[CIFS] Resize cifs request buffer mempools as tcp sessions are added to avoid potential deadlocks.

Signed-off-by: Steve French (sfrench@us.ibm.com)

fs/cifs/cifsfs.c

@@ -41,8 +41,6 @@
 #include "cifs_fs_sb.h"
 #include <linux/mm.h>
 #define CIFS_MAGIC_NUMBER 0xFF534D42	/* the first four bytes of SMB PDUs */
-/* BB when mempool_resize is added back in, we will resize pool on new mount */
-#define CIFS_MIN_RCV_POOL 11 /* enough for progress to five servers */
 
 #ifdef CONFIG_CIFS_QUOTA
 static struct quotactl_ops cifs_quotactl_ops;
@@ -742,6 +740,7 @@ init_cifs(void)
  */
 	atomic_set(&sesInfoAllocCount, 0);
 	atomic_set(&tconInfoAllocCount, 0);
+	atomic_set(&tcpSesAllocCount,0);
 	atomic_set(&tcpSesReconnectCount, 0);
 	atomic_set(&tconInfoReconnectCount, 0);
 

fs/cifs/cifsglob.h

@@ -32,6 +32,8 @@
 				   termination then *2 for unicode versions */
 #define MAX_PASSWORD_SIZE 16
 
+#define CIFS_MIN_RCV_POOL 4
+
 /*
  * MAX_REQ is the maximum number of requests that WE will send
  * on one socket concurently. It also matches the most common
@@ -391,7 +393,7 @@ GLOBAL_EXTERN char Local_System_Name[15];
  */
 GLOBAL_EXTERN atomic_t sesInfoAllocCount;
 GLOBAL_EXTERN atomic_t tconInfoAllocCount;
-
+GLOBAL_EXTERN atomic_t tcpSesAllocCount;
 GLOBAL_EXTERN atomic_t tcpSesReconnectCount;
 GLOBAL_EXTERN atomic_t tconInfoReconnectCount;
 

fs/cifs/connect.c

@@ -28,6 +28,7 @@
 #include <linux/pagemap.h>
 #include <linux/ctype.h>
 #include <linux/utsname.h>
+#include <linux/mempool.h>
 #include <asm/uaccess.h>
 #include <asm/processor.h>
 #include "cifspdu.h"
@@ -49,6 +50,8 @@ extern void SMBNTencrypt(unsigned char *passwd, unsigned char *c8,
 			 unsigned char *p24);
 extern int cifs_inet_pton(int, const char *, void *dst);
 
+extern mempool_t *cifs_req_poolp;
+
 struct smb_vol {
 	char *username;
 	char *password;
@@ -204,6 +207,15 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	current->flags |= PF_MEMALLOC;
 	server->tsk = current;	/* save process info to wake at shutdown */
 	cFYI(1, ("Demultiplex PID: %d", current->pid));
+	write_lock(&GlobalSMBSeslock);
+	atomic_inc(&tcpSesAllocCount);
+	length = tcpSesAllocCount.counter;
+	write_unlock(&GlobalSMBSeslock);
+	if(length  > 1) {
+		mempool_resize(cifs_req_poolp,
+			length + CIFS_MIN_RCV_POOL,
+			GFP_KERNEL);
+	}
 
 	while (server->tcpStatus != CifsExiting) {
 		if (smb_buffer == NULL)
@@ -467,6 +479,16 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
 	}
 	kfree(server);
 
+	write_lock(&GlobalSMBSeslock);
+	atomic_dec(&tcpSesAllocCount);
+	length = tcpSesAllocCount.counter;
+	write_unlock(&GlobalSMBSeslock);
+	if(length  > 0) {
+		mempool_resize(cifs_req_poolp,
+			length + CIFS_MIN_RCV_POOL,
+			GFP_KERNEL);
+	}
+
 	set_current_state(TASK_INTERRUPTIBLE);
 	schedule_timeout(HZ/4);
 	return 0;