	unsigned int rdhash;
+	struct dentry *d;
+
+	d = a->dst_dentry;
+	SiMustAnyLock(d->d_sb);
+
+	err = 0;
+	if (au_ftest_ren(a->auren_flags, ISDIR_DST) && a->dst_inode) {
+		rdhash = au_sbi(d->d_sb)->si_rdhash;
+		if (!rdhash)
+			rdhash = au_rdhash_est(au_dir_size(/*file*/NULL, d));
+		err = au_nhash_alloc(&a->whlist, rdhash, GFP_NOFS);
+		if (unlikely(err))
+			goto out;
+
+		if (!a->exchange) {
+			au_set_dbtop(d, a->dst_btop);
+			err = may_rename_dstdir(d, &a->whlist);
+			au_set_dbtop(d, a->btgt);
+		} else
+			err = may_rename_srcdir(d, a->btgt);
+	}
+	a->dst_h_dentry = au_h_dptr(d, au_dbtop(d));
+	if (unlikely(err))
+		goto out;
+
+	d = a->src_dentry;
+	a->src_h_dentry = au_h_dptr(d, au_dbtop(d));
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC)) {
+		err = may_rename_srcdir(d, a->btgt);
+		if (unlikely(err)) {
+			au_nhash_wh_free(&a->whlist);
+			a->whlist.nh_num = 0;
+		}
+	}
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * simple tests for rename.
+ * following the checks in vfs, plus the parent-child relationship.
+ */
+static int au_may_ren(struct au_ren_args *a)
+{
+	int err, isdir;
+	struct inode *h_inode;
+
+	if (a->src_btop == a->btgt) {
+		err = au_may_del(a->src_dentry, a->btgt, a->src_h_parent,
+				 au_ftest_ren(a->auren_flags, ISDIR_SRC));
+		if (unlikely(err))
+			goto out;
+		err = -EINVAL;
+		if (unlikely(a->src_h_dentry == a->h_trap))
+			goto out;
+	}
+
+	err = 0;
+	if (a->dst_btop != a->btgt)
+		goto out;
+
+	err = -ENOTEMPTY;
+	if (unlikely(a->dst_h_dentry == a->h_trap))
+		goto out;
+
+	err = -EIO;
+	isdir = !!au_ftest_ren(a->auren_flags, ISDIR_DST);
+	if (d_really_is_negative(a->dst_dentry)) {
+		if (d_is_negative(a->dst_h_dentry))
+			err = au_may_add(a->dst_dentry, a->btgt,
+					 a->dst_h_parent, isdir);
+	} else {
+		if (unlikely(d_is_negative(a->dst_h_dentry)))
+			goto out;
+		h_inode = d_inode(a->dst_h_dentry);
+		if (h_inode->i_nlink)
+			err = au_may_del(a->dst_dentry, a->btgt,
+					 a->dst_h_parent, isdir);
+	}
+
+out:
+	if (unlikely(err == -ENOENT || err == -EEXIST))
+		err = -EIO;
+	AuTraceErr(err);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+/*
+ * locking order
+ * (VFS)
+ * - src_dir and dir by lock_rename()
+ * - inode if exists
+ * (aufs)
+ * - lock all
+ *   + src_dentry and dentry by aufs_read_and_write_lock2() which calls,
+ *     + si_read_lock
+ *     + di_write_lock2_child()
+ *       + di_write_lock_child()
+ *	   + ii_write_lock_child()
+ *       + di_write_lock_child2()
+ *	   + ii_write_lock_child2()
+ *     + src_parent and parent
+ *       + di_write_lock_parent()
+ *	   + ii_write_lock_parent()
+ *       + di_write_lock_parent2()
+ *	   + ii_write_lock_parent2()
+ *   + lower src_dir and dir by vfsub_lock_rename()
+ *   + verify the every relationships between child and parent. if any
+ *     of them failed, unlock all and return -EBUSY.
