aufs: debug print

Print various info about aufs inode. This feature is enabled when
CONFIG_AUFS_DEBUG and the module parameter 'debug' are set.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/Makefile

@@ -2,6 +2,9 @@
 
 -include ${srctree}/${src}/priv_def.mk
 
+# cf. include/linux/kernel.h
+# enable pr_debug
+ccflags-y += -DDEBUG
 # sparse requires the full pathname
 ccflags-y += -include ${srctree}/include/uapi/linux/aufs_type.h
 

fs/aufs/aufs.h

@@ -22,6 +22,7 @@
 
 #include "debug.h"
 
+#include "fstype.h"
 #include "inode.h"
 #include "module.h"
 #include "rwsem.h"

fs/aufs/debug.c

@@ -7,6 +7,7 @@
  * debug print functions
  */
 
+#include <linux/iversion.h>
 #include "aufs.h"
 
 /* Returns 0, or -errno.  arg is in kp->arg. */
@@ -42,3 +43,57 @@ static struct kernel_param_ops param_ops_atomic_t = {
 atomic_t aufs_debug = ATOMIC_INIT(0);
 MODULE_PARM_DESC(debug, "debug print");
 module_param_named(debug, aufs_debug, atomic_t, 0664);
+
+DEFINE_MUTEX(au_dbg_mtx);	/* just to serialize the dbg msgs */
+char *au_plevel = KERN_DEBUG;
+#define dpri(fmt, ...) do {					\
+	if ((au_plevel						\
+	     && strcmp(au_plevel, KERN_DEBUG))			\
+	    || au_debug_test())					\
+		printk("%s" fmt, au_plevel, ##__VA_ARGS__);	\
+} while (0)
+
+/* ---------------------------------------------------------------------- */
+
+static int do_pri_inode(aufs_bindex_t bindex, struct inode *inode)
+{
+	if (!inode || IS_ERR(inode)) {
+		dpri("i%d: err %ld\n", bindex, PTR_ERR(inode));
+		return -1;
+	}
+
+	/* the type of i_blocks depends upon CONFIG_LBDAF */
+	BUILD_BUG_ON(sizeof(inode->i_blocks) != sizeof(unsigned long)
+		     && sizeof(inode->i_blocks) != sizeof(u64));
+
+	dpri("i%d: %p, i%lu, %s, cnt %d, nl %u, 0%o, sz %llu, blk %llu,"
+	     " ct %lld, np %lu, st 0x%lx, f 0x%x, v %llu, g %x\n",
+	     bindex, inode,
+	     inode->i_ino, inode->i_sb ? au_sbtype(inode->i_sb) : "??",
+	     atomic_read(&inode->i_count), inode->i_nlink, inode->i_mode,
+	     i_size_read(inode), (unsigned long long)inode->i_blocks,
+	     (long long)timespec64_to_ns(&inode->i_ctime) & 0x0ffff,
+	     inode->i_mapping ? inode->i_mapping->nrpages : 0,
+	     inode->i_state, inode->i_flags, inode_peek_iversion(inode),
+	     inode->i_generation);
+	return 0;
+}
+
+void au_dpri_inode(struct inode *inode)
+{
+	struct au_iinfo *iinfo;
+	aufs_bindex_t bindex;
+	int err;
+
+	err = do_pri_inode(-1, inode);
+	if (err || !au_test_aufs(inode->i_sb) || au_is_bad_inode(inode))
+		return;
+
+	iinfo = au_ii(inode);
+	dpri("i-1: btop %d, bbot %d\n",
+	     iinfo->ii_btop, iinfo->ii_bbot);
+	if (iinfo->ii_btop < 0)
+		return;
+	for (bindex = iinfo->ii_btop; bindex <= iinfo->ii_bbot; bindex++)
+		do_pri_inode(bindex, iinfo->ii_hinode[0 + bindex].hi_inode);
+}

fs/aufs/debug.h

@@ -42,5 +42,34 @@ AuStubInt0(au_debug_test, void)
 
 #define param_check_atomic_t(name, p) __param_check(name, p, atomic_t)
 
+/* ---------------------------------------------------------------------- */
+
+/* debug print */
+
+#define AuDbg(fmt, ...) do { \
+	if (au_debug_test()) \
+		pr_debug("DEBUG: " fmt, ##__VA_ARGS__); \
+} while (0)
+#define AuLabel(l)		AuDbg(#l "\n")
+
+/* ---------------------------------------------------------------------- */
+
+struct dentry;
+#ifdef CONFIG_AUFS_DEBUG
+extern struct mutex au_dbg_mtx;
+extern char *au_plevel;
+struct inode;
+void au_dpri_inode(struct inode *inode);
+
+#define AuDbgInode(i) do { \
+	mutex_lock(&au_dbg_mtx); \
+	AuDbg(#i "\n"); \
+	au_dpri_inode(i); \
+	mutex_unlock(&au_dbg_mtx); \
+} while (0)
+#else
+#define AuDbgInode(i)		do {} while (0)
+#endif /* CONFIG_AUFS_DEBUG */
+
 #endif /* __KERNEL__ */
 #endif /* __AUFS_DEBUG_H__ */

fs/aufs/fstype.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005-2019 Junjiro R. Okajima
+ */
+
+/*
+ * judging filesystem type
+ */
+
+#ifndef __AUFS_FSTYPE_H__
+#define __AUFS_FSTYPE_H__
+
+#ifdef __KERNEL__
+
+#include <linux/fs.h>
+#include <linux/magic.h>
+
+static inline int au_test_aufs(struct super_block *sb)
+{
+	return sb->s_magic == AUFS_SUPER_MAGIC;
+}
+
+static inline const char *au_sbtype(struct super_block *sb)
+{
+	return sb->s_type->name;
+}
+
+#endif /* __KERNEL__ */
+#endif /* __AUFS_FSTYPE_H__ */

fs/aufs/inode.h

@@ -115,7 +115,9 @@ AuRWLockFuncs(new_child, NEW_CHILD);
 
 static inline void au_icntnr_init(struct au_icntnr *c)
 {
-	/* re-commit later */
+#ifdef CONFIG_AUFS_DEBUG
+	c->vfs_inode.i_mode = 0;
+#endif
 }
 
 /* ---------------------------------------------------------------------- */