aufs: inode op, add an entry

Here are entry adding inode operations, i_op->create(), symlink(),
mkdir(), mknod(), and tmpfile().
Obviously they return EOPNOTSUPP when the target branch fs doesn't
support the operation.
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
+	iinfo.o inode.o i_op.o i_op_add.o
 
 # all are boolean
 aufs-$(CONFIG_PROC_FS) += procfs.o plink.o

fs/aufs/debug.c

@@ -210,9 +210,10 @@ void au_dpri_dentry(struct dentry *dentry)
 	dinfo = au_di(dentry);
 	if (!dinfo)
 		return;
-	dpri("d-1: btop %d, bbot %d, bwh %d, bdiropq %d, gen %d\n",
+	dpri("d-1: btop %d, bbot %d, bwh %d, bdiropq %d, gen %d, tmp %d\n",
 	     dinfo->di_btop, dinfo->di_bbot,
-	     dinfo->di_bwh, dinfo->di_bdiropq, au_digen(dentry));
+	     dinfo->di_bwh, dinfo->di_bdiropq, au_digen(dentry),
+	     dinfo->di_tmpfile);
 	if (dinfo->di_btop < 0)
 		return;
 	for (bindex = dinfo->di_btop; bindex <= dinfo->di_bbot; bindex++)

fs/aufs/dentry.c

@@ -704,7 +704,7 @@ int au_refresh_dentry(struct dentry *dentry, struct dentry *parent)
 	if (!ebrange)
 		ebrange = au_do_refresh_hdentry(dentry, parent);
 
-	if (d_unhashed(dentry) || ebrange) {
+	if (d_unhashed(dentry) || ebrange /* || dinfo->di_tmpfile */) {
 		AuDebugOn(au_dbtop(dentry) < 0 && au_dbbot(dentry) >= 0);
 		if (d_really_is_positive(dentry)) {
 			inode = d_inode(dentry);
@@ -793,7 +793,7 @@ static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
 	int err;
 	umode_t mode, h_mode;
 	aufs_bindex_t bindex, btail, btop, ibs, ibe;
-	unsigned char plus, unhashed, is_root, h_plus, h_nfs;
+	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;
@@ -806,6 +806,7 @@ static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
 	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
@@ -838,7 +839,8 @@ static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
 			     && !is_root
 			     && ((!h_nfs
 				  && (unhashed != !!d_unhashed(h_dentry)
-				      || !au_qstreq(name, h_name)
+				      || (!tmpfile
+					  && !au_qstreq(name, h_name))
 					  ))
 				 || (h_nfs
 				     && !(flags & LOOKUP_OPEN)
@@ -882,7 +884,7 @@ static int h_d_revalidate(struct dentry *dentry, struct inode *inode,
 			h_cached_inode = au_h_iptr(inode, bindex);
 
 		if (!h_nfs) {
-			if (unlikely(plus != h_plus))
+			if (unlikely(plus != h_plus && !tmpfile))
 				goto err;
 		} else {
 			if (unlikely(!(h_dentry->d_flags & DCACHE_NFSFS_RENAMED)

fs/aufs/dentry.h

@@ -25,6 +25,7 @@ struct au_dinfo {
 
 	struct au_rwsem		di_rwsem;
 	aufs_bindex_t		di_btop, di_bbot, di_bwh, di_bdiropq;
+	unsigned char		di_tmpfile; /* to allow the different name */
 	struct au_hdentry	*di_hdentry;
 	struct rcu_head		rcu;
 } ____cacheline_aligned_in_smp;
@@ -87,6 +88,7 @@ void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
 int au_digen_test(struct dentry *dentry, unsigned int sigen);
 int au_dbrange_test(struct dentry *dentry);
 void au_update_digen(struct dentry *dentry);
+void au_update_dbrange(struct dentry *dentry, int do_put_zero);
 void au_update_dbtop(struct dentry *dentry);
 void au_update_dbbot(struct dentry *dentry);
 int au_find_dbindex(struct dentry *dentry, struct dentry *h_dentry);

