When we use btrfs with raid5/6, the output of df is unexpected as below.
Example:
# mkfs.btrfs -f /dev/vdf1 /dev/vdf2 -d raid5
# 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 4.2G 1.3G 2.9G 32% /mnt
[root@atest-guest linux_btrfs]# btrfs fi show /mnt
Label: none uuid: f7fac7f2-3898-482e-9cf2-fbcd7fdd7084
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
The @size should be 2G rather than 4.2G.
This patch makes the btrfs_calc_avail_data_space() consider raid5/6,
then we can get the correct result of it.
Example:
# mkfs.btrfs -f /dev/vdf1 /dev/vdf2 -d raid5
# 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
[root@atest-guest linux_btrfs]# btrfs fi show /mnt
Label: none uuid: ea3a6e6e-fbe1-47aa-b4b5-bc37b98565d9
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
Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
---
fs/btrfs/super.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 1f0f080..4a190de 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -52,6 +52,7 @@
#include "props.h"
#include "xattr.h"
#include "volumes.h"
+#include "raid56.h"
#include "export.h"
#include "compression.h"
#include "rcu-string.h"
@@ -1688,6 +1689,14 @@ static int btrfs_calc_avail_data_space(struct btrfs_root
*root, u64 *free_bytes)
min_stripes = 4;
num_stripes = 4;
data_stripes = 2;
+ } else if (type & BTRFS_BLOCK_GROUP_RAID5) {
+ min_stripes = 2;
+ num_stripes = nr_devices;
+ data_stripes = num_stripes - nr_parity_stripes(type);
+ } else if (type & BTRFS_BLOCK_GROUP_RAID6) {
+ min_stripes = 3;
+ num_stripes = nr_devices;
+ data_stripes = num_stripes - nr_parity_stripes(type);
}
if (type & BTRFS_BLOCK_GROUP_DUP)
@@ -1777,8 +1786,11 @@ static int btrfs_calc_avail_data_space(struct btrfs_root
*root, u64 *free_bytes)
while (nr_devices >= min_stripes) {
if (num_stripes > nr_devices) {
num_stripes = nr_devices;
- if (type & BTRFS_BLOCK_GROUP_RAID0)
- data_stripes = num_stripes;
+ /* Only RAID0, RAID5 and RAID6 will get here.
+ * And we can use the following calculation
+ * for all the three cases.
+ **/
+ data_stripes = num_stripes - nr_parity_stripes(type);
}
if (devices_info[i].max_avail >= min_stripe_size) {
--
1.8.4.2
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
