On Wed, 23 May 2012 09:29:12 +0800, Liu Bo wrote:
> On 05/22/2012 06:53 PM, Stefan Behrens wrote:
>
>> 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@xxxxxxxxxxxxxxxx>
>> ---
>> fs/btrfs/ctree.h | 51 ++++++++++++
>> fs/btrfs/disk-io.c | 7 ++
>> fs/btrfs/print-tree.c | 3 +
>> fs/btrfs/transaction.c | 4 +
>> fs/btrfs/volumes.c | 205 ++++++++++++++++++++++++++++++++++++++++++++++++
>> fs/btrfs/volumes.h | 9 +++
>> 6 files changed, 279 insertions(+)
>>
> [...]
>> +static int update_device_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_device_stats_item *ptr;
>> + int ret;
>> +
>> + key.objectid = 0;
>> + key.type = BTRFS_DEVICE_STATS_KEY;
>> + key.offset = device->devid;
>> +
>> + path = btrfs_alloc_path();
>> + BUG_ON(!path);
>> + ret = btrfs_search_slot(trans, dev_root, &key, path, 0, 1);
>
>
> Since we may delete this item, I prefer cow: -1,
>
> btrfs_search_slot(trans, dev_root, &key, path, 0, -1);
>
> thanks,
> liubo
I am sure you mean to set ins_len (the 5th parameter) to -1 and you are
right. Thanks for this finding! I will send a v5.
>> + if (ret < 0) {
>> + printk(KERN_WARNING "btrfs: error %d while searching for device_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 device_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 device_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_device_stats_item);
>> + btrfs_set_device_stats_cnt_write_io_errs(eb, ptr,
>> + btrfs_device_stat_read(&device->cnt_write_io_errs));
>> + btrfs_set_device_stats_cnt_read_io_errs(eb, ptr,
>> + btrfs_device_stat_read(&device->cnt_read_io_errs));
>> + btrfs_set_device_stats_cnt_flush_io_errs(eb, ptr,
>> + btrfs_device_stat_read(&device->cnt_flush_io_errs));
>> + btrfs_set_device_stats_cnt_corruption_errs(eb, ptr,
>> + btrfs_device_stat_read(&device->cnt_corruption_errs));
>> + btrfs_set_device_stats_cnt_generation_errs(eb, ptr,
>> + btrfs_device_stat_read(&device->cnt_generation_errs));
>> + btrfs_mark_buffer_dirty(eb);
>> +
>> +out:
>> + btrfs_free_path(path);
>> + return ret;
>> +}
[...]
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
