ceph: quota: add counter for snaprealms with quota

By keeping a counter with the number of snaprealms that have quota set
allows to optimize the functions that need to walk throught the realms
hierarchy looking for quotas.  Thus, if this counter is zero it's safe to
assume that there are no realms with quota.
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/inode.c

@@ -539,6 +539,9 @@ void ceph_destroy_inode(struct inode *inode)
 
 	ceph_queue_caps_release(inode);
 
+	if (__ceph_has_any_quota(ci))
+		ceph_adjust_quota_realms_count(inode, false);
+
 	/*
 	 * we may still have a snap_realm reference if there are stray
 	 * caps in i_snap_caps.
@@ -796,8 +799,7 @@ static int fill_inode(struct inode *inode, struct page *locked_page,
 	inode->i_rdev = le32_to_cpu(info->rdev);
 	inode->i_blkbits = fls(le32_to_cpu(info->layout.fl_stripe_unit)) - 1;
 
-	ci->i_max_bytes = iinfo->max_bytes;
-	ci->i_max_files = iinfo->max_files;
+	__ceph_update_quota(ci, iinfo->max_bytes, iinfo->max_files);
 
 	if ((new_version || (new_issued & CEPH_CAP_AUTH_SHARED)) &&
 	    (issued & CEPH_CAP_AUTH_EXCL) == 0) {

fs/ceph/mds_client.c

@@ -3609,6 +3609,7 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
 	atomic_set(&mdsc->num_sessions, 0);
 	mdsc->max_sessions = 0;
 	mdsc->stopping = 0;
+	atomic64_set(&mdsc->quotarealms_count, 0);
 	mdsc->last_snap_seq = 0;
 	init_rwsem(&mdsc->snap_rwsem);
 	mdsc->snap_realms = RB_ROOT;

fs/ceph/mds_client.h

@@ -314,6 +314,8 @@ struct ceph_mds_client {
 	int                     max_sessions;  /* len of s_mds_sessions */
 	int                     stopping;      /* true if shutting down */
 
+	atomic64_t		quotarealms_count; /* # realms with quota */
+
 	/*
 	 * snap_rwsem will cover cap linkage into snaprealms, and
 	 * realm snap contexts.  (later, we can do per-realm snap

fs/ceph/quota.c

@@ -21,9 +21,19 @@
 #include "super.h"
 #include "mds_client.h"
 
-static inline bool ceph_has_quota(struct ceph_inode_info *ci)
+void ceph_adjust_quota_realms_count(struct inode *inode, bool inc)
 {
-	return (ci && (ci->i_max_files || ci->i_max_bytes));
+	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
+	if (inc)
+		atomic64_inc(&mdsc->quotarealms_count);
+	else
+		atomic64_dec(&mdsc->quotarealms_count);
+}
+
+static inline bool ceph_has_realms_with_quotas(struct inode *inode)
+{
+	struct ceph_mds_client *mdsc = ceph_inode_to_client(inode)->mdsc;
+	return atomic64_read(&mdsc->quotarealms_count) > 0;
 }
 
 void ceph_handle_quota(struct ceph_mds_client *mdsc,
@@ -62,8 +72,8 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc,
 	ci->i_rbytes = le64_to_cpu(h->rbytes);
 	ci->i_rfiles = le64_to_cpu(h->rfiles);
 	ci->i_rsubdirs = le64_to_cpu(h->rsubdirs);
-	ci->i_max_bytes = le64_to_cpu(h->max_bytes);
-	ci->i_max_files = le64_to_cpu(h->max_files);
+	__ceph_update_quota(ci, le64_to_cpu(h->max_bytes),
+		            le64_to_cpu(h->max_files));
 	spin_unlock(&ci->i_ceph_lock);
 
 	iput(inode);
@@ -103,7 +113,7 @@ static struct ceph_snap_realm *get_quota_realm(struct ceph_mds_client *mdsc,
 			break;
 
 		ci = ceph_inode(in);
-		has_quota = ceph_has_quota(ci);
+		has_quota = __ceph_has_any_quota(ci);
 		iput(in);
 
 		next = realm->parent;
@@ -241,6 +251,9 @@ static bool check_quota_exceeded(struct inode *inode, enum quota_check_op op,
  */
 bool ceph_quota_is_max_files_exceeded(struct inode *inode)
 {
+	if (!ceph_has_realms_with_quotas(inode))
+		return false;
+
 	WARN_ON(!S_ISDIR(inode->i_mode));
 
 	return check_quota_exceeded(inode, QUOTA_CHECK_MAX_FILES_OP, 0);
@@ -258,6 +271,9 @@ bool ceph_quota_is_max_bytes_exceeded(struct inode *inode, loff_t newsize)
 {
 	loff_t size = i_size_read(inode);
 
+	if (!ceph_has_realms_with_quotas(inode))
+		return false;
+
 	/* return immediately if we're decreasing file size */
 	if (newsize <= size)
 		return false;
@@ -277,6 +293,9 @@ bool ceph_quota_is_max_bytes_approaching(struct inode *inode, loff_t newsize)
 {
 	loff_t size = ceph_inode(inode)->i_reported_size;
 
+	if (!ceph_has_realms_with_quotas(inode))
+		return false;
+
 	/* return immediately if we're decreasing file size */
 	if (newsize <= size)
 		return false;

fs/ceph/super.h

@@ -1075,6 +1075,26 @@ extern int ceph_fs_debugfs_init(struct ceph_fs_client *client);
 extern void ceph_fs_debugfs_cleanup(struct ceph_fs_client *client);
 
 /* quota.c */
+static inline bool __ceph_has_any_quota(struct ceph_inode_info *ci)
+{
+	return ci->i_max_files || ci->i_max_bytes;
+}
+
+extern void ceph_adjust_quota_realms_count(struct inode *inode, bool inc);
+
+static inline void __ceph_update_quota(struct ceph_inode_info *ci,
+				       u64 max_bytes, u64 max_files)
+{
+	bool had_quota, has_quota;
+	had_quota = __ceph_has_any_quota(ci);
+	ci->i_max_bytes = max_bytes;
+	ci->i_max_files = max_files;
+	has_quota = __ceph_has_any_quota(ci);
+
+	if (had_quota != has_quota)
+		ceph_adjust_quota_realms_count(&ci->vfs_inode, has_quota);
+}
+
 extern void ceph_handle_quota(struct ceph_mds_client *mdsc,
 			      struct ceph_mds_session *session,
 			      struct ceph_msg *msg);