linux-ext4 - [PATCH 3/6] resize2fs: reserve all metadata blocks for flex

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Message-Id: <1356771328-18196-4-git-send-email-tytso@mit.edu>
Date:	Sat, 29 Dec 2012 03:55:25 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	George Spelvin <linux@...izon.com>, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 3/6] resize2fs: reserve all metadata blocks for flex_bg file systems

For flex_bg file systems, if we need to relocate an allocation bitmap
or inode table, we need to make sure that all metadata blocks have
been reserved, lest we end up overwriting a metadata block belonging
to a different block group.

This change fixes the following test case:

rm -f foo.img; touch foo.img
truncate -s 32G foo.img
mke2fs -F -t ext4 -E resize=12582912 foo.img
e2fsck -f foo.img
truncate -s 64G foo.img
./resize2fs foo.img
e2fsck -fy foo.img

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 resize/resize2fs.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index c5d8a23..9702645 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -783,6 +783,7 @@ static errcode_t blocks_to_move(ext2_resize_t rfs)
 	ext2_filsys 	fs, old_fs;
 	ext2fs_block_bitmap	meta_bmap;
 	__u32		save_incompat_flag;
+	int		flex_bg;
 
 	fs = rfs->new_fs;
 	old_fs = rfs->old_fs;
@@ -874,6 +875,8 @@ static errcode_t blocks_to_move(ext2_resize_t rfs)
 	 * gets interesting....
 	 */
 	meta_bg_size = EXT2_DESC_PER_BLOCK(fs->super);
+	flex_bg = fs->super->s_feature_incompat &
+		EXT4_FEATURE_INCOMPAT_FLEX_BG;
 	/* first reserve all of the existing fs meta blocks */
 	for (i = 0; i < max_groups; i++) {
 		has_super = ext2fs_bg_has_super(fs, i);
@@ -903,18 +906,37 @@ static errcode_t blocks_to_move(ext2_resize_t rfs)
 		/*
 		 * Reserve the existing meta blocks that we know
 		 * aren't to be moved.
+		 *
+		 * For flex_bg file systems, in order to avoid
+		 * overwriting fs metadata (especially inode table
+		 * blocks) belonging to a different block group when
+		 * we are relocating the inode tables, we need to
+		 * reserve all existing fs metadata blocks.
 		 */
 		if (ext2fs_block_bitmap_loc(fs, i))
 			ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
 				 ext2fs_block_bitmap_loc(fs, i));
+		else if (flex_bg && i < old_fs->group_desc_count)
+			ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
+				 ext2fs_block_bitmap_loc(old_fs, i));
+
 		if (ext2fs_inode_bitmap_loc(fs, i))
 			ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
 				 ext2fs_inode_bitmap_loc(fs, i));
+		else if (flex_bg && i < old_fs->group_desc_count)
+			ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
+				 ext2fs_inode_bitmap_loc(old_fs, i));
+
 		if (ext2fs_inode_table_loc(fs, i))
 			for (blk = ext2fs_inode_table_loc(fs, i), j=0;
 			     j < fs->inode_blocks_per_group ; j++, blk++)
 				ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
 							 blk);
+		else if (flex_bg && i < old_fs->group_desc_count)
+			for (blk = ext2fs_inode_table_loc(old_fs, i), j=0;
+			     j < old_fs->inode_blocks_per_group ; j++, blk++)
+				ext2fs_mark_block_bitmap2(rfs->reserve_blocks,
+							  blk);
 
 		group_blk += rfs->new_fs->super->s_blocks_per_group;
 	}
-- 
1.7.12.rc0.22.gcdd159b

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