Re: [PATCH v8 4/5] xfs: Add proper versioning support to fs_quota_stat

Jeff Liu
2013-05-13T04:29:11Z

On 05/11/2013 05:21 AM, 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 just set the version of the data
> structure being passed, and kernel will fill as much data as requested.
>
> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
> ---
> fs/gfs2/quota.c | 3 ---
> fs/quota/quota.c | 40 ++++++++++++++++++++++++++++++++++++++--
> fs/xfs/xfs_qm_syscalls.c | 4 ----
> include/uapi/linux/dqblk_xfs.h | 38 ++++++++++++++++++++++++++++++++++++--
> 4 files changed, 74 insertions(+), 11 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..510464e 100644
> --- a/fs/quota/quota.c
> +++ b/fs/quota/quota.c
> @@ -207,12 +207,48 @@ static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
> static int quota_getxstate(struct super_block *sb, void __user *addr)
> {
> struct fs_quota_stat fqs;
> - int ret;
> + struct fs_quota_stat_v1 fqs_v1;
> + int ret, size;
> + void *cp = &fqs;
>
> if (!sb->s_qcop->get_xstate)
> return -ENOSYS;
> +
> + memset(&fqs, 0, sizeof(struct fs_quota_stat));
> + if (copy_from_user(&fqs, addr, 1)) /* just get the version */
> + return -EFAULT;
> +
> + switch (fqs.qs_version) {
> + case FS_QSTAT_VERSION_2:
> + size = FS_QSTAT_V2_SIZE;
> + break;
> + default:
> + fqs.qs_version = FS_QSTAT_VERSION;
> + /* fallthrough */
> + case FS_QSTAT_VERSION:
> + size = FS_QSTAT_V1_SIZE;
> + cp = &fqs_v1;
> + }
> +
> ret = sb->s_qcop->get_xstate(sb, &fqs);
> - if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
> + if (ret)
> + return ret;
> +
> + if (fqs.qs_version == FS_QSTAT_VERSION) {
> + fqs_v1.qs_version = fqs.qs_version;
> + fqs_v1.qs_flags = fqs.qs_flags;
> + fqs_v1.qs_pad = 0;
> + fqs_v1.qs_uquota = fqs.qs_uquota;
> + fqs_v1.qs_gquota = fqs.qs_gquota;
> + fqs_v1.qs_incoredqs = fqs.qs_incoredqs;
> + fqs_v1.qs_btimelimit = fqs.qs_btimelimit;
> + fqs_v1.qs_itimelimit = fqs.qs_itimelimit;
> + fqs_v1.qs_rtbtimelimit = fqs.qs_rtbtimelimit;
> + fqs_v1.qs_bwarnlimit = fqs.qs_bwarnlimit;
> + fqs_v1.qs_iwarnlimit = fqs.qs_iwarnlimit;
> + }
> +
> + if (copy_to_user(addr, &cp, size))
> return -EFAULT;
> return ret;
> }
> diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
> index 65c0a7d..c27b0e4 100644
> --- a/fs/xfs/xfs_qm_syscalls.c
> +++ b/fs/xfs/xfs_qm_syscalls.c
> @@ -420,9 +420,6 @@ xfs_qm_scall_getqstat(
> bool tempgqip = false;
> bool temppqip = false;
>
> - memset(out, 0, sizeof(fs_quota_stat_t));
> -
> - out->qs_version = FS_QSTAT_VERSION;
> if (!xfs_sb_version_hasquota(&mp->m_sb)) {
> out->qs_uquota.qfs_ino = NULLFSINO;
> out->qs_gquota.qfs_ino = NULLFSINO;
> @@ -432,7 +429,6 @@ xfs_qm_scall_getqstat(
> out->qs_flags = (__uint16_t) xfs_qm_export_flags(mp->m_qflags &
> (XFS_ALL_QUOTA_ACCT|
> XFS_ALL_QUOTA_ENFD));
> - out->qs_pad = 0;
> out->qs_uquota.qfs_ino = mp->m_sb.sb_uquotino;
> out->qs_gquota.qfs_ino = mp->m_sb.sb_gquotino;
> if (&out->qs_gquota != &out->qs_pquota)
> diff --git a/include/uapi/linux/dqblk_xfs.h b/include/uapi/linux/dqblk_xfs.h
> index f17e3bb..d9629c1 100644
> --- a/include/uapi/linux/dqblk_xfs.h
> +++ b/include/uapi/linux/dqblk_xfs.h
> @@ -18,6 +18,7 @@
> #define _LINUX_DQBLK_XFS_H
>
> #include <linux/types.h>
> +#include <linux/stddef.h>
>
> /*
> * Disk quota - quotactl(2) commands for the XFS Quota Manager (XQM).
> @@ -137,8 +138,12 @@ 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.
> + * User space caller should set qs_version to the appropriate version
> + * of the fs_quota_stat data structure they are providing. Not providing
> + * a version will be treated as FS_QSTAT_VERSION.
> */
> #define FS_QSTAT_VERSION 1 /* fs_quota_stat.qs_version */
> +#define FS_QSTAT_VERSION_2 2 /* new field qs_pquota */
>
> /*
> * Some basic information about 'quota files'.
> @@ -149,19 +154,48 @@ typedef struct fs_qfilestat {
> __u32 qfs_nextents; /* number of extents */
> } fs_qfilestat_t;
>
> +typedef struct fs_quota_stat_v1 {
> + __s8 qs_version; /* version number for future changes */
> + __u16 qs_flags; /* FS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
> + __u8 qs_pad; /* unused */
> + fs_qfilestat_t qs_uquota; /* user quota storage information */
> + fs_qfilestat_t qs_gquota; /* group quota storage information */
> + __u32 qs_incoredqs; /* number of dquots incore */
> + __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 */
> +} fs_quota_stat_v1_t;
Dave has mentioned that we should not introduce typedef again. :-P.
> +
> typedef struct fs_quota_stat {
> __s8 qs_version; /* version number for future changes */
> + __u8 qs_pad1; /* unused */
> __u16 qs_flags; /* FS_QUOTA_{U,P,G}DQ_{ACCT,ENFD} */
> - __s8 qs_pad; /* unused */
> + __u8 qs_pad2[4]; /* unused */
> fs_qfilestat_t qs_uquota; /* user quota storage information */
> fs_qfilestat_t qs_gquota; /* group quota storage information */
> -#define qs_pquota qs_gquota
> __u32 qs_incoredqs; /* number of dquots incore */
...
> __s32 qs_btimelimit; /* limit for blks timer */
> __s32 qs_itimelimit; /* limit for inodes timer */
> __s32 qs_rtbtimelimit;/* limit for rt blks timer */
Found trailing whitespace for above three lines when applying this patch.
> __u16 qs_bwarnlimit; /* limit for num warnings */
> __u16 qs_iwarnlimit; /* limit for num warnings */
> + __u8 qs_pad3[4]; /* unused */
> + fs_qfilestat_t qs_pquota; /* project quota storage information */
> + /* End of Data structure for FS_QSTAT_VERSION_2 */
> } fs_quota_stat_t;
>
> +/*
> + * 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 (offsetof(struct fs_quota_stat, qs_pquota) + \
> + sizeof(fs_qfilestat_t))
> +
> #endif /* _LINUX_DQBLK_XFS_H */
>
Thanks,
-Jeff