In worst case we need one extent per moved block. Number of blocks to
be moved is less or equals to blks_needed.
Signed-off-by: Dmitry Monakhov <dmonakhov@xxxxxxxxxx>
---
resize/resize2fs.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/resize/resize2fs.c b/resize/resize2fs.c
index f5f1337..8ca53a3 100644
--- a/resize/resize2fs.c
+++ b/resize/resize2fs.c
@@ -2587,11 +2587,17 @@ blk64_t calculate_minimum_resize_size(ext2_filsys fs, int flags)
/*
* We need to reserve a few extra blocks if extents are
* enabled, in case we need to grow the extent tree. The more
- * we shrink the file system, the more space we need.
+ * we shrink the file system, the more blocks will be moved.
+ * Worse case is one extent per moved block.
*/
if (fs->super->s_feature_incompat & EXT3_FEATURE_INCOMPAT_EXTENTS) {
- blk64_t safe_margin = (ext2fs_blocks_count(fs->super) -
- blks_needed)/500;
+ blk64_t safe_margin = ext2fs_blocks_count(fs->super)
+ - blks_needed;
+
+ if (safe_margin > blks_needed)
+ safe_margin = blks_needed;
+ safe_margin /= 500;
+
#ifdef RESIZE2FS_DEBUG
if (flags & RESIZE_DEBUG_MIN_CALC)
printf("Extents safety margin: %llu\n", safe_margin);
--
1.7.1
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