+ */
+static void au_ren_unlock(struct au_ren_args *a)
+{
+	vfsub_unlock_rename(a->src_h_parent, a->src_hdir,
+			    a->dst_h_parent, a->dst_hdir);
+	if (au_ftest_ren(a->auren_flags, MNT_WRITE))
+		vfsub_mnt_drop_write(au_br_mnt(a->br));
+}
+
+static int au_ren_lock(struct au_ren_args *a)
+{
+	int err;
+	unsigned int udba;
+
+	err = 0;
+	a->src_h_parent = au_h_dptr(a->src_parent, a->btgt);
+	a->src_hdir = au_hi(a->src_dir, a->btgt);
+	a->dst_h_parent = au_h_dptr(a->dst_parent, a->btgt);
+	a->dst_hdir = au_hi(a->dst_dir, a->btgt);
+
+	err = vfsub_mnt_want_write(au_br_mnt(a->br));
+	if (unlikely(err))
+		goto out;
+	au_fset_ren(a->auren_flags, MNT_WRITE);
+	a->h_trap = vfsub_lock_rename(a->src_h_parent, a->src_hdir,
+				      a->dst_h_parent, a->dst_hdir);
+	udba = au_opt_udba(a->src_dentry->d_sb);
+	if (unlikely(a->src_hdir->hi_inode != d_inode(a->src_h_parent)
+		     || a->dst_hdir->hi_inode != d_inode(a->dst_h_parent)))
+		err = au_busy_or_stale();
+	if (!err && au_dbtop(a->src_dentry) == a->btgt)
+		err = au_h_verify(a->src_h_dentry, udba,
+				  d_inode(a->src_h_parent), a->src_h_parent,
+				  a->br);
+	if (!err && au_dbtop(a->dst_dentry) == a->btgt)
+		err = au_h_verify(a->dst_h_dentry, udba,
+				  d_inode(a->dst_h_parent), a->dst_h_parent,
+				  a->br);
+	if (!err)
+		goto out; /* success */
+
+	err = au_busy_or_stale();
+	au_ren_unlock(a);
+
+out:
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+static void au_ren_refresh_dir(struct au_ren_args *a)
+{
+	struct inode *dir;
+
+	dir = a->dst_dir;
+	inode_inc_iversion(dir);
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC)) {
+		/* is this updating defined in POSIX? */
+		au_cpup_attr_timesizes(a->src_inode);
+		au_cpup_attr_nlink(dir, /*force*/1);
+	}
+	au_dir_ts(dir, a->btgt);
+
+	if (a->exchange) {
+		dir = a->src_dir;
+		inode_inc_iversion(dir);
+		if (au_ftest_ren(a->auren_flags, ISDIR_DST)) {
+			/* is this updating defined in POSIX? */
+			au_cpup_attr_timesizes(a->dst_inode);
+			au_cpup_attr_nlink(dir, /*force*/1);
+		}
+		au_dir_ts(dir, a->btgt);
+	}
+
+	if (au_ftest_ren(a->auren_flags, ISSAMEDIR))
+		return;
+
+	dir = a->src_dir;
+	inode_inc_iversion(dir);
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC))
+		au_cpup_attr_nlink(dir, /*force*/1);
+	au_dir_ts(dir, a->btgt);
+}
+
+static void au_ren_refresh(struct au_ren_args *a)
+{
+	aufs_bindex_t bbot, bindex;
+	struct dentry *d, *h_d;
+	struct inode *i, *h_i;
+	struct super_block *sb;
+
+	d = a->dst_dentry;
+	d_drop(d);
+	if (a->h_dst)
+		/* already dget-ed by au_ren_or_cpup() */
+		au_set_h_dptr(d, a->btgt, a->h_dst);
+
+	i = a->dst_inode;
+	if (i) {
+		if (!a->exchange) {
+			if (!au_ftest_ren(a->auren_flags, ISDIR_DST))
+				vfsub_drop_nlink(i);
+			else {
+				vfsub_dead_dir(i);
+				au_cpup_attr_timesizes(i);
+			}
+			au_update_dbrange(d, /*do_put_zero*/1);
+		} else
+			au_cpup_attr_nlink(i, /*force*/1);
+	} else {
+		bbot = a->btgt;
+		for (bindex = au_dbtop(d); bindex < bbot; bindex++)
+			au_set_h_dptr(d, bindex, NULL);
+		bbot = au_dbbot(d);
