[PATCH] cifs: Do not use large smb buffers in response path

unless response is larger than 256 bytes.  This cuts more than 1/3 of
the large memory allocations that cifs does and should be a huge help to
memory pressure under stress. 

Signed-off-by: Steve French (sfrench@us.ibm.com)
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 53 insertions, 27 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 383e55fa7d26..390f22fa3439 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1,7 +1,7 @@
 /*
  *   fs/cifs/connect.c
  *
- *   Copyright (C) International Business Machines  Corp., 2002,2004
+ *   Copyright (C) International Business Machines  Corp., 2002,2005
  *   Author(s): Steve French (sfrench@us.ibm.com)
  *
  *   This library is free software; you can redistribute it and/or modify
@@ -28,6 +28,7 @@
 #include <linux/ctype.h>
 #include <linux/utsname.h>
 #include <linux/mempool.h>
+#include <linux/delay.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include "cifspdu.h"
@@ -198,6 +199,8 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
         int length;
         unsigned int pdu_length, total_read;
         struct smb_hdr *smb_buffer = NULL;
+        struct smb_hdr *bigbuf = NULL;
+        struct smb_hdr *smallbuf = NULL;
         struct msghdr smb_msg;
         struct kvec iov;
         struct socket *csocket = server->ssocket;
@@ -206,6 +209,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
         struct task_struct *task_to_wake = NULL;
         struct mid_q_entry *mid_entry;
         char *temp;
+        int isLargeBuf = FALSE;
 
         daemonize("cifsd");
         allow_signal(SIGKILL);
@@ -223,17 +227,33 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
         }
 
         while (server->tcpStatus != CifsExiting) {
-                if (smb_buffer == NULL)
-                        smb_buffer = cifs_buf_get();
-                else
-                        memset(smb_buffer, 0, sizeof (struct smb_hdr));
-
-                if (smb_buffer == NULL) {
-                        cERROR(1,("Can not get memory for SMB response"));
-                        set_current_state(TASK_INTERRUPTIBLE);
-                        schedule_timeout(HZ * 3); /* give system time to free memory */
-                        continue;
+                if (bigbuf == NULL) {
+                        bigbuf = cifs_buf_get();
+                        if(bigbuf == NULL) {
+                                cERROR(1,("No memory for large SMB response"));
+                                msleep(3000);
+                                /* retry will check if exiting */
+                                continue;
+                        }
+                } else if(isLargeBuf) {
+                        /* we are reusing a dirtry large buf, clear its start */
+                        memset(bigbuf, 0, sizeof (struct smb_hdr));
                 }
+
+                if (smallbuf == NULL) {
+                        smallbuf = cifs_small_buf_get();
+                        if(smallbuf == NULL) {
+                                cERROR(1,("No memory for SMB response"));
+                                msleep(1000);
+                                /* retry will check if exiting */
+                                continue;
+                        }
+                        /* beginning of smb buffer is cleared in our buf_get */
+                } else /* if existing small buf clear beginning */
+                        memset(smallbuf, 0, sizeof (struct smb_hdr));
+
+                isLargeBuf = FALSE;
+                smb_buffer = smallbuf;
                 iov.iov_base = smb_buffer;
                 iov.iov_len = 4;
                 smb_msg.msg_control = NULL;
@@ -251,8 +271,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                         csocket = server->ssocket;
                         continue;
                 } else if ((length == -ERESTARTSYS) || (length == -EAGAIN)) {
-                        set_current_state(TASK_INTERRUPTIBLE);
-                        schedule_timeout(1); /* minimum sleep to prevent looping
+                        msleep(1); /* minimum sleep to prevent looping
                                 allowing socket to clear and app threads to set
                                 tcpStatus CifsNeedReconnect if server hung */
                         continue;
@@ -295,8 +314,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                                 } else {
                                         /* give server a second to
                                         clean up before reconnect attempt */
-                                        set_current_state(TASK_INTERRUPTIBLE);
-                                        schedule_timeout(HZ);
+                                        msleep(1000);
                                         /* always try 445 first on reconnect
                                         since we get NACK on some if we ever
                                         connected to port 139 (the NACK is 
@@ -325,6 +343,11 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                                         wake_up(&server->response_q);
                                         continue;
                                 } else { /* length ok */
+                                        if(pdu_length > MAX_CIFS_HDR_SIZE - 4) {
+                                                isLargeBuf = TRUE;
+                                                memcpy(bigbuf, smallbuf, 4);
+                                                smb_buffer = bigbuf;
+                                        }
                                         length = 0;
                                         iov.iov_base = 4 + (char *)smb_buffer;
                                         iov.iov_len = pdu_length;
@@ -377,6 +400,10 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                                 }
                                 spin_unlock(&GlobalMid_Lock);
                                 if (task_to_wake) {
+                                        if(isLargeBuf)
+                                                bigbuf = NULL;
+                                        else
+                                                smallbuf = NULL;
                                         smb_buffer = NULL;      /* will be freed by users thread after he is done */
                                         wake_up_process(task_to_wake);
                                 } else if (is_valid_oplock_break(smb_buffer) == FALSE) {                          
@@ -406,15 +433,17 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
         and get out of SendReceive.  */
         wake_up_all(&server->request_q);
         /* give those requests time to exit */
-        set_current_state(TASK_INTERRUPTIBLE);
-        schedule_timeout(HZ/8);
-
+        msleep(125);
+        
         if(server->ssocket) {
                 sock_release(csocket);
                 server->ssocket = NULL;
         }
-        if (smb_buffer) /* buffer usually freed in free_mid - need to free it on error or exit */
-                cifs_buf_release(smb_buffer);
+        /* buffer usuallly freed in free_mid - need to free it here on exit */
+        if (bigbuf != NULL)
+                cifs_buf_release(bigbuf);
+        if (smallbuf != NULL)
+                cifs_small_buf_release(smallbuf);
 
         read_lock(&GlobalSMBSeslock);
         if (list_empty(&server->pending_mid_q)) {
@@ -444,17 +473,15 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                 }
                 spin_unlock(&GlobalMid_Lock);
                 read_unlock(&GlobalSMBSeslock);
-                set_current_state(TASK_INTERRUPTIBLE);
                 /* 1/8th of sec is more than enough time for them to exit */
-                schedule_timeout(HZ/8); 
+                msleep(125);
         }
 
         if (list_empty(&server->pending_mid_q)) {
                 /* mpx threads have not exited yet give them 
                 at least the smb send timeout time for long ops */
                 cFYI(1, ("Wait for exit from demultiplex thread"));
-                set_current_state(TASK_INTERRUPTIBLE);
-                schedule_timeout(46 * HZ);      
+                msleep(46);
                 /* if threads still have not exited they are probably never
                 coming home not much else we can do but free the memory */
         }
@@ -469,9 +496,8 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
                         length + cifs_min_rcv,
                         GFP_KERNEL);
         }
-
-        set_current_state(TASK_INTERRUPTIBLE);
-        schedule_timeout(HZ/4);
+        
+        msleep(250);
         return 0;
 }