When shrinking a file system, if the number block groups drops below
the point where we started using the meta_bg layout, disable the
meta_bg feature and set s_first_meta_bg to zero. This is necessary to
avoid creating an invalid/corrupted file system after the shrink.
Addresses-Debian-Bug: 756922
Reported-by: Marcin Wolcendorf <antymat+debian@xxxxxxxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
---
resize/resize2fs.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index 9641b1e..b3755f6 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -489,6 +489,13 @@ retry:
fs->super->s_reserved_gdt_blocks = new;
}
+ if ((fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) &&
+ (fs->super->s_first_meta_bg > fs->desc_blocks)) {
+ fs->super->s_feature_incompat &=
+ ~EXT2_FEATURE_INCOMPAT_META_BG;
+ fs->super->s_first_meta_bg = 0;
+ }
+
/*
* Update the location of the backup superblocks if the
* sparse_super2 feature is enabled.
@@ -998,13 +1005,15 @@ static errcode_t blocks_to_move(ext2_resize_t rfs)
ext2fs_mark_block_bitmap2(rfs->reserve_blocks, blk);
}
- if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) {
+ if (old_fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
old_blocks = old_fs->super->s_first_meta_bg;
+ else
+ old_blocks = old_fs->desc_blocks +
+ old_fs->super->s_reserved_gdt_blocks;
+ if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
new_blocks = fs->super->s_first_meta_bg;
- } else {
- old_blocks = old_fs->desc_blocks + old_fs->super->s_reserved_gdt_blocks;
+ else
new_blocks = fs->desc_blocks + fs->super->s_reserved_gdt_blocks;
- }
retval = reserve_sparse_super2_last_group(rfs, meta_bmap);
if (retval)
--
2.0.0
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