@@ -13,3 +13,4 @@ ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
ext4-$(CONFIG_EXT4_FS_SNAPSHOT) += snapshot.o snapshot_ctl.o
ext4-$(CONFIG_EXT4_FS_SNAPSHOT) += snapshot_inode.o snapshot_buffer.o
+ext4-$(CONFIG_EXT4_FS_SNAPSHOT) += snapshot_debug.o
@@ -2658,10 +2658,13 @@ static void __init ext4_create_debugfs_entry(void)
S_IRUGO | S_IWUSR,
debugfs_dir,
&mb_enable_debug);
+ if (debugfs_dir)
+ ext4_snapshot_create_debugfs_entry(debugfs_dir);
}
static void ext4_remove_debugfs_entry(void)
{
+ ext4_snapshot_remove_debugfs_entry();
debugfs_remove(debugfs_debug);
debugfs_remove(debugfs_dir);
}
@@ -18,6 +18,7 @@
#include <linux/version.h>
#include <linux/delay.h>
#include "ext4.h"
+#include "snapshot_debug.h"
/*
@@ -109,6 +110,14 @@
static inline void snapshot_size_extend(struct inode *inode,
ext4_fsblk_t blocks)
{
+#ifdef CONFIG_EXT4_DEBUG
+ ext4_fsblk_t old_blocks = SNAPSHOT_PROGRESS(inode);
+ ext4_fsblk_t max_blocks = SNAPSHOT_BLOCKS(inode);
+
+ /* sleep total of tunable delay unit over 100% progress */
+ snapshot_test_delay_progress(SNAPTEST_DELETE,
+ old_blocks, blocks, max_blocks);
+#endif
i_size_write((inode), (loff_t)(blocks) << SNAPSHOT_BLOCK_SIZE_BITS);
}
@@ -0,0 +1,100 @@
+/*
+ * linux/fs/ext4/snapshot_debug.c
+ *
+ * Written by Amir Goldstein <amir73il@users.sf.net>, 2008
+ *
+ * Copyright (C) 2008-2011 CTERA Networks
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Ext4 snapshot debugging.
+ */
+
+
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/debugfs.h>
+#include "snapshot.h"
+
+#if defined(CONFIG_EXT4_FS_SNAPSHOT) && defined(CONFIG_EXT4_DEBUG)
+/*
+ * debugfs tunables
+ */
+
+const char *snapshot_indent = SNAPSHOT_INDENT_STR + SNAPSHOT_INDENT_MAX;
+
+/*
+ * Tunable delay values per snapshot operation for testing of
+ * COW race conditions and master snapshot_mutex lock
+ */
+static const char *snapshot_test_names[SNAPSHOT_TESTS_NUM] = {
+ /* delay completion of snapshot create|take */
+ "test-take-delay-msec",
+ /* delay completion of snapshot shrink|cleanup */
+ "test-delete-delay-msec",
+ /* delay completion of COW operation */
+ "test-cow-delay-msec",
+ /* delay submission of tracked read */
+ "test-read-delay-msec",
+ /* delay completion of COW bitmap operation */
+ "test-bitmap-delay-msec",
+};
+
+#define SNAPSHOT_TEST_NAMES (sizeof(snapshot_test_names) / \
+ sizeof(snapshot_test_names[0]))
+
+u16 snapshot_enable_test[SNAPSHOT_TESTS_NUM] __read_mostly = {0};
+u8 snapshot_enable_debug __read_mostly = 1;
+
+static struct dentry *snapshot_debug;
+static struct dentry *snapshot_version;
+static struct dentry *snapshot_test[SNAPSHOT_TESTS_NUM];
+
+static char snapshot_version_str[] = EXT4_SNAPSHOT_VERSION;
+static struct debugfs_blob_wrapper snapshot_version_blob = {
+ .data = snapshot_version_str,
+ .size = sizeof(snapshot_version_str)
+};
+
+
+/*
+ * ext4_snapshot_create_debugfs_entry - register ext4 snapshot debug hooks
+ * Void function doesn't return error if debug hooks are not registered.
+ */
+void ext4_snapshot_create_debugfs_entry(struct dentry *debugfs_dir)
+{
+ int i;
+
+ BUG_ON(!debugfs_dir);
+ snapshot_debug = debugfs_create_u8("snapshot-debug", S_IRUGO|S_IWUSR,
+ debugfs_dir,
+ &snapshot_enable_debug);
+ snapshot_version = debugfs_create_blob("snapshot-version", S_IRUGO,
+ debugfs_dir,
+ &snapshot_version_blob);
+ for (i = 0; i < SNAPSHOT_TESTS_NUM && i < SNAPSHOT_TEST_NAMES; i++)
+ snapshot_test[i] = debugfs_create_u16(snapshot_test_names[i],
+ S_IRUGO|S_IWUSR,
+ debugfs_dir,
+ &snapshot_enable_test[i]);
+}
+
+/*
+ * ext4_snapshot_remove_debugfs_entry - unregister ext4 snapshot debug hooks
+ * checks if the hooks have been registered before unregistering them.