+		for (bindex = a->btgt + 1; bindex <= bbot; bindex++)
+			au_set_h_dptr(d, bindex, NULL);
+		au_update_dbrange(d, /*do_put_zero*/0);
+	}
+
+	d = a->src_dentry;
+	if (!a->exchange) {
+		au_set_dbwh(d, -1);
+		bbot = au_dbbot(d);
+		for (bindex = a->btgt + 1; bindex <= bbot; bindex++) {
+			h_d = au_h_dptr(d, bindex);
+			if (h_d)
+				au_set_h_dptr(d, bindex, NULL);
+		}
+		au_set_dbbot(d, a->btgt);
+
+		sb = d->d_sb;
+		i = a->src_inode;
+		if (au_opt_test(au_mntflags(sb), PLINK) && au_plink_test(i))
+			return; /* success */
+
+		bbot = au_ibbot(i);
+		for (bindex = a->btgt + 1; bindex <= bbot; bindex++) {
+			h_i = au_h_iptr(i, bindex);
+			if (h_i) {
+				au_xino_write(sb, bindex, h_i->i_ino, /*ino*/0);
+				/* ignore this error */
+				au_set_h_iptr(i, bindex, NULL, 0);
+			}
+		}
+		au_set_ibbot(i, a->btgt);
+	}
+	d_drop(a->src_dentry);
+}
+
+/* ---------------------------------------------------------------------- */
+
+/* mainly for link(2) and rename(2) */
+int au_wbr(struct dentry *dentry, aufs_bindex_t btgt)
+{
+	aufs_bindex_t bdiropq, bwh;
+	struct dentry *parent;
+	struct au_branch *br;
+
+	parent = dentry->d_parent;
+	IMustLock(d_inode(parent)); /* dir is locked */
+
+	bdiropq = au_dbdiropq(parent);
+	bwh = au_dbwh(dentry);
+	br = au_sbr(dentry->d_sb, btgt);
+	if (au_br_rdonly(br)
+	    || (0 <= bdiropq && bdiropq < btgt)
+	    || (0 <= bwh && bwh < btgt))
+		btgt = -1;
+
+	AuDbg("btgt %d\n", btgt);
+	return btgt;
+}
+
+/* sets src_btop, dst_btop and btgt */
+static int au_ren_wbr(struct au_ren_args *a)
+{
+	int err;
+	struct au_wr_dir_args wr_dir_args = {
+		/* .force_btgt	= -1, */
+		.flags		= AuWrDir_ADD_ENTRY
+	};
+
+	a->src_btop = au_dbtop(a->src_dentry);
+	a->dst_btop = au_dbtop(a->dst_dentry);
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC)
+	    || au_ftest_ren(a->auren_flags, ISDIR_DST))
+		au_fset_wrdir(wr_dir_args.flags, ISDIR);
+	wr_dir_args.force_btgt = a->src_btop;
+	if (a->dst_inode && a->dst_btop < a->src_btop)
+		wr_dir_args.force_btgt = a->dst_btop;
+	wr_dir_args.force_btgt = au_wbr(a->dst_dentry, wr_dir_args.force_btgt);
+	err = au_wr_dir(a->dst_dentry, a->src_dentry, &wr_dir_args);
+	a->btgt = err;
+	if (a->exchange)
+		au_update_dbtop(a->dst_dentry);
+
+	return err;
+}
+
+static void au_ren_dt(struct au_ren_args *a)
+{
+	a->h_path.dentry = a->src_h_parent;
+	au_dtime_store(a->src_dt + AuPARENT, a->src_parent, &a->h_path);
+	if (!au_ftest_ren(a->auren_flags, ISSAMEDIR)) {
+		a->h_path.dentry = a->dst_h_parent;
+		au_dtime_store(a->dst_dt + AuPARENT, a->dst_parent, &a->h_path);
+	}
+
+	au_fclr_ren(a->auren_flags, DT_DSTDIR);
+	if (!au_ftest_ren(a->auren_flags, ISDIR_SRC)
+	    && !a->exchange)
+		return;
+
+	a->h_path.dentry = a->src_h_dentry;
+	au_dtime_store(a->src_dt + AuCHILD, a->src_dentry, &a->h_path);
+	if (d_is_positive(a->dst_h_dentry)) {
+		au_fset_ren(a->auren_flags, DT_DSTDIR);
+		a->h_path.dentry = a->dst_h_dentry;
+		au_dtime_store(a->dst_dt + AuCHILD, a->dst_dentry, &a->h_path);
+	}
+}
+
+static void au_ren_rev_dt(int err, struct au_ren_args *a)
+{
+	struct dentry *h_d;
