reiser4: fix dummy ioctl_cryptcompress

Andrew,
please, apply.

Thanks,
Edward.

. Problem: unexpected resolving to prompt when merging/updating
stuff with python-based Gentoo manager (reported by rvalles <[email protected]> and
Dushan Tcholich <[email protected]>).

Bug: User application made wrong decision about file's nature based on returned value of ->ioctl() method for cryptcompress file plugin.

Fix: make dummy ->ioctl() method for cryptcompress file plugin to return -EINVAL instead of zero.

. Drop some redundant ifs.

. Update comments. Add precise definition of FCS (file conversion set)
that should be protected during file plugin conversion.

---
 linux-2.6.24-rc6-mm1/fs/reiser4/plugin/file/cryptcompress.c   |    2 
 linux-2.6.24-rc6-mm1/fs/reiser4/plugin/file/file.c            |    7 
 linux-2.6.24-rc6-mm1/fs/reiser4/plugin/file/file_conversion.c |  118 ++++++----
 3 files changed, 78 insertions(+), 49 deletions(-)

@@ -3627,7 +3627,7 @@
 int ioctl_cryptcompress(struct inode *inode, struct file *filp,
 			unsigned int cmd, unsigned long arg)
 {
-	return 0;
+	return RETERR(-ENOSYS);
 }
 
 /* plugin->mmap */

@@ -1006,12 +1006,9 @@
 
 	/* clear MOVED tag for all found pages */
 	for (i = 0; i < pagevec_count(&pvec); i++) {
-		void *p;
-
 		page_cache_get(pvec.pages[i]);
-		p = radix_tree_tag_clear(&mapping->page_tree, pvec.pages[i]->index,
-					 PAGECACHE_TAG_REISER4_MOVED);
-		assert("vs-49", p == pvec.pages[i]);
+		radix_tree_tag_clear(&mapping->page_tree, pvec.pages[i]->index,
+				     PAGECACHE_TAG_REISER4_MOVED);
 	}
 	write_unlock_irq(&mapping->tree_lock);