aufs: dentry op, opt-out ->d_revalidate()

Optimize out ->d_revalidate() if possible.
If the refreshing failed, then ->d_revalidate() remains. In this case,
aufs has two types of dentries. One has ->d_revalidate, the other
doesn't. I am afraid it will confuse me someday.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/dentry.c

@@ -655,6 +655,28 @@ out:
 	return err;
 }
 
+void au_refresh_dop(struct dentry *dentry, int force_reval)
+{
+	const struct dentry_operations *dop
+		= force_reval ? &aufs_dop : dentry->d_sb->s_d_op;
+	static const unsigned int mask
+		= DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE;
+
+	BUILD_BUG_ON(sizeof(mask) != sizeof(dentry->d_flags));
+
+	if (dentry->d_op == dop)
+		return;
+
+	AuDbg("%pd\n", dentry);
+	spin_lock(&dentry->d_lock);
+	if (dop == &aufs_dop)
+		dentry->d_flags |= mask;
+	else
+		dentry->d_flags &= ~mask;
+	dentry->d_op = dop;
+	spin_unlock(&dentry->d_lock);
+}
+
 int au_refresh_dentry(struct dentry *dentry, struct dentry *parent)
 {
 	int err, ebrange, nbr;
@@ -1064,3 +1086,8 @@ const struct dentry_operations aufs_dop = {
 	.d_weak_revalidate	= aufs_d_revalidate,
 	.d_release		= aufs_d_release
 };
+
+/* aufs_dop without d_revalidate */
+const struct dentry_operations aufs_dop_noreval = {
+	.d_release		= aufs_d_release
+};

fs/aufs/dentry.h

@@ -49,7 +49,7 @@ struct au_do_lookup_args {
 /* ---------------------------------------------------------------------- */
 
 /* dentry.c */
-extern const struct dentry_operations aufs_dop;
+extern const struct dentry_operations aufs_dop, aufs_dop_noreval;
 struct au_branch;
 struct dentry *au_sio_lkup_one(struct qstr *name, struct dentry *parent);
 int au_h_verify(struct dentry *h_dentry, unsigned int udba, struct inode *h_dir,
@@ -60,6 +60,7 @@ int au_lkup_dentry(struct dentry *dentry, aufs_bindex_t btop,
 int au_lkup_neg(struct dentry *dentry, aufs_bindex_t bindex, int wh);
 int au_refresh_dentry(struct dentry *dentry, struct dentry *parent);
 int au_reval_dpath(struct dentry *dentry, unsigned int sigen);
+void au_refresh_dop(struct dentry *dentry, int force_reval);
 
 /* dinfo.c */
 void au_di_init_once(void *_di);

fs/aufs/opts.c

@@ -1062,10 +1062,10 @@ int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
 {
 	int err;
 	aufs_bindex_t bindex, bbot;
-	unsigned char do_plink, skip, do_free;
+	unsigned char do_plink, skip, do_free, can_no_dreval;
 	struct au_branch *br;
 	struct au_wbr *wbr;
-	struct dentry *root;
+	struct dentry *root, *dentry;
 	struct inode *dir, *h_dir;
 	struct au_sbinfo *sbinfo;
 	struct au_hinode *hdir;
@@ -1084,6 +1084,8 @@ int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
 	root = sb->s_root;
 	dir = d_inode(root);
 	do_plink = !!au_opt_test(sbinfo->si_mntflags, PLINK);
+	can_no_dreval = !!au_opt_test((sbinfo->si_mntflags | pending),
+				      UDBA_NONE);
 	bbot = au_sbbot(sb);
 	for (bindex = 0; !err && bindex <= bbot; bindex++) {
 		skip = 0;
@@ -1123,6 +1125,15 @@ int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
 		if (wbr)
 			wbr_wh_read_unlock(wbr);
 
+		if (can_no_dreval) {
+			dentry = br->br_path.dentry;
+			spin_lock(&dentry->d_lock);
+			if (dentry->d_flags &
+			    (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE))
+				can_no_dreval = 0;
+			spin_unlock(&dentry->d_lock);
+		}
+
 		if (skip)
 			continue;
 
@@ -1141,6 +1152,11 @@ int au_opts_verify(struct super_block *sb, unsigned long sb_flags,
 		}
 	}
 
+	if (can_no_dreval)
+		au_fset_si(sbinfo, NO_DREVAL);
+	else
+		au_fclr_si(sbinfo, NO_DREVAL);
+
 	return err;
 }
 
