cifs: Fix df output for users with quota limits

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@redhat.com>
Signed-off-by: Pierguido Lambri <plambri@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Cc: <stable@vger.kernel.org>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 5fb2fc2d0080b6e62fd0ad10e1a9c90c08308f2d..97edb4d376cd40e1e6044ed6b5ff7072e0d1b10c 100644 (file)
--- 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;
 }