Hi,
Please keep Abhi cc'd on this thread. Thanks,
Steve.
On Thu, 2013-07-11 at 18:05 +1000, Dave Chinner wrote:
> On Thu, Jul 11, 2013 at 12:00:42AM -0500, Chandra Seetharaman wrote:
> > Added appropriate pads and code for backward compatibility.
> >
> > Copied over the old version as it is different from the newer padded
> > version.
> >
> > New callers of the system call have to set the version of the data
> > structure being passed, and kernel will fill as much data as requested.
> >
> > Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx>
> > ---
> > fs/gfs2/quota.c | 3 --
> > fs/quota/quota.c | 67 +++++++++++++++++++++++++++++++++++++--
> > fs/xfs/xfs_qm_syscalls.c | 4 --
> > include/uapi/linux/dqblk_xfs.h | 60 +++++++++++++++++++++++++++++++----
> > 4 files changed, 116 insertions(+), 18 deletions(-)
> >
> > diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
> > index c7c840e..ca0dccd 100644
> > --- a/fs/gfs2/quota.c
> > +++ b/fs/gfs2/quota.c
> > @@ -1443,9 +1443,6 @@ static int gfs2_quota_get_xstate(struct super_block *sb,
> > {
> > struct gfs2_sbd *sdp = sb->s_fs_info;
> >
> > - memset(fqs, 0, sizeof(struct fs_quota_stat));
> > - fqs->qs_version = FS_QSTAT_VERSION;
> > -
> > switch (sdp->sd_args.ar_quota) {
> > case GFS2_QUOTA_ON:
> > fqs->qs_flags |= (FS_QUOTA_UDQ_ENFD | FS_QUOTA_GDQ_ENFD);
> > diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> > index c7314f1..ac5dd3a 100644
> > --- a/fs/quota/quota.c
> > +++ b/fs/quota/quota.c
> > @@ -204,15 +204,72 @@ static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
> > return sb->s_qcop->set_xstate(sb, flags, cmd);
> > }
> >
> > -static int quota_getxstate(struct super_block *sb, void __user *addr)
> > +static int quota_getxstate(struct super_block *sb, void __user *addr,
> > + bool older_version)
>
> I'd suggest that the two API calls should be handled by separate
> functions so there are no overlapping, dependent branches in the
> code.
>
> > {
> > struct fs_quota_stat fqs;
> > - int ret;
> > + struct fs_quota_stat_v1 fqs_v1;
> > + int ret, size;
> > + void *fqsp;
> >
> > if (!sb->s_qcop->get_xstate)
> > return -ENOSYS;
>
> I'd also suggest that a sb->s_qcop->get_xstatev vector is added
> so that filesystems keep the separate as well.
>
> And that means we don't need to play the fs_quota_stat and
> conversion-to-fs_quota_stat_v1 games. i.e. the existing
> quota_getxstate() remains and uses the existing struct
> fs_quota_stat, and the new Q_XGETQSTATV calls quota_getxstatev() and
> uses the newly defined struct fs_quota_statv and ->get_xstatev()
> call....
>
> > @@ -137,31 +139,75 @@ typedef struct fs_disk_quota {
> > * Provides a centralized way to get meta information about the quota subsystem.
> > * eg. space taken up for user and group quotas, number of dquots currently
> > * incore.
> > + * With version FS_QSTAT_VERSION, user space can send in an uninitialized
> > + * buffer and data will be filled by the kernel.
> > + * Starting FS_QSTAT_VERSION_2, to be used with Q_XGETQSTATV, user space
> > + * caller should set qs_version to the appropriate version of the
> > + * fs_quota_stat data structure they are providing. On return, user
> > + * space should check qs_version and use appropriate fields supported by
> > + * that version.
> > */
> > #define FS_QSTAT_VERSION 1 /* fs_quota_stat.qs_version */
> > +#define FS_QSTAT_VERSION_2 2 /* new field qs_pquota; realignment */
>
> As per above, this reasoning and logic is all invalid now because we
> aren't trying to maintain compatibility between users of the same
> quotactl.
>
> We are using a new quotactl, so we do not need to overload the
> existing structure or versions.
>
> > +/*
> > + * Some basic information about 'quota files'. Version 2.
> > + */
> > +struct fs_qfilestat {
> > + __u64 qfs_ino; /* inode number */
> > + __u64 qfs_nblks; /* number of BBs 512-byte-blks */
> > + __u32 qfs_nextents; /* number of extents */
> > + __u32 qfs_pad; /* pad for 8-byte alignment */
> > +};
> > +
> > +struct fs_quota_stat {
> > + __s8 qs_version; /* version for future changes */
> > + __u8 qs_pad1; /* pad for 16bit alignment */
> > + __u16 qs_flags; /* FS_QUOTA_.* flags */
> > + __u32 qs_incoredqs; /* number of dquots incore */
> > + struct fs_qfilestat qs_uquota; /* user quota information */
> > + struct fs_qfilestat qs_gquota; /* group quota information */
> > + struct fs_qfilestat qs_pquota; /* project quota information */
> > + __s32 qs_btimelimit; /* limit for blks timer */
> > + __s32 qs_itimelimit; /* limit for inodes timer */
> > + __s32 qs_rtbtimelimit;/* limit for rt blks timer */
> > + __u16 qs_bwarnlimit; /* limit for num warnings */
> > + __u16 qs_iwarnlimit; /* limit for num warnings */
> > + __u64 qs_pad2[8]; /* for future proofing */
> > +};
>
> these are what become fs_quota_statv and fs_qfilestatv structures
> for the new quotactl.
>
> > +/*
> > + * Since Version 1 did not have padding at appropriate places,
> > + * a new data structure has been defined for the older version to
> > + * provide backward compatibility.
> > + * Future extentions of this data structure won't require new
> > + * data structure definitions as the current one can be extended
> > + * with the logic and padding in place now.
> > + */
> > +#define FS_QSTAT_V1_SIZE (sizeof(struct fs_quota_stat_v1))
> > +#define FS_QSTAT_V2_SIZE (sizeof(struct fs_quota_stat))
>
> And these can go away completely.
>
> Cheers,
>
> Dave.
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