Patch "cifs: Fix df output for users with quota limits" has been added to the 4.12-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    cifs: Fix df output for users with quota limits

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cifs-fix-df-output-for-users-with-quota-limits.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 42bec214d8bd432be6d32a1acb0a9079ecd4d142 Mon Sep 17 00:00:00 2001
From: Sachin Prabhu <sprabhu@redhat.com>
Date: Thu, 3 Aug 2017 13:09:03 +0530
Subject: cifs: Fix df output for users with quota limits

From: Sachin Prabhu <sprabhu@redhat.com>

commit 42bec214d8bd432be6d32a1acb0a9079ecd4d142 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/cifs/smb2pdu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3195,8 +3195,8 @@ copy_fs_info_to_kstatfs(struct smb2_fs_f
 	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;
 }
 


Patches currently in stable-queue which might be from sprabhu@redhat.com are

queue-4.12/cifs-fix-df-output-for-users-with-quota-limits.patch