NTFS: Add handling for initialized_size != data_size in compressed files.

fs/ntfs/ChangeLog

@@ -20,6 +20,10 @@ ToDo:
 	  sufficient for synchronisation here. We then just need to make sure
 	  ntfs_readpage/writepage/truncate interoperate properly with us.
 
+2.1.1 - WIP
+
+	- Add handling for initialized_size != data_size in compressed files.
+
 2.1.0 - First steps towards write support: implement file overwrite.
 
 	- Add configuration option for developmental write support with an

fs/ntfs/compress.c

@@ -2,8 +2,8 @@
  * compress.c - NTFS kernel compressed attributes handling.
  *		Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001,2002 Anton Altaparmakov.
- * Copyright (C) 2002 Richard Russon.
+ * Copyright (c) 2001-2003 Anton Altaparmakov
+ * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -44,7 +44,7 @@ typedef enum {
 	 * The maximum compression block size is by definition 16 * the cluster
 	 * size, with the maximum supported cluster size being 4kiB. Thus the
 	 * maximum compression buffer size is 64kiB, so we use this when
-	 * initializing the per-CPU buffers.
+	 * initializing the compression buffer.
 	 */
 	NTFS_MAX_CB_SIZE	= 64 * 1024,
 } ntfs_compression_constants;
@@ -88,6 +88,40 @@ void free_compression_buffers(void)
 	ntfs_compression_buffer = NULL;
 }
 
+/**
+ * zero_partial_compressed_page - zero out of bounds compressed page region
+ */
+static void zero_partial_compressed_page(ntfs_inode *ni, struct page *page)
+{
+	u8 *kp = page_address(page);
+	unsigned int kp_ofs;
+
+	ntfs_debug("Zeroing page region outside initialized size.");
+	if (((s64)page->index << PAGE_CACHE_SHIFT) >= ni->initialized_size) {
+		/*
+		 * FIXME: Using clear_page() will become wrong when we get
+		 * PAGE_CACHE_SIZE != PAGE_SIZE but for now there is no problem.
+		 */
+		clear_page(kp);
+		return;
+	}
+	kp_ofs = ni->initialized_size & ~PAGE_CACHE_MASK;
+	memset(kp + kp_ofs, 0, PAGE_CACHE_SIZE - kp_ofs);
+	return;
+}
+
+/**
+ * handle_bounds_compressed_page - test for&handle out of bounds compressed page
+ */
+static inline void handle_bounds_compressed_page(ntfs_inode *ni,
+		struct page *page)
+{
+	if ((page->index >= (ni->initialized_size >> PAGE_CACHE_SHIFT)) &&
+			(ni->initialized_size < VFS_I(ni)->i_size))
+		zero_partial_compressed_page(ni, page);
+	return;
+}
+
 /**
  * ntfs_decompress - decompress a compression block into an array of pages
  * @dest_pages:		destination array of pages
@@ -173,10 +207,19 @@ static int ntfs_decompress(struct page *dest_pages[], int *dest_index,
 		/* We can sleep from now on, so we drop lock. */
 		spin_unlock(&ntfs_cb_lock);
 		/* Second stage: finalize completed pages. */
+		if (nr_completed_pages > 0) {
+			struct page *page = dest_pages[completed_pages[0]];
+			ntfs_inode *ni = NTFS_I(page->mapping->host);
+
 			for (i = 0; i < nr_completed_pages; i++) {
 				int di = completed_pages[i];
 
 				dp = dest_pages[di];
+				/*
+				 * If we are outside the initialized size, zero
+				 * the out of bounds page range.
+				 */
+				handle_bounds_compressed_page(ni, dp);
 				flush_dcache_page(dp);
 				kunmap(dp);
 				SetPageUptodate(dp);
@@ -187,6 +230,7 @@ static int ntfs_decompress(struct page *dest_pages[], int *dest_index,
 					page_cache_release(dp);
 				dest_pages[di] = NULL;
 			}
+		}
 		return err;
 	}
 
@@ -763,6 +807,11 @@ int ntfs_read_compressed_block(struct page *page)
 		for (; cur2_page < cb_max_page; cur2_page++) {
 			page = pages[cur2_page];
 			if (page) {
+				/*
+				 * If we are outside the initialized size, zero
+				 * the out of bounds page range.
+				 */
+				handle_bounds_compressed_page(ni, page);
 				flush_dcache_page(page);
 				kunmap(page);
 				SetPageUptodate(page);

fs/ntfs/inode.c

 /**
  * inode.c - NTFS kernel inode handling. Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001,2002 Anton Altaparmakov.
+ * Copyright (c) 2001-2003 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -996,16 +996,6 @@ static int ntfs_read_locked_inode(struct inode *vi)
 			if (NInoCompressed(ni)) {
 				ni->_ICF(compressed_size) = sle64_to_cpu(
 					ctx->attr->_ANR(compressed_size));
-				if (vi->i_size != ni->initialized_size)
-					ntfs_warning(vi->i_sb, "BUG: Found "
-						"compressed file with "
-						"data_size not equal to "
-						"initialized_size. This will "
-						"probably cause problems when "
-						"trying to access the file. "
-						"Please notify linux-ntfs-dev@"
-						"lists.sf.net that you saw "
-						"this message. Thanks!");
 			}
 		} else { /* Resident attribute. */
 			/*