+ */
+void ext4_snapshot_remove_debugfs_entry(void)
+{
+ int i;
+
+ for (i = 0; i < SNAPSHOT_TESTS_NUM && i < SNAPSHOT_TEST_NAMES; i++)
+ if (snapshot_test[i])
+ debugfs_remove(snapshot_test[i]);
+ if (snapshot_version)
+ debugfs_remove(snapshot_version);
+ if (snapshot_debug)
+ debugfs_remove(snapshot_debug);
+}
+#endif
@@ -0,0 +1,105 @@
+/*
+ * linux/fs/ext4/snapshot_debug.h
+ *
+ * Written by Amir Goldstein <amir73il@users.sf.net>, 2008
+ *
+ * Copyright (C) 2008-2011 CTERA Networks
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * Ext4 snapshot debugging.
+ */
+
+#ifndef _LINUX_EXT4_SNAPSHOT_DEBUG_H
+#define _LINUX_EXT4_SNAPSHOT_DEBUG_H
+
+#if defined(CONFIG_EXT4_FS_SNAPSHOT) && defined(CONFIG_EXT4_DEBUG)
+#include <linux/delay.h>
+
+#define SNAPSHOT_INDENT_MAX 4
+#define SNAPSHOT_INDENT_STR "\t\t\t\t"
+
+#define SNAPTEST_TAKE 0
+#define SNAPTEST_DELETE 1
+#define SNAPTEST_COW 2
+#define SNAPTEST_READ 3
+#define SNAPTEST_BITMAP 4
+#define SNAPSHOT_TESTS_NUM 5
+
+extern const char *snapshot_indent;
+extern u8 snapshot_enable_debug;
+extern u16 snapshot_enable_test[SNAPSHOT_TESTS_NUM];
+extern u8 cow_cache_enabled;
+
+#define snapshot_test_delay(i) \
+ do { \
+ if (snapshot_enable_test[i]) \
+ msleep_interruptible(snapshot_enable_test[i]); \
+ } while (0)
+
+/*
+ * Sleep 1ms every 'blocks_per_ms', amounting to the total test delay
+ * over 100% of progress (when 'to' reaches 'max').
+ * snapshot_enable_test[i] (msec) is limited to 64K and max (blocks_count)
+ * is likely much more than 64K, so 'blocks_per_ms' is likely non zero.
+ */
+#define snapshot_test_delay_progress(i, from, to, max) \
+ do { \
+ if (snapshot_enable_test[i] && \
+ (max) > snapshot_enable_test[i] && \
+ (from) <= (to) && (to) <= (max)) { \
+ unsigned long blocks_per_ms = \
+ do_div((max), snapshot_enable_test[i]); \
+ unsigned long x = do_div((from), blocks_per_ms);\
+ unsigned long y = do_div((to), blocks_per_ms); \
+ if (y > x) \
+ msleep_interruptible(y - x); \
+ } \
+ } while (0)
+
+#define snapshot_debug_l(n, l, f, a...) \
+ do { \
+ if ((n) <= snapshot_enable_debug && \
+ (l) <= SNAPSHOT_INDENT_MAX) { \
+ printk(KERN_DEBUG "snapshot: %s" f, \
+ snapshot_indent - (l), \
+ ## a); \
+ } \
+ } while (0)
+
+#define snapshot_debug(n, f, a...) snapshot_debug_l(n, 0, f, ## a)
+
+#define snapshot_debug_once(n, f, a...) \
+ do { \
+ static bool __once; \
+ if (!__once) { \
+ snapshot_debug(n, f, ## a); \
+ __once = true; \
+ } \
+ } while (0)
+
+extern void ext4_snapshot_create_debugfs_entry(struct dentry *debugfs_dir);
+extern void ext4_snapshot_remove_debugfs_entry(void);
+
+#else
+#define snapshot_enable_debug (0)
+#define snapshot_test_delay(i)
+#define snapshot_test_delay_progress(i, from, to, max)
+#define snapshot_debug(n, f, a...)
+#define snapshot_debug_l(n, l, f, a...)
+#define snapshot_debug_once(n, f, a...)
+#define ext4_snapshot_create_debugfs_entry(d)
+#define ext4_snapshot_remove_debugfs_entry()
+#endif
+
+
+/* debug levels */
+#define SNAP_ERR 1 /* errors and summary */
+#define SNAP_WARN 2 /* warnings */
+#define SNAP_INFO 3 /* info */
+#define SNAP_DEBUG 4 /* debug */
+#define SNAP_DUMP 5 /* dump snapshot file */
+
+#endif /* _LINUX_EXT4_SNAPSHOT_DEBUG_H */