[PATCH] cifs: Fix df output for users with quota limits

[PATCH] cifs: Fix df output for users with quota limits

[Sachin Prabhu]

The df for a SMB2 share triggers a GetInfo call for
FS_FULL_SIZE_INFORMATION. The values returned are used to populate
struct statfs.

The problem is that none of the information returned by the call
contains the total blocks available on the filesystem. Instead we use
the blocks available to the user ie. quota limitation when filling out
statfs.f_blocks. The information returned does contain Actual free units
on the filesystem and is used to populate statfs.f_bfree. For users with
quota enabled, it can lead to situations where the total free space
reported is more than the total blocks on the system ending up with df
reports like the following

 # df -h /mnt/a
Filesystem         Size  Used Avail Use% Mounted on
//192.168.22.10/a  2.5G -2.3G  2.5G    - /mnt/a

To fix this problem, we instead populate both statfs.f_bfree with the
same value as statfs.f_bavail ie. CallerAvailableAllocationUnits. This
is similar to what is done already in the code for cifs and df now
reports the quota information for the user used to mount the share.

 # df --si /mnt/a
Filesystem         Size  Used Avail Use% Mounted on
//192.168.22.10/a  2.7G  101M  2.6G   4% /mnt/a

Signed-off-by: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Pierguido Lambri <plambri-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/smb2pdu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 5fb2fc2..97edb4d3 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3219,8 +3219,8 @@ copy_fs_info_to_kstatfs(struct smb2_fs_full_size_info *pfs_inf,
 	kst->f_bsize = le32_to_cpu(pfs_inf->BytesPerSector) *
 			  le32_to_cpu(pfs_inf->SectorsPerAllocationUnit);
 	kst->f_blocks = le64_to_cpu(pfs_inf->TotalAllocationUnits);
-	kst->f_bfree  = le64_to_cpu(pfs_inf->ActualAvailableAllocationUnits);
-	kst->f_bavail = le64_to_cpu(pfs_inf->CallerAvailableAllocationUnits);
+	kst->f_bfree  = kst->f_bavail =
+			le64_to_cpu(pfs_inf->CallerAvailableAllocationUnits);
 	return;
 }
 
-- 
2.9.4

Re: [PATCH] cifs: Fix df output for users with quota limits

[Steve French]

merged into cifs-2.6.git for-next and added cc: stable

On Thu, Aug 3, 2017 at 2:39 AM, Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> The df for a SMB2 share triggers a GetInfo call for
> FS_FULL_SIZE_INFORMATION. The values returned are used to populate
> struct statfs.
>
> The problem is that none of the information returned by the call
> contains the total blocks available on the filesystem. Instead we use
> the blocks available to the user ie. quota limitation when filling out
> statfs.f_blocks. The information returned does contain Actual free units
> on the filesystem and is used to populate statfs.f_bfree. For users with
> quota enabled, it can lead to situations where the total free space
> reported is more than the total blocks on the system ending up with df
> reports like the following
>
>  # df -h /mnt/a
> Filesystem         Size  Used Avail Use% Mounted on
> //192.168.22.10/a  2.5G -2.3G  2.5G    - /mnt/a
>
> To fix this problem, we instead populate both statfs.f_bfree with the
> same value as statfs.f_bavail ie. CallerAvailableAllocationUnits. This
> is similar to what is done already in the code for cifs and df now
> reports the quota information for the user used to mount the share.
>
>  # df --si /mnt/a
> Filesystem         Size  Used Avail Use% Mounted on
> //192.168.22.10/a  2.7G  101M  2.6G   4% /mnt/a
>
> Signed-off-by: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Pierguido Lambri <plambri-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  fs/cifs/smb2pdu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
> index 5fb2fc2..97edb4d3 100644
> --- a/fs/cifs/smb2pdu.c
> +++ b/fs/cifs/smb2pdu.c
> @@ -3219,8 +3219,8 @@ copy_fs_info_to_kstatfs(struct smb2_fs_full_size_info *pfs_inf,
>         kst->f_bsize = le32_to_cpu(pfs_inf->BytesPerSector) *
>                           le32_to_cpu(pfs_inf->SectorsPerAllocationUnit);
>         kst->f_blocks = le64_to_cpu(pfs_inf->TotalAllocationUnits);
> -       kst->f_bfree  = le64_to_cpu(pfs_inf->ActualAvailableAllocationUnits);
> -       kst->f_bavail = le64_to_cpu(pfs_inf->CallerAvailableAllocationUnits);
> +       kst->f_bfree  = kst->f_bavail =
> +                       le64_to_cpu(pfs_inf->CallerAvailableAllocationUnits);
>         return;
>  }
>
> --
> 2.9.4
>
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-- 
Thanks,

Steve