On Fri, Jul 05, 2019 at 07:05:33AM -0400, Brian Foster wrote:
> On Wed, Jul 03, 2019 at 01:01:43PM -0700, Darrick J. Wong wrote:
> > On Wed, Jul 03, 2019 at 12:11:36PM -0400, Brian Foster wrote:
> > > On Wed, Jul 03, 2019 at 07:52:56AM -0700, Darrick J. Wong wrote:
> > > > On Wed, Jul 03, 2019 at 09:24:41AM -0400, Brian Foster wrote:
> > > > > On Wed, Jun 26, 2019 at 01:46:13PM -0700, Darrick J. Wong wrote:
> > > > > > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > > > > >
> > > > > > Wire up the V5 BULKSTAT_SINGLE ioctl and rename the old one V1.
> > > > > >
> > > > > > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > > > > > ---
> > > > > > fs/xfs/libxfs/xfs_fs.h | 16 ++++++++++
> > > > > > fs/xfs/xfs_ioctl.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++
> > > > > > fs/xfs/xfs_ioctl32.c | 1 +
> > > > > > fs/xfs/xfs_ondisk.h | 1 +
> > > > > > 4 files changed, 97 insertions(+)
> > > > > >
> > > > > >
> > > > > > diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> > > > > > index 960f3542e207..95d0411dae9b 100644
> > > > > > --- a/fs/xfs/libxfs/xfs_fs.h
> > > > > > +++ b/fs/xfs/libxfs/xfs_fs.h
> > > > > > @@ -468,6 +468,16 @@ struct xfs_bulk_ireq {
> > > > > >
> > > > > > #define XFS_BULK_IREQ_FLAGS_ALL (0)
> > > > > >
> > > > > > +/* Header for a single inode request. */
> > > > > > +struct xfs_ireq {
> > > > > > + uint64_t ino; /* I/O: start with this inode */
> > > > > > + uint32_t flags; /* I/O: operation flags */
> > > > > > + uint32_t reserved32; /* must be zero */
> > > > > > + uint64_t reserved[2]; /* must be zero */
> > > > > > +};
> > > > > > +
> > > > > > +#define XFS_IREQ_FLAGS_ALL (0)
> > > > > > +
> > > > > > /*
> > > > > > * ioctl structures for v5 bulkstat and inumbers requests
> > > > > > */
> > > > > > @@ -478,6 +488,11 @@ struct xfs_bulkstat_req {
> > > > > > #define XFS_BULKSTAT_REQ_SIZE(nr) (sizeof(struct xfs_bulkstat_req) + \
> > > > > > (nr) * sizeof(struct xfs_bulkstat))
> > > > > >
> > > > > > +struct xfs_bulkstat_single_req {
> > > > > > + struct xfs_ireq hdr;
> > > > > > + struct xfs_bulkstat bulkstat;
> > > > > > +};
> > > > > > +
> > > > >
> > > > > What's the reasoning for separate data structures when the single
> > > > > command is basically a subset of standard bulkstat (similar to the older
> > > > > interface)?
> > > >
> > > > I split them up to avoid having irrelevant bulk_req fields (specifically
> > > > icount and ocount) cluttering up the single_req header. In patch 9 the
> > > > bulkstat single command grows the ability to request the root inode to
> > > > fix xfsdump's inability to correctly guess the root directory.
> > > >
> > >
> > > Ok, figured as much once I got to the magic inode flag patch. It's
> > > probably reasonable either way, the tradeoff to this approach is the
> > > extra boilerplate code associated with processing the separate data
> > > structure.
> >
> > <nod>
> >
> > > Thinking about it a bit more.. what was the purpose of the separate
> > > BULKSTAT_SINGLE command in the first place? AFAICT it just toggles the
> > > hacky ->lastip semantic. If we've addressed that with an entirely new
> > > data structure, do we need the separate ioctl at all anymore?
