[PATCH 04/39] ocfs2: track local alloc state via debugfs

Mark Fasheh
2008-09-24T22:08:56Z

A per-mount debugfs file, "local_alloc" is created which when read will
expose live state of the nodes local alloc file. Performance impact is
minimal, only a bit of memory overhead per mount point. Still, the code is
hidden behind CONFIG_OCFS2_FS_STATS. This feature will help us debug
local alloc performance problems on a live system.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
---
fs/ocfs2/localalloc.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/ocfs2/ocfs2.h | 5 +++
2 files changed, 92 insertions(+), 0 deletions(-)

diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
index f71658a..b889f10 100644
--- a/fs/ocfs2/localalloc.c
+++ b/fs/ocfs2/localalloc.c
@@ -28,6 +28,7 @@
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/bitops.h>
+#include <linux/debugfs.h>

#define MLOG_MASK_PREFIX ML_DISK_ALLOC
#include <cluster/masklog.h>
@@ -73,6 +74,85 @@ static int ocfs2_local_alloc_new_window(struct ocfs2_super *osb,
static int ocfs2_local_alloc_slide_window(struct ocfs2_super *osb,
struct inode *local_alloc_inode);

+#ifdef CONFIG_OCFS2_FS_STATS
+
+DEFINE_MUTEX(la_debug_mutex);
+
+static int ocfs2_la_debug_open(struct inode *inode, struct file *file)
+{
+ file->private_data = inode->i_private;
+ return 0;
+}
+
+#define LA_DEBUG_BUF_SZ PAGE_CACHE_SIZE
+#define LA_DEBUG_VER 1
+static ssize_t ocfs2_la_debug_read(struct file *file, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct ocfs2_super *osb = file->private_data;
+ int written, ret;
+ char *buf = osb->local_alloc_debug_buf;
+
+ mutex_lock(&la_debug_mutex);
+ memset(buf, 0, LA_DEBUG_BUF_SZ);
+
+ written = snprintf(buf, LA_DEBUG_BUF_SZ,
+ "0x%x\t0x%llx\t%u\t%u\t0x%x\n",
+ LA_DEBUG_VER,
+ (unsigned long long)osb->la_last_gd,
+ osb->local_alloc_default_bits,
+ osb->local_alloc_bits, osb->local_alloc_state);
+
+ ret = simple_read_from_buffer(userbuf, count, ppos, buf, written);
+
+ mutex_unlock(&la_debug_mutex);
+ return ret;
+}
+
+static const struct file_operations ocfs2_la_debug_fops = {
+ .open = ocfs2_la_debug_open,
+ .read = ocfs2_la_debug_read,
+};
+
+static void ocfs2_init_la_debug(struct ocfs2_super *osb)
+{
+ osb->local_alloc_debug_buf = kmalloc(LA_DEBUG_BUF_SZ, GFP_NOFS);
+ if (!osb->local_alloc_debug_buf)
+ return;
+
+ osb->local_alloc_debug = debugfs_create_file("local_alloc_stats",
+ S_IFREG|S_IRUSR,
+ osb->osb_debug_root,
+ osb,
+ &ocfs2_la_debug_fops);
+ if (!osb->local_alloc_debug) {
+ kfree(osb->local_alloc_debug_buf);
+ osb->local_alloc_debug_buf = NULL;
+ }
+}
+
+static void ocfs2_shutdown_la_debug(struct ocfs2_super *osb)
+{
+ if (osb->local_alloc_debug)
+ debugfs_remove(osb->local_alloc_debug);
+
+ if (osb->local_alloc_debug_buf)
+ kfree(osb->local_alloc_debug_buf);
+
+ osb->local_alloc_debug_buf = NULL;
+ osb->local_alloc_debug = NULL;
+}
+#else /* CONFIG_OCFS2_FS_STATS */
+static void ocfs2_init_la_debug(struct ocfs2_super *osb)
+{
+ return;
+}
+static void ocfs2_shutdown_la_debug(struct ocfs2_super *osb)
+{
+ return;
+}
+#endif
+
static inline int ocfs2_la_state_enabled(struct ocfs2_super *osb)
{
return (osb->local_alloc_state == OCFS2_LA_THROTTLED ||
@@ -146,6 +226,8 @@ int ocfs2_load_local_alloc(struct ocfs2_super *osb)

mlog_entry_void();

+ ocfs2_init_la_debug(osb);
+
if (osb->local_alloc_bits == 0)
goto bail;

@@ -218,6 +300,9 @@ bail:
if (inode)
iput(inode);

+ if (status < 0)
+ ocfs2_shutdown_la_debug(osb);
+
mlog(0, "Local alloc window bits = %d\n", osb->local_alloc_bits);

mlog_exit(status);
@@ -247,6 +332,8 @@ void ocfs2_shutdown_local_alloc(struct ocfs2_super *osb)
cancel_delayed_work(&osb->la_enable_wq);
flush_workqueue(ocfs2_wq);

+ ocfs2_shutdown_la_debug(osb);
+
if (osb->local_alloc_state == OCFS2_LA_UNUSED)
goto out;

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 4d6e200..1282799 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -272,6 +272,11 @@ struct ocfs2_super

u64 la_last_gd;

+#ifdef CONFIG_OCFS2_FS_STATS
+ struct dentry *local_alloc_debug;
+ char *local_alloc_debug_buf;
+#endif
+
/* Next two fields are for local node slot recovery during
* mount. */
int dirty;
--
1.5.4.5