[f2fs-dev] [PATCH v2 1/2] f2fs: don't allow unaligned truncation to smaller size on pinned file

[wangzijie]

> To prevent scattered pin block generation, don't allow non-section aligned truncation
> to smaller size on pinned file. But for truncation to larger size, after
> commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned files"),
> we only support overwrite IO to pinned file, so we don't need to consider
> attr->ia_size > i_size case.
> 
> Signed-off-by: wangzijie <wangzijie1@xxxxxxxxx>
> ---
> v2:
> - add comments and change a proper subject
> ---
>  fs/f2fs/file.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6bd3de64f..09be6e849 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1026,6 +1026,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
>  {
>  	struct inode *inode = d_inode(dentry);
>  	struct f2fs_inode_info *fi = F2FS_I(inode);
> +	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>  	int err;
>  
>  	if (unlikely(f2fs_cp_error(F2FS_I_SB(inode))))
> @@ -1047,6 +1048,17 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
>  			!IS_ALIGNED(attr->ia_size,
>  			F2FS_BLK_TO_BYTES(fi->i_cluster_size)))
>  			return -EINVAL;
> +		/*
> +		 * To prevent scattered pin block generation, we don't
> +		 * allow smaller size unaligned truncation for pinned file.
> +		 * We only support overwrite IO to pinned file, so don't
> +		 * care about larger size truncation.
> +		 */
> +		if (f2fs_is_pinned_file(inode) &&
> +			attr->ia_size < i_size_read(inode) &&
> +			!IS_ALIGNED(attr->ia_size,
> +			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
> +			return -EINVAL;
>  	}
>  
>  	err = setattr_prepare(idmap, dentry, attr);
> -- 
> 2.25.1

I missed attr->ia_size == i_size case...I will cover that in next version.