[PATCH 25/31] e2fsck: Only release clusters when shortening a directory during a rehash

Darrick J. Wong
2013-10-01T01:29:26Z

When the rehash process is running on a bigalloc filesystem, it compresses all
the directory entries and hash structures into the beginning of the directory
file and then uses block_iterate3() to free the blocks off the end of the file.
It seems to call ext2fs_block_alloc_stats2() for every block in a cluster,
which is unfortunate because this function allocates and frees entire clusters
(and updates the summary counts accordingly). In this case e2fsck writes out
incorrect summary counts.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
e2fsck/rehash.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/e2fsck/rehash.c b/e2fsck/rehash.c
index 6ef3568..29da9a1 100644
--- a/e2fsck/rehash.c
+++ b/e2fsck/rehash.c
@@ -719,10 +719,18 @@ static int write_dir_block(ext2_filsys fs,
/* We don't need this block, so release it */
e2fsck_read_bitmaps(wd->ctx);
blk = *block_nr;
- ext2fs_unmark_block_bitmap2(wd->ctx->block_found_map, blk);
- ext2fs_block_alloc_stats2(fs, blk, -1);
+ /*
+ * In theory, we only release blocks from the end of the
+ * directory file, so it's fine to clobber a whole cluster at
+ * once.
+ */
+ if (blk % EXT2FS_CLUSTER_RATIO(fs) == 0) {
+ ext2fs_unmark_block_bitmap2(wd->ctx->block_found_map,
+ blk);
+ ext2fs_block_alloc_stats2(fs, blk, -1);
+ wd->cleared++;
+ }
*block_nr = 0;
- wd->cleared++;
return BLOCK_CHANGED;
}