aufs: infos generation 2/2

The generation of iinfo and dinfo inherit sbinfo's.
Also iinfo generation tracks the branch inode's generation to test the
matching after the branch management.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/Makefile

@@ -11,6 +11,7 @@ ccflags-y += -include ${srctree}/include/uapi/linux/aufs_type.h
 obj-$(CONFIG_AUFS_FS) += aufs.o
 aufs-y := module.o sbinfo.o super.o \
 	dcsub.o \
+	cpup.o \
 	dinfo.o \
 	iinfo.o
 

fs/aufs/aufs.h

@@ -22,6 +22,7 @@
 
 #include "debug.h"
 
+#include "cpup.h"
 #include "dcsub.h"
 #include "dentry.h"
 #include "fstype.h"

fs/aufs/cpup.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * copy-up functions, see wbr_policy.c for copy-down
+ */
+
+#include "aufs.h"
+
+void au_cpup_igen(struct inode *inode, struct inode *h_inode)
+{
+	struct au_iinfo *iinfo = au_ii(inode);
+
+	IiMustWriteLock(inode);
+
+	iinfo->ii_higen = h_inode->i_generation;
+	iinfo->ii_hsb1 = h_inode->i_sb;
+}

fs/aufs/cpup.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * copy-up/down functions
+ */
+
+#ifndef __AUFS_CPUP_H__
+#define __AUFS_CPUP_H__
+
+#ifdef __KERNEL__
+
+struct inode;
+
+void au_cpup_igen(struct inode *inode, struct inode *h_inode);
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_CPUP_H__ */

fs/aufs/debug.c

@@ -90,8 +90,8 @@ void au_dpri_inode(struct inode *inode)
 		return;
 
 	iinfo = au_ii(inode);
-	dpri("i-1: btop %d, bbot %d\n",
-	     iinfo->ii_btop, iinfo->ii_bbot);
+	dpri("i-1: btop %d, bbot %d, gen %d\n",
+	     iinfo->ii_btop, iinfo->ii_bbot, au_iigen(inode));
 	if (iinfo->ii_btop < 0)
 		return;
 	for (bindex = iinfo->ii_btop; bindex <= iinfo->ii_bbot; bindex++)
@@ -138,8 +138,9 @@ void au_dpri_dentry(struct dentry *dentry)
 	dinfo = au_di(dentry);
 	if (!dinfo)
 		return;
-	dpri("d-1: btop %d, bbot %d\n",
-	     dinfo->di_btop, dinfo->di_bbot);
+	dpri("d-1: btop %d, bbot %d, gen %d\n",
+	     dinfo->di_btop, dinfo->di_bbot,
+	     au_digen(dentry));
 	if (dinfo->di_btop < 0)
 		return;
 	for (bindex = dinfo->di_btop; bindex <= dinfo->di_bbot; bindex++)
@@ -181,3 +182,23 @@ void __au_dbg_verify_dinode(struct dentry *dentry, const char *func, int line)
 		}
 	}
 }
+
+void au_dbg_verify_gen(struct dentry *parent, unsigned int sigen)
+{
+	int err, i, j;
+	struct au_dcsub_pages dpages;
+	struct au_dpage *dpage;
+	struct dentry **dentries;
+
+	err = au_dpages_init(&dpages, GFP_NOFS);
+	AuDebugOn(err);
+	err = au_dcsub_pages_rev_aufs(&dpages, parent, /*do_include*/1);
+	AuDebugOn(err);
+	for (i = dpages.ndpage - 1; !err && i >= 0; i--) {
+		dpage = dpages.dpages + i;
+		dentries = dpage->dentries;
+		for (j = dpage->ndentry - 1; !err && j >= 0; j--)
+			AuDebugOn(au_digen_test(dentries[j], sigen));
+	}
+	au_dpages_free(&dpages);
+}

fs/aufs/debug.h

@@ -75,6 +75,7 @@ void au_dpri_dentry(struct dentry *dentry);
 
 #define au_dbg_verify_dinode(d) __au_dbg_verify_dinode(d, __func__, __LINE__)
 void __au_dbg_verify_dinode(struct dentry *dentry, const char *func, int line);
+void au_dbg_verify_gen(struct dentry *parent, unsigned int sigen);
 
 #define AuDbgInode(i) do { \
 	mutex_lock(&au_dbg_mtx); \
@@ -98,6 +99,7 @@ void __au_dbg_verify_dinode(struct dentry *dentry, const char *func, int line);
 } while (0)
 #else
 AuStubVoid(au_dbg_verify_dinode, struct dentry *dentry)
+AuStubVoid(au_dbg_verify_gen, struct dentry *parent, unsigned int sigen)
 
