Re: [PATCH 5/9] xfs: wire up new v5 bulkstat ioctls

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jun 05, 2019 at 03:30:21PM -0700, Allison Collins wrote:
> On 5/29/19 3:28 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Wire up the new v5 BULKSTAT ioctl and rename the old one to V1.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >   fs/xfs/libxfs/xfs_fs.h |   24 +++++++++++
> >   fs/xfs/xfs_ioctl.c     |  104 ++++++++++++++++++++++++++++++++++++++++++++++++
> >   fs/xfs/xfs_ioctl32.c   |    1
> >   fs/xfs/xfs_ondisk.h    |    1
> >   4 files changed, 129 insertions(+), 1 deletion(-)
> > 
> > 
> > diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> > index 8b8fe78511fb..960f3542e207 100644
> > --- a/fs/xfs/libxfs/xfs_fs.h
> > +++ b/fs/xfs/libxfs/xfs_fs.h
> > @@ -435,7 +435,6 @@ struct xfs_fsop_bulkreq {
> >   	__s32		__user *ocount;	/* output count pointer		*/
> >   };
> > -
> >   /*
> >    * Structures returned from xfs_inumbers routine (XFS_IOC_FSINUMBERS).
> >    */
> > @@ -457,6 +456,28 @@ struct xfs_inumbers {
> >   #define XFS_INUMBERS_VERSION_V1	(1)
> >   #define XFS_INUMBERS_VERSION_V5	(5)
> > +/* Header for bulk inode requests. */
> > +struct xfs_bulk_ireq {
> > +	uint64_t	ino;		/* I/O: start with this inode	*/
> > +	uint32_t	flags;		/* I/O: operation flags		*/
> > +	uint32_t	icount;		/* I: count of entries in buffer */
> > +	uint32_t	ocount;		/* O: count of entries filled out */
> > +	uint32_t	reserved32;	/* must be zero			*/
> > +	uint64_t	reserved[5];	/* must be zero			*/
> > +};
> > +
> > +#define XFS_BULK_IREQ_FLAGS_ALL	(0)
> > +
> > +/*
> > + * ioctl structures for v5 bulkstat and inumbers requests
> > + */
> > +struct xfs_bulkstat_req {
> > +	struct xfs_bulk_ireq	hdr;
> > +	struct xfs_bulkstat	bulkstat[];
> > +};
> > +#define XFS_BULKSTAT_REQ_SIZE(nr)	(sizeof(struct xfs_bulkstat_req) + \
> > +					 (nr) * sizeof(struct xfs_bulkstat))
> > +
> >   /*
> >    * Error injection.
> >    */
> > @@ -758,6 +779,7 @@ struct xfs_scrub_metadata {
> >   #define XFS_IOC_FSGEOMETRY_V4	     _IOR ('X', 124, struct xfs_fsop_geom_v4)
> >   #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)
> >   /*	XFS_IOC_GETFSUUID ---------- deprecated 140	 */
> > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > index e43ad688e683..f6724c75ba97 100644
> > --- a/fs/xfs/xfs_ioctl.c
> > +++ b/fs/xfs/xfs_ioctl.c
> > @@ -822,6 +822,107 @@ xfs_ioc_fsbulkstat(
> >   	return 0;
> >   }
> > +/* Return 0 on success or positive error */
> > +static int
> > +xfs_bulkstat_fmt(
> > +	struct xfs_ibulk		*breq,
> > +	const struct xfs_bulkstat	*bstat)
> > +{
> > +	if (copy_to_user(breq->ubuffer, bstat, sizeof(struct xfs_bulkstat)))
> > +		return -EFAULT;
> > +	return xfs_ibulk_advance(breq, sizeof(struct xfs_bulkstat));
> > +}
> > +
> > +/*
> > + * Check the incoming bulk request @hdr from userspace and initialize the
> > + * internal @breq bulk request appropriately.  Returns 0 if the bulk request
> > + * should proceed; 1 if there's nothing to do; or the usual negative error
> > + * code.
> > + */
> > +static int
> > +xfs_bulk_ireq_setup(
> > +	struct xfs_mount	*mp,
> > +	struct xfs_bulk_ireq	*hdr,
> > +	struct xfs_ibulk	*breq,
> > +	void __user		*ubuffer)
> > +{
> > +	if (hdr->icount == 0 ||
> > +	    (hdr->flags & ~XFS_BULK_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)
> > +		goto no_results;
> > +
> > +	breq->ubuffer = ubuffer;
> > +	breq->icount = hdr->icount;
> > +	breq->startino = hdr->ino;
> > +	return 0;
> > +no_results:
> > +	hdr->ocount = 0;
> > +	return 1;
> > +}
> > +
> > +/*
> > + * Update the userspace bulk request @hdr to reflect the end state of the
> > + * internal bulk request @breq.  If @error is negative then we return just
> > + * that; otherwise (@error is 0 or 1) we copy the state so that userspace
> > + * can discover what happened.
> > + */
> > +static int
> > +xfs_bulk_ireq_teardown(
> > +	struct xfs_bulk_ireq	*hdr,
> > +	struct xfs_ibulk	*breq,
> > +	int			error)
> > +{
> > +	if (error < 0)
> > +		return error;
> Hmm, passing in error just to bail on error seemed a little out of scope to
> me.  Is there a reason we're doing it here?  Instead of after the preceding
> call made in the caller?  Referenced below.....
> 
> > +
> > +	hdr->ino = breq->startino;
> > +	hdr->ocount = breq->ocount;
> > +	return 0;
> > +}
> > +
> > +/* Handle the v5 bulkstat ioctl. */
> > +STATIC int
> > +xfs_ioc_bulkstat(
> > +	struct xfs_mount		*mp,
> > +	unsigned int			cmd,
> > +	struct xfs_bulkstat_req __user	*arg)
> > +{
> > +	struct xfs_bulk_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_bulk_ireq_setup(mp, &hdr, &breq, arg->bulkstat);
> > +	if (error < 0)
> > +		return error;
> > +
> > +	if (!error)
> > +		error = xfs_bulkstat(&breq, xfs_bulkstat_fmt);
> > +
>         Right here.  How about
> 
>         if (error < 0)
>            return error;
> 
>         It seems functionally equivalent.  If error < 0, teardown will
> bounce it back anyway and then the error check below will toss it back up.
> Is that what you meant?

