Re: [PATCH 0/7 V3] quota: add new quotactl Q_GETNEXTQUOTA

Jan Kara
2016-01-26T13:10:05Z

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Just for reference attached are two patches that implement support for
Q_GETNEXTQUOTA and Q_XGETNEXTQUOTA in quota-tools. I have used it for
testing XFS and VFS infrastructure for these new quotactls.

Honza
On Fri 22-01-16 12:25:29, Eric Sandeen wrote:
> This adds a new quotactl, Q_GETNEXTQUOTA.
>
> Q_GETNEXTQUOTA is exactly like Q_GETQUOTA, except that it will
> return quota information for the id equal to or greater than
> the id requested. In other words, if the specified 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.
>
> So if you ask for id X, you can get back quota for id X,
> id X+N, or -ESRCH if no higher id has a quota.
>
> This allows filesystems to do efficient iteration in kernelspace,
> much like extN filesystems do in userspace when asked to report
> all active quotas.
>
> 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.
>
> Patches 1 and 4 are just small fixups that turned up along the way;
> 2 and 3 add the actual quota plumbing, and the rest are xfs-specific
> to allow xfs to support this new interface.
>
> For non-xfs quota, this does require a new structure which is
> able to pass back the discovered ID along with the quota info.
> For xfs-quota, the id is already present in the structure.
>
> V3:
> * Remove 32-bit compat stuff (i686/x86_64 at least works w/o it...)
> * Require CAP_SYS_ADMIN for these calls
> * Pass back found ID in &qid passed to ->get_nextdqblk, rather
> than modifying struct qc_dqblk
> * Munge that found ID back through user-namespace conversions
> before returning it in the user structure.
>
> Thanks,
> -Eric
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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>From 9ae91376373b1b0a8d4573834d0d99722a5909f6 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 26 Jan 2016 13:10:59 +0100
Subject: [PATCH 1/2] Scan dquots using Q_GETNEXTQUOTA

Check for new kernel quotactl Q_GETNEXTQUOTA and if available use it for
scanning all dquot structures.

Signed-off-by: Jan Kara <jack@suse.cz>
---
quota.h | 14 ++++++++++++++
quotaio_generic.c | 34 ++++++++++++++++++++++++++++++++++
quotaio_generic.h | 4 ++++
quotaio_meta.c | 14 +++++++++++++-
4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/quota.h b/quota.h
index 0c3842774e6f..0607e04b1f02 100644
--- a/quota.h
+++ b/quota.h
@@ -63,6 +63,7 @@ typedef int64_t qsize_t; /* Type in which we store size limitations */
#define Q_SETINFO 0x800006 /* set information about quota files */
#define Q_GETQUOTA 0x800007 /* get user quota structure */
#define Q_SETQUOTA 0x800008 /* set user quota structure */
+#define Q_GETNEXTQUOTA 0x800009 /* get disk limits and usage >= ID */

/*
* Quota structure used for communication with userspace via quotactl
@@ -91,6 +92,19 @@ struct if_dqblk {
u_int32_t dqb_valid;
};

+struct if_nextdqblk {
+ u_int64_t dqb_bhardlimit;
+ u_int64_t dqb_bsoftlimit;
+ u_int64_t dqb_curspace;
+ u_int64_t dqb_ihardlimit;
+ u_int64_t dqb_isoftlimit;
+ u_int64_t dqb_curinodes;
+ u_int64_t dqb_btime;
+ u_int64_t dqb_itime;
+ u_int32_t dqb_valid;
+ u_int32_t dqb_id;
+};
+
/*
* Structure used for setting quota information about file via quotactl
* Following flags are used to specify which fields are valid
diff --git a/quotaio_generic.c b/quotaio_generic.c
index 5001a56f8a6b..06b16e791624 100644
--- a/quotaio_generic.c
+++ b/quotaio_generic.c
@@ -161,3 +161,37 @@ int generic_scan_dquots(struct quota_handle *h,
free(dquot);
return ret;
}
+
+int vfs_scan_dquots(struct quota_handle *h,
+ int (*process_dquot)(struct dquot *dquot, char *dqname))
+{
+ struct dquot *dquot = get_empty_dquot();
+ qid_t id = 0;
+ struct if_nextdqblk kdqblk;
+ int ret;
+
+ dquot->dq_h = h;
+ while (1) {
+ ret = quotactl(QCMD(Q_GETNEXTQUOTA, h->qh_type),
+ h->qh_quotadev, id, (void *)&kdqblk);
+ if (ret < 0)
+ break;
+
+ /*
+ * This is a slight hack but we know struct if_dqblk is a
+ * subset of struct if_nextdqblk
+ */
+ generic_kern2utildqblk(&dquot->dq_dqb,
+ (struct if_dqblk *)&kdqblk);
+ dquot->dq_id = kdqblk.dqb_id;
+ ret = process_dquot(dquot, NULL);
+ if (ret < 0)
+ break;
+ id = kdqblk.dqb_id + 1;
+ }
+ free(dquot);
+
+ if (errno == ESRCH)
+ return 0;
+ return ret;
+}
diff --git a/quotaio_generic.h b/quotaio_generic.h
index 5edc11cd947e..a7930f0214bd 100644
--- a/quotaio_generic.h
+++ b/quotaio_generic.h
@@ -27,4 +27,8 @@ int generic_scan_dquots(struct quota_handle *h,
int (*process_dquot)(struct dquot *dquot, char *dqname),
int (*get_dquot)(struct dquot *dquot));