 #define AuDbgInode(i)		do {} while (0)
 #define AuDbgDAlias(i)		do {} while (0)

fs/aufs/dentry.h

@@ -20,6 +20,8 @@ struct au_hdentry {
 };
 
 struct au_dinfo {
+	atomic_t		di_generation;
+
 	struct au_rwsem		di_rwsem;
 	aufs_bindex_t		di_btop, di_bbot;
 	struct au_hdentry	*di_hdentry;
@@ -45,6 +47,8 @@ struct dentry *au_h_dptr(struct dentry *dentry, aufs_bindex_t bindex);
 
 void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
 		   struct dentry *h_dentry);
+int au_digen_test(struct dentry *dentry, unsigned int sigen);
+void au_update_digen(struct dentry *dentry);
 void au_update_dbtop(struct dentry *dentry);
 void au_update_dbbot(struct dentry *dentry);
 
@@ -105,6 +109,12 @@ AuRWLockFuncs(parent3, PARENT3);
 
 /* ---------------------------------------------------------------------- */
 
+/* todo: memory barrier? */
+static inline unsigned int au_digen(struct dentry *d)
+{
+	return atomic_read(&au_di(d)->di_generation);
+}
+
 static inline void au_h_dentry_init(struct au_hdentry *hdentry)
 {
 	hdentry->hd_dentry = NULL;

fs/aufs/dinfo.c

@@ -67,9 +67,11 @@ int au_di_init(struct dentry *dentry)
 	err = 0;
 	sb = dentry->d_sb;
 	dinfo = au_di_alloc(sb, AuLsc_DI_CHILD);
-	if (dinfo)
+	if (dinfo) {
+		atomic_set(&dinfo->di_generation, au_sigen(sb));
+		/* smp_mb(); */ /* atomic_set */
 		dentry->d_fsdata = dinfo;
-	else
+	} else
 		err = -ENOMEM;
 
 	return err;
@@ -223,6 +225,24 @@ void au_set_h_dptr(struct dentry *dentry, aufs_bindex_t bindex,
 	hd->hd_dentry = h_dentry;
 }
 
+int au_digen_test(struct dentry *dentry, unsigned int sigen)
+{
+	int err;
+
+	err = 0;
+	if (unlikely(au_digen(dentry) != sigen
+		     || au_iigen_test(d_inode(dentry), sigen)))
+		err = -EIO;
+
+	return err;
+}
+
+void au_update_digen(struct dentry *dentry)
+{
+	atomic_set(&au_di(dentry)->di_generation, au_sigen(dentry->d_sb));
+	/* smp_mb(); */ /* atomic_set */
+}
+
 void au_update_dbtop(struct dentry *dentry)
 {
 	aufs_bindex_t bindex, bbot;

fs/aufs/iinfo.c

@@ -48,10 +48,25 @@ void au_set_h_iptr(struct inode *inode, aufs_bindex_t bindex,
 		AuDebugOn(inode->i_mode
 			  && (h_inode->i_mode & S_IFMT)
 			  != (inode->i_mode & S_IFMT));
-		/* add more later */
+		if (bindex == iinfo->ii_btop)
+			au_cpup_igen(inode, h_inode);
 	}
 }
 
+void au_update_iigen(struct inode *inode, int half)
+{
+	struct au_iinfo *iinfo;
+	struct au_iigen *iigen;
+	unsigned int sigen;
+
+	sigen = au_sigen(inode->i_sb);
+	iinfo = au_ii(inode);
+	iigen = &iinfo->ii_generation;
+	spin_lock(&iigen->ig_spin);
+	iigen->ig_generation = sigen;
+	spin_unlock(&iigen->ig_spin);
+}
+
 /* ---------------------------------------------------------------------- */
 
 void au_icntnr_init_once(void *_c)
@@ -59,6 +74,7 @@ void au_icntnr_init_once(void *_c)
 	struct au_icntnr *c = _c;
 	struct au_iinfo *iinfo = &c->iinfo;
 
+	spin_lock_init(&iinfo->ii_generation.ig_spin);
 	au_rw_init(&iinfo->ii_rwsem);
 	inode_init_once(&c->vfs_inode);
 }
@@ -84,6 +100,7 @@ int au_iinfo_init(struct inode *inode)
 		for (i = 0; i < nbr; i++, hi++)
 			au_hinode_init(hi);
 
+		iinfo->ii_generation.ig_generation = au_sigen(sb);
 		iinfo->ii_btop = -1;
 		iinfo->ii_bbot = -1;
 		return 0;

fs/aufs/inode.h

@@ -19,9 +19,18 @@ struct au_hinode {
 	struct inode		*hi_inode;
 };
 