+	struct inode *h_inode;
+
+	au_dtime_revert(a->src_dt + AuPARENT);
+	if (!au_ftest_ren(a->auren_flags, ISSAMEDIR))
+		au_dtime_revert(a->dst_dt + AuPARENT);
+
+	if (au_ftest_ren(a->auren_flags, ISDIR_SRC) && err != -EIO) {
+		h_d = a->src_dt[AuCHILD].dt_h_path.dentry;
+		h_inode = d_inode(h_d);
+		inode_lock_nested(h_inode, AuLsc_I_CHILD);
+		au_dtime_revert(a->src_dt + AuCHILD);
+		inode_unlock(h_inode);
+
+		if (au_ftest_ren(a->auren_flags, DT_DSTDIR)) {
+			h_d = a->dst_dt[AuCHILD].dt_h_path.dentry;
+			h_inode = d_inode(h_d);
+			inode_lock_nested(h_inode, AuLsc_I_CHILD);
+			au_dtime_revert(a->dst_dt + AuCHILD);
+			inode_unlock(h_inode);
+		}
+	}
+}
+
+/* ---------------------------------------------------------------------- */
+
+int aufs_rename(struct inode *_src_dir, struct dentry *_src_dentry,
+		struct inode *_dst_dir, struct dentry *_dst_dentry,
+		unsigned int _flags)
+{
+	int err, lock_flags;
+	/* reduce stack space */
+	struct au_ren_args *a;
+	struct au_pin pin;
+
+	AuDbg("%pd, %pd, 0x%x\n", _src_dentry, _dst_dentry, _flags);
+	IMustLock(_src_dir);
+	IMustLock(_dst_dir);
+
+	err = -EINVAL;
+	if (unlikely(_flags & RENAME_WHITEOUT))
+		goto out;
+
+	err = -ENOMEM;
+	BUILD_BUG_ON(sizeof(*a) > PAGE_SIZE);
+	a = kzalloc(sizeof(*a), GFP_NOFS);
+	if (unlikely(!a))
+		goto out;
+
+	a->flags = _flags;
+	BUILD_BUG_ON(sizeof(a->exchange) == sizeof(u8)
+		     && RENAME_EXCHANGE > U8_MAX);
+	a->exchange = _flags & RENAME_EXCHANGE;
+	a->src_dir = _src_dir;
+	a->src_dentry = _src_dentry;
+	a->src_inode = NULL;
+	if (d_really_is_positive(a->src_dentry))
+		a->src_inode = d_inode(a->src_dentry);
+	a->src_parent = a->src_dentry->d_parent; /* dir inode is locked */
+	a->dst_dir = _dst_dir;
+	a->dst_dentry = _dst_dentry;
+	a->dst_inode = NULL;
+	if (d_really_is_positive(a->dst_dentry))
+		a->dst_inode = d_inode(a->dst_dentry);
+	a->dst_parent = a->dst_dentry->d_parent; /* dir inode is locked */
+	if (a->dst_inode) {
+		/*
+		 * if EXCHANGE && src is non-dir && dst is dir,
+		 * dst is not locked.
+		 */
+		/* IMustLock(a->dst_inode); */
+		au_igrab(a->dst_inode);
+	}
+
+	err = -ENOTDIR;
+	lock_flags = AuLock_FLUSH | AuLock_NOPLM | AuLock_GEN;
+	if (d_is_dir(a->src_dentry)) {
+		au_fset_ren(a->auren_flags, ISDIR_SRC);
+		if (unlikely(!a->exchange
+			     && d_really_is_positive(a->dst_dentry)
+			     && !d_is_dir(a->dst_dentry)))
+			goto out_free;
+		lock_flags |= AuLock_DIRS;
+	}
+	if (a->dst_inode && d_is_dir(a->dst_dentry)) {
+		au_fset_ren(a->auren_flags, ISDIR_DST);
+		if (unlikely(!a->exchange
+			     && d_really_is_positive(a->src_dentry)
+			     && !d_is_dir(a->src_dentry)))
+			goto out_free;
+		lock_flags |= AuLock_DIRS;
+	}
+	err = aufs_read_and_write_lock2(a->dst_dentry, a->src_dentry,
+					lock_flags);
+	if (unlikely(err))
+		goto out_free;
+
+	err = au_d_hashed_positive(a->src_dentry);
+	if (unlikely(err))
+		goto out_unlock;
+	err = -ENOENT;
+	if (a->dst_inode) {
+		/*
+		 * If it is a dir, VFS unhash it before this
+		 * function. It means we cannot rely upon d_unhashed().
