Subject: Support for 64KB blocksize in ext2-4 directories.

When block size is 64KB, we have to take care that rec_len does not overflow.
Kernel stores 0xffff in case 0x10000 should be stored - perform appropriate
conversion when reading from / writing to disk.

Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/lib/ext2fs/dirblock.c b/lib/ext2fs/dirblock.c
index fb20fa0..db73edd 100644
--- a/lib/ext2fs/dirblock.c
+++ b/lib/ext2fs/dirblock.c
@@ -38,9 +38,9 @@ errcode_t ext2fs_read_dir_block2(ext2_fi
 		dirent = (struct ext2_dir_entry *) p;
 #ifdef WORDS_BIGENDIAN
 		dirent->inode = ext2fs_swab32(dirent->inode);
-		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
 		dirent->name_len = ext2fs_swab16(dirent->name_len);
 #endif
+		dirent->rec_len = ext2fs_rec_len_from_disk(dirent->rec_len);
 		name_len = dirent->name_len;
 #ifdef WORDS_BIGENDIAN
 		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
@@ -68,12 +68,15 @@ errcode_t ext2fs_read_dir_block(ext2_fil
 errcode_t ext2fs_write_dir_block2(ext2_filsys fs, blk_t block,
 				  void *inbuf, int flags EXT2FS_ATTR((unused)))
 {
-#ifdef WORDS_BIGENDIAN
 	errcode_t	retval;
 	char		*p, *end;
 	char		*buf = 0;
 	struct ext2_dir_entry *dirent;
 
+#ifndef WORDS_BIGENDIAN
+	if (fs->blocksize < EXT2_MAX_REC_LEN)
+		goto just_write;
+#endif
 	retval = ext2fs_get_mem(fs->blocksize, &buf);
 	if (retval)
 		return retval;
@@ -88,19 +91,18 @@ errcode_t ext2fs_write_dir_block2(ext2_f
 			return (EXT2_ET_DIR_CORRUPTED);
 		}
 		p += dirent->rec_len;
+		dirent->rec_len = ext2fs_rec_len_to_disk(dirent->rec_len);
+#ifdef WORDS_BIGENDIAN
 		dirent->inode = ext2fs_swab32(dirent->inode);
-		dirent->rec_len = ext2fs_swab16(dirent->rec_len);
-		dirent->name_len = ext2fs_swab16(dirent->name_len);
-
-		if (flags & EXT2_DIRBLOCK_V2_STRUCT)
+		if (!(flags & EXT2_DIRBLOCK_V2_STRUCT))
 			dirent->name_len = ext2fs_swab16(dirent->name_len);
+#endif
 	}
  	retval = io_channel_write_blk(fs->io, block, 1, buf);
 	ext2fs_free_mem(&buf);
 	return retval;
-#else
+just_write:
  	return io_channel_write_blk(fs->io, block, 1, (char *) inbuf);
-#endif
 }
 
 
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index a316665..21747c2 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -717,6 +718,32 @@ struct ext2_dir_entry_2 {
 #define EXT2_DIR_ROUND			(EXT2_DIR_PAD - 1)
 #define EXT2_DIR_REC_LEN(name_len)	(((name_len) + 8 + EXT2_DIR_ROUND) & \
 					 ~EXT2_DIR_ROUND)
+#define EXT2_MAX_REC_LEN		((1<<16)-1)
+
+static inline unsigned ext2fs_rec_len_from_disk(unsigned len)
+{
+#ifdef WORDS_BIGENDIAN
+	len = ext2fs_swab16(dlen);
+#endif
+	if (len == EXT2_MAX_REC_LEN)
+		return 1 << 16;
+	return len;
+}
+
+static inline unsigned ext2fs_rec_len_to_disk(unsigned len)
+{
+	if (len == (1 << 16))
+#ifdef WORDS_BIGENDIAN
+		return ext2fs_swab16(EXT2_MAX_REC_LEN);
+#else
+		return EXT2_MAX_REC_LEN;
+#endif
+#ifdef WORDS_BIGENDIAN
+	return ext2fs_swab_16(len);
+#else
+	return len;
+#endif
+}
 
 /*
  * This structure will be used for multiple mount protection. It will be
diff --git a/misc/e2image.c b/misc/e2image.c
index 1fbb267..4e2c9fb 100644
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -345,10 +345,7 @@ static void scramble_dir_block(ext2_fils
 	end = buf + fs->blocksize;
 	for (p = buf; p < end-8; p += rec_len) {
 		dirent = (struct ext2_dir_entry_2 *) p;
-		rec_len = dirent->rec_len;
-#ifdef WORDS_BIGENDIAN
-		rec_len = ext2fs_swab16(rec_len);
-#endif
+		rec_len = ext2fs_rec_len_from_disk(dirent->rec_len);
 #if 0
 		printf("rec_len = %d, name_len = %d\n", rec_len, dirent->name_len);
 #endif
@@ -358,9 +355,7 @@ static void scramble_dir_block(ext2_fils
 			       "bad rec_len (%d)\n", (unsigned long) blk, 
 			       rec_len);
 			rec_len = end - p;
-#ifdef WORDS_BIGENDIAN
-				dirent->rec_len = ext2fs_swab16(rec_len);
-#endif
+			dirent->rec_len = ext2fs_rec_len_to_disk(rec_len);
 			continue;
 		}
 		if (dirent->name_len + 8 > rec_len) {