+/* Scan all dquots using kernel quotactl to get existing ids */
+int vfs_scan_dquots(struct quota_handle *h,
+ int (*process_dquot)(struct dquot *dquot, char *dqname));
+
#endif
diff --git a/quotaio_meta.c b/quotaio_meta.c
index e52b4f4322f1..ad6ff7ab2299 100644
--- a/quotaio_meta.c
+++ b/quotaio_meta.c
@@ -8,6 +8,7 @@

#include <string.h>
#include <stdlib.h>
+#include <errno.h>

#include <sys/types.h>

@@ -55,7 +56,18 @@ static int meta_commit_dquot(struct dquot *dquot, int flags)

static int meta_scan_dquots(struct quota_handle *h, int (*process_dquot)(struct dquot *dquot, char *dqname))
{
- return generic_scan_dquots(h, process_dquot, vfs_get_dquot);
+ struct if_nextdqblk kdqblk;
+ int ret;
+
+ ret = quotactl(QCMD(Q_GETNEXTQUOTA, h->qh_type), h->qh_quotadev, 0,
+ (void *)&kdqblk);
+ /*
+ * Fall back to scanning using passwd if Q_GETNEXTQUOTA is not
+ * supported
+ */
+ if (ret < 0 && (errno == ENOSYS || errno == EINVAL))
+ return generic_scan_dquots(h, process_dquot, vfs_get_dquot);
+ return vfs_scan_dquots(h, process_dquot);
}

struct quotafile_ops quotafile_ops_meta = {
--
2.6.2

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>From 304bed24716fdbb7c636ea8df0462d4f979f23a0 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 26 Jan 2016 14:06:59 +0100
Subject: [PATCH 2/2] Add support for scanning using Q_XGETNEXTQUOTA

Add support for scanning of all available quota structures using
Q_XGETNEXTQUOTA quotactl.

Signed-off-by: Jan Kara <jack@suse.cz>
---
quotaio_xfs.c | 42 +++++++++++++++++++++++++++++++++++++++---
quotaio_xfs.h | 1 +
2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/quotaio_xfs.c b/quotaio_xfs.c
index 903c03e6d3f8..14646411dbab 100644
--- a/quotaio_xfs.c
+++ b/quotaio_xfs.c
@@ -191,15 +191,51 @@ static int xfs_get_dquot(struct dquot *dq)
return 0;
}

+static int xfs_kernel_scan_dquots(struct quota_handle *h,
+ int (*process_dquot)(struct dquot *dquot, char *dqname))
+{
+ struct dquot *dquot = get_empty_dquot();
+ qid_t id = 0;
+ struct xfs_kern_dqblk xdqblk;
+ int ret;
+
+ dquot->dq_h = h;
+ while (1) {
+ ret = quotactl(QCMD(Q_XGETNEXTQUOTA, h->qh_type),
+ h->qh_quotadev, id, (void *)&xdqblk);
+ if (ret < 0)
+ break;
+
+ xfs_kern2utildqblk(&dquot->dq_dqb, &xdqblk);
+ dquot->dq_id = xdqblk.d_id;
+ ret = process_dquot(dquot, NULL);
+ if (ret < 0)
+ break;
+ id = xdqblk.d_id + 1;
+ }
+ free(dquot);
+
+ if (errno == ESRCH)
+ return 0;
+ return ret;
+}
+
/*
* Scan all known dquots and call callback on each
*/
static int xfs_scan_dquots(struct quota_handle *h, int (*process_dquot) (struct dquot *dquot, char *dqname))
{
- if (!XFS_USRQUOTA(h) && !XFS_GRPQUOTA(h))
- return 0;
+ int ret;
+ struct xfs_kern_dqblk xdqblk;

- return generic_scan_dquots(h, process_dquot, xfs_get_dquot);
+ ret = quotactl(QCMD(Q_XGETNEXTQUOTA, h->qh_type), h->qh_quotadev, 0,
+ (void *)&xdqblk);
+ if (ret < 0 && (errno == ENOSYS || errno == EINVAL)) {
+ if (!XFS_USRQUOTA(h) && !XFS_GRPQUOTA(h))
+ return 0;
+ return generic_scan_dquots(h, process_dquot, xfs_get_dquot);
+ }
+ return xfs_kernel_scan_dquots(h, process_dquot);
}

/*
diff --git a/quotaio_xfs.h b/quotaio_xfs.h
index 54725b044d63..2236da48f832 100644
--- a/quotaio_xfs.h
+++ b/quotaio_xfs.h
@@ -46,6 +46,7 @@
#define Q_XSETQLIM XQM_CMD(0x4) /* set disk limits only */
#define Q_XGETQSTAT XQM_CMD(0x5) /* returns fs_quota_stat_t struct */
#define Q_XQUOTARM XQM_CMD(0x6) /* free quota files' space */
+#define Q_XGETNEXTQUOTA XQM_CMD(0x9) /* get disk limits and usage >= ID */

/*
* fs_disk_quota structure:
--
2.6.2

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