fs/aufs/dinfo.c

@@ -35,6 +35,7 @@ struct au_dinfo *au_di_alloc(struct super_block *sb, unsigned int lsc)
 		dinfo->di_bbot = -1;
 		dinfo->di_bwh = -1;
 		dinfo->di_bdiropq = -1;
+		dinfo->di_tmpfile = 0;
 		for (i = 0; i < nbr; i++)
 			dinfo->di_hdentry[i].hd_id = -1;
 		goto out;
@@ -358,6 +359,48 @@ void au_update_digen(struct dentry *dentry)
 	/* smp_mb(); */ /* atomic_set */
 }
 
+void au_update_dbrange(struct dentry *dentry, int do_put_zero)
+{
+	struct au_dinfo *dinfo;
+	struct dentry *h_d;
+	struct au_hdentry *hdp;
+	aufs_bindex_t bindex, bbot;
+
+	DiMustWriteLock(dentry);
+
+	dinfo = au_di(dentry);
+	if (!dinfo || dinfo->di_btop < 0)
+		return;
+
+	if (do_put_zero) {
+		bbot = dinfo->di_bbot;
+		bindex = dinfo->di_btop;
+		hdp = au_hdentry(dinfo, bindex);
+		for (; bindex <= bbot; bindex++, hdp++) {
+			h_d = hdp->hd_dentry;
+			if (h_d && d_is_negative(h_d))
+				au_set_h_dptr(dentry, bindex, NULL);
+		}
+	}
+
+	dinfo->di_btop = 0;
+	hdp = au_hdentry(dinfo, dinfo->di_btop);
+	for (; dinfo->di_btop <= dinfo->di_bbot; dinfo->di_btop++, hdp++)
+		if (hdp->hd_dentry)
+			break;
+	if (dinfo->di_btop > dinfo->di_bbot) {
+		dinfo->di_btop = -1;
+		dinfo->di_bbot = -1;
+		return;
+	}
+
+	hdp = au_hdentry(dinfo, dinfo->di_bbot);
+	for (; dinfo->di_bbot >= 0; dinfo->di_bbot--, hdp--)
+		if (hdp->hd_dentry)
+			break;
+	AuDebugOn(dinfo->di_btop > dinfo->di_bbot || dinfo->di_bbot < 0);
+}
+
 void au_update_dbtop(struct dentry *dentry)
 {
 	aufs_bindex_t bindex, bbot;

fs/aufs/i_op.c

@@ -232,6 +232,134 @@ out:
 
