linux-kernel - Re: [PATCH 08/13] ext4: calculate free_clusters_count in cluster unit in verify_group

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Message-ID: <20230816032212.GP2247938@mit.edu>
Date:   Tue, 15 Aug 2023 23:22:12 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Kemeng Shi <shikemeng@...weicloud.com>
Cc:     adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/13] ext4: calculate free_clusters_count in cluster
 unit in verify_group_input

On Thu, Jun 29, 2023 at 08:00:39PM +0800, Kemeng Shi wrote:
> We treat free_clusters_count in cluster unit while free_blocks_count is
> in block unit. Convert free_blocks_count to cluster unit to match the
> unit.
> Currently, verify_group_input is only called from ext4_ioctl_group_add
> which does not support bigalloc yet. The dismatch is easily ingored
> when we try to support bigalloc in ext4_ioctl_group_add (ext4_resize_fs
> already supports resize with bigalloc enabled). Just fix this in
> advance.
> 
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>

I'd rewrite the commit description a bit:

The field free_cluster_count in struct ext4_new_group_data should be
in units of clusters.  In verify_group_input() this field is being
filled in units of blocks.  Fortunately, we don't support online
resizing of bigalloc file systems, and for non-bigalloc file systems,
the cluster size == block size.  But fix this in case we do support
online resizing of bigalloc file systems in the future.

Other than that:

Reviewed-by: Theodore Ts'o <tytso@....edu>

						- Ted