Re: [PATCH] ceph: fix duplicate increment of opened_inodes metric

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On 11/22/21 10:22 PM, Hu Weiwen wrote:
opened_inodes is incremented twice when the same inode is opened twice
with O_RDONLY and O_WRONLY respectively.

To reproduce, run this python script, then check the metrics:

import os
for _ in range(10000):
     fd_r = os.open('a', os.O_RDONLY)
     fd_w = os.open('a', os.O_WRONLY)
     os.close(fd_r)
     os.close(fd_w)

Fixes: 1dd8d4708136 ("ceph: metrics for opened files, pinned caps and opened inodes")
Signed-off-by: Hu Weiwen <sehuww@xxxxxxxxxxxxxxxx>
---
  fs/ceph/caps.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index b9460b6fb76f..c447fa2e2d1f 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -4350,7 +4350,7 @@ void ceph_get_fmode(struct ceph_inode_info *ci, int fmode, int count)
  {
  	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(ci->vfs_inode.i_sb);
  	int bits = (fmode << 1) | 1;
-	bool is_opened = false;
+	bool already_opened = false;
  	int i;
if (count == 1)
@@ -4358,19 +4358,19 @@ void ceph_get_fmode(struct ceph_inode_info *ci, int fmode, int count)
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,
+		 * If any of the mode ref is larger than 0,
  		 * 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 (i && ci->i_nr_by_mode[i])
+			already_opened = true;
+
+		if (bits & (1 << i))
+			ci->i_nr_by_mode[i] += count;
  	}
- if (!is_opened)
+	if (!already_opened)
  		percpu_counter_inc(&mdsc->metric.opened_inodes);
  	spin_unlock(&ci->i_ceph_lock);
  }

LGTM.

Reviewed-by: Xiubo Li <xiubli@xxxxxxxxxx>






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