ceph: metrics for opened files, pinned caps and opened inodes

In client for each inode, it may have many opened files and may
have been pinned in more than one MDS servers. And some inodes
are idle, which have no any opened files.

This patch will show these metrics in the debugfs, likes:

item                               total
-----------------------------------------
opened files  / total inodes       14 / 5
pinned i_caps / total inodes       7  / 5
opened inodes / total inodes       3  / 5

Will send these metrics to ceph, which will be used by the `fs top`,
later.

[ jlayton: drop unrelated hunk, count hashed inodes instead of
           allocated ones ]

URL: https://tracker.ceph.com/issues/47005
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 36 insertions, 2 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 39753e0e0e5a..c7e69547628e 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -4283,13 +4283,30 @@ void __ceph_touch_fmode(struct ceph_inode_info *ci,
 
 void ceph_get_fmode(struct ceph_inode_info *ci, int fmode, int count)
 {
-	int i;
+	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->vfs_inode.i_sb);
 	int bits = (fmode << 1) | 1;
+	bool is_opened = false;
+	int i;
+
+	if (count == 1)
+		atomic64_inc(&mdsc->metric.opened_files);
+
 	spin_lock(&ci->i_ceph_lock);
 	for (i = 0; i < CEPH_FILE_MODE_BITS; i++) {
 		if (bits & (1 << i))
 			ci->i_nr_by_mode[i] += count;
+
+		/*
+		 * If any of the mode ref is larger than 1,
+		 * that means it has been already opened by
+		 * others. Just skip checking the PIN ref.
+		 */
+		if (i && ci->i_nr_by_mode[i] > 1)
+			is_opened = true;
 	}
+
+	if (!is_opened)
+		percpu_counter_inc(&mdsc->metric.opened_inodes);
 	spin_unlock(&ci->i_ceph_lock);
 }
 
@@ -4300,15 +4317,32 @@ void ceph_get_fmode(struct ceph_inode_info *ci, int fmode, int count)
  */
 void ceph_put_fmode(struct ceph_inode_info *ci, int fmode, int count)
 {
-	int i;
+	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->vfs_inode.i_sb);
 	int bits = (fmode << 1) | 1;
+	bool is_closed = true;
+	int i;
+
+	if (count == 1)
+		atomic64_dec(&mdsc->metric.opened_files);
+
 	spin_lock(&ci->i_ceph_lock);
 	for (i = 0; i < CEPH_FILE_MODE_BITS; i++) {
 		if (bits & (1 << i)) {
 			BUG_ON(ci->i_nr_by_mode[i] < count);
 			ci->i_nr_by_mode[i] -= count;
 		}
+
+		/*
+		 * If any of the mode ref is not 0 after
+		 * decreased, that means it is still opened
+		 * by others. Just skip checking the PIN ref.
+		 */
+		if (i && ci->i_nr_by_mode[i])
+			is_closed = false;
 	}
+
+	if (is_closed)
+		percpu_counter_dec(&mdsc->metric.opened_inodes);
 	spin_unlock(&ci->i_ceph_lock);
 }