fuse: trust kernel i_ctime only

Let the kernel maintain i_ctime locally: update i_ctime explicitly on
truncate, fallocate, open(O_TRUNC), setxattr, removexattr, link, rename,
unlink.

The inode flag I_DIRTY_SYNC serves as indication that local i_ctime should
be flushed to the server eventually.  The patch sets the flag and updates
i_ctime in course of operations listed above.

Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 560eafc..e9ecb18 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -175,9 +175,9 @@
 	if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
 		inode->i_mtime.tv_sec   = attr->mtime;
 		inode->i_mtime.tv_nsec  = attr->mtimensec;
+		inode->i_ctime.tv_sec   = attr->ctime;
+		inode->i_ctime.tv_nsec  = attr->ctimensec;
 	}
-	inode->i_ctime.tv_sec   = attr->ctime;
-	inode->i_ctime.tv_nsec  = attr->ctimensec;
 
 	if (attr->blksize != 0)
 		inode->i_blkbits = ilog2(attr->blksize);
@@ -256,6 +256,8 @@
 	inode->i_size = attr->size;
 	inode->i_mtime.tv_sec  = attr->mtime;
 	inode->i_mtime.tv_nsec = attr->mtimensec;
+	inode->i_ctime.tv_sec  = attr->ctime;
+	inode->i_ctime.tv_nsec = attr->ctimensec;
 	if (S_ISREG(inode->i_mode)) {
 		fuse_init_common(inode);
 		fuse_init_file_inode(inode);