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authorMiao Xie <miaox@cn.fujitsu.com>2011-01-05 10:07:31 +0000
committerChris Mason <chris.mason@oracle.com>2011-01-16 11:30:19 -0500
commit6d07bcec969af335d4e35b3921131b7929bd634e (patch)
tree2d1e0bb5f69bdf9dafa2862b6cad965184d67c84 /fs/btrfs/volumes.h
parentb2117a39fa96cf4814e7cab8c11494149ba6f29d (diff)
btrfs: fix wrong free space information of btrfs
When we store data by raid profile in btrfs with two or more different size disks, df command shows there is some free space in the filesystem, but the user can not write any data in fact, df command shows the wrong free space information of btrfs. # mkfs.btrfs -d raid1 /dev/sda9 /dev/sda10 # btrfs-show Label: none uuid: a95cd49e-6e33-45b8-8741-a36153ce4b64 Total devices 2 FS bytes used 28.00KB devid 1 size 5.01GB used 2.03GB path /dev/sda9 devid 2 size 10.00GB used 2.01GB path /dev/sda10 # btrfs device scan /dev/sda9 /dev/sda10 # mount /dev/sda9 /mnt # dd if=/dev/zero of=tmpfile0 bs=4K count=9999999999 (fill the filesystem) # sync # df -TH Filesystem Type Size Used Avail Use% Mounted on /dev/sda9 btrfs 17G 8.6G 5.4G 62% /mnt # btrfs-show Label: none uuid: a95cd49e-6e33-45b8-8741-a36153ce4b64 Total devices 2 FS bytes used 3.99GB devid 1 size 5.01GB used 5.01GB path /dev/sda9 devid 2 size 10.00GB used 4.99GB path /dev/sda10 It is because btrfs cannot allocate chunks when one of the pairing disks has no space, the free space on the other disks can not be used for ever, and should be subtracted from the total space, but btrfs doesn't subtract this space from the total. It is strange to the user. This patch fixes it by calcing the free space that can be used to allocate chunks. Implementation: 1. get all the devices free space, and align them by stripe length. 2. sort the devices by the free space. 3. check the free space of the devices, 3.1. if it is not zero, and then check the number of the devices that has more free space than this device, if the number of the devices is beyond the min stripe number, the free space can be used, and add into total free space. if the number of the devices is below the min stripe number, we can not use the free space, the check ends. 3.2. if the free space is zero, check the next devices, goto 3.1 This implementation is just likely fake chunk allocation. After appling this patch, df can show correct space information: # df -TH Filesystem Type Size Used Avail Use% Mounted on /dev/sda9 btrfs 17G 8.6G 0 100% /mnt Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/volumes.h')
-rw-r--r--fs/btrfs/volumes.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index a5cfedf393f9..7af6144a7954 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -161,6 +161,9 @@ static inline void btrfs_descending_sort_devices(
btrfs_cmp_device_free_bytes, NULL);
}
+int btrfs_account_dev_extents_size(struct btrfs_device *device, u64 start,
+ u64 end, u64 *length);
+
#define btrfs_multi_bio_size(n) (sizeof(struct btrfs_multi_bio) + \
(sizeof(struct btrfs_bio_stripe) * (n)))