quota: Switch ->get_dqblk() and ->set_dqblk() to use bytes as space units

Currently ->get_dqblk() and ->set_dqblk() use struct fs_disk_quota which
tracks space limits and usage in 512-byte blocks. However VFS quotas
track usage in bytes (as some filesystems require that) and we need to
somehow pass this information. Upto now it wasn't a problem because we
didn't do any unit conversion (thus VFS quota routines happily stuck
number of bytes into d_bcount field of struct fd_disk_quota). Only if
you tried to use Q_XGETQUOTA or Q_XSETQLIM for VFS quotas (or Q_GETQUOTA
/ Q_SETQUOTA for XFS quotas), you got bogus results. Hardly anyone
tried this but reportedly some Samba users hit the problem in practice.
So when we want interfaces compatible we need to fix this.

We bite the bullet and define another quota structure used for passing
information from/to ->get_dqblk()/->set_dqblk. It's somewhat sad we have
to have more conversion routines in fs/quota/quota.c and another copying
of quota structure slows down getting of quota information by about 2%
but it seems cleaner than overloading e.g. units of d_bcount to bytes.

CC: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 45 insertions, 2 deletions

diff --git a/include/linux/quota.h b/include/linux/quota.h
index 50978b781a19..097d7eb2441e 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -321,6 +321,49 @@ struct dquot_operations {
 
 struct path;
 
+/* Structure for communicating via ->get_dqblk() & ->set_dqblk() */
+struct qc_dqblk {
+        int d_fieldmask;        /* mask of fields to change in ->set_dqblk() */
+        u64 d_spc_hardlimit;    /* absolute limit on used space */
+        u64 d_spc_softlimit;    /* preferred limit on used space */
+        u64 d_ino_hardlimit;    /* maximum # allocated inodes */
+        u64 d_ino_softlimit;    /* preferred inode limit */
+        u64 d_space;            /* Space owned by the user */
+        u64 d_ino_count;        /* # inodes owned by the user */
+        s64 d_ino_timer;        /* zero if within inode limits */
+                                /* if not, we refuse service */
+        s64 d_spc_timer;        /* similar to above; for space */
+        int d_ino_warns;        /* # warnings issued wrt num inodes */
+        int d_spc_warns;        /* # warnings issued wrt used space */
+        u64 d_rt_spc_hardlimit; /* absolute limit on realtime space */
+        u64 d_rt_spc_softlimit; /* preferred limit on RT space */
+        u64 d_rt_space;         /* realtime space owned */
+        s64 d_rt_spc_timer;     /* similar to above; for RT space */
+        int d_rt_spc_warns;     /* # warnings issued wrt RT space */
+};
+
+/* Field specifiers for ->set_dqblk() in struct qc_dqblk */
+#define QC_INO_SOFT     (1<<0)
+#define QC_INO_HARD     (1<<1)
+#define QC_SPC_SOFT     (1<<2)
+#define QC_SPC_HARD     (1<<3)
+#define QC_RT_SPC_SOFT  (1<<4)
+#define QC_RT_SPC_HARD  (1<<5)
+#define QC_LIMIT_MASK (QC_INO_SOFT | QC_INO_HARD | QC_SPC_SOFT | QC_SPC_HARD | \
+                       QC_RT_SPC_SOFT | QC_RT_SPC_HARD)
+#define QC_SPC_TIMER    (1<<6)
+#define QC_INO_TIMER    (1<<7)
+#define QC_RT_SPC_TIMER (1<<8)
+#define QC_TIMER_MASK (QC_SPC_TIMER | QC_INO_TIMER | QC_RT_SPC_TIMER)
+#define QC_SPC_WARNS    (1<<9)
+#define QC_INO_WARNS    (1<<10)
+#define QC_RT_SPC_WARNS (1<<11)
+#define QC_WARNS_MASK (QC_SPC_WARNS | QC_INO_WARNS | QC_RT_SPC_WARNS)
+#define QC_SPACE        (1<<12)
+#define QC_INO_COUNT    (1<<13)
+#define QC_RT_SPACE     (1<<14)
+#define QC_ACCT_MASK (QC_SPACE | QC_INO_COUNT | QC_RT_SPACE)
+
 /* Operations handling requests from userspace */
 struct quotactl_ops {
         int (*quota_on)(struct super_block *, int, int, struct path *);
@@ -329,8 +372,8 @@ struct quotactl_ops {
         int (*quota_sync)(struct super_block *, int);
         int (*get_info)(struct super_block *, int, struct if_dqinfo *);
         int (*set_info)(struct super_block *, int, struct if_dqinfo *);
-        int (*get_dqblk)(struct super_block *, struct kqid, struct fs_disk_quota *);
-        int (*set_dqblk)(struct super_block *, struct kqid, struct fs_disk_quota *);
+        int (*get_dqblk)(struct super_block *, struct kqid, struct qc_dqblk *);
+        int (*set_dqblk)(struct super_block *, struct kqid, struct qc_dqblk *);
         int (*get_xstate)(struct super_block *, struct fs_quota_stat *);
         int (*set_xstate)(struct super_block *, unsigned int, int);
         int (*get_xstatev)(struct super_block *, struct fs_quota_statv *);