Re: [PATCH] ext4: compare inode's i_projid with EXT4_DEF_PROJID rather than check EXT4_INODE_PROJINHERIT flag

[Roman Anufriev <dotdot@yandex-team.ru>]

On Tue, 7 Dec 2021, Roman Anufriev wrote:

> Commit 7ddf79a10395 ("ext4: only set project inherit bit for directory")
> removes EXT4_INODE_PROJINHERIT flag from regular files. This makes
> ext4_statfs() output incorrect (function does not apply quota limits
> on used/available space, etc) when called on dentry of regular file
> with project quota enabled.
>
> This patch fixes this by comparing inode's i_projid with
> EXT4_DEF_PROJID, as there is no point in calling ext4_statfs_project()
> for inode with default project id.
>
> $ sudo project_quota info dir/
> project   2147516417
> usage     4096
> limit     5242880
> inodes    4
> ilimit    0
> $ sudo project_quota info dir/file | grep project
> project   2147516417
> $ df -h /dev/loop0
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/loop0      232M  2.1M  214M   1% /mnt/ext4img
>
> without patch:
> $ df -h dir/
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/loop0      5.0M  4.0K  5.0M   1% /mnt/ext4img
> $ df -h dir/file
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/loop0      232M  2.1M  214M   1% /mnt/ext4img
>
> with patch:
> $ df -h dir/
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/loop0      5.0M  4.0K  5.0M   1% /mnt/ext4img
> $ df -h dir/file
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/loop0      5.0M  4.0K  5.0M   1% /mnt/ext4img
>
> Signed-off-by: Roman Anufriev <dotdot@yandex-team.ru>
> ---
> fs/ext4/super.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 79b6a0c..682d675 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -6074,6 +6074,7 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
> 	struct super_block *sb = dentry->d_sb;
> 	struct ext4_sb_info *sbi = EXT4_SB(sb);
> 	struct ext4_super_block *es = sbi->s_es;
> +	kprojid_t kprojid;
> 	ext4_fsblk_t overhead = 0, resv_blocks;
> 	s64 bfree;
> 	resv_blocks = EXT4_C2B(sbi, atomic64_read(&sbi->s_resv_clusters));
> @@ -6098,9 +6099,10 @@ static int ext4_statfs(struct dentry *dentry, struct kstatfs *buf)
> 	buf->f_fsid = uuid_to_fsid(es->s_uuid);
>
> #ifdef CONFIG_QUOTA
> -	if (ext4_test_inode_flag(dentry->d_inode, EXT4_INODE_PROJINHERIT) &&
> +	kprojid = EXT4_I(dentry->d_inode)->i_projid;
> +	if ((from_kprojid(current_user_ns(), kprojid) != EXT4_DEF_PROJID) &&
> 	    sb_has_quota_limits_enabled(sb, PRJQUOTA))
> -		ext4_statfs_project(sb, EXT4_I(dentry->d_inode)->i_projid, buf);
> +		ext4_statfs_project(sb, kprojid, buf);
> #endif
> 	return 0;
> }
> -- 
> 2.7.4
>
>

+Cc Wang Shilong <wshilong@ddn.com> author of 7ddf79a10395