linux-ext4 - [RFC 01/13] gen_bitmaps: Fix ext2fs_compare_generic

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Message-Id: <39eb8ba0a5a0adb7250a595e33460b16d6c5066f.1656912918.git.ritesh.list@gmail.com>
Date:   Mon,  4 Jul 2022 12:36:50 +0530
From:   Ritesh Harjani <ritesh.list@...il.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Harshad Shirwadkar <harshadshirwadkar@...il.com>,
        Andreas Dilger <adilger@...ger.ca>,
        linux-ext4 <linux-ext4@...r.kernel.org>,
        Ritesh Harjani <ritesh.list@...il.com>
Subject: [RFC 01/13] gen_bitmaps: Fix ext2fs_compare_generic_bmap/bitmap logic

Currently this function was not correctly comparing against the right
length of the bitmap. Also when we compare bitarray v/s rbtree bitmap
the value returned by ext2fs_test_generic_bmap() could be different in
these two implementations. Hence only check against boolean value.

Signed-off-by: Ritesh Harjani <ritesh.list@...il.com>
---
 lib/ext2fs/gen_bitmap.c   |  9 ++++++---
 lib/ext2fs/gen_bitmap64.c | 10 +++++++---
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/lib/ext2fs/gen_bitmap.c b/lib/ext2fs/gen_bitmap.c
index 1536d4b3..f7764fca 100644
--- a/lib/ext2fs/gen_bitmap.c
+++ b/lib/ext2fs/gen_bitmap.c
@@ -385,10 +385,13 @@ errcode_t ext2fs_compare_generic_bitmap(errcode_t magic, errcode_t neq,
 		    (size_t) (bm1->end - bm1->start)/8)))
 		return neq;
 
-	for (i = bm1->end - ((bm1->end - bm1->start) % 8); i <= bm1->end; i++)
-		if (ext2fs_fast_test_block_bitmap(gen_bm1, i) !=
-		    ext2fs_fast_test_block_bitmap(gen_bm2, i))
+	for (i = bm1->start; i <= bm1->end; i++) {
+		int ret1, ret2;
+		ret1 = !!ext2fs_fast_test_block_bitmap(gen_bm1, i);
+		ret2 = !!ext2fs_fast_test_block_bitmap(gen_bm2, i);
+		if (ret1 != ret2)
 			return neq;
+	}
 
 	return 0;
 }
diff --git a/lib/ext2fs/gen_bitmap64.c b/lib/ext2fs/gen_bitmap64.c
index d9809084..90c700ca 100644
--- a/lib/ext2fs/gen_bitmap64.c
+++ b/lib/ext2fs/gen_bitmap64.c
@@ -629,10 +629,14 @@ errcode_t ext2fs_compare_generic_bmap(errcode_t neq,
 	    (bm1->end != bm2->end))
 		return neq;
 
-	for (i = bm1->end - ((bm1->end - bm1->start) % 8); i <= bm1->end; i++)
-		if (ext2fs_test_generic_bmap(gen_bm1, i) !=
-		    ext2fs_test_generic_bmap(gen_bm2, i))
+	for (i = bm1->start; i < bm1->end; i++) {
+		int ret1, ret2;
+		ret1 = !!ext2fs_test_generic_bmap(gen_bm1, i);
+		ret2 = !!ext2fs_test_generic_bmap(gen_bm2, i);
+		if (ret1 != ret2) {
 			return neq;
+		}
+	}
 
 	return 0;
 }
-- 
2.35.3