Don't delay freeing mids when blocked on slow socket write of request

When processing responses, and in particular freeing mids (DeleteMidQEntry),
which is very important since it also frees the associated buffers (cifs_buf_release),
we can block a long time if (writes to) socket is slow due to low memory or networking
issues.

We can block in send (smb request) waiting for memory, and be blocked in processing
responess (which could free memory if we let it) - since they both grab the
server->srv_mutex.

In practice, in the DeleteMidQEntry case - there is no reason we need to
grab the srv_mutex so remove these around DeleteMidQEntry, and it allows
us to free memory faster.

Signed-off-by: Steve French <steve.french@primarydata.com>
Acked-by: Pavel Shilovsky <pshilov@microsoft.com>

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 4c01b3f9abf02efb70648e030998220bab13bd55..4de3186d8a71b31772dfd586fa1fcfe31b23dded 100644 (file)
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -697,9 +697,7 @@ cifs_echo_callback(struct mid_q_entry *mid)
 {
        struct TCP_Server_Info *server = mid->callback_data;
 
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(server, 1, CIFS_ECHO_OP);
 }
 
@@ -1599,9 +1597,7 @@ cifs_readv_callback(struct mid_q_entry *mid)
        }
 
        queue_work(cifsiod_wq, &rdata->work);
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(server, 1, 0);
 }
 
@@ -2058,7 +2054,6 @@ cifs_writev_callback(struct mid_q_entry *mid)
 {
        struct cifs_writedata *wdata = mid->callback_data;
        struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
-       struct TCP_Server_Info *server = tcon->ses->server;
        unsigned int written;
        WRITE_RSP *smb = (WRITE_RSP *)mid->resp_buf;
 
@@ -2095,9 +2090,7 @@ cifs_writev_callback(struct mid_q_entry *mid)
        }
 
        queue_work(cifsiod_wq, &wdata->work);
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(tcon->ses->server, 1, 0);
 }
 

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 48ff7703b91912c79b8412539919c3ce6fe76ac6..e0517f499c38033606e6cc203876d1933bea6ed8 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2173,9 +2173,7 @@ smb2_echo_callback(struct mid_q_entry *mid)
        if (mid->mid_state == MID_RESPONSE_RECEIVED)
                credits_received = le16_to_cpu(rsp->hdr.sync_hdr.CreditRequest);
 
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(server, credits_received, CIFS_ECHO_OP);
 }
 
@@ -2433,9 +2431,7 @@ smb2_readv_callback(struct mid_q_entry *mid)
                cifs_stats_fail_inc(tcon, SMB2_READ_HE);
 
        queue_work(cifsiod_wq, &rdata->work);
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(server, credits_received, 0);
 }
 
@@ -2594,7 +2590,6 @@ smb2_writev_callback(struct mid_q_entry *mid)
 {
        struct cifs_writedata *wdata = mid->callback_data;
        struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
-       struct TCP_Server_Info *server = tcon->ses->server;
        unsigned int written;
        struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf;
        unsigned int credits_received = 1;
@@ -2634,9 +2629,7 @@ smb2_writev_callback(struct mid_q_entry *mid)
                cifs_stats_fail_inc(tcon, SMB2_WRITE_HE);
 
        queue_work(cifsiod_wq, &wdata->work);
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        add_credits(tcon->ses->server, credits_received, 0);
 }
 

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 4d64b5b8fc9c6fae67f7f3e0ec74284548ff7c32..de589d0d3739275c5aeac9b4a489055a4695203a 100644 (file)
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -613,9 +613,7 @@ cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
        }
        spin_unlock(&GlobalMid_Lock);
 
-       mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
-       mutex_unlock(&server->srv_mutex);
        return rc;
 }