[CIFS] Allow update of EOF on remote extend of file

Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsproto.h

@@ -57,7 +57,7 @@ extern int SendReceiveBlockingLock(const unsigned int /* xid */ ,
 				int * /* bytes returned */);
 extern int checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length);
 extern int is_valid_oplock_break(struct smb_hdr *smb, struct TCP_Server_Info *);
-extern int is_size_safe_to_change(struct cifsInodeInfo *);
+extern int is_size_safe_to_change(struct cifsInodeInfo *, __u64 eof);
 extern struct cifsFileInfo *find_writable_file(struct cifsInodeInfo *);
 extern unsigned int smbCalcSize(struct smb_hdr *ptr);
 extern unsigned int smbCalcSize_LE(struct smb_hdr *ptr);

fs/cifs/file.c

@@ -1954,7 +1954,7 @@ static int cifs_readpage(struct file *file, struct page *page)
    refreshing the inode only on increases in the file size 
    but this is tricky to do without racing with writebehind
    page caching in the current Linux kernel design */
-int is_size_safe_to_change(struct cifsInodeInfo *cifsInode)
+int is_size_safe_to_change(struct cifsInodeInfo *cifsInode, __u64 end_of_file)
 {
 	struct cifsFileInfo *open_file = NULL;
 
@@ -1976,6 +1976,9 @@ int is_size_safe_to_change(struct cifsInodeInfo *cifsInode)
 			return 1;
 		}
 
+		if(i_size_read(&cifsInode->vfs_inode) < end_of_file)
+			return 1;
+
 		return 0;
 	} else
 		return 1;

fs/cifs/inode.c

@@ -140,7 +140,7 @@ int cifs_get_inode_info_unix(struct inode **pinode,
 		inode->i_gid = le64_to_cpu(findData.Gid);
 		inode->i_nlink = le64_to_cpu(findData.Nlinks);
 
-		if (is_size_safe_to_change(cifsInfo)) {
+		if (is_size_safe_to_change(cifsInfo, end_of_file)) {
 		/* can not safely change the file size here if the
 		   client is writing to it due to potential races */
 
@@ -491,8 +491,8 @@ int cifs_get_inode_info(struct inode **pinode,
 		/* BB add code here -
 		   validate if device or weird share or device type? */
 		}
-		if (is_size_safe_to_change(cifsInfo)) {
-			/* can not safely change the file size here if the
+		if (is_size_safe_to_change(cifsInfo, le64_to_cpu(pfindData->EndOfFile))) {
+			/* can not safely shrink the file size here if the
 			   client is writing to it due to potential races */
 			i_size_write(inode,le64_to_cpu(pfindData->EndOfFile));
 

fs/cifs/readdir.c

@@ -222,7 +222,7 @@ static void fill_in_inode(struct inode *tmp_inode, int new_buf_type,
 		atomic_set(&cifsInfo->inUse, 1);
 	}
 
-	if (is_size_safe_to_change(cifsInfo)) {
+	if (is_size_safe_to_change(cifsInfo, end_of_file)) {
 		/* can not safely change the file size here if the 
 		client is writing to it due to potential races */
 		i_size_write(tmp_inode, end_of_file);
@@ -351,10 +351,10 @@ static void unix_fill_in_inode(struct inode *tmp_inode,
 	tmp_inode->i_gid = le64_to_cpu(pfindData->Gid);
 	tmp_inode->i_nlink = le64_to_cpu(pfindData->Nlinks);
 
-	if (is_size_safe_to_change(cifsInfo)) {
+	if (is_size_safe_to_change(cifsInfo, end_of_file)) {
 		/* can not safely change the file size here if the 
 		client is writing to it due to potential races */
-		i_size_write(tmp_inode,end_of_file);
+		i_size_write(tmp_inode, end_of_file);
 
 	/* 512 bytes (2**9) is the fake blocksize that must be used */
 	/* for this calculation, not the real blocksize */