quota: Split dquot_quota_sync() to writeback and cache flushing part

Split off part of dquot_quota_sync() which writes dquots into a quota file
to a separate function. In the next patch we will use the function from
filesystems and we do not want to abuse ->quota_sync quotactl callback more
than necessary.
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/gfs2/quota.c

@@ -1108,7 +1108,7 @@ void gfs2_quota_change(struct gfs2_inode *ip, s64 change,
 	}
 }
 
-int gfs2_quota_sync(struct super_block *sb, int type, int wait)
+int gfs2_quota_sync(struct super_block *sb, int type)
 {
 	struct gfs2_sbd *sdp = sb->s_fs_info;
 	struct gfs2_quota_data **qda;
@@ -1154,7 +1154,7 @@ int gfs2_quota_sync(struct super_block *sb, int type, int wait)
 
 static int gfs2_quota_sync_timeo(struct super_block *sb, int type)
 {
-	return gfs2_quota_sync(sb, type, 0);
+	return gfs2_quota_sync(sb, type);
 }
 
 int gfs2_quota_refresh(struct gfs2_sbd *sdp, int user, u32 id)

fs/gfs2/quota.h

@@ -26,7 +26,7 @@ extern int gfs2_quota_check(struct gfs2_inode *ip, u32 uid, u32 gid);
 extern void gfs2_quota_change(struct gfs2_inode *ip, s64 change,
 			      u32 uid, u32 gid);
 
-extern int gfs2_quota_sync(struct super_block *sb, int type, int wait);
+extern int gfs2_quota_sync(struct super_block *sb, int type);
 extern int gfs2_quota_refresh(struct gfs2_sbd *sdp, int user, u32 id);
 
 extern int gfs2_quota_init(struct gfs2_sbd *sdp);

fs/gfs2/super.c

@@ -838,7 +838,7 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 	int error;
 
 	flush_workqueue(gfs2_delete_workqueue);
-	gfs2_quota_sync(sdp->sd_vfs, 0, 1);
+	gfs2_quota_sync(sdp->sd_vfs, 0);
 	gfs2_statfs_sync(sdp->sd_vfs, 0);
 
 	error = gfs2_glock_nq_init(sdp->sd_trans_gl, LM_ST_SHARED, GL_NOCACHE,

fs/gfs2/sys.c

@@ -168,7 +168,7 @@ static ssize_t quota_sync_store(struct gfs2_sbd *sdp, const char *buf,
 	if (simple_strtol(buf, NULL, 0) != 1)
 		return -EINVAL;
 
-	gfs2_quota_sync(sdp->sd_vfs, 0, 1);
+	gfs2_quota_sync(sdp->sd_vfs, 0);
 	return len;
 }
 

fs/quota/dquot.c

@@ -595,12 +595,14 @@ int dquot_scan_active(struct super_block *sb,
 }
 EXPORT_SYMBOL(dquot_scan_active);
 
-int dquot_quota_sync(struct super_block *sb, int type, int wait)
+/* Write all dquot structures to quota files */
+int dquot_writeback_dquots(struct super_block *sb, int type)
 {
 	struct list_head *dirty;
 	struct dquot *dquot;
 	struct quota_info *dqopt = sb_dqopt(sb);
 	int cnt;
+	int err, ret = 0;
 
 	mutex_lock(&dqopt->dqonoff_mutex);
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
@@ -624,7 +626,9 @@ int dquot_quota_sync(struct super_block *sb, int type, int wait)
 			atomic_inc(&dquot->dq_count);
 			spin_unlock(&dq_list_lock);
 			dqstats_inc(DQST_LOOKUPS);
-			sb->dq_op->write_dquot(dquot);
+			err = sb->dq_op->write_dquot(dquot);
+			if (!ret && err)
+				err = ret;
 			dqput(dquot);
 			spin_lock(&dq_list_lock);
 		}
@@ -638,7 +642,21 @@ int dquot_quota_sync(struct super_block *sb, int type, int wait)
 	dqstats_inc(DQST_SYNCS);
 	mutex_unlock(&dqopt->dqonoff_mutex);
 
-	if (!wait || (dqopt->flags & DQUOT_QUOTA_SYS_FILE))
+	return ret;
+}
+EXPORT_SYMBOL(dquot_writeback_dquots);
+
+/* Write all dquot structures to disk and make them visible from userspace */
+int dquot_quota_sync(struct super_block *sb, int type)
+{
+	struct quota_info *dqopt = sb_dqopt(sb);
+	int cnt;
+	int ret;
+
+	ret = dquot_writeback_dquots(sb, type);
+	if (ret)
+		return ret;
+	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
 		return 0;
 
 	/* This is not very clever (and fast) but currently I don't know about

fs/quota/quota.c

@@ -47,7 +47,7 @@ static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
 static void quota_sync_one(struct super_block *sb, void *arg)
 {
 	if (sb->s_qcop && sb->s_qcop->quota_sync)
-		sb->s_qcop->quota_sync(sb, *(int *)arg, 1);
+		sb->s_qcop->quota_sync(sb, *(int *)arg);
 }
 
 static int quota_sync_all(int type)
@@ -270,7 +270,7 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
 	case Q_SYNC:
 		if (!sb->s_qcop->quota_sync)
 			return -ENOSYS;
-		return sb->s_qcop->quota_sync(sb, type, 1);
+		return sb->s_qcop->quota_sync(sb, type);
 	case Q_XQUOTAON:
 	case Q_XQUOTAOFF:
 	case Q_XQUOTARM:

fs/sync.c

@@ -30,7 +30,7 @@
 static int __sync_filesystem(struct super_block *sb, int wait)
 {
 	if (sb->s_qcop && sb->s_qcop->quota_sync)
-		sb->s_qcop->quota_sync(sb, -1, wait);
+		sb->s_qcop->quota_sync(sb, -1);
 
 	if (wait)
 		sync_inodes_sb(sb);

include/linux/quota.h

@@ -333,7 +333,7 @@ struct quotactl_ops {
 	int (*quota_on)(struct super_block *, int, int, struct path *);
 	int (*quota_on_meta)(struct super_block *, int, int);
 	int (*quota_off)(struct super_block *, int);
-	int (*quota_sync)(struct super_block *, int, int);
+	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 *, int, qid_t, struct fs_disk_quota *);

include/linux/quotaops.h

@@ -83,7 +83,8 @@ int dquot_quota_on(struct super_block *sb, int type, int format_id,
 int dquot_quota_on_mount(struct super_block *sb, char *qf_name,
  	int format_id, int type);
 int dquot_quota_off(struct super_block *sb, int type);
-int dquot_quota_sync(struct super_block *sb, int type, int wait);
+int dquot_writeback_dquots(struct super_block *sb, int type);
+int dquot_quota_sync(struct super_block *sb, int type);
 int dquot_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
 int dquot_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
 int dquot_get_dqblk(struct super_block *sb, int type, qid_t id,
@@ -255,6 +256,11 @@ static inline int dquot_resume(struct super_block *sb, int type)
 
 #define dquot_file_open		generic_file_open
 
+static inline int dquot_writeback_dquots(struct super_block *sb, int type)
+{
+	return 0;
+}
+
 #endif /* CONFIG_QUOTA */
 
 static inline int dquot_alloc_space_nodirty(struct inode *inode, qsize_t nr)