Re: [PATCH v1 2/4] ntfs: fix rollback after MFT bitmap run coalescing

[liubaolin]

在 2026/9/24 09:45, Xuewen Wang 写道:
> After the direct allocation attempt drops lcnbmp_lock, a concurrent free
> can let ntfs_cluster_alloc() return the adjacent cluster. The merged
> runlist then extends the existing last run, but rollback assumes a new
> run was added. A later metadata failure removes the old mapping and
> frees its first cluster.
>
> Record whether the allocated cluster is adjacent before merging the
> runlists. On rollback, shorten a coalesced run by one cluster and free
> only that cluster; remove the new run for a non-adjacent allocation.
>
> Suggested-by: Baolin Liu <liubaolin@xxxxxxxxxx>
> Reviewed-by: Baolin Liu <liubaolin@xxxxxxxxxx>
> Signed-off-by: Xuewen Wang <wangxuewen@xxxxxxxxxx>
> ---
>   fs/ntfs/mft.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
> index 88bac85d22bc..12666668a80e 100644
> --- a/fs/ntfs/mft.c
> +++ b/fs/ntfs/mft.c
> @@ -1428,6 +1428,8 @@ static int ntfs_mft_bitmap_extend_allocation_nolock(struct ntfs_volume *vol)
>   					"Failed to allocate a cluster for the mft bitmap.");
>   			return PTR_ERR(rl2);
>   		}
> +		/* The adjacent cluster may have become available while unlocked. */
> +		status.added_cluster = rl2->lcn == lcn;
>   		rl = ntfs_runlists_merge(&mftbmp_ni->runlist, rl2, 0, &new_rl_count);
>   		if (IS_ERR(rl)) {
>   			up_write(&mftbmp_ni->runlist.lock);
> @@ -1442,8 +1444,8 @@ static int ntfs_mft_bitmap_extend_allocation_nolock(struct ntfs_volume *vol)
>   		}
>   		mftbmp_ni->runlist.rl = rl;
>   		mftbmp_ni->runlist.count = new_rl_count;
> -		status.added_run = 1;
> -		ntfs_debug("Adding one run to mft bitmap.");
> +		status.added_run = !status.added_cluster;
> +		ntfs_debug("Allocated one cluster for mft bitmap.");
>   		/* Find the last run in the new runlist. */
>   		for (; rl[1].length; rl++)
>   			;

Looks good to me.

Reviewed-by: Baolin Liu <liubaolin@xxxxxxxxxx>