btrfs: Add ratelimit to btrfs printing

This patch adds ratelimiting to all messages which are not using the _rl
version of the various printing APIs in btrfs. This is designed to be
used as a safety net, since a flood messages might cause the softlockup
detector to trigger. To reduce interference between different classes of
messages use a separate ratelimit state for every class of message.

Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 24 insertions, 2 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 60e7179ed4b7..8766d560a48f 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -184,6 +184,22 @@ static const char * const logtypes[] = {
         "debug",
 };
 
+
+/*
+ * Use one ratelimit state per log level so that a flood of less important
+ * messages doesn't cause more important ones to be dropped.
+ */
+static struct ratelimit_state printk_limits[] = {
+        RATELIMIT_STATE_INIT(printk_limits[0], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[1], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[2], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[3], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[4], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[5], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[6], DEFAULT_RATELIMIT_INTERVAL, 100),
+        RATELIMIT_STATE_INIT(printk_limits[7], DEFAULT_RATELIMIT_INTERVAL, 100),
+};
+
 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
 {
         struct super_block *sb = fs_info->sb;
@@ -192,6 +208,7 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
         va_list args;
         const char *type = logtypes[4];
         int kern_level;
+        struct ratelimit_state *ratelimit;
 
         va_start(args, fmt);
 
@@ -202,13 +219,18 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
                 lvl[size] = '\0';
                 fmt += size;
                 type = logtypes[kern_level - '0'];
-        } else
+                ratelimit = &printk_limits[kern_level - '0'];
+        } else {
                 *lvl = '\0';
+                /* Default to debug output */
+                ratelimit = &printk_limits[7];
+        }
 
         vaf.fmt = fmt;
         vaf.va = &args;
 
-        printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
+        if (__ratelimit(ratelimit))
+                printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
 
         va_end(args);
 }