jbd2: convert instrumentation from markers to tracepoints
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 62be7d2..18bfd5d 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -38,6 +38,10 @@
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/math64.h>
+#include <linux/hash.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/jbd2.h>
#include <asm/uaccess.h>
#include <asm/page.h>
@@ -2377,6 +2381,71 @@
jbd2_journal_destroy_caches();
}
+/*
+ * jbd2_dev_to_name is a utility function used by the jbd2 and ext4
+ * tracing infrastructure to map a dev_t to a device name.
+ *
+ * The caller should use rcu_read_lock() in order to make sure the
+ * device name stays valid until its done with it. We use
+ * rcu_read_lock() as well to make sure we're safe in case the caller
+ * gets sloppy, and because rcu_read_lock() is cheap and can be safely
+ * nested.
+ */
+struct devname_cache {
+ struct rcu_head rcu;
+ dev_t device;
+ char devname[BDEVNAME_SIZE];
+};
+#define CACHE_SIZE_BITS 6
+static struct devname_cache *devcache[1 << CACHE_SIZE_BITS];
+static DEFINE_SPINLOCK(devname_cache_lock);
+
+static void free_devcache(struct rcu_head *rcu)
+{
+ kfree(rcu);
+}
+
+const char *jbd2_dev_to_name(dev_t device)
+{
+ int i = hash_32(device, CACHE_SIZE_BITS);
+ char *ret;
+ struct block_device *bd;
+
+ rcu_read_lock();
+ if (devcache[i] && devcache[i]->device == device) {
+ ret = devcache[i]->devname;
+ rcu_read_unlock();
+ return ret;
+ }
+ rcu_read_unlock();
+
+ spin_lock(&devname_cache_lock);
+ if (devcache[i]) {
+ if (devcache[i]->device == device) {
+ ret = devcache[i]->devname;
+ spin_unlock(&devname_cache_lock);
+ return ret;
+ }
+ call_rcu(&devcache[i]->rcu, free_devcache);
+ }
+ devcache[i] = kmalloc(sizeof(struct devname_cache), GFP_KERNEL);
+ if (!devcache[i]) {
+ spin_unlock(&devname_cache_lock);
+ return "NODEV-ALLOCFAILURE"; /* Something non-NULL */
+ }
+ devcache[i]->device = device;
+ bd = bdget(device);
+ if (bd) {
+ bdevname(bd, devcache[i]->devname);
+ bdput(bd);
+ } else
+ __bdevname(device, devcache[i]->devname);
+ ret = devcache[i]->devname;
+ spin_unlock(&devname_cache_lock);
+ return ret;
+}
+EXPORT_SYMBOL(jbd2_dev_to_name);
+
MODULE_LICENSE("GPL");
module_init(journal_init);
module_exit(journal_exit);