> >
> > At the moment, somewhat simpler setup in userspace:
> >
> > struct xfs_bulkstat_single_req b = { 0 };
> > int ret;
> >
> > b.hdr.ino = some_ino;
> > ret = ioctl(fd, XFS_IOC_BULKSTAT_SINGLE, &b);
> > if (ret)
> > abort();
> >
> > printf("%d\n", b.bulkstat.bs_ino);
> >
> > vs. a single-inode bulkstat:
> >
> > struct xfs_bulkstat_req *b;
> > int ret;
> >
> > b = calloc(1, XFS_BULKSTAT_REQ_SIZE(1));
> > if (!b)
> > abort();
> >
> > b->hdr.ino = some_ino;
> > ret = ioctl(fd, XFS_IOC_BULKSTAT, b);
> > if (ret)
> > abort();
> >
> > if (b->hdr.ocount)
> > printf("%d\n", b->bulkstat[0].bs_ino);
> >
> > free(b);
> >
> > AFAICT, the main advantages are (1) replacing the heap allocation with a
> > stack allocation and (2) not cluttering the regular bulkstat with the
> > "just grab this one symbolic inode" interface. We could very well just
> > drop this one, particularly since I'm in the process of wrapping most of
> > the ioctl invocation complexity in libfrog wrapper functions anyway...
> >
>
> That seems preferable to me. I'm not that invested in the semantics
> between bulkstat and bulkstat_single, but if the only reason we
> originally had the latter as a separate ioctl was to deal with the
> ->lastip interface wart then I think it would be unfortunate to
> unnecessarily carry that mess forward through another generation of the
> interface that doesn't have the original problem. Userspace should be
> able to easily abstract the single case.
Indeed, it was trivially easy to rewrite the xfrog_bulkstat_single
wrapper. :)
--D
> Brian
>
> > --D
> >
> > > Brian
> > >
> > > > --D
> > > >
> > > > > Brian
> > > > >
> > > > > > /*
> > > > > > * Error injection.
> > > > > > */
> > > > > > @@ -780,6 +795,7 @@ struct xfs_scrub_metadata {
> > > > > > #define XFS_IOC_GOINGDOWN _IOR ('X', 125, uint32_t)
> > > > > > #define XFS_IOC_FSGEOMETRY _IOR ('X', 126, struct xfs_fsop_geom)
> > > > > > #define XFS_IOC_BULKSTAT _IOR ('X', 127, struct xfs_bulkstat_req)
> > > > > > +#define XFS_IOC_BULKSTAT_SINGLE _IOR ('X', 128, struct xfs_bulkstat_single_req)
> > > > > > /* XFS_IOC_GETFSUUID ---------- deprecated 140 */
> > > > > >
> > > > > >
> > > > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > > > > > index cf6a38c2a3ed..2c821fa601a4 100644
> > > > > > --- a/fs/xfs/xfs_ioctl.c
> > > > > > +++ b/fs/xfs/xfs_ioctl.c
> > > > > > @@ -922,6 +922,83 @@ xfs_ioc_bulkstat(
> > > > > > return 0;
> > > > > > }
> > > > > >
> > > > > > +/*
> > > > > > + * Check the incoming singleton request @hdr from userspace and initialize the
> > > > > > + * internal @breq bulk request appropriately. Returns 0 if the bulk request
> > > > > > + * should proceed; or the usual negative error code.
> > > > > > + */
> > > > > > +static int
> > > > > > +xfs_ireq_setup(
> > > > > > + struct xfs_mount *mp,
> > > > > > + struct xfs_ireq *hdr,
> > > > > > + struct xfs_ibulk *breq,
> > > > > > + void __user *ubuffer)
> > > > > > +{
> > > > > > + if ((hdr->flags & ~XFS_IREQ_FLAGS_ALL) ||
> > > > > > + hdr->reserved32 ||
> > > > > > + memchr_inv(hdr->reserved, 0, sizeof(hdr->reserved)))
> > > > > > + return -EINVAL;
> > > > > > +
> > > > > > + if (XFS_INO_TO_AGNO(mp, hdr->ino) >= mp->m_sb.sb_agcount)
> > > > > > + return -EINVAL;
> > > > > > +
> > > > > > + breq->ubuffer = ubuffer;
> > > > > > + breq->icount = 1;
> > > > > > + breq->startino = hdr->ino;
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > +/*
> > > > > > + * Update the userspace singleton request @hdr to reflect the end state of the
> > > > > > + * internal bulk request @breq. If @error is negative then we return just
> > > > > > + * that; otherwise we copy the state so that userspace can discover what
> > > > > > + * happened.