@@ -1238,6 +1254,7 @@ out:
 int au_opts_remount(struct super_block *sb, struct au_opts *opts)
 {
 	int err, rerr;
+	unsigned char no_dreval;
 	struct inode *dir;
 	struct au_opt_xino *opt_xino;
 	struct au_opt *opt;
@@ -1263,10 +1280,14 @@ int au_opts_remount(struct super_block *sb, struct au_opts *opts)
 	AuTraceErr(err);
 	/* go on even err */
 
+	no_dreval = !!au_ftest_si(sbinfo, NO_DREVAL);
 	rerr = au_opts_verify(sb, opts->sb_flags, /*pending*/0);
 	if (unlikely(rerr && !err))
 		err = rerr;
 
+	if (no_dreval != !!au_ftest_si(sbinfo, NO_DREVAL))
+		au_fset_opts(opts->flags, REFRESH_DOP);
+
 	if (au_ftest_opts(opts->flags, TRUNC_XIB)) {
 		rerr = au_xib_trunc(sb);
 		if (unlikely(rerr && !err))
@@ -1275,7 +1296,10 @@ int au_opts_remount(struct super_block *sb, struct au_opts *opts)
 
 	/* will be handled by the caller */
 	if (!au_ftest_opts(opts->flags, REFRESH)
-	    && (opts->given_udba || au_opt_test(sbinfo->si_mntflags, XINO)))
+	    && (opts->given_udba
+		|| au_opt_test(sbinfo->si_mntflags, XINO)
+		|| au_ftest_opts(opts->flags, REFRESH_DOP)
+		    ))
 		au_fset_opts(opts->flags, REFRESH);
 
 	AuDbg("status 0x%x\n", opts->flags);

fs/aufs/opts.h

@@ -135,6 +135,7 @@ struct au_opt {
 #define AuOpts_REFRESH		(1 << 1)
 #define AuOpts_TRUNC_XIB	(1 << 2)
 #define AuOpts_REFRESH_DYAOP	(1 << 3)
+#define AuOpts_REFRESH_DOP	(1 << 4)
 #define au_ftest_opts(flags, name)	((flags) & AuOpts_##name)
 #define au_fset_opts(flags, name) \
 	do { (flags) |= AuOpts_##name; } while (0)

fs/aufs/super.c

@@ -460,7 +460,7 @@ static int au_do_refresh(struct dentry *dentry, unsigned int dir_flags,
 
 static int au_do_refresh_d(struct dentry *dentry, unsigned int sigen,
 			   struct au_sbinfo *sbinfo,
-			   const unsigned int dir_flags)
+			   const unsigned int dir_flags, unsigned int do_dop)
 {
 	int err;
 	struct dentry *parent;
@@ -483,11 +483,17 @@ static int au_do_refresh_d(struct dentry *dentry, unsigned int sigen,
 	}
 	dput(parent);
 
+	if (!err) {
+		if (do_dop)
+			au_refresh_dop(dentry, /*force_reval*/0);
+	} else
+		au_refresh_dop(dentry, /*force_reval*/1);
+
 	AuTraceErr(err);
 	return err;
 }
 
-static int au_refresh_d(struct super_block *sb)
+static int au_refresh_d(struct super_block *sb, unsigned int do_dop)
 {
 	int err, i, j, ndentry, e;
 	unsigned int sigen;
@@ -498,6 +504,9 @@ static int au_refresh_d(struct super_block *sb)
 	struct dentry *root = sb->s_root;
 	const unsigned int dir_flags = au_hi_flags(d_inode(root), /*isdir*/1);
 
+	if (do_dop)
+		au_refresh_dop(root, /*force_reval*/0);
+
 	err = au_dpages_init(&dpages, GFP_NOFS);
 	if (unlikely(err))
 		goto out;
@@ -513,7 +522,8 @@ static int au_refresh_d(struct super_block *sb)
 		ndentry = dpage->ndentry;
 		for (j = 0; j < ndentry; j++) {
 			d = dentries[j];
-			e = au_do_refresh_d(d, sigen, sbinfo, dir_flags);
+			e = au_do_refresh_d(d, sigen, sbinfo, dir_flags,
+					    do_dop);
 			if (unlikely(e && !err))
 				err = e;
 			/* go on even err */
@@ -563,7 +573,7 @@ out:
 	return err;
 }
 
