Re: [PATCH 2/7] quota: add new quotactl Q_XGETNEXTQUOTA
From: Jan Kara <jack@suse.cz>
Date: 2016-01-22 08:55:38
Also in:
linux-fsdevel
On Thu 21-01-16 22:07:19, Eric Sandeen wrote:
Q_XGETNEXTQUOTA is exactly like Q_XGETQUOTA, except that it will return quota information for the id equal to or greater than the id requested. In other words, if the requested id has no quota, the command will return quota information for the next higher id which does have a quota set. If no higher id has an active quota, -ESRCH is returned. This allows filesystems to do efficient iteration in kernelspace, much like extN filesystems do in userspace when asked to report all active quotas. The patch adds a d_id field to struct qc_dqblk so that we can pass back the id of the quota which was found, and return it to userspace. Today, filesystems such as XFS require getpwent-style iterations, and for systems which have i.e. LDAP backends, this can be very slow, or even impossible if iteration is not allowed in the configuration. Signed-off-by: Eric Sandeen <redacted>
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quoted hunk ↗ jump to hunk
diff --git a/fs/quota/quota.c b/fs/quota/quota.c index ea66670..4bf8d40 100644 --- a/fs/quota/quota.c +++ b/fs/quota/quota.c@@ -33,6 +33,7 @@ static int check_quotactl_permission(struct super_block *sb, int type, int cmd, /* allow to query information for dquots we "own" */ case Q_GETQUOTA: case Q_XGETQUOTA: + case Q_XGETNEXTQUOTA:
IMO you should require CAP_SYS_ADMIN for the quotactl. Definitely doing the UID and GID checks for GETNEXTQUOTA looks strange to me since the returned structure may be for a different ID. Or did you assume that existing user will have quota structure allocated so we always return quotas for that ID in that case? I'm not sure this is good to rely on...
+ ret = sb->s_qcop->get_nextdqblk(sb, qid, &qdq); + if (ret) + return ret; + copy_to_xfs_dqblk(&fdq, &qdq, type, qdq.d_id); + if (copy_to_user(addr, &fdq, sizeof(fdq))) + return -EFAULT; + return ret; +}
So how about passing pointer to 'qid' to ->get_nextdqblk() and return the ID that way? That will also force you to fix the issue that you currently completely miss user-namespace conversions for the ID ;). I definitely dislike mixing d_id in the qdq structure with arguments of fs callbacks and that d_id doesn't get filled for most callbacks. That is going to cause confusion. Honza -- Jan Kara [off-list ref] SUSE Labs, CR _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs