Re: [PATCH 1/2] ntfs: take invalidate_lock in ntfs_setattr_size()

[liubaolin]

在 2026/8/28 14:16, Hongling Zeng 写道:
> ntfs_setattr_size() updates i_size and resizes the on-disk attribute
> without holding mapping->invalidate_lock.  Page faults take the lock
> shared, so a fault racing the resize can resolve a VCN against the
> transient runlist state of ntfs_non_resident_attr_expand() and fail
> with a spurious SIGBUS, and can interleave with the size-change
> epilogue (truncate_pagecache(), i_size_write(),
> pagecache_isize_extended()).
>
> Take invalidate_lock exclusively around the whole resize after
> inode_dio_wait(), matching the fallocate path and other filesystems
> such as xfs, which wraps truncate in its mmaplock (= invalidate_lock).
>
> Fixes: 9c87959601e8 ("ntfs: update file operations")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
> ---
>   fs/ntfs/file.c | 15 +++++++++++----
>   1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
> index 1969e4f444f7..585ab2145797 100644
> --- a/fs/ntfs/file.c
> +++ b/fs/ntfs/file.c
> @@ -270,18 +270,25 @@ static int ntfs_setattr_size(struct inode *vi, struct iattr *attr)
>   		return err;
>   
>   	inode_dio_wait(vi);
> +
> +	/*
> +	 * Serialize with page faults and pagecache instantiation so that
> +	 * readers cannot observe the size change until the attribute
> +	 * updates below have completed.
> +	 */
> +	filemap_invalidate_lock(vi->i_mapping);
>   	if (attr->ia_size > old_size) {
>   		truncate_pagecache(vi, old_size);
>   		i_size_write(vi, attr->ia_size);
>   		pagecache_isize_extended(vi, old_size, attr->ia_size);
> -	} else
> +	} else {
>   		truncate_setsize(vi, attr->ia_size);
> +	}
>   
>   	err = ntfs_truncate_vfs(vi, attr->ia_size, old_size);
> -	if (err) {
> +	if (err)
>   		i_size_write(vi, old_size);
> -		return err;
> -	}
> +	filemap_invalidate_unlock(vi->i_mapping);
>   
>   	return err;
>   }

Looks good to me.
Reviewed-by: Baolin Liu <liubaolin@xxxxxxxxxx>