NTFS: Ensure the mft record size does not exceed the PAGE_CACHE_SIZE at

      mount time as this cannot work with the current implementation.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -38,6 +38,8 @@ ToDo/Notes:
 	- In fs/ntfs/aops.c::mark_ntfs_record_dirty(), take the
 	  mapping->private_lock around the dirtying of the buffer heads
 	  analagous to the way it is done in __set_page_dirty_buffers().
+	- Ensure the mft record size does not exceed the PAGE_CACHE_SIZE at
+	  mount time as this cannot work with the current implementation.
 
 2.1.21 - Fix some races and bugs, rewrite mft write code, add mft allocator.
 

fs/ntfs/super.c

@@ -742,6 +742,18 @@ static BOOL parse_ntfs_boot_sector(ntfs_volume *vol, const NTFS_BOOT_SECTOR *b)
 			vol->mft_record_size_mask);
 	ntfs_debug("vol->mft_record_size_bits = %i (0x%x)",
 			vol->mft_record_size_bits, vol->mft_record_size_bits);
+	/*
+	 * We cannot support mft record sizes above the PAGE_CACHE_SIZE since
+	 * we store $MFT/$DATA, the table of mft records in the page cache.
+	 */
+	if (vol->mft_record_size > PAGE_CACHE_SIZE) {
+		ntfs_error(vol->sb, "Mft record size %i (0x%x) exceeds the "
+				"page cache size on your system %lu (0x%lx).  "
+				"This is not supported.  Sorry.",
+				vol->mft_record_size, vol->mft_record_size,
+				PAGE_CACHE_SIZE, PAGE_CACHE_SIZE);
+		return FALSE;
+	}
 	clusters_per_index_record = b->clusters_per_index_record;
 	ntfs_debug("clusters_per_index_record = %i (0x%x)",
 			clusters_per_index_record, clusters_per_index_record);
@@ -785,8 +797,8 @@ static BOOL parse_ntfs_boot_sector(ntfs_volume *vol, const NTFS_BOOT_SECTOR *b)
 	if (sizeof(unsigned long) < 8) {
 		if ((ll << vol->cluster_size_bits) >= (1ULL << 41)) {
 			ntfs_error(vol->sb, "Volume size (%lluTiB) is too "
-					"large for this architecture. Maximum "
-					"supported is 2TiB. Sorry.",
+					"large for this architecture.  "
+					"Maximum supported is 2TiB.  Sorry.",
 					(unsigned long long)ll >> (40 -
 					vol->cluster_size_bits));
 			return FALSE;