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.
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);
--
1.8.4.2
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