Btrfs: read device stats on mount, write modified ones during commit
The device statistics are written into the device tree with each
transaction commit. Only modified statistics are written.
When a filesystem is mounted, the device statistics for each involved
device are read from the device tree and used to initialize the
counters.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a112b75..7782020 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -40,6 +40,8 @@
struct btrfs_root *root,
struct btrfs_device *device);
static int btrfs_relocate_sys_chunks(struct btrfs_root *root);
+static void __btrfs_reset_dev_stats(struct btrfs_device *dev);
+static void btrfs_dev_stat_print_on_load(struct btrfs_device *device);
static DEFINE_MUTEX(uuid_mutex);
static LIST_HEAD(fs_uuids);
@@ -362,6 +364,7 @@
return -ENOMEM;
}
device->devid = devid;
+ device->dev_stats_valid = 0;
device->work.func = pending_bios_fn;
memcpy(device->uuid, disk_super->dev_item.uuid,
BTRFS_UUID_SIZE);
@@ -4654,6 +4657,162 @@
return ret;
}
+static void __btrfs_reset_dev_stats(struct btrfs_device *dev)
+{
+ int i;
+
+ for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++)
+ btrfs_dev_stat_reset(dev, i);
+}
+
+int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_key key;
+ struct btrfs_key found_key;
+ struct btrfs_root *dev_root = fs_info->dev_root;
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct extent_buffer *eb;
+ int slot;
+ int ret = 0;
+ struct btrfs_device *device;
+ struct btrfs_path *path = NULL;
+ int i;
+
+ path = btrfs_alloc_path();
+ if (!path) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ mutex_lock(&fs_devices->device_list_mutex);
+ list_for_each_entry(device, &fs_devices->devices, dev_list) {
+ int item_size;
+ struct btrfs_dev_stats_item *ptr;
+
+ key.objectid = 0;
+ key.type = BTRFS_DEV_STATS_KEY;
+ key.offset = device->devid;
+ ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
+ if (ret) {
+ printk(KERN_WARNING "btrfs: no dev_stats entry found for device %s (devid %llu) (OK on first mount after mkfs)\n",
+ device->name, (unsigned long long)device->devid);
+ __btrfs_reset_dev_stats(device);
+ device->dev_stats_valid = 1;
+ btrfs_release_path(path);
+ continue;
+ }
+ slot = path->slots[0];
+ eb = path->nodes[0];
+ btrfs_item_key_to_cpu(eb, &found_key, slot);
+ item_size = btrfs_item_size_nr(eb, slot);
+
+ ptr = btrfs_item_ptr(eb, slot,
+ struct btrfs_dev_stats_item);
+
+ for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++) {
+ if (item_size >= (1 + i) * sizeof(__le64))
+ btrfs_dev_stat_set(device, i,
+ btrfs_dev_stats_value(eb, ptr, i));
+ else
+ btrfs_dev_stat_reset(device, i);
+ }
+
+ device->dev_stats_valid = 1;
+ btrfs_dev_stat_print_on_load(device);
+ btrfs_release_path(path);
+ }
+ mutex_unlock(&fs_devices->device_list_mutex);
+
+out:
+ btrfs_free_path(path);
+ return ret < 0 ? ret : 0;
+}
+
+static int update_dev_stat_item(struct btrfs_trans_handle *trans,
+ struct btrfs_root *dev_root,
+ struct btrfs_device *device)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct extent_buffer *eb;
+ struct btrfs_dev_stats_item *ptr;
+ int ret;
+ int i;
+
+ key.objectid = 0;
+ key.type = BTRFS_DEV_STATS_KEY;
+ key.offset = device->devid;
+
+ path = btrfs_alloc_path();
+ BUG_ON(!path);
+ ret = btrfs_search_slot(trans, dev_root, &key, path, -1, 1);
+ if (ret < 0) {
+ printk(KERN_WARNING "btrfs: error %d while searching for dev_stats item for device %s!\n",
+ ret, device->name);
+ goto out;
+ }
+
+ if (ret == 0 &&
+ btrfs_item_size_nr(path->nodes[0], path->slots[0]) < sizeof(*ptr)) {
+ /* need to delete old one and insert a new one */
+ ret = btrfs_del_item(trans, dev_root, path);
+ if (ret != 0) {
+ printk(KERN_WARNING "btrfs: delete too small dev_stats item for device %s failed %d!\n",
+ device->name, ret);
+ goto out;
+ }
+ ret = 1;
+ }
+
+ if (ret == 1) {
+ /* need to insert a new item */
+ btrfs_release_path(path);
+ ret = btrfs_insert_empty_item(trans, dev_root, path,
+ &key, sizeof(*ptr));
+ if (ret < 0) {
+ printk(KERN_WARNING "btrfs: insert dev_stats item for device %s failed %d!\n",
+ device->name, ret);
+ goto out;
+ }
+ }
+
+ eb = path->nodes[0];
+ ptr = btrfs_item_ptr(eb, path->slots[0], struct btrfs_dev_stats_item);
+ for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++)
+ btrfs_set_dev_stats_value(eb, ptr, i,
+ btrfs_dev_stat_read(device, i));
+ btrfs_mark_buffer_dirty(eb);
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+/*
+ * called from commit_transaction. Writes all changed device stats to disk.
+ */
+int btrfs_run_dev_stats(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info)
+{
+ struct btrfs_root *dev_root = fs_info->dev_root;
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct btrfs_device *device;
+ int ret = 0;
+
+ mutex_lock(&fs_devices->device_list_mutex);
+ list_for_each_entry(device, &fs_devices->devices, dev_list) {
+ if (!device->dev_stats_valid || !device->dev_stats_dirty)
+ continue;
+
+ ret = update_dev_stat_item(trans, dev_root, device);
+ if (!ret)
+ device->dev_stats_dirty = 0;
+ }
+ mutex_unlock(&fs_devices->device_list_mutex);
+
+ return ret;
+}
+
void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index)
{
btrfs_dev_stat_inc(dev, index);
@@ -4662,6 +4821,8 @@
void btrfs_dev_stat_print_on_error(struct btrfs_device *dev)
{
+ if (!dev->dev_stats_valid)
+ return;
printk_ratelimited(KERN_ERR
"btrfs: bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
dev->name,
@@ -4674,6 +4835,17 @@
BTRFS_DEV_STAT_GENERATION_ERRS));
}
+static void btrfs_dev_stat_print_on_load(struct btrfs_device *dev)
+{
+ printk(KERN_INFO "btrfs: bdev %s errs: wr %u, rd %u, flush %u, corrupt %u, gen %u\n",
+ dev->name,
+ btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_WRITE_ERRS),
+ btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_READ_ERRS),
+ btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_FLUSH_ERRS),
+ btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_CORRUPTION_ERRS),
+ btrfs_dev_stat_read(dev, BTRFS_DEV_STAT_GENERATION_ERRS));
+}
+
int btrfs_get_dev_stats(struct btrfs_root *root,
struct btrfs_ioctl_get_dev_stats *stats,
int reset_after_read)
@@ -4690,6 +4862,10 @@
printk(KERN_WARNING
"btrfs: get dev_stats failed, device not found\n");
return -ENODEV;
+ } else if (!dev->dev_stats_valid) {
+ printk(KERN_WARNING
+ "btrfs: get dev_stats failed, not yet valid\n");
+ return -ENODEV;
} else if (reset_after_read) {
for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++) {
if (stats->nr_items > i)