 /* ---------------------------------------------------------------------- */
 
+static int au_wr_dir_cpup(struct dentry *dentry, struct dentry *parent,
+			  const unsigned char add_entry, aufs_bindex_t bcpup,
+			  aufs_bindex_t btop)
+{
+	int err;
+	struct dentry *h_parent;
+	struct inode *h_dir;
+
+	if (add_entry)
+		IMustLock(d_inode(parent));
+	else
+		di_write_lock_parent(parent);
+
+	err = 0;
+	if (!au_h_dptr(parent, bcpup)) {
+		if (btop > bcpup)
+			err = au_cpup_dirs(dentry, bcpup);
+		else if (btop < bcpup)
+			err = au_cpdown_dirs(dentry, bcpup);
+		else
+			BUG();
+	}
+	if (!err && add_entry && !au_ftest_wrdir(add_entry, TMPFILE)) {
+		h_parent = au_h_dptr(parent, bcpup);
+		h_dir = d_inode(h_parent);
+		inode_lock_shared_nested(h_dir, AuLsc_I_PARENT);
+		err = au_lkup_neg(dentry, bcpup, /*wh*/0);
+		/* todo: no unlock here */
+		inode_unlock_shared(h_dir);
+
+		AuDbg("bcpup %d\n", bcpup);
+		if (!err) {
+			if (d_really_is_negative(dentry))
+				au_set_h_dptr(dentry, btop, NULL);
+			au_update_dbrange(dentry, /*do_put_zero*/0);
+		}
+	}
+
+	if (!add_entry)
+		di_write_unlock(parent);
+	if (!err)
+		err = bcpup; /* success */
+
+	AuTraceErr(err);
+	return err;
+}
+
+/*
+ * decide the branch and the parent dir where we will create a new entry.
+ * returns new bindex or an error.
+ * copyup the parent dir if needed.
+ */
+int au_wr_dir(struct dentry *dentry, struct dentry *src_dentry,
+	      struct au_wr_dir_args *args)
+{
+	int err;
+	unsigned int flags;
+	aufs_bindex_t bcpup, btop, src_btop;
+	const unsigned char add_entry
+		= au_ftest_wrdir(args->flags, ADD_ENTRY)
+		| au_ftest_wrdir(args->flags, TMPFILE);
+	struct super_block *sb;
+	struct dentry *parent;
+	struct au_sbinfo *sbinfo;
+
+	sb = dentry->d_sb;
+	sbinfo = au_sbi(sb);
+	parent = dget_parent(dentry);
+	btop = au_dbtop(dentry);
+	bcpup = btop;
+	if (args->force_btgt < 0) {
+		if (src_dentry) {
+			src_btop = au_dbtop(src_dentry);
+			if (src_btop < btop)
+				bcpup = src_btop;
+		} else if (add_entry) {
+			flags = 0;
+			if (au_ftest_wrdir(args->flags, ISDIR))
+				au_fset_wbr(flags, DIR);
+			err = AuWbrCreate(sbinfo, dentry, flags);
+			bcpup = err;
+		}
+
+		if (bcpup < 0 || au_test_ro(sb, bcpup, d_inode(dentry))) {
+			if (add_entry)
+				err = AuWbrCopyup(sbinfo, dentry);
+			else {
+				if (!IS_ROOT(dentry)) {
+					di_read_lock_parent(parent, !AuLock_IR);
+					err = AuWbrCopyup(sbinfo, dentry);
+					di_read_unlock(parent, !AuLock_IR);
+				} else
+					err = AuWbrCopyup(sbinfo, dentry);
+			}
+			bcpup = err;
+			if (unlikely(err < 0))
+				goto out;
+		}
+	} else {
+		bcpup = args->force_btgt;
+		AuDebugOn(au_test_ro(sb, bcpup, d_inode(dentry)));
+	}
+
+	AuDbg("btop %d, bcpup %d\n", btop, bcpup);
+	err = bcpup;
+	if (bcpup == btop)
+		goto out; /* success */
+
+	/* copyup the new parent into the branch we process */
+	err = au_wr_dir_cpup(dentry, parent, add_entry, bcpup, btop);
+	if (err >= 0) {
+		if (d_really_is_negative(dentry)) {
+			au_set_h_dptr(dentry, btop, NULL);
+			au_set_dbtop(dentry, bcpup);
+			au_set_dbbot(dentry, bcpup);
+		}
+		AuDebugOn(add_entry
+			  && !au_ftest_wrdir(args->flags, TMPFILE)
+			  && !au_h_dptr(dentry, bcpup));
+	}
+
+out:
+	dput(parent);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
 void au_pin_hdir_unlock(struct au_pin *p)
 {
 	if (p->hdir)
@@ -517,9 +645,15 @@ struct inode_operations aufs_iop[] = {
 		.get_link	= aufs_get_link
 	},
 	[AuIop_DIR] = {
+		.create		= aufs_create,
 		.lookup		= aufs_lookup,
+		.symlink	= aufs_symlink,
+		.mkdir		= aufs_mkdir,
+		.mknod		= aufs_mknod,
 
