ocfs2/dlm: Dumps the purgelist into a debugfs file

This patch dumps all the lockres' on the purgelist it can fit in one page
into a debugfs file. Useful for debugging.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

2 files changed, 72 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
index 6de326bf603a..a109005f70da 100644
--- a/fs/ocfs2/dlm/dlmdebug.c
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -303,6 +303,7 @@ static int stringify_lockname(const char *lockname, int locklen,
 #define DLM_DEBUGFS_DLM_STATE                   "dlm_state"
 #define DLM_DEBUGFS_LOCKING_STATE               "locking_state"
 #define DLM_DEBUGFS_MLE_STATE                   "mle_state"
+#define DLM_DEBUGFS_PURGE_LIST                  "purge_list"
 
 /* begin - utils funcs */
 static void dlm_debug_free(struct kref *kref)
@@ -396,6 +397,63 @@ static int debug_buffer_release(struct inode *inode, struct file *file)
 }
 /* end - util funcs */
 
+/* begin - purge list funcs */
+static int debug_purgelist_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+        struct dlm_lock_resource *res;
+        int out = 0;
+        unsigned long total = 0;
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Dumping Purgelist for Domain: %s\n", dlm->name);
+
+        spin_lock(&dlm->spinlock);
+        list_for_each_entry(res, &dlm->purge_list, purge) {
+                ++total;
+                if (db->len - out < 100)
+                        continue;
+                spin_lock(&res->spinlock);
+                out += stringify_lockname(res->lockname.name,
+                                          res->lockname.len,
+                                          db->buf + out, db->len - out);
+                out += snprintf(db->buf + out, db->len - out, "\t%ld\n",
+                                (jiffies - res->last_used)/HZ);
+                spin_unlock(&res->spinlock);
+        }
+        spin_unlock(&dlm->spinlock);
+
+        out += snprintf(db->buf + out, db->len - out,
+                        "Total on list: %ld\n", total);
+
+        return out;
+}
+
+static int debug_purgelist_open(struct inode *inode, struct file *file)
+{
+        struct dlm_ctxt *dlm = inode->i_private;
+        struct debug_buffer *db;
+
+        db = debug_buffer_allocate();
+        if (!db)
+                goto bail;
+
+        db->len = debug_purgelist_print(dlm, db);
+
+        file->private_data = db;
+
+        return 0;
+bail:
+        return -ENOMEM;
+}
+
+static struct file_operations debug_purgelist_fops = {
+        .open =         debug_purgelist_open,
+        .release =      debug_buffer_release,
+        .read =         debug_buffer_read,
+        .llseek =       debug_buffer_llseek,
+};
+/* end - purge list funcs */
+
 /* begin - debug mle funcs */
 static int dump_mle(struct dlm_master_list_entry *mle, char *buf, int len)
 {
@@ -906,6 +964,17 @@ int dlm_debug_init(struct dlm_ctxt *dlm)
                 goto bail;
         }
 
+        /* for dumping lockres on the purge list */
+        dc->debug_purgelist_dentry =
+                        debugfs_create_file(DLM_DEBUGFS_PURGE_LIST,
+                                            S_IFREG|S_IRUSR,
+                                            dlm->dlm_debugfs_subroot,
+                                            dlm, &debug_purgelist_fops);
+        if (!dc->debug_purgelist_dentry) {
+                mlog_errno(-ENOMEM);
+                goto bail;
+        }
+
         dlm_debug_get(dc);
         return 0;
 
@@ -919,6 +988,8 @@ void dlm_debug_shutdown(struct dlm_ctxt *dlm)
         struct dlm_debug_ctxt *dc = dlm->dlm_debug_ctxt;
 
         if (dc) {
+                if (dc->debug_purgelist_dentry)
+                        debugfs_remove(dc->debug_purgelist_dentry);
                 if (dc->debug_mle_dentry)
                         debugfs_remove(dc->debug_mle_dentry);
                 if (dc->debug_lockres_dentry)
diff --git a/fs/ocfs2/dlm/dlmdebug.h b/fs/ocfs2/dlm/dlmdebug.h
index cbc69f295782..8857743e8f32 100644
--- a/fs/ocfs2/dlm/dlmdebug.h
+++ b/fs/ocfs2/dlm/dlmdebug.h
@@ -32,6 +32,7 @@ struct dlm_debug_ctxt {
         struct dentry *debug_state_dentry;
         struct dentry *debug_lockres_dentry;
         struct dentry *debug_mle_dentry;
+        struct dentry *debug_purgelist_dentry;
 };
 
 struct debug_buffer {