[PATCH] CIFS: CIFSSMBRead was returning an invalid pointer in buf on socket error

Thanks to Adrian Bunk for debugging the problem and to Shaggy for
helping find the solution.

Also added a fix for 64K pages we found in loosely-related testing
Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/cifs/cifssmb.c

@@ -1048,13 +1048,14 @@ CIFSSMBRead(const int xid, struct cifsTconInfo *tcon,
 			cifs_small_buf_release(iov[0].iov_base);
 		else if(resp_buf_type == CIFS_LARGE_BUFFER)
 			cifs_buf_release(iov[0].iov_base);
-	} else /* return buffer to caller to free */ /* BB FIXME how do we tell caller if it is not a large buffer */ {
+	} else if(resp_buf_type != CIFS_NO_BUFFER) {
+		/* return buffer to caller to free */ 
 		*buf = iov[0].iov_base;		
 		if(resp_buf_type == CIFS_SMALL_BUFFER)
 			*pbuf_type = CIFS_SMALL_BUFFER;
 		else if(resp_buf_type == CIFS_LARGE_BUFFER)
 			*pbuf_type = CIFS_LARGE_BUFFER;
-	}
+	} /* else no valid buffer on return - leave as null */
 
 	/* Note: On -EAGAIN error only caller can retry on handle based calls
 		since file handle passed in no longer valid */

fs/cifs/connect.c

@@ -1795,10 +1795,10 @@ cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
 			   conjunction with 52K kvec constraint on arch with 4K
 			   page size  */
 
-		if(cifs_sb->rsize < PAGE_CACHE_SIZE) {
-			cifs_sb->rsize = PAGE_CACHE_SIZE; 
-			/* Windows ME does this */
-			cFYI(1,("Attempt to set readsize for mount to less than one page (4096)"));
+		if(cifs_sb->rsize < 2048) {
+			cifs_sb->rsize = 2048; 
+			/* Windows ME may prefer this */
+			cFYI(1,("readsize set to minimum 2048"));
 		}
 		cifs_sb->mnt_uid = volume_info.linux_uid;
 		cifs_sb->mnt_gid = volume_info.linux_gid;