> > > > > > + */
> > > > > > +static void
> > > > > > +xfs_ireq_teardown(
> > > > > > + struct xfs_ireq *hdr,
> > > > > > + struct xfs_ibulk *breq)
> > > > > > +{
> > > > > > + hdr->ino = breq->startino;
> > > > > > +}
> > > > > > +
> > > > > > +/* Handle the v5 bulkstat_single ioctl. */
> > > > > > +STATIC int
> > > > > > +xfs_ioc_bulkstat_single(
> > > > > > + struct xfs_mount *mp,
> > > > > > + unsigned int cmd,
> > > > > > + struct xfs_bulkstat_single_req __user *arg)
> > > > > > +{
> > > > > > + struct xfs_ireq hdr;
> > > > > > + struct xfs_ibulk breq = {
> > > > > > + .mp = mp,
> > > > > > + };
> > > > > > + int error;
> > > > > > +
> > > > > > + if (!capable(CAP_SYS_ADMIN))
> > > > > > + return -EPERM;
> > > > > > +
> > > > > > + if (XFS_FORCED_SHUTDOWN(mp))
> > > > > > + return -EIO;
> > > > > > +
> > > > > > + if (copy_from_user(&hdr, &arg->hdr, sizeof(hdr)))
> > > > > > + return -EFAULT;
> > > > > > +
> > > > > > + error = xfs_ireq_setup(mp, &hdr, &breq, &arg->bulkstat);
> > > > > > + if (error)
> > > > > > + return error;
> > > > > > +
> > > > > > + error = xfs_bulkstat_one(&breq, xfs_bulkstat_fmt);
> > > > > > + if (error)
> > > > > > + return error;
> > > > > > +
> > > > > > + xfs_ireq_teardown(&hdr, &breq);
> > > > > > + if (copy_to_user(&arg->hdr, &hdr, sizeof(hdr)))
> > > > > > + return -EFAULT;
> > > > > > +
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > STATIC int
> > > > > > xfs_ioc_fsgeometry(
> > > > > > struct xfs_mount *mp,
> > > > > > @@ -2088,6 +2165,8 @@ xfs_file_ioctl(
> > > > > >
> > > > > > case XFS_IOC_BULKSTAT:
> > > > > > return xfs_ioc_bulkstat(mp, cmd, arg);
> > > > > > + case XFS_IOC_BULKSTAT_SINGLE:
> > > > > > + return xfs_ioc_bulkstat_single(mp, cmd, arg);
> > > > > >
> > > > > > case XFS_IOC_FSGEOMETRY_V1:
> > > > > > return xfs_ioc_fsgeometry(mp, arg, 3);
> > > > > > diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
> > > > > > index df107adbdbf3..6fa0f41dbae5 100644
> > > > > > --- a/fs/xfs/xfs_ioctl32.c
> > > > > > +++ b/fs/xfs/xfs_ioctl32.c
> > > > > > @@ -581,6 +581,7 @@ xfs_file_compat_ioctl(
> > > > > > case FS_IOC_GETFSMAP:
> > > > > > case XFS_IOC_SCRUB_METADATA:
> > > > > > case XFS_IOC_BULKSTAT:
> > > > > > + case XFS_IOC_BULKSTAT_SINGLE:
> > > > > > return xfs_file_ioctl(filp, cmd, p);
> > > > > > #if !defined(BROKEN_X86_ALIGNMENT) || defined(CONFIG_X86_X32)
> > > > > > /*
> > > > > > diff --git a/fs/xfs/xfs_ondisk.h b/fs/xfs/xfs_ondisk.h
> > > > > > index 954484c6eb96..fa1252657b08 100644
> > > > > > --- a/fs/xfs/xfs_ondisk.h
> > > > > > +++ b/fs/xfs/xfs_ondisk.h
> > > > > > @@ -150,6 +150,7 @@ xfs_check_ondisk_structs(void)
> > > > > > XFS_CHECK_STRUCT_SIZE(struct xfs_bulkstat, 192);
> > > > > > XFS_CHECK_STRUCT_SIZE(struct xfs_inumbers, 24);
> > > > > > XFS_CHECK_STRUCT_SIZE(struct xfs_bulkstat_req, 64);
> > > > > > + XFS_CHECK_STRUCT_SIZE(struct xfs_bulkstat_single_req, 224);
> > > > > > }
> > > > > >
> > > > > > #endif /* __XFS_ONDISK_H */
> > > > > >
