ext4: add ratelimiting to ext4 messages

In the case of a storage device that suddenly disappears, or in the
case of significant file system corruption, this can result in a huge
flood of messages being sent to the console.  This can overflow the
file system containing /var/log/messages, or if a serial console is
configured, this can slow down the system so much that a hardware
watchdog can end up triggering forcing a system reboot.

Google-Bug-Id: 7258357

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 100 insertions, 58 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index af815ea9d7c..65485ab7a88 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -29,6 +29,7 @@
 #include <linux/wait.h>
 #include <linux/blockgroup_lock.h>
 #include <linux/percpu_counter.h>
+#include <linux/ratelimit.h>
 #include <crypto/hash.h>
 #ifdef __KERNEL__
 #include <linux/compat.h>
@@ -1314,6 +1315,11 @@ struct ext4_sb_info {
 	unsigned long s_es_last_sorted;
 	struct percpu_counter s_extent_cache_cnt;
 	spinlock_t s_es_lru_lock ____cacheline_aligned_in_smp;
+
+	/* Ratelimit ext4 messages. */
+	struct ratelimit_state s_err_ratelimit_state;
+	struct ratelimit_state s_warning_ratelimit_state;
+	struct ratelimit_state s_msg_ratelimit_state;
 };
 
 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 2c2e6cbc6be..d3a857bfae4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -411,20 +411,26 @@ static void ext4_handle_error(struct super_block *sb)
 			sb->s_id);
 }
 
+#define ext4_error_ratelimit(sb)					\
+		___ratelimit(&(EXT4_SB(sb)->s_err_ratelimit_state),	\
+			     "EXT4-fs error")
+
 void __ext4_error(struct super_block *sb, const char *function,
 		  unsigned int line, const char *fmt, ...)
 {
 	struct va_format vaf;
 	va_list args;
 
-	va_start(args, fmt);
-	vaf.fmt = fmt;
-	vaf.va = &args;
-	printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: comm %s: %pV\n",
-	       sb->s_id, function, line, current->comm, &vaf);
-	va_end(args);
+	if (ext4_error_ratelimit(sb)) {
+		va_start(args, fmt);
+		vaf.fmt = fmt;
+		vaf.va = &args;
+		printk(KERN_CRIT
+		       "EXT4-fs error (device %s): %s:%d: comm %s: %pV\n",
+		       sb->s_id, function, line, current->comm, &vaf);
+		va_end(args);
+	}
 	save_error_info(sb, function, line);
-
 	ext4_handle_error(sb);
 }
 
@@ -438,22 +444,23 @@ void __ext4_error_inode(struct inode *inode, const char *function,
 
 	es->s_last_error_ino = cpu_to_le32(inode->i_ino);
 	es->s_last_error_block = cpu_to_le64(block);
+	if (ext4_error_ratelimit(inode->i_sb)) {
+		va_start(args, fmt);
+		vaf.fmt = fmt;
+		vaf.va = &args;
+		if (block)
+			printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: "
+			       "inode #%lu: block %llu: comm %s: %pV\n",
+			       inode->i_sb->s_id, function, line, inode->i_ino,
+			       block, current->comm, &vaf);
+		else
+			printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: "
+			       "inode #%lu: comm %s: %pV\n",
+			       inode->i_sb->s_id, function, line, inode->i_ino,
+			       current->comm, &vaf);
+		va_end(args);
+	}
 	save_error_info(inode->i_sb, function, line);
-	va_start(args, fmt);
-	vaf.fmt = fmt;
-	vaf.va = &args;
-	if (block)
-		printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: "
-		       "inode #%lu: block %llu: comm %s: %pV\n",
-		       inode->i_sb->s_id, function, line, inode->i_ino,
-		       block, current->comm, &vaf);
-	else
-		printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: "
-		       "inode #%lu: comm %s: %pV\n",
-		       inode->i_sb->s_id, function, line, inode->i_ino,
-		       current->comm, &vaf);
-	va_end(args);
-
 	ext4_handle_error(inode->i_sb);
 }
 
@@ -469,27 +476,28 @@ void __ext4_error_file(struct file *file, const char *function,
 
 	es = EXT4_SB(inode->i_sb)->s_es;
 	es->s_last_error_ino = cpu_to_le32(inode->i_ino);
+	if (ext4_error_ratelimit(inode->i_sb)) {
+		path = d_path(&(file->f_path), pathname, sizeof(pathname));
+		if (IS_ERR(path))
+			path = "(unknown)";
+		va_start(args, fmt);
+		vaf.fmt = fmt;
+		vaf.va = &args;
+		if (block)
+			printk(KERN_CRIT
+			       "EXT4-fs error (device %s): %s:%d: inode #%lu: "
+			       "block %llu: comm %s: path %s: %pV\n",
+			       inode->i_sb->s_id, function, line, inode->i_ino,
+			       block, current->comm, path, &vaf);
+		else
+			printk(KERN_CRIT
+			       "EXT4-fs error (device %s): %s:%d: inode #%lu: "
+			       "comm %s: path %s: %pV\n",
+			       inode->i_sb->s_id, function, line, inode->i_ino,
+			       current->comm, path, &vaf);
+		va_end(args);
+	}
 	save_error_info(inode->i_sb, function, line);
-	path = d_path(&(file->f_path), pathname, sizeof(pathname));
-	if (IS_ERR(path))
-		path = "(unknown)";
-	va_start(args, fmt);
-	vaf.fmt = fmt;
-	vaf.va = &args;
-	if (block)
-		printk(KERN_CRIT
-		       "EXT4-fs error (device %s): %s:%d: inode #%lu: "
-		       "block %llu: comm %s: path %s: %pV\n",
-		       inode->i_sb->s_id, function, line, inode->i_ino,
-		       block, current->comm, path, &vaf);
-	else
-		printk(KERN_CRIT
-		       "EXT4-fs error (device %s): %s:%d: inode #%lu: "
-		       "comm %s: path %s: %pV\n",
-		       inode->i_sb->s_id, function, line, inode->i_ino,
-		       current->comm, path, &vaf);
-	va_end(args);
-
 	ext4_handle_error(inode->i_sb);
 }
 