-static void au_remount_refresh(struct super_block *sb)
+static void au_remount_refresh(struct super_block *sb, unsigned int do_dop)
 {
 	int err, e;
 	unsigned int udba;
@@ -571,9 +581,11 @@ static void au_remount_refresh(struct super_block *sb)
 	struct dentry *root;
 	struct inode *inode;
 	struct au_branch *br;
+	struct au_sbinfo *sbi;
 
 	au_sigen_inc(sb);
-	au_fclr_si(au_sbi(sb), FAILED_REFRESH_DIR);
+	sbi = au_sbi(sb);
+	au_fclr_si(sbi, FAILED_REFRESH_DIR);
 
 	root = sb->s_root;
 	DiMustNoWaiters(root);
@@ -592,8 +604,19 @@ static void au_remount_refresh(struct super_block *sb)
 	}
 	au_hn_reset(inode, au_hi_flags(inode, /*isdir*/1));
 
+	if (do_dop) {
+		if (au_ftest_si(sbi, NO_DREVAL)) {
+			AuDebugOn(sb->s_d_op == &aufs_dop_noreval);
+			sb->s_d_op = &aufs_dop_noreval;
+		} else {
+			AuDebugOn(sb->s_d_op == &aufs_dop);
+			sb->s_d_op = &aufs_dop;
+		}
+		pr_info("reset to %ps\n", sb->s_d_op);
+	}
+
 	di_write_unlock(root);
-	err = au_refresh_d(sb);
+	err = au_refresh_d(sb, do_dop);
 	e = au_refresh_i(sb);
 	if (unlikely(e && !err))
 		err = e;
@@ -670,7 +693,7 @@ static int aufs_remount_fs(struct super_block *sb, int *flags, char *data)
 	au_opts_free(&opts);
 
 	if (au_ftest_opts(opts.flags, REFRESH))
-		au_remount_refresh(sb);
+		au_remount_refresh(sb, au_ftest_opts(opts.flags, REFRESH_DOP));
 
 	if (au_ftest_opts(opts.flags, REFRESH_DYAOP)) {
 		mntflags = au_mntflags(sb);
@@ -747,6 +770,7 @@ static int aufs_fill_super(struct super_block *sb, void *raw_data,
 	struct au_opts opts = {
 		.opt = NULL
 	};
+	struct au_sbinfo *sbinfo;
 	struct dentry *root;
 	struct inode *inode;
 	char *arg = raw_data;
@@ -767,6 +791,7 @@ static int aufs_fill_super(struct super_block *sb, void *raw_data,
 	err = au_si_alloc(sb);
 	if (unlikely(err))
 		goto out_opts;
+	sbinfo = au_sbi(sb);
 
 	/* all timestamps always follow the ones on the branch */
 	sb->s_flags |= SB_NOATIME | SB_NODIRATIME;
@@ -801,6 +826,11 @@ static int aufs_fill_super(struct super_block *sb, void *raw_data,
 	aufs_write_lock(root);
 	err = au_opts_mount(sb, &opts);
 	au_opts_free(&opts);
+	if (!err && au_ftest_si(sbinfo, NO_DREVAL)) {
+		sb->s_d_op = &aufs_dop_noreval;
+		pr_info("%ps\n", sb->s_d_op);
+		au_refresh_dop(root, /*force_reval*/0);
+	}
 	aufs_write_unlock(root);
 	inode_unlock(inode);
 	if (!err)
@@ -810,7 +840,7 @@ out_root:
 	dput(root);
 	sb->s_root = NULL;
 out_info:
-	kobject_put(&au_sbi(sb)->si_kobj);
+	kobject_put(&sbinfo->si_kobj);
 	sb->s_fs_info = NULL;
 out_opts:
 	free_page((unsigned long)opts.opt);
@@ -853,7 +883,7 @@ static void aufs_kill_sb(struct super_block *sb)
 			sbinfo->si_wbr_create_ops->fin(sb);
 		if (au_opt_test(sbinfo->si_mntflags, UDBA_HNOTIFY)) {
 			au_opt_set_udba(sbinfo->si_mntflags, UDBA_NONE);
-			au_remount_refresh(sb);
+			au_remount_refresh(sb, /*do_idop*/0);
 		}
 		if (au_opt_test(sbinfo->si_mntflags, PLINK))
 			au_plink_put(sb, /*verbose*/1);

fs/aufs/super.h

@@ -156,6 +156,8 @@ struct au_sbinfo {
  * if it is false, refreshing dirs at access time is unnecessary
  */
 #define AuSi_FAILED_REFRESH_DIR	1
+/* add later */
+#define AuSi_NO_DREVAL		(1 << 2)	/* disable all d_revalidate */
 
 static inline unsigned char au_do_ftest_si(struct au_sbinfo *sbi,
 					   unsigned int flag)