cifs: Fix locking usage for tcon fields

We used to use the cifs_tcp_ses_lock to protect a lot of objects
that are not just the server, ses or tcon lists. We later introduced
srv_lock, ses_lock and tc_lock to protect fields within the
corresponding structs. This was done to provide a more granular
protection and avoid unnecessary serialization.

There were still a couple of uses of cifs_tcp_ses_lock to provide
tcon fields. In this patch, I've replaced them with tc_lock.

Cc: stable@vger.kernel.org
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/cached_dir.c b/fs/smb/client/cached_dir.c
index df9977030d199f6919d743b7b98887da204ad415..2a6b8ce80be2308b29a8543418617f3de330fafd 100644 (file)
--- a/fs/smb/client/cached_dir.c
+++ b/fs/smb/client/cached_dir.c
@@ -792,11 +792,11 @@ static void cfids_laundromat_worker(struct work_struct *work)
                cfid->dentry = NULL;
 
                if (cfid->is_open) {
-                       spin_lock(&cifs_tcp_ses_lock);
+                       spin_lock(&cfid->tcon->tc_lock);
                        ++cfid->tcon->tc_count;
                        trace_smb3_tcon_ref(cfid->tcon->debug_id, cfid->tcon->tc_count,
                                            netfs_trace_tcon_ref_get_cached_laundromat);
-                       spin_unlock(&cifs_tcp_ses_lock);
+                       spin_unlock(&cfid->tcon->tc_lock);
                        queue_work(serverclose_wq, &cfid->close_work);
                } else
                        /*

diff --git a/fs/smb/client/smb2misc.c b/fs/smb/client/smb2misc.c
index f3cb62d914502fffef041a4801de11c93dab8771..0871b9f1f86a6fa697753f1a7746a28037829c10 100644 (file)
--- a/fs/smb/client/smb2misc.c
+++ b/fs/smb/client/smb2misc.c
@@ -820,14 +820,14 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
        int rc;
 
        cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
-       spin_lock(&cifs_tcp_ses_lock);
+       spin_lock(&tcon->tc_lock);
        if (tcon->tc_count <= 0) {
                struct TCP_Server_Info *server = NULL;
 
                trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                    netfs_trace_tcon_ref_see_cancelled_close);
                WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");
-               spin_unlock(&cifs_tcp_ses_lock);
+               spin_unlock(&tcon->tc_lock);
 
                if (tcon->ses) {
                        server = tcon->ses->server;
@@ -841,7 +841,7 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid,
        tcon->tc_count++;
        trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                            netfs_trace_tcon_ref_get_cancelled_close);
-       spin_unlock(&cifs_tcp_ses_lock);
+       spin_unlock(&tcon->tc_lock);
 
        rc = __smb2_handle_cancelled_cmd(tcon, SMB2_CLOSE_HE, 0,
                                         persistent_fid, volatile_fid);

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index f6806946d0eeec30ec569c4a163f6eedfbe02d63..653e2f29384d4f04555177bf4e097124160d2cc8 100644 (file)
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -3107,7 +3107,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
                                                struct cifs_tcon,
                                                tcon_list);
                if (tcon) {
+                       spin_lock(&tcon->tc_lock);
                        tcon->tc_count++;
+                       spin_unlock(&tcon->tc_lock);
                        trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                            netfs_trace_tcon_ref_get_dfs_refer);
                }
@@ -3176,13 +3178,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
  out:
        if (tcon && !tcon->ipc) {
                /* ipc tcons are not refcounted */
-               spin_lock(&cifs_tcp_ses_lock);
-               tcon->tc_count--;
+               cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_dfs_refer);
                trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                    netfs_trace_tcon_ref_dec_dfs_refer);
-               /* tc_count can never go negative */
-               WARN_ON(tcon->tc_count < 0);
-               spin_unlock(&cifs_tcp_ses_lock);
        }
        kfree(utf16_path);
        kfree(dfs_req);

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index fa22702a61a6e9701672f654decf7de5f6a598e9..a88b21e5b30e20ff4b86b5f7b919719d5cd331bb 100644 (file)
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -4263,7 +4263,9 @@ void smb2_reconnect_server(struct work_struct *work)
 
                list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
                        if (tcon->need_reconnect || tcon->need_reopen_files) {
+                               spin_lock(&tcon->tc_lock);
                                tcon->tc_count++;
+                               spin_unlock(&tcon->tc_lock);
                                trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,
                                                    netfs_trace_tcon_ref_get_reconnect_server);
                                list_add_tail(&tcon->rlist, &tmp_list);

diff --git a/fs/smb/client/trace.h b/fs/smb/client/trace.h
index a584a77431132910387714628e5477b7227c1bdd..191f02344dcdd7aef7bb5294f94f9882dd8a2320 100644 (file)
--- a/fs/smb/client/trace.h
+++ b/fs/smb/client/trace.h
@@ -189,6 +189,7 @@
        EM(netfs_trace_tcon_ref_put_cancelled_close_fid, "PUT Cn-Fid") \
        EM(netfs_trace_tcon_ref_put_cancelled_mid,      "PUT Cn-Mid") \
        EM(netfs_trace_tcon_ref_put_mnt_ctx,            "PUT MntCtx") \
+       EM(netfs_trace_tcon_ref_put_dfs_refer,          "PUT DfsRfr") \
        EM(netfs_trace_tcon_ref_put_reconnect_server,   "PUT Reconn") \
        EM(netfs_trace_tcon_ref_put_tlink,              "PUT Tlink ") \
        EM(netfs_trace_tcon_ref_see_cancelled_close,    "SEE Cn-Cls") \