-		.permission	= aufs_permission
+		.permission	= aufs_permission,
+
+		.tmpfile	= aufs_tmpfile
 	},
 	[AuIop_OTHER] = {
 		.permission	= aufs_permission

fs/aufs/i_op_add.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * inode operations (add entry)
+ */
+
+#include <linux/iversion.h>
+#include "aufs.h"
+
+/*
+ * final procedure of adding a new entry, except link(2).
+ * remove whiteout, instantiate, copyup the parent dir's times and size
+ * and update version.
+ * if it failed, re-create the removed whiteout.
+ */
+static int epilog(struct inode *dir, aufs_bindex_t bindex,
+		  struct dentry *wh_dentry, struct dentry *dentry)
+{
+	int err, rerr;
+	aufs_bindex_t bwh;
+	struct path h_path;
+	struct super_block *sb;
+	struct inode *inode, *h_dir;
+	struct dentry *wh;
+
+	bwh = -1;
+	sb = dir->i_sb;
+	if (wh_dentry) {
+		h_dir = d_inode(wh_dentry->d_parent); /* dir inode is locked */
+		IMustLock(h_dir);
+		AuDebugOn(au_h_iptr(dir, bindex) != h_dir);
+		bwh = au_dbwh(dentry);
+		h_path.dentry = wh_dentry;
+		h_path.mnt = au_sbr_mnt(sb, bindex);
+		err = au_wh_unlink_dentry(au_h_iptr(dir, bindex), &h_path,
+					  dentry);
+		if (unlikely(err))
+			goto out;
+	}
+
+	inode = au_new_inode(dentry, /*must_new*/1);
+	if (!IS_ERR(inode)) {
+		d_instantiate(dentry, inode);
+		dir = d_inode(dentry->d_parent); /* dir inode is locked */
+		IMustLock(dir);
+		au_dir_ts(dir, bindex);
+		inode_inc_iversion(dir);
+		return 0; /* success */
+	}
+
+	err = PTR_ERR(inode);
+	if (!wh_dentry)
+		goto out;
+
+	/* revert */
+	/* dir inode is locked */
+	wh = au_wh_create(dentry, bwh, wh_dentry->d_parent);
+	rerr = PTR_ERR(wh);
+	if (IS_ERR(wh)) {
+		AuIOErr("%pd reverting whiteout failed(%d, %d)\n",
+			dentry, err, rerr);
+		err = -EIO;
+	} else
+		dput(wh);
+
+out:
+	return err;
+}
+
+static int au_d_may_add(struct dentry *dentry)
+{
+	int err;
+
+	err = 0;
+	if (unlikely(d_unhashed(dentry)))
+		err = -ENOENT;
+	if (unlikely(d_really_is_positive(dentry)))
+		err = -EEXIST;
+	return err;
+}
+
+/*
+ * simple tests for the adding inode operations.
+ * following the checks in vfs, plus the parent-child relationship.
+ */
+int au_may_add(struct dentry *dentry, aufs_bindex_t bindex,
+	       struct dentry *h_parent, int isdir)
+{
+	int err;
+	umode_t h_mode;
+	struct dentry *h_dentry;
+	struct inode *h_inode;
+
+	err = -ENAMETOOLONG;
+	if (unlikely(dentry->d_name.len > AUFS_MAX_NAMELEN))
+		goto out;
+
+	h_dentry = au_h_dptr(dentry, bindex);
+	if (d_really_is_negative(dentry)) {
+		err = -EEXIST;
+		if (unlikely(d_is_positive(h_dentry)))
+			goto out;
+	} else {
+		/* rename(2) case */
+		err = -EIO;
+		if (unlikely(d_is_negative(h_dentry)))
+			goto out;
+		h_inode = d_inode(h_dentry);
+		if (unlikely(!h_inode->i_nlink))
+			goto out;
+
+		h_mode = h_inode->i_mode;
+		if (!isdir) {
+			err = -EISDIR;
+			if (unlikely(S_ISDIR(h_mode)))
+				goto out;
+		} else if (unlikely(!S_ISDIR(h_mode))) {
+			err = -ENOTDIR;
+			goto out;
+		}
+	}
+
+	err = 0;
+	/* expected parent dir is locked */
+	if (unlikely(h_parent != h_dentry->d_parent))
+		err = -EIO;
+
+out:
+	AuTraceErr(err);
+	return err;
+}
+
+/*
+ * initial procedure of adding a new entry.
+ * prepare writable branch and the parent dir, lock it,