Yeah, I could do that too. :)

TBH I only threw it in as a helper function because xfs_bulk_ireq_setup
seemed to need a counterpart; it's such a short function that I could
just opencode it...  Thoughts?

--D

> Allison
> 
> > +	error = xfs_bulk_ireq_teardown(&hdr, &breq, error);
> > +	if (error)
> > +		return error;
> > +
> > +	if (copy_to_user(&arg->hdr, &hdr, sizeof(hdr)))
> > +		return -EFAULT;
> > +
> > +	return 0;
> > +}
> > +
> >   STATIC int
> >   xfs_ioc_fsgeometry(
> >   	struct xfs_mount	*mp,
> > @@ -1986,6 +2087,9 @@ xfs_file_ioctl(
> >   	case XFS_IOC_FSINUMBERS:
> >   		return xfs_ioc_fsbulkstat(mp, cmd, arg);
> > +	case XFS_IOC_BULKSTAT:
> > +		return xfs_ioc_bulkstat(mp, cmd, arg);
> > +
> >   	case XFS_IOC_FSGEOMETRY_V1:
> >   		return xfs_ioc_fsgeometry(mp, arg, 3);
> >   	case XFS_IOC_FSGEOMETRY_V4:
> > diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c
> > index bfe71747776b..84c342be4536 100644
> > --- a/fs/xfs/xfs_ioctl32.c
> > +++ b/fs/xfs/xfs_ioctl32.c
> > @@ -576,6 +576,7 @@ xfs_file_compat_ioctl(
> >   	case XFS_IOC_ERROR_CLEARALL:
> >   	case FS_IOC_GETFSMAP:
> >   	case XFS_IOC_SCRUB_METADATA:
> > +	case XFS_IOC_BULKSTAT:
> >   		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 d8f941b4d51c..954484c6eb96 100644
> > --- a/fs/xfs/xfs_ondisk.h
> > +++ b/fs/xfs/xfs_ondisk.h
> > @@ -149,6 +149,7 @@ 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);
> >   }
> >   #endif /* __XFS_ONDISK_H */
> >