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Btrfs: read device stats on mount, write modified ones during commit
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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>
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Stefan Behrens authored and Josef Bacik committed May 30, 2012
1 parent c11d2c2 commit 733f4fb
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Showing 6 changed files with 232 additions and 0 deletions.
38 changes: 38 additions & 0 deletions fs/btrfs/ctree.h
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Original file line number Diff line number Diff line change
Expand Up @@ -823,6 +823,14 @@ struct btrfs_csum_item {
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)
Expand Down Expand Up @@ -1507,6 +1515,12 @@ struct btrfs_ioctl_defrag_range_args {

#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
Expand Down Expand Up @@ -2415,6 +2429,30 @@ static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
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;
Expand Down
7 changes: 7 additions & 0 deletions fs/btrfs/disk-io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2354,6 +2354,13 @@ int open_ctree(struct super_block *sb,
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);
Expand Down
3 changes: 3 additions & 0 deletions fs/btrfs/print-tree.c
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Original file line number Diff line number Diff line change
Expand Up @@ -294,6 +294,9 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
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;
};
}
}
Expand Down
4 changes: 4 additions & 0 deletions fs/btrfs/transaction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
#include "locking.h"
#include "tree-log.h"
#include "inode-map.h"
#include "volumes.h"

#define BTRFS_ROOT_TRANS_TAG 0

Expand Down Expand Up @@ -758,6 +759,9 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
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);
Expand Down
176 changes: 176 additions & 0 deletions fs/btrfs/volumes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,8 @@ static int init_first_rw_device(struct btrfs_trans_handle *trans,
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);
Expand Down Expand Up @@ -362,6 +364,7 @@ static noinline int device_list_add(const char *path,
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);
Expand Down Expand Up @@ -4654,6 +4657,162 @@ int btrfs_read_chunk_tree(struct btrfs_root *root)
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);
Expand All @@ -4662,6 +4821,8 @@ void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index)

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,
Expand All @@ -4674,6 +4835,17 @@ void btrfs_dev_stat_print_on_error(struct btrfs_device *dev)
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)
Expand All @@ -4690,6 +4862,10 @@ int btrfs_get_dev_stats(struct btrfs_root *root,
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)
Expand Down
4 changes: 4 additions & 0 deletions fs/btrfs/volumes.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -109,6 +109,7 @@ struct btrfs_device {

/* 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];
};
Expand Down Expand Up @@ -293,6 +294,9 @@ void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index);
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)
Expand Down

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