[PATCH][SMB3] Increment num_remote_opens stats counter even in case of smb2_query_dir_first

* [PATCH][SMB3] Increment num_remote_opens stats counter even in case of smb2_query_dir_first
@ 2020-03-11  4:36 Steve French
  2020-03-11 11:14 ` Aurélien Aptel
  0 siblings, 1 reply; 3+ messages in thread
From: Steve French @ 2020-03-11  4:36 UTC (permalink / raw)
  To: Shyam Prasad N, CIFS

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Patch from Shyam attached (tentatively merged into cifs-2.6.git
for-next). See his description below:

The num_remote_opens counter keeps track of the number of open files
which must be maintained by the server at any point. This is a
per-tree-connect counter, and the value of this counter gets displayed
in the /proc/fs/cifs/Stats output as a following...

    Open files: 0 total (local), 1 open on server
                                 ^^^^^^^^^^^^^^^^
    As a thumb-rule, we want to increment this counter for each
open/create that we successfully execute on the server. Similarly, we
should decrement the counter when we successfully execute a close.

    In this case, an increment was being missed in case of smb2_query_dir_first,
    in case of successful open. As a result, we would underflow the
counter and we could even see the counter go to negative after
sufficient smb2_query_dir_first calls.

    I tested the stats counter for a bunch of filesystem operations
with the fix.
    And it looks like the counter looks correct to me.

    I also check if we missed the increments and decrements elsewhere.
It does not seem so. Few other cases where an open is done and we
don't increment the counter are
    the compound calls where the corresponding close is also sent in
the request.

-- 
Thanks,

Steve

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From f34d2f84852219dd8b252f08773f4e49c3b2db4d Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <nspmangalore@gmail.com>
Date: Mon, 9 Mar 2020 01:35:09 -0700
Subject: [PATCH] CIFS: Increment num_remote_opens stats counter even in case
 of smb2_query_dir_first

The num_remote_opens counter keeps track of the number of open files which must be
maintained by the server at any point. This is a per-tree-connect counter, and the value
of this counter gets displayed in the /proc/fs/cifs/Stats output as a following...

Open files: 0 total (local), 1 open on server
                             ^^^^^^^^^^^^^^^^
As a thumb-rule, we want to increment this counter for each open/create that we
successfully execute on the server. Similarly, we should decrement the counter when
we successfully execute a close.

In this case, an increment was being missed in case of smb2_query_dir_first,
in case of successful open. As a result, we would underflow the counter and we
could even see the counter go to negative after sufficient smb2_query_dir_first calls.

I tested the stats counter for a bunch of filesystem operations with the fix.
And it looks like the counter looks correct to me.

I also check if we missed the increments and decrements elsewhere. It does not
seem so. Few other cases where an open is done and we don't increment the counter are
the compound calls where the corresponding close is also sent in the request.

Signed-off-by: Shyam Prasad N <nspmangalore@gmail.com>
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2ops.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 83e5b351d5af..ea9fcdca4d20 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2226,6 +2226,8 @@ smb2_query_dir_first(const unsigned int xid, struct cifs_tcon *tcon,
 		goto qdf_free;
 	}
 
+	atomic_inc(&tcon->num_remote_opens);
+
 	qd_rsp = (struct smb2_query_directory_rsp *)rsp_iov[1].iov_base;
 	if (qd_rsp->sync_hdr.Status == STATUS_NO_MORE_FILES) {
 		trace_smb3_query_dir_done(xid, fid->persistent_fid,
-- 
2.20.1


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