+ * and lookup whiteout for the new entry.
+ */
+static struct dentry*
+lock_hdir_lkup_wh(struct dentry *dentry, struct au_dtime *dt,
+		  struct dentry *src_dentry, struct au_pin *pin,
+		  struct au_wr_dir_args *wr_dir_args)
+{
+	struct dentry *wh_dentry, *h_parent;
+	struct super_block *sb;
+	struct au_branch *br;
+	int err;
+	unsigned int udba;
+	aufs_bindex_t bcpup;
+
+	AuDbg("%pd\n", dentry);
+
+	err = au_wr_dir(dentry, src_dentry, wr_dir_args);
+	bcpup = err;
+	wh_dentry = ERR_PTR(err);
+	if (unlikely(err < 0))
+		goto out;
+
+	sb = dentry->d_sb;
+	udba = au_opt_udba(sb);
+	err = au_pin(pin, dentry, bcpup, udba,
+		     AuPin_DI_LOCKED | AuPin_MNT_WRITE);
+	wh_dentry = ERR_PTR(err);
+	if (unlikely(err))
+		goto out;
+
+	h_parent = au_pinned_h_parent(pin);
+	if (udba != AuOpt_UDBA_NONE
+	    && au_dbtop(dentry) == bcpup)
+		err = au_may_add(dentry, bcpup, h_parent,
+				 au_ftest_wrdir(wr_dir_args->flags, ISDIR));
+	else if (unlikely(dentry->d_name.len > AUFS_MAX_NAMELEN))
+		err = -ENAMETOOLONG;
+	wh_dentry = ERR_PTR(err);
+	if (unlikely(err))
+		goto out_unpin;
+
+	br = au_sbr(sb, bcpup);
+	if (dt) {
+		struct path tmp = {
+			.dentry	= h_parent,
+			.mnt	= au_br_mnt(br)
+		};
+		au_dtime_store(dt, au_pinned_parent(pin), &tmp);
+	}
+
+	wh_dentry = NULL;
+	if (bcpup != au_dbwh(dentry))
+		goto out; /* success */
+
+	/*
+	 * ENAMETOOLONG here means that if we allowed create such name, then it
+	 * would not be able to removed in the future. So we don't allow such
+	 * name here and we don't handle ENAMETOOLONG differently here.
+	 */
+	wh_dentry = au_wh_lkup(h_parent, &dentry->d_name, br);
+
+out_unpin:
+	if (IS_ERR(wh_dentry))
+		au_unpin(pin);
+out:
+	return wh_dentry;
+}
+
+/* ---------------------------------------------------------------------- */
+
+enum { Mknod, Symlink, Creat };
+struct simple_arg {
+	int type;
+	union {
+		struct {
+			umode_t mode;
+			bool want_excl;
+		} c;
+		struct {
+			const char *symname;
+		} s;
+		struct {
+			umode_t mode;
+			dev_t dev;
+		} m;
+	} u;
+};
+
+static int add_simple(struct inode *dir, struct dentry *dentry,
+		      struct simple_arg *arg)
+{
+	int err, rerr;
+	aufs_bindex_t btop;
+	unsigned char created;
+	struct dentry *wh_dentry, *parent;
+	struct inode *h_dir;
+	/* to reduce stack size */
+	struct {
+		struct au_dtime dt;
+		struct au_pin pin;
+		struct path h_path;
+		struct au_wr_dir_args wr_dir_args;
+	} *a;
+
+	AuDbg("%pd\n", dentry);
+	IMustLock(dir);
+
+	err = -ENOMEM;
+	a = kmalloc(sizeof(*a), GFP_NOFS);
+	if (unlikely(!a))
+		goto out;
+	a->wr_dir_args.force_btgt = -1;
+	a->wr_dir_args.flags = AuWrDir_ADD_ENTRY;
+
+	parent = dentry->d_parent; /* dir inode is locked */
+	err = aufs_read_lock(dentry, AuLock_DW | AuLock_GEN);
+	if (unlikely(err))
+		goto out_free;
+	err = au_d_may_add(dentry);
+	if (unlikely(err))
+		goto out_unlock;
+	di_write_lock_parent(parent);
+	wh_dentry = lock_hdir_lkup_wh(dentry, &a->dt, /*src_dentry*/NULL,
+				      &a->pin, &a->wr_dir_args);
+	err = PTR_ERR(wh_dentry);
+	if (IS_ERR(wh_dentry))
+		goto out_parent;
+
+	btop = au_dbtop(dentry);
+	a->h_path.dentry = au_h_dptr(dentry, btop);
+	a->h_path.mnt = au_sbr_mnt(dentry->d_sb, btop);
+	h_dir = au_pinned_h_dir(&a->pin);
+	switch (arg->type) {
+	case Creat:
+		err = vfsub_create(h_dir, &a->h_path, arg->u.c.mode,
+				   arg->u.c.want_excl);
+		break;
+	case Symlink:
+		err = vfsub_symlink(h_dir, &a->h_path, arg->u.s.symname);
+		break;
+	case Mknod:
+		err = vfsub_mknod(h_dir, &a->h_path, arg->u.m.mode,
+				  arg->u.m.dev);
+		break;
+	default:
+		BUG();
+	}
+	created = !err;
+	if (!err)
+		err = epilog(dir, btop, wh_dentry, dentry);
+
+	/* revert */
+	if (unlikely(created && err && d_is_positive(a->h_path.dentry))) {
+		/* no delegation since it is just created */
+		rerr = vfsub_unlink(h_dir, &a->h_path, /*delegated*/NULL,
+				    /*force*/0);
+		if (rerr) {
+			AuIOErr("%pd revert failure(%d, %d)\n",
+				dentry, err, rerr);
+			err = -EIO;
+		}
+		au_dtime_revert(&a->dt);
+	}
+
+	au_unpin(&a->pin);
+	dput(wh_dentry);
+
+out_parent:
+	di_write_unlock(parent);
+out_unlock:
+	if (unlikely(err)) {
+		au_update_dbtop(dentry);
+		d_drop(dentry);
+	}
+	aufs_read_unlock(dentry, AuLock_DW);
+out_free:
+	au_kfree_rcu(a);
+out:
+	return err;
+}
+
+int aufs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+	       dev_t dev)
+{
+	struct simple_arg arg = {
+		.type = Mknod,
+		.u.m = {
+			.mode	= mode,
+			.dev	= dev
+		}
+	};
+	return add_simple(dir, dentry, &arg);
+}
+
+int aufs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+	struct simple_arg arg = {
+		.type = Symlink,
+		.u.s.symname = symname
+	};
+	return add_simple(dir, dentry, &arg);
+}
+
+int aufs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+		bool want_excl)
+{
+	struct simple_arg arg = {
+		.type = Creat,
+		.u.c = {
+			.mode		= mode,
+			.want_excl	= want_excl
+		}
+	};
+	return add_simple(dir, dentry, &arg);
+}
+
+int aufs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	int err;
+	aufs_bindex_t bindex;
+	struct super_block *sb;
+	struct dentry *parent, *h_parent, *h_dentry;
+	struct inode *h_dir, *inode;
+	struct vfsmount *h_mnt;
+	struct au_wr_dir_args wr_dir_args = {
+		.force_btgt	= -1,
+		.flags		= AuWrDir_TMPFILE
+	};
+
+	/* copy-up may happen */
+	inode_lock(dir);
+
+	sb = dir->i_sb;
+	err = si_read_lock(sb, AuLock_FLUSH | AuLock_NOPLM);
+	if (unlikely(err))
+		goto out;
+
+	err = au_di_init(dentry);
+	if (unlikely(err))
+		goto out_si;
+
+	err = -EBUSY;
+	parent = d_find_any_alias(dir);
+	AuDebugOn(!parent);
+	di_write_lock_parent(parent);
+	if (unlikely(d_inode(parent) != dir))
+		goto out_parent;
+
+	err = au_digen_test(parent, au_sigen(sb));
+	if (unlikely(err))
+		goto out_parent;
+
+	bindex = au_dbtop(parent);
+	au_set_dbtop(dentry, bindex);
+	au_set_dbbot(dentry, bindex);
+	err = au_wr_dir(dentry, /*src_dentry*/NULL, &wr_dir_args);
+	bindex = err;
+	if (unlikely(err < 0))
+		goto out_parent;
+
+	err = -EOPNOTSUPP;
+	h_dir = au_h_iptr(dir, bindex);
+	if (unlikely(!h_dir->i_op->tmpfile))
+		goto out_parent;
+
+	h_mnt = au_sbr_mnt(sb, bindex);
+	err = vfsub_mnt_want_write(h_mnt);
+	if (unlikely(err))
+		goto out_parent;
+
+	h_parent = au_h_dptr(parent, bindex);
+	h_dentry = vfs_tmpfile(h_parent, mode, /*open_flag*/0);
+	if (IS_ERR(h_dentry)) {
+		err = PTR_ERR(h_dentry);
+		goto out_mnt;
+	}
+
+	au_set_dbtop(dentry, bindex);
+	au_set_dbbot(dentry, bindex);
+	au_set_h_dptr(dentry, bindex, dget(h_dentry));