+		 */
+		if (unlikely(!a->dst_inode->i_nlink))
+			goto out_unlock;
+		if (!au_ftest_ren(a->auren_flags, ISDIR_DST)) {
+			err = au_d_hashed_positive(a->dst_dentry);
+			if (unlikely(err && !a->exchange))
+				goto out_unlock;
+		} else if (unlikely(IS_DEADDIR(a->dst_inode)))
+			goto out_unlock;
+	} else if (unlikely(d_unhashed(a->dst_dentry)))
+		goto out_unlock;
+
+	/*
+	 * is it possible?
+	 * yes, it happened (in linux-3.3-rcN) but I don't know why.
+	 * there may exist a problem somewhere else.
+	 */
+	err = -EINVAL;
+	if (unlikely(d_inode(a->dst_parent) == d_inode(a->src_dentry)))
+		goto out_unlock;
+
+	au_fset_ren(a->auren_flags, ISSAMEDIR); /* temporary */
+	di_write_lock_parent(a->dst_parent);
+
+	/* which branch we process */
+	err = au_ren_wbr(a);
+	if (unlikely(err < 0))
+		goto out_parent;
+	a->br = au_sbr(a->dst_dentry->d_sb, a->btgt);
+	a->h_path.mnt = au_br_mnt(a->br);
+
+	/* are they available to be renamed */
+	err = au_ren_may_dir(a);
+	if (unlikely(err))
+		goto out_children;
+
+	/* prepare the writable parent dir on the same branch */
+	if (a->dst_btop == a->btgt) {
+		au_fset_ren(a->auren_flags, WHDST);
+	} else {
+		err = au_cpup_dirs(a->dst_dentry, a->btgt);
+		if (unlikely(err))
+			goto out_children;
+	}
+
+	err = 0;
+	if (!a->exchange) {
+		if (a->src_dir != a->dst_dir) {
+			/*
+			 * this temporary unlock is safe,
+			 * because both dir->i_mutex are locked.
+			 */
+			di_write_unlock(a->dst_parent);
+			di_write_lock_parent(a->src_parent);
+			err = au_wr_dir_need_wh(a->src_dentry,
+						au_ftest_ren(a->auren_flags,
+							     ISDIR_SRC),
+						&a->btgt);
+			di_write_unlock(a->src_parent);
+			di_write_lock2_parent(a->src_parent, a->dst_parent,
+					      /*isdir*/1);
+			au_fclr_ren(a->auren_flags, ISSAMEDIR);
+		} else
+			err = au_wr_dir_need_wh(a->src_dentry,
+						au_ftest_ren(a->auren_flags,
+							     ISDIR_SRC),
+						&a->btgt);
+	}
+	if (unlikely(err < 0))
+		goto out_children;
+	if (err)
+		au_fset_ren(a->auren_flags, WHSRC);
+
+	/* cpup src */
+	if (a->src_btop != a->btgt) {
+		err = au_pin(&pin, a->src_dentry, a->btgt,
+			     au_opt_udba(a->src_dentry->d_sb),
+			     AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+		if (!err) {
+			struct au_cp_generic cpg = {
+				.dentry	= a->src_dentry,
+				.bdst	= a->btgt,
+				.bsrc	= a->src_btop,
+				.len	= -1,
+				.pin	= &pin,
+				.flags	= AuCpup_DTIME
+			};
+			AuDebugOn(au_dbtop(a->src_dentry) != a->src_btop);
+			err = au_sio_cpup_simple(&cpg);
+			au_unpin(&pin);
+		}
+		if (unlikely(err))
+			goto out_children;
+		a->src_btop = a->btgt;
+		a->src_h_dentry = au_h_dptr(a->src_dentry, a->btgt);
+		if (!a->exchange)
+			au_fset_ren(a->auren_flags, WHSRC);
+	}
+
+	/* cpup dst */
