linux-ext4 - [PATCH] libext2fs: fix to read the bitmaps for image file correctly

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Date:   Wed, 14 Mar 2018 05:47:00 +0000
From:   Kazuya Mio <k-mio@...jp.nec.com>
To:     "tytso@....edu" <tytso@....edu>,
        "adilger.kernel@...ger.ca" <adilger.kernel@...ger.ca>
CC:     "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: [PATCH] libext2fs: fix to read the bitmaps for image file correctly

When read_bitmaps() is called to read block/inode bitmap from the image file
created by e2image, it can read only one bitmap block due to the wrong
loop condition. read_bitmaps() doesn't need to split the code between
the filesystem and the image file, so remove EXT2_FLAG_IMAGE_FILE-specific code.

Signed-off-by: Kazuya Mio <k-mio@...jp.nec.com>
---
 lib/ext2fs/rw_bitmaps.c |   57 ++++++++----------------------------------------
 1 file changed, 10 insertions(+), 47 deletions(-)
diff --git a/lib/ext2fs/rw_bitmaps.c b/lib/ext2fs/rw_bitmaps.c
index 9db76eb..5f606b8 100644
--- a/lib/ext2fs/rw_bitmaps.c
+++ b/lib/ext2fs/rw_bitmaps.c
@@ -207,9 +207,7 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 	unsigned int	cnt;
 	blk64_t	blk;
 	blk64_t	blk_itr = EXT2FS_B2C(fs, fs->super->s_first_data_block);
-	blk64_t   blk_cnt;
 	ext2_ino_t ino_itr = 1;
-	ext2_ino_t ino_cnt;
 
 	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
 
@@ -252,51 +250,13 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 		inode_nbytes = 0;
 	ext2fs_free_mem(&buf);
 
-	if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
-		blk = (fs->image_header->offset_inodemap / fs->blocksize);
-		ino_cnt = fs->super->s_inodes_count;
-		while (inode_nbytes > 0) {
-			retval = io_channel_read_blk64(fs->image_io, blk++,
-						     1, inode_bitmap);
-			if (retval)
-				goto cleanup;
-			cnt = fs->blocksize << 3;
-			if (cnt > ino_cnt)
-				cnt = ino_cnt;
-			retval = ext2fs_set_inode_bitmap_range2(fs->inode_map,
-					       ino_itr, cnt, inode_bitmap);
-			if (retval)
-				goto cleanup;
-			ino_itr += fs->blocksize << 3;
-			ino_cnt -= fs->blocksize << 3;
-			inode_nbytes -= fs->blocksize;
-		}
-		blk = (fs->image_header->offset_blockmap /
-		       fs->blocksize);
-		blk_cnt = EXT2_GROUPS_TO_CLUSTERS(fs->super,
-						  fs->group_desc_count);
-		while (block_nbytes > 0) {
-			retval = io_channel_read_blk64(fs->image_io, blk++,
-						     1, block_bitmap);
-			if (retval)
-				goto cleanup;
-			cnt = fs->blocksize << 3;
-			if (cnt > blk_cnt)
-				cnt = blk_cnt;
-			retval = ext2fs_set_block_bitmap_range2(fs->block_map,
-				       blk_itr, cnt, block_bitmap);
-			if (retval)
-				goto cleanup;
-			blk_itr += fs->blocksize << 3;
-			blk_cnt -= fs->blocksize << 3;
-			block_nbytes -= fs->blocksize;
-		}
-		goto success_cleanup;
-	}
-
 	for (i = 0; i < fs->group_desc_count; i++) {
 		if (block_bitmap) {
-			blk = ext2fs_block_bitmap_loc(fs, i);
+			if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
+				blk = (fs->image_header->offset_blockmap /
+					fs->blocksize) + i;
+			} else
+				blk = ext2fs_block_bitmap_loc(fs, i);
 			if (csum_flag &&
 			    ext2fs_bg_flags_test(fs, i, EXT2_BG_BLOCK_UNINIT) &&
 			    ext2fs_group_desc_csum_verify(fs, i))
@@ -327,7 +287,11 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 			blk_itr += block_nbytes << 3;
 		}
 		if (inode_bitmap) {
-			blk = ext2fs_inode_bitmap_loc(fs, i);
+			if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
+				blk = (fs->image_header->offset_inodemap /
+					fs->blocksize) + i;
+			} else
+				blk = ext2fs_inode_bitmap_loc(fs, i);
 			if (csum_flag &&
 			    ext2fs_bg_flags_test(fs, i, EXT2_BG_INODE_UNINIT) &&
 			    ext2fs_group_desc_csum_verify(fs, i))
@@ -367,7 +331,6 @@ static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
 			goto cleanup;
 	}
 
-success_cleanup:
 	if (inode_bitmap)
 		ext2fs_free_mem(&inode_bitmap);
 	if (block_bitmap)