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btrfs: init device stats for seed devices 

We recently started recording device stats across the fleet, and noticed
a large increase in messages such as this

  BTRFS warning (device dm-0): get dev_stats failed, not yet valid

on our tiers that use seed devices for their root devices.  This is
because we do not initialize the device stats for any seed devices if we
have a sprout device and mount using that sprout device.  The basic
steps for reproducing are:

  $ mkfs seed device
  $ mount seed device
  # fill seed device
  $ umount seed device
  $ btrfstune -S 1 seed device
  $ mount seed device
  $ btrfs device add -f sprout device /mnt/wherever
  $ umount /mnt/wherever
  $ mount sprout device /mnt/wherever
  $ btrfs device stats /mnt/wherever

This will fail with the above message in dmesg.

Fix this by iterating over the fs_devices->seed if they exist in
btrfs_init_dev_stats.  This fixed the problem and properly reports the
stats for both devices.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ rename to btrfs_device_init_dev_stats ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2020-09-18 16:44:32 -04:00 committed by David Sterba
parent 905eb88bce
commit 124604eb50
1 changed files with 46 additions and 41 deletions
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87
fs/btrfs/volumes.c
View File

@ -7223,61 +7223,66 @@ static void btrfs_set_dev_stats_value(struct extent_buffer *eb,
sizeof(val));
}
static void btrfs_device_init_dev_stats(struct btrfs_device *device,
struct btrfs_path *path)
{
struct btrfs_dev_stats_item *ptr;
struct extent_buffer *eb;
struct btrfs_key key;
int item_size;
int i, ret, slot;
key.objectid = BTRFS_DEV_STATS_OBJECTID;
key.type = BTRFS_PERSISTENT_ITEM_KEY;
key.offset = device->devid;
ret = btrfs_search_slot(NULL, device->fs_info->dev_root, &key, path, 0, 0);
if (ret) {
for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++)
btrfs_dev_stat_set(device, i, 0);
device->dev_stats_valid = 1;
btrfs_release_path(path);
return;
}
slot = path->slots[0];
eb = path->nodes[0];
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_set(device, i, 0);
}
device->dev_stats_valid = 1;
btrfs_dev_stat_print_on_load(device);
btrfs_release_path(path);
}
int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info)
{
struct btrfs_key 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_fs_devices *fs_devices = fs_info->fs_devices, *seed_devs;
struct btrfs_device *device;
struct btrfs_path *path = NULL;
int i;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
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 = BTRFS_DEV_STATS_OBJECTID;
key.type = BTRFS_PERSISTENT_ITEM_KEY;
key.offset = device->devid;
ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0);
if (ret) {
for (i = 0; i < BTRFS_DEV_STAT_VALUES_MAX; i++)
btrfs_dev_stat_set(device, i, 0);
device->dev_stats_valid = 1;
btrfs_release_path(path);
continue;
}
slot = path->slots[0];
eb = path->nodes[0];
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_set(device, i, 0);
}
device->dev_stats_valid = 1;
btrfs_dev_stat_print_on_load(device);
btrfs_release_path(path);
list_for_each_entry(device, &fs_devices->devices, dev_list)
btrfs_device_init_dev_stats(device, path);
list_for_each_entry(seed_devs, &fs_devices->seed_list, seed_list) {
list_for_each_entry(device, &seed_devs->devices, dev_list)
btrfs_device_init_dev_stats(device, path);
}
mutex_unlock(&fs_devices->device_list_mutex);
btrfs_free_path(path);
return ret < 0 ? ret : 0;
return 0;
}
static int update_dev_stat_item(struct btrfs_trans_handle *trans,