[PATCH v1 3/4] ntfs: wait for the bitmap scan before MFT bitmap extension

[Xuewen Wang]

If MFT bitmap extension fails before the initial $Bitmap scan completes,
rollback calls ntfs_bitmap_clear_bit(), which holds a folio lock while
ntfs_set_lcn_empty_bits() waits for the scan. The scanner deadlocks if it
still needs that folio.

Wait for the initial scan before taking the runlist or bitmap folio locks
and attempting allocation.

Fixes: 11ccc9107dc4 ("ntfs: update runlist handling and cluster allocator")
Reviewed-by: Baolin Liu <liubaolin@xxxxxxxxxx>
Signed-off-by: Xuewen Wang <wangxuewen@xxxxxxxxxx>
---
 fs/ntfs/mft.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index 12666668a80e..489a5935202c 100644
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -1352,6 +1352,10 @@ static int ntfs_mft_bitmap_extend_allocation_nolock(struct ntfs_volume *vol)
 	size_t new_rl_count;
 
 	ntfs_debug("Extending mft bitmap allocation.");
+	/* The initial bitmap scan must finish before we lock or change a folio. */
+	if (!NVolFreeClusterKnown(vol))
+		wait_event(vol->free_waitq, NVolFreeClusterKnown(vol));
+
 	mft_ni = NTFS_I(vol->mft_ino);
 	mftbmp_ni = NTFS_I(vol->mftbmp_ino);
 	/*
-- 
2.25.1