[PATCH 5.15 048/177] ceph: fix duplicate increment of opened_inodes metric

Greg Kroah-Hartman
2021-12-20T14:56:24Z

From: Hu Weiwen <sehuww@mail.scut.edu.cn>

[ Upstream commit 973e5245637accc4002843f6b888495a6a7762bc ]

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@mail.scut.edu.cn>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 8f537f1d9d1d3..8be4da2e2b826 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -4349,7 +4349,7 @@ 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)
@@ -4357,19 +4357,19 @@ 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);
}
--
2.33.0