+	inode = au_new_inode(dentry, /*must_new*/1);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		au_set_h_dptr(dentry, bindex, NULL);
+		au_set_dbtop(dentry, -1);
+		au_set_dbbot(dentry, -1);
+	} else {
+		if (!inode->i_nlink)
+			set_nlink(inode, 1);
+		d_tmpfile(dentry, inode);
+		au_di(dentry)->di_tmpfile = 1;
+
+		/* update without i_mutex */
+		if (au_ibtop(dir) == au_dbtop(dentry))
+			au_cpup_attr_timesizes(dir);
+	}
+	dput(h_dentry);
+
+out_mnt:
+	vfsub_mnt_drop_write(h_mnt);
+out_parent:
+	di_write_unlock(parent);
+	dput(parent);
+	di_write_unlock(dentry);
+	if (unlikely(err)) {
+		au_di_fin(dentry);
+		dentry->d_fsdata = NULL;
+	}
+out_si:
+	si_read_unlock(sb);
+out:
+	inode_unlock(dir);
+	return err;
+}
+
+/* ---------------------------------------------------------------------- */
+
+int aufs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	int err, rerr;
+	aufs_bindex_t bindex;
+	unsigned char diropq;
+	struct path h_path;
+	struct dentry *wh_dentry, *parent, *opq_dentry;
+	struct inode *h_inode;
+	struct super_block *sb;
+	struct {
+		struct au_pin pin;
+		struct au_dtime dt;
+	} *a; /* reduce the stack usage */
+	struct au_wr_dir_args wr_dir_args = {
+		.force_btgt	= -1,
+		.flags		= AuWrDir_ADD_ENTRY | AuWrDir_ISDIR
+	};
+
+	IMustLock(dir);
+
+	err = -ENOMEM;
+	a = kmalloc(sizeof(*a), GFP_NOFS);
+	if (unlikely(!a))
+		goto out;
+
+	err = aufs_read_lock(dentry, AuLock_DW | AuLock_GEN);
+	if (unlikely(err))
+		goto out_free;
+	err = au_d_may_add(dentry);
+	if (unlikely(err))
+		goto out_unlock;
+
+	parent = dentry->d_parent; /* dir inode is locked */
+	di_write_lock_parent(parent);
+	wh_dentry = lock_hdir_lkup_wh(dentry, &a->dt, /*src_dentry*/NULL,
+				      &a->pin, &wr_dir_args);
+	err = PTR_ERR(wh_dentry);
+	if (IS_ERR(wh_dentry))
+		goto out_parent;
+
+	sb = dentry->d_sb;
+	bindex = au_dbtop(dentry);
+	h_path.dentry = au_h_dptr(dentry, bindex);
+	h_path.mnt = au_sbr_mnt(sb, bindex);
+	err = vfsub_mkdir(au_pinned_h_dir(&a->pin), &h_path, mode);
+	if (unlikely(err))
+		goto out_unpin;
+
+	/* make the dir opaque */
+	diropq = 0;
+	h_inode = d_inode(h_path.dentry);
+	if (wh_dentry) {
+		inode_lock_nested(h_inode, AuLsc_I_CHILD);
+		opq_dentry = au_diropq_create(dentry, bindex);
+		inode_unlock(h_inode);
+		err = PTR_ERR(opq_dentry);
+		if (IS_ERR(opq_dentry))
+			goto out_dir;
+		dput(opq_dentry);
+		diropq = 1;
+	}
+
+	err = epilog(dir, bindex, wh_dentry, dentry);
+	if (!err) {
+		inc_nlink(dir);
+		goto out_unpin; /* success */
+	}
+
+	/* revert */
+	if (diropq) {
+		AuLabel(revert opq);
+		inode_lock_nested(h_inode, AuLsc_I_CHILD);
+		rerr = au_diropq_remove(dentry, bindex);
+		inode_unlock(h_inode);
+		if (rerr) {
+			AuIOErr("%pd reverting diropq failed(%d, %d)\n",
+				dentry, err, rerr);
+			err = -EIO;
+		}
+	}
+
+out_dir:
+	AuLabel(revert dir);
+	rerr = vfsub_rmdir(au_pinned_h_dir(&a->pin), &h_path);
+	if (rerr) {
+		AuIOErr("%pd reverting dir failed(%d, %d)\n",
+			dentry, err, rerr);
+		err = -EIO;
+	}
+	au_dtime_revert(&a->dt);
+out_unpin:
+	au_unpin(&a->pin);
+	dput(wh_dentry);
+out_parent:
+	di_write_unlock(parent);
+out_unlock:
+	if (unlikely(err)) {
+		au_update_dbtop(dentry);
+		d_drop(dentry);
+	}
+	aufs_read_unlock(dentry, AuLock_DW);
+out_free:
+	au_kfree_rcu(a);
+out:
+	return err;
+}

