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/ctree.h b/fs/btrfs/ctree.h
index aad2600..e176f8c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -823,6 +823,14 @@
u8 csum;
} __attribute__ ((__packed__));
+struct btrfs_dev_stats_item {
+ /*
+ * grow this item struct at the end for future enhancements and keep
+ * the existing values unchanged
+ */
+ __le64 values[BTRFS_DEV_STAT_VALUES_MAX];
+} __attribute__ ((__packed__));
+
/* different types of block groups (and chunks) */
#define BTRFS_BLOCK_GROUP_DATA (1ULL << 0)
#define BTRFS_BLOCK_GROUP_SYSTEM (1ULL << 1)
@@ -1508,6 +1516,12 @@
#define BTRFS_BALANCE_ITEM_KEY 248
/*
+ * Persistantly stores the io stats in the device tree.
+ * One key for all stats, (0, BTRFS_DEV_STATS_KEY, devid).
+ */
+#define BTRFS_DEV_STATS_KEY 249
+
+/*
* string items are for debugging. They just store a short string of
* data in the FS
*/
@@ -2415,6 +2429,30 @@
return btrfs_item_size(eb, e) - offset;
}
+/* btrfs_dev_stats_item */
+static inline u64 btrfs_dev_stats_value(struct extent_buffer *eb,
+ struct btrfs_dev_stats_item *ptr,
+ int index)
+{
+ u64 val;
+
+ read_extent_buffer(eb, &val,
+ offsetof(struct btrfs_dev_stats_item, values) +
+ ((unsigned long)ptr) + (index * sizeof(u64)),
+ sizeof(val));
+ return val;
+}
+
+static inline void btrfs_set_dev_stats_value(struct extent_buffer *eb,
+ struct btrfs_dev_stats_item *ptr,
+ int index, u64 val)
+{
+ write_extent_buffer(eb, &val,
+ offsetof(struct btrfs_dev_stats_item, values) +
+ ((unsigned long)ptr) + (index * sizeof(u64)),
+ sizeof(val));
+}
+
static inline struct btrfs_fs_info *btrfs_sb(struct super_block *sb)
{
return sb->s_fs_info;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 46d474e..b0d49e2 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2354,6 +2354,13 @@
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
+ ret = btrfs_init_dev_stats(fs_info);
+ if (ret) {
+ printk(KERN_ERR "btrfs: failed to init dev_stats: %d\n",
+ ret);
+ goto fail_block_groups;
+ }
+
ret = btrfs_init_space_info(fs_info);
if (ret) {
printk(KERN_ERR "Failed to initial space info: %d\n", ret);
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index f38e452..5e23684 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -294,6 +294,9 @@
btrfs_dev_extent_chunk_offset(l, dev_extent),
(unsigned long long)
btrfs_dev_extent_length(l, dev_extent));
+ case BTRFS_DEV_STATS_KEY:
+ printk(KERN_INFO "\t\tdevice stats\n");
+ break;
};
}
}
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 3642225..82b03af 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -28,6 +28,7 @@
#include "locking.h"
#include "tree-log.h"
#include "inode-map.h"
+#include "volumes.h"
#define BTRFS_ROOT_TRANS_TAG 0
@@ -758,6 +759,9 @@
if (ret)
return ret;
+ ret = btrfs_run_dev_stats(trans, root->fs_info);
+ BUG_ON(ret);
+
while (!list_empty(&fs_info->dirty_cowonly_roots)) {
next = fs_info->dirty_cowonly_roots.next;
list_del_init(next);
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)
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 6798f86..3406a88 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -109,6 +109,7 @@
/* disk I/O failure stats. For detailed description refer to
* enum btrfs_dev_stat_values in ioctl.h */
+ int dev_stats_valid;
int dev_stats_dirty; /* counters need to be written to disk */
atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];
};
@@ -293,6 +294,9 @@
int btrfs_get_dev_stats(struct btrfs_root *root,
struct btrfs_ioctl_get_dev_stats *stats,
int reset_after_read);
+int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
+int btrfs_run_dev_stats(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info);
static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
int index)