@@ -543,11 +551,13 @@ void __ext4_std_error(struct super_block *sb, const char *function,
 	    (sb->s_flags & MS_RDONLY))
 		return;
 
-	errstr = ext4_decode_error(sb, errno, nbuf);
-	printk(KERN_CRIT "EXT4-fs error (device %s) in %s:%d: %s\n",
-	       sb->s_id, function, line, errstr);
-	save_error_info(sb, function, line);
+	if (ext4_error_ratelimit(sb)) {
+		errstr = ext4_decode_error(sb, errno, nbuf);
+		printk(KERN_CRIT "EXT4-fs error (device %s) in %s:%d: %s\n",
+		       sb->s_id, function, line, errstr);
+	}
 
+	save_error_info(sb, function, line);
 	ext4_handle_error(sb);
 }
 
@@ -597,6 +607,9 @@ void __ext4_msg(struct super_block *sb,
 	struct va_format vaf;
 	va_list args;
 
+	if (!___ratelimit(&(EXT4_SB(sb)->s_msg_ratelimit_state), "EXT4-fs"))
+		return;
+
 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
@@ -610,6 +623,10 @@ void __ext4_warning(struct super_block *sb, const char *function,
 	struct va_format vaf;
 	va_list args;
 
+	if (!___ratelimit(&(EXT4_SB(sb)->s_warning_ratelimit_state),
+			  "EXT4-fs warning"))
+		return;
+
 	va_start(args, fmt);
 	vaf.fmt = fmt;
 	vaf.va = &args;
@@ -633,18 +650,20 @@ __acquires(bitlock)
 	es->s_last_error_block = cpu_to_le64(block);
 	__save_error_info(sb, function, line);
 
-	va_start(args, fmt);
-
-	vaf.fmt = fmt;
-	vaf.va = &args;
-	printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: group %u, ",
-	       sb->s_id, function, line, grp);
-	if (ino)
-		printk(KERN_CONT "inode %lu: ", ino);
-	if (block)
-		printk(KERN_CONT "block %llu:", (unsigned long long) block);
-	printk(KERN_CONT "%pV\n", &vaf);
-	va_end(args);
+	if (ext4_error_ratelimit(sb)) {
+		va_start(args, fmt);
+		vaf.fmt = fmt;
+		vaf.va = &args;
+		printk(KERN_CRIT "EXT4-fs error (device %s): %s:%d: group %u, ",
+		       sb->s_id, function, line, grp);
+		if (ino)
+			printk(KERN_CONT "inode %lu: ", ino);
+		if (block)
+			printk(KERN_CONT "block %llu:",
+			       (unsigned long long) block);
+		printk(KERN_CONT "%pV\n", &vaf);
+		va_end(args);
+	}
 
 	if (test_opt(sb, ERRORS_CONT)) {
 		ext4_commit_super(sb, 0);
@@ -2606,6 +2625,12 @@ EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
 EXT4_DEPRECATED_ATTR(max_writeback_mb_bump, 128);
 EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
 EXT4_ATTR(trigger_fs_error, 0200, NULL, trigger_test_error);
+EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
+EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
+EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
+EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
 
 static struct attribute *ext4_attrs[] = {
 	ATTR_LIST(delayed_allocation_blocks),
@@ -2623,6 +2648,12 @@ static struct attribute *ext4_attrs[] = {
 	ATTR_LIST(max_writeback_mb_bump),
 	ATTR_LIST(extent_max_zeroout_kb),
 	ATTR_LIST(trigger_fs_error),
+	ATTR_LIST(err_ratelimit_interval_ms),
+	ATTR_LIST(err_ratelimit_burst),
+	ATTR_LIST(warning_ratelimit_interval_ms),
+	ATTR_LIST(warning_ratelimit_burst),
+	ATTR_LIST(msg_ratelimit_interval_ms),
+	ATTR_LIST(msg_ratelimit_burst),
 	NULL,
 };
 
@@ -4118,6 +4149,11 @@ no_journal:
 	if (es->s_error_count)
 		mod_timer(&sbi->s_err_report, jiffies + 300*HZ); /* 5 minutes */
 
+	/* Enable message ratelimiting. Default is 10 messages per 5 secs. */
+	ratelimit_state_init(&sbi->s_err_ratelimit_state, 5 * HZ, 10);
+	ratelimit_state_init(&sbi->s_warning_ratelimit_state, 5 * HZ, 10);
+	ratelimit_state_init(&sbi->s_msg_ratelimit_state, 5 * HZ, 10);
+
 	kfree(orig_data);
 	return 0;