On Sat, Dec 13, 2014 at 3:25 AM, Goffredo Baroncelli <kreij...@inwind.it> wrote:
> On 12/11/2014 09:31 AM, Dongsheng Yang wrote:
>> When function btrfs_statfs() calculate the tatol size of fs, it is
>> calculating
>> the total size of disks and then dividing it by a factor. But in some
>> usecase,
>> the result is not good to user.
>
>
> I Yang; during my test I discovered an error:
>
> $ sudo lvcreate -L +10G -n disk vgtest
> $ sudo /home/ghigo/mkfs.btrfs -f /dev/vgtest/disk
> Btrfs v3.17
> See http://btrfs.wiki.kernel.org for more information.
>
> Turning ON incompat feature 'extref': increased hardlink limit per file to
> 65536
> fs created label (null) on /dev/vgtest/disk
> nodesize 16384 leafsize 16384 sectorsize 4096 size 10.00GiB
> $ sudo mount /dev/vgtest/disk /mnt/btrfs1/
> $ df /mnt/btrfs1/
> Filesystem 1K-blocks Used Available Use% Mounted on
> /dev/mapper/vgtest-disk 9428992 1069312 8359680 12% /mnt/btrfs1
> $ sudo ~/btrfs fi df /mnt/btrfs1/
> Data, single: total=8.00MiB, used=256.00KiB
> System, DUP: total=8.00MiB, used=16.00KiB
> System, single: total=4.00MiB, used=0.00B
> Metadata, DUP: total=1.00GiB, used=112.00KiB
> Metadata, single: total=8.00MiB, used=0.00B
> GlobalReserve, single: total=16.00MiB, used=0.00B
>
> What seems me strange is the 9428992KiB of total disk space as reported
> by df. About 600MiB are missing !
>
> Without your patch, I got:
>
> $ df /mnt/btrfs1/
> Filesystem 1K-blocks Used Available Use% Mounted on
> /dev/mapper/vgtest-disk 10485760 16896 8359680 1% /mnt/btrfs1
>
Hi Goffredo, thanx for pointing this. Let me try to show the reason of it.
In this case you provided here, the metadata is 1G in DUP. It means
we spent 2G device space for it. But from the view point of user, they
can only see 9G size for this fs. It's show as below:
1G
-----|---------------- Filesystem space (9G)
| \
| \
| \
| 2G \
-----|----|----------------- Device space (10G)
DUP |
The main idea about the new btrfs_statfs() is hiding the detail in Device
space and only show the information in the FS space level.
Actually, the similar idea is adopted in btrfs fi df.
Example:
# lvcreate -L +10G -n disk Group0
# mkfs.btrfs -f /dev/Group0/disk
# dd if=/dev/zero of=/mnt/data bs=1M count=10240
dd: error writing ‘/mnt/data’: No space left on device
8163+0 records in
8162+0 records out
8558477312 bytes (8.6 GB) copied, 207.565 s, 41.2 MB/s
# df /mnt
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/Group0-disk 9428992 8382896 2048 100% /mnt
# btrfs fi df /mnt
Data, single: total=7.97GiB, used=7.97GiB
System, DUP: total=8.00MiB, used=16.00KiB
System, single: total=4.00MiB, used=0.00B
Metadata, DUP: total=1.00GiB, used=8.41MiB
Metadata, single: total=8.00MiB, used=0.00B
GlobalReserve, single: total=16.00MiB, used=0.00B
Now, the all space is used and got a ENOSPC error.
But from the output of btrfs fi df. We can only find almost 9G (data
8G + metadata 1G)
is used. The difference is that it show the DUP here to make
it more clear.
Wish this description is clear to you :).
If there is anything confusing or sounds incorrect to you, please point it out.
Thanx
Yang
>
>> Example:
>> # mkfs.btrfs -f /dev/vdf1 /dev/vdf2 -d raid1
>> # mount /dev/vdf1 /mnt
>> # dd if=/dev/zero of=/mnt/zero bs=1M count=1000
>> # df -h /mnt
>> Filesystem Size Used Avail Use% Mounted on
>> /dev/vdf1 3.0G 1018M 1.3G 45% /mnt
>> # btrfs fi show /dev/vdf1
>> Label: none uuid: f85d93dc-81f4-445d-91e5-6a5cd9563294
>> Total devices 2 FS bytes used 1001.53MiB
>> devid 1 size 2.00GiB used 1.85GiB path /dev/vdf1
>> devid 2 size 4.00GiB used 1.83GiB path /dev/vdf2
>> a. df -h should report Size as 2GiB rather than as 3GiB.