+	if (a->exchange && a->dst_inode
+	    && a->dst_btop != a->btgt) {
+		err = au_pin(&pin, a->dst_dentry, a->btgt,
+			     au_opt_udba(a->dst_dentry->d_sb),
+			     AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+		if (!err) {
+			struct au_cp_generic cpg = {
+				.dentry	= a->dst_dentry,
+				.bdst	= a->btgt,
+				.bsrc	= a->dst_btop,
+				.len	= -1,
+				.pin	= &pin,
+				.flags	= AuCpup_DTIME
+			};
+			err = au_sio_cpup_simple(&cpg);
+			au_unpin(&pin);
+		}
+		if (unlikely(err))
+			goto out_children;
+		a->dst_btop = a->btgt;
+		a->dst_h_dentry = au_h_dptr(a->dst_dentry, a->btgt);
+	}
+
+	/* lock them all */
+	err = au_ren_lock(a);
+	if (unlikely(err))
+		/* leave the copied-up one */
+		goto out_children;
+
+	if (!a->exchange) {
+		if (!au_opt_test(au_mntflags(a->dst_dir->i_sb), UDBA_NONE))
+			err = au_may_ren(a);
+		else if (unlikely(a->dst_dentry->d_name.len > AUFS_MAX_NAMELEN))
+			err = -ENAMETOOLONG;
+		if (unlikely(err))
+			goto out_hdir;
+	}
+
+	/* store timestamps to be revertible */
+	au_ren_dt(a);
+
+	/* here we go */
+	err = do_rename(a);
+	if (unlikely(err))
+		goto out_dt;
+
+	/* update dir attributes */
+	au_ren_refresh_dir(a);
+
+	/* dput/iput all lower dentries */
+	au_ren_refresh(a);
+
+	goto out_hdir; /* success */
+
+out_dt:
+	au_ren_rev_dt(err, a);
+out_hdir:
+	au_ren_unlock(a);
+out_children:
+	au_nhash_wh_free(&a->whlist);
+	if (err && a->dst_inode && a->dst_btop != a->btgt) {
+		AuDbg("btop %d, btgt %d\n", a->dst_btop, a->btgt);
+		au_set_h_dptr(a->dst_dentry, a->btgt, NULL);
+		au_set_dbtop(a->dst_dentry, a->dst_btop);
+	}
+out_parent:
+	if (!err) {
+		if (!a->exchange)
+			d_move(a->src_dentry, a->dst_dentry);
+		else
+			d_exchange(a->src_dentry, a->dst_dentry);
+	} else {
+		au_update_dbtop(a->dst_dentry);
+		if (!a->dst_inode)
+			d_drop(a->dst_dentry);
+	}
+	if (au_ftest_ren(a->auren_flags, ISSAMEDIR))
+		di_write_unlock(a->dst_parent);
+	else
+		di_write_unlock2(a->src_parent, a->dst_parent);
+out_unlock:
+	aufs_read_and_write_unlock2(a->dst_dentry, a->src_dentry);
+out_free:
+	iput(a->dst_inode);
+	if (a->thargs)
+		au_whtmp_rmdir_free(a->thargs);
+	au_kfree_rcu(a);
+out:
+	AuTraceErr(err);
+	return err;
+}

fs/aufs/inode.h

@@ -179,6 +179,12 @@ int au_may_del(struct dentry *dentry, aufs_bindex_t bindex,
 int aufs_unlink(struct inode *dir, struct dentry *dentry);
 int aufs_rmdir(struct inode *dir, struct dentry *dentry);
 
+/* i_op_ren.c */
+int au_wbr(struct dentry *dentry, aufs_bindex_t btgt);
+int aufs_rename(struct inode *src_dir, struct dentry *src_dentry,
+		struct inode *dir, struct dentry *dentry,
+		unsigned int flags);
+
 /* iinfo.c */
 struct inode *au_h_iptr(struct inode *inode, aufs_bindex_t bindex);
 void au_hiput(struct au_hinode *hinode);