[PATCH v2] fs/ntfs3: Fix case when index is reused during tree transformation

[Konstantin Komarov]

In most cases when adding a cluster to the directory index,
they are placed at the end, and in the bitmap, this cluster corresponds
to the last bit. The new directory size is calculated as follows:

	data_size = (u64)(bit + 1) << indx->index_bits;

In the case of reusing a non-final cluster from the index,
data_size is calculated incorrectly, resulting in the directory size
differing from the actual size.

A check for cluster reuse has been added, and the size update is skipped.

Fixes: 82cae269cfa95 ("fs/ntfs3: Add initialization of super block")
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@xxxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 fs/ntfs3/index.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ntfs3/index.c b/fs/ntfs3/index.c
index daabaad63aaf..14284f0ed46a 100644
--- a/fs/ntfs3/index.c
+++ b/fs/ntfs3/index.c
@@ -1533,6 +1533,11 @@ static int indx_add_allocate(struct ntfs_index *indx, struct ntfs_inode *ni,
 		goto out1;
 	}
 
+	if (data_size <= le64_to_cpu(alloc->nres.data_size)) {
+		/* Reuse index. */
+		goto out;
+	}
+
 	/* Increase allocation. */
 	err = attr_set_size(ni, ATTR_ALLOC, in->name, in->name_len,
 			    &indx->alloc_run, data_size, &data_size, true,
@@ -1546,6 +1551,7 @@ static int indx_add_allocate(struct ntfs_index *indx, struct ntfs_inode *ni,
 	if (in->name == I30_NAME)
 		i_size_write(&ni->vfs_inode, data_size);
 
+out:
 	*vbn = bit << indx->idx2vbn_bits;
 
 	return 0;
-- 
2.34.1