fs/aufs/inode.h

@@ -135,6 +135,23 @@ enum {
 };
 extern struct inode_operations aufs_iop[AuIop_Last];
 
+/* au_wr_dir flags */
+#define AuWrDir_ADD_ENTRY	1
+#define AuWrDir_ISDIR		(1 << 1)
+#define AuWrDir_TMPFILE		(1 << 2)
+#define au_ftest_wrdir(flags, name)	((flags) & AuWrDir_##name)
+#define au_fset_wrdir(flags, name) \
+	do { (flags) |= AuWrDir_##name; } while (0)
+#define au_fclr_wrdir(flags, name) \
+	do { (flags) &= ~AuWrDir_##name; } while (0)
+
+struct au_wr_dir_args {
+	aufs_bindex_t force_btgt;
+	unsigned char flags;
+};
+int au_wr_dir(struct dentry *dentry, struct dentry *src_dentry,
+	      struct au_wr_dir_args *args);
+
 struct dentry *au_pinned_h_parent(struct au_pin *pin);
 void au_pin_init(struct au_pin *pin, struct dentry *dentry,
 		 aufs_bindex_t bindex, int lsc_di, int lsc_hi,
@@ -144,6 +161,17 @@ int au_pin(struct au_pin *pin, struct dentry *dentry, aufs_bindex_t bindex,
 int au_do_pin(struct au_pin *pin) __must_check;
 void au_unpin(struct au_pin *pin);
 
+/* i_op_add.c */
+int au_may_add(struct dentry *dentry, aufs_bindex_t bindex,
+	       struct dentry *h_parent, int isdir);
+int aufs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+	       dev_t dev);
+int aufs_symlink(struct inode *dir, struct dentry *dentry, const char *symname);
+int aufs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+		bool want_excl);
+int aufs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode);
+int aufs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode);
+
 /* iinfo.c */
 struct inode *au_h_iptr(struct inode *inode, aufs_bindex_t bindex);
 void au_hiput(struct au_hinode *hinode);