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SubjectRe: [PATCH] quota: fix wrong condition in is_quota_modification()
On Wed 11-09-19 17:36:50, Chao Yu wrote:
> Quoted from
> commit 3da40c7b0898 ("ext4: only call ext4_truncate when size <= isize")
>
> " At LSF we decided that if we truncate up from isize we shouldn't trim
> fallocated blocks that were fallocated with KEEP_SIZE and are past the
> new i_size. This patch fixes ext4 to do this. "
>
> And generic/092 of fstest have covered this case for long time, however
> is_quota_modification() didn't adjust based on that rule, so that in
> below condition, we will lose to quota block change:
> - fallocate blocks beyond EOF
> - remount
> - truncate(file_path, file_size)
>
> Fix it.
>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> include/linux/quotaops.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
> index dc905a4ff8d7..bd30acad3a7f 100644
> --- a/include/linux/quotaops.h
> +++ b/include/linux/quotaops.h
> @@ -22,7 +22,7 @@ static inline struct quota_info *sb_dqopt(struct super_block *sb)
> /* i_mutex must being held */
> static inline bool is_quota_modification(struct inode *inode, struct iattr *ia)
> {
> - return (ia->ia_valid & ATTR_SIZE && ia->ia_size != inode->i_size) ||
> + return (ia->ia_valid & ATTR_SIZE && ia->ia_size <= inode->i_size) ||
> (ia->ia_valid & ATTR_UID && !uid_eq(ia->ia_uid, inode->i_uid)) ||
> (ia->ia_valid & ATTR_GID && !gid_eq(ia->ia_gid, inode->i_gid));
> }

OK, but your change makes i_size extension not to be quota modification
which is IMO wrong. So I think the condition should just be:

return (ia->ia_valid & ATTR_SIZE) || ...

I'll fix the patch up and pull it into my tree.

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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