>> Because this is 2 device raid1, the limiting factor is devid 1 @2GiB.
>>
>> b. df -h should report Avail as 0.97GiB or less, rather than as 1.3GiB.
>> 1.85 (the capacity of the allocated chunk)
>> -1.018 (the file stored)
>> +(2-1.85=0.15) (the residual capacity of the disks
>> considering a raid1 fs)
>> ---------------
>> = 0.97
>>
>> This patch drops the factor at all and calculate the size observable to
>> user without considering which raid level the data is in and what's the
>> size exactly in disk.
>> After this patch applied:
>> # mkfs.btrfs -f /dev/vdf1 /dev/vdf2 -d raid1
>> # mount /dev/vdf1 /mnt
>> # dd if=/dev/zero of=/mnt/zero bs=1M count=1000
>> # df -h /mnt
>> Filesystem Size Used Avail Use% Mounted on
>> /dev/vdf1 2.0G 1.3G 713M 66% /mnt
>> # df /mnt
>> Filesystem 1K-blocks Used Available Use% Mounted on
>> /dev/vdf1 2097152 1359424 729536 66% /mnt
>> # btrfs fi show /dev/vdf1
>> Label: none uuid: e98c1321-645f-4457-b20d-4f41dc1cf2f4
>> Total devices 2 FS bytes used 1001.55MiB
>> devid 1 size 2.00GiB used 1.85GiB path /dev/vdf1
>> devid 2 size 4.00GiB used 1.83GiB path /dev/vdf2
>> a). The @Size is 2G as we expected.
>> b). @Available is 700M = 1.85G - 1.3G + (2G - 1.85G).
>> c). @Used is changed to 1.3G rather than 1018M as above. Because
>> this patch do not treat the free space in metadata chunk
>> and system chunk as available to user. It's true, user can
>> not use these space to store data, then it should not be
>> thought as available. At the same time, it will make the
>> @Used + @Available == @Size as possible to user.
>>
>> Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
>> ---
>> Changelog:
>> v1 -> v2:
>> a. account the total_bytes in medadata chunk and
>> system chunk as used to user.
>> b. set data_stripes to the correct value in RAID0.
>>
>> fs/btrfs/extent-tree.c | 13 ++----------
>> fs/btrfs/super.c | 56
>> ++++++++++++++++++++++----------------------------
>> 2 files changed, 26 insertions(+), 43 deletions(-)
>>
>> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>> index a84e00d..9954d60 100644
>> --- a/fs/btrfs/extent-tree.c
>> +++ b/fs/btrfs/extent-tree.c
>> @@ -8571,7 +8571,6 @@ static u64
>> __btrfs_get_ro_block_group_free_space(struct list_head *groups_list)
>> {
>> struct btrfs_block_group_cache *block_group;
>> u64 free_bytes = 0;
>> - int factor;
>>
>> list_for_each_entry(block_group, groups_list, list) {
>> spin_lock(&block_group->lock);
>> @@ -8581,16 +8580,8 @@ static u64
>> __btrfs_get_ro_block_group_free_space(struct list_head *groups_list)
>> continue;
>> }
>>
>> - if (block_group->flags & (BTRFS_BLOCK_GROUP_RAID1 |
>> - BTRFS_BLOCK_GROUP_RAID10 |
>> - BTRFS_BLOCK_GROUP_DUP))
>> - factor = 2;
>> - else
>> - factor = 1;
>> -
>> - free_bytes += (block_group->key.offset -
>> - btrfs_block_group_used(&block_group->item)) *
>> - factor;
>> + free_bytes += block_group->key.offset -
>> + btrfs_block_group_used(&block_group->item);
>>
>> spin_unlock(&block_group->lock);
>> }
>> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
>> index 54bd91e..40f41a2 100644
>> --- a/fs/btrfs/super.c
>> +++ b/fs/btrfs/super.c
>> @@ -1641,6 +1641,8 @@ static int btrfs_calc_avail_data_space(struct
>> btrfs_root *root, u64 *free_bytes)
>> u64 used_space;
>> u64 min_stripe_size;
>> int min_stripes = 1, num_stripes = 1;
>> + /* How many stripes used to store data, without considering mirrors. */
>> + int data_stripes = 1;
>> int i = 0, nr_devices;
>> int ret;
>>
>> @@ -1657,12 +1659,15 @@ static int btrfs_calc_avail_data_space(struct
>> btrfs_root *root, u64 *free_bytes)
>> if (type & BTRFS_BLOCK_GROUP_RAID0) {
>> min_stripes = 2;
>> num_stripes = nr_devices;
>> + data_stripes = num_stripes;
>> } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
>> min_stripes = 2;
>> num_stripes = 2;
>> + data_stripes = 1;
>> } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
>> min_stripes = 4;
>> num_stripes = 4;
>> + data_stripes = 2;
>> }
>>
>> if (type & BTRFS_BLOCK_GROUP_DUP)
>> @@ -1733,14 +1738,17 @@ static int btrfs_calc_avail_data_space(struct
>> btrfs_root *root, u64 *free_bytes)
>> i = nr_devices - 1;
>> avail_space = 0;
>> while (nr_devices >= min_stripes) {
>> - if (num_stripes > nr_devices)
>> + if (num_stripes > nr_devices) {
>> num_stripes = nr_devices;
>> + if (type & BTRFS_BLOCK_GROUP_RAID0)
>> + data_stripes = num_stripes;
>> + }
>>
>> if (devices_info[i].max_avail >= min_stripe_size) {
>> int j;
>> u64 alloc_size;
>>
>> - avail_space += devices_info[i].max_avail * num_stripes;
>> + avail_space += devices_info[i].max_avail *
>> data_stripes;
>> alloc_size = devices_info[i].max_avail;
>> for (j = i + 1 - num_stripes; j <= i; j++)
>> devices_info[j].max_avail -= alloc_size;
>> @@ -1772,15 +1780,13 @@ static int btrfs_calc_avail_data_space(struct
>> btrfs_root *root, u64 *free_bytes)
>> static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
>> {
>> struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
>> - struct btrfs_super_block *disk_super = fs_info->super_copy;
>> struct list_head *head = &fs_info->space_info;
>> struct btrfs_space_info *found;
>> u64 total_used = 0;
>> + u64 total_alloc = 0;
>> u64 total_free_data = 0;
>> int bits = dentry->d_sb->s_blocksize_bits;
>> __be32 *fsid = (__be32 *)fs_info->fsid;
>> - unsigned factor = 1;
>> - struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
>> int ret;
>>
>> /*
>> @@ -1792,38 +1798,20 @@ static int btrfs_statfs(struct dentry *dentry,
>> struct kstatfs *buf)
>> rcu_read_lock();
>> list_for_each_entry_rcu(found, head, list) {
>> if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
>> - int i;
>> -
>> - total_free_data += found->disk_total -
>> found->disk_used;
>> + total_free_data += found->total_bytes -
>> found->bytes_used;
>> total_free_data -=
>>
>> btrfs_account_ro_block_groups_free_space(found);
>> -
>> - for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
>> - if (!list_empty(&found->block_groups[i])) {
>> - switch (i) {
>> - case BTRFS_RAID_DUP:
>> - case BTRFS_RAID_RAID1:
>> - case BTRFS_RAID_RAID10:
>> - factor = 2;
>> - }
>> - }
>> - }
>> + total_used += found->bytes_used;
>> + } else {
>> + /* For metadata and system, we treat the total_bytes as
>> + * not available to file data. So show it as Used in
>> df.
>> + **/
>> + total_used += found->total_bytes;
>> }
>> -
>> - total_used += found->disk_used;
>> + total_alloc += found->total_bytes;
>> }
>> -
>> rcu_read_unlock();
>>
>> - buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
>> - buf->f_blocks >>= bits;
>> - buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
>> -
>> - /* Account global block reserve as used, it's in logical size already
>> */
>> - spin_lock(&block_rsv->lock);
>> - buf->f_bfree -= block_rsv->size >> bits;
>> - spin_unlock(&block_rsv->lock);
>> -
>> buf->f_bavail = total_free_data;
>> ret = btrfs_calc_avail_data_space(fs_info->tree_root,
>> &total_free_data);
>> if (ret) {
>> @@ -1831,8 +1819,12 @@ static int btrfs_statfs(struct dentry *dentry, struct
>> kstatfs *buf)
>> mutex_unlock(&fs_info->fs_devices->device_list_mutex);
>> return ret;
>> }
>> - buf->f_bavail += div_u64(total_free_data, factor);
>> + buf->f_bavail += total_free_data;
>> buf->f_bavail = buf->f_bavail >> bits;
>> + buf->f_blocks = total_alloc + total_free_data;
>> + buf->f_blocks >>= bits;
>> + buf->f_bfree = buf->f_blocks - (total_used >> bits);
>> +
>> mutex_unlock(&fs_info->chunk_mutex);
>> mutex_unlock(&fs_info->fs_devices->device_list_mutex);
>>
>>
>
>
> --
> gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it>
> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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