+struct au_iigen {
+	spinlock_t	ig_spin;
+	__u32		ig_generation;
+};
+
 struct au_iinfo {
+	struct au_iigen		ii_generation;
+	struct super_block	*ii_hsb1;	/* no get/put */
+
 	struct au_rwsem		ii_rwsem;
 	aufs_bindex_t		ii_btop, ii_bbot;
+	__u32			ii_higen;
 	struct au_hinode	*ii_hinode;
 };
 
@@ -48,6 +57,8 @@ void au_hiput(struct au_hinode *hinode);
 void au_set_h_iptr(struct inode *inode, aufs_bindex_t bindex,
 		   struct inode *h_inode, unsigned int flags);
 
+void au_update_iigen(struct inode *inode, int half);
+
 void au_icntnr_init_once(void *_c);
 void au_hinode_init(struct au_hinode *hinode);
 int au_iinfo_init(struct inode *inode);
@@ -120,6 +131,56 @@ static inline void au_icntnr_init(struct au_icntnr *c)
 #endif
 }
 
+static inline unsigned int au_iigen(struct inode *inode)
+{
+	unsigned int gen;
+	struct au_iinfo *iinfo;
+	struct au_iigen *iigen;
+
+	iinfo = au_ii(inode);
+	iigen = &iinfo->ii_generation;
+	spin_lock(&iigen->ig_spin);
+	gen = iigen->ig_generation;
+	spin_unlock(&iigen->ig_spin);
+
+	return gen;
+}
+
+/* tiny test for inode number */
+/* tmpfs generation is too rough */
+static inline int au_test_higen(struct inode *inode, struct inode *h_inode)
+{
+	struct au_iinfo *iinfo;
+
+	iinfo = au_ii(inode);
+	AuRwMustAnyLock(&iinfo->ii_rwsem);
+	return !(iinfo->ii_hsb1 == h_inode->i_sb
+		 && iinfo->ii_higen == h_inode->i_generation);
+}
+
+static inline void au_iigen_dec(struct inode *inode)
+{
+	struct au_iinfo *iinfo;
+	struct au_iigen *iigen;
+
+	iinfo = au_ii(inode);
+	iigen = &iinfo->ii_generation;
+	spin_lock(&iigen->ig_spin);
+	iigen->ig_generation--;
+	spin_unlock(&iigen->ig_spin);
+}
+
+static inline int au_iigen_test(struct inode *inode, unsigned int sigen)
+{
+	int err;
+
+	err = 0;
+	if (unlikely(inode && au_iigen(inode) != sigen))
+		err = -EIO;
+
+	return err;
+}
+
 /* ---------------------------------------------------------------------- */
 
 static inline struct au_hinode *au_hinode(struct au_iinfo *iinfo,

fs/aufs/sbinfo.c

@@ -7,6 +7,7 @@
  * superblock private data
  */
 
+#include <linux/iversion.h>
 #include "aufs.h"
 
 /*
@@ -52,3 +53,20 @@ out_sbinfo:
 out:
 	return err;
 }
+
+/* ---------------------------------------------------------------------- */
+
+unsigned int au_sigen_inc(struct super_block *sb)
+{
+	unsigned int gen;
+	struct inode *inode;
+
+	SiMustWriteLock(sb);
+
+	gen = ++au_sbi(sb)->si_generation;
+	au_update_digen(sb->s_root);
+	inode = d_inode(sb->s_root);
+	au_update_iigen(inode, /*half*/0);
+	inode_inc_iversion(inode);
+	return gen;
+}

fs/aufs/super.h

@@ -25,6 +25,8 @@ struct au_sbinfo {
 	struct au_rwsem		si_rwsem;
 
 	/* branch management */
+	unsigned int		si_generation;
+
 	aufs_bindex_t		si_bbot;
 	struct au_branch	**si_branch;
 
@@ -58,6 +60,8 @@ struct inode *au_iget_locked(struct super_block *sb, ino_t ino);
 void au_si_free(struct kobject *kobj);
 int au_si_alloc(struct super_block *sb);
 
+unsigned int au_sigen_inc(struct super_block *sb);
+
 /* ---------------------------------------------------------------------- */
 
 static inline struct au_sbinfo *au_sbi(struct super_block *sb)
@@ -95,5 +99,11 @@ static inline aufs_bindex_t au_sbbot(struct super_block *sb)
 	return au_sbi(sb)->si_bbot;
 }
 
+static inline unsigned int au_sigen(struct super_block *sb)
+{
+	SiMustAnyLock(sb);
+	return au_sbi(sb)->si_generation;
+}
+
 #endif /* __KERNEL__ */
 #endif /* __AUFS_SUPER_H__ */