fix hang in truncate setting file size

fs/cifs/CHANGES

+Version 0.74
+------------
+Fix truncate bug (set file size) that could cause hangs e.g. running fsx
+
 Version 0.73
 ------------
 unload nls if mount fails.

fs/cifs/cifssmb.c

@@ -2020,21 +2020,21 @@ CIFSSMBSetEOF(int xid, struct cifsTconInfo *tcon, char *fileName,
 	pSMB->ParameterOffset = offsetof(struct smb_com_transaction2_spi_req,
                                      InformationLevel) - 4;
 	pSMB->DataOffset = pSMB->ParameterOffset + pSMB->ParameterCount;
-    if(SetAllocation) {
-        if (tcon->ses->capabilities & CAP_INFOLEVEL_PASSTHRU)
-            pSMB->InformationLevel =
-                cpu_to_le16(SMB_SET_FILE_ALLOCATION_INFO2);
-        else
-            pSMB->InformationLevel =
-                cpu_to_le16(SMB_SET_FILE_ALLOCATION_INFO);
-    } else /* Set File Size */  {    
+	if(SetAllocation) {
+        	if (tcon->ses->capabilities & CAP_INFOLEVEL_PASSTHRU)
+	            pSMB->InformationLevel =
+                	cpu_to_le16(SMB_SET_FILE_ALLOCATION_INFO2);
+        	else
+	            pSMB->InformationLevel =
+        	        cpu_to_le16(SMB_SET_FILE_ALLOCATION_INFO);
+	} else /* Set File Size */  {    
 	    if (tcon->ses->capabilities & CAP_INFOLEVEL_PASSTHRU)
 		    pSMB->InformationLevel =
 		        cpu_to_le16(SMB_SET_FILE_END_OF_FILE_INFO2);
 	    else
 		    pSMB->InformationLevel =
 		        cpu_to_le16(SMB_SET_FILE_END_OF_FILE_INFO);
-    }
+	}
 
 	parm_data =
 	    (struct file_end_of_file_info *) (((char *) &pSMB->hdr.Protocol) +
@@ -2071,10 +2071,10 @@ CIFSSMBSetFileSize(const int xid, struct cifsTconInfo *tcon, __u64 size,
 	struct smb_com_transaction2_sfi_req *pSMB  = NULL;
 	struct smb_com_transaction2_sfi_rsp *pSMBr = NULL;
 	char *data_offset;
-    struct file_end_of_file_info *parm_data;
+	struct file_end_of_file_info *parm_data;
 	int rc = 0;
 	int bytes_returned = 0;
-    __u32 tmp;
+	__u32 tmp;
 
 	cFYI(1, ("SetFileSize (via SetFileInfo)"));
 

fs/cifs/inode.c

@@ -21,6 +21,7 @@
 #include <linux/fs.h>
 #include <linux/buffer_head.h>
 #include <linux/stat.h>
+#include <linux/pagemap.h>
 #include <asm/div64.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
@@ -587,6 +588,29 @@ cifs_truncate_file(struct inode *inode)
 	return;
 }
 
+static int cifs_trunc_page(struct address_space *mapping, loff_t from)
+{
+        pgoff_t index = from >> PAGE_CACHE_SHIFT;
+        unsigned offset = from & (PAGE_CACHE_SIZE-1);
+        struct page *page;
+        char *kaddr;
+        int rc = 0;
+
+        page = grab_cache_page(mapping, index);
+        if (!page)
+                return -ENOMEM;
+
+
+        kaddr = kmap_atomic(page, KM_USER0);
+        memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
+        flush_dcache_page(page);
+        kunmap_atomic(kaddr, KM_USER0);
+        set_page_dirty(page);
+        unlock_page(page);
+        page_cache_release(page);
+        return rc;
+}
+
 int
 cifs_setattr(struct dentry *direntry, struct iattr *attrs)
 {
@@ -639,7 +663,8 @@ cifs_setattr(struct dentry *direntry, struct iattr *attrs)
 	/*	CIFSSMBSetEOF(xid, pTcon, full_path, attrs->ia_size, TRUE, cifs_sb->local_nls);*/
 		if (rc == 0) {
 			rc = vmtruncate(direntry->d_inode, attrs->ia_size);
-			nobh_truncate_page(direntry->d_inode->i_mapping, direntry->d_inode->i_size);
+			cifs_trunc_page(direntry->d_inode->i_mapping, direntry->d_inode->i_size); 
+
 /*          cFYI(1,("truncate_page to 0x%lx \n",direntry->d_inode->i_size)); */
 		}
 	}