2023-08-10 15:13:46

by Miklos Szeredi

Subject: Re: Subject: [PATCH] nlookup missing decrement in fuse_direntplus_link

On Thu, 10 Aug 2023 at 05:25, <[email protected]> wrote:
>
>
> From 53aad83672123dbe01bcef9f9026becc4e93ee9f Mon Sep 17 00:00:00 2001
>
> From: ruanmeisi <[email protected]>
>
> Date: Tue, 25 Apr 2023 19:13:54 +0800
>
> Subject: [PATCH] nlookup missing decrement in fuse_direntplus_link
>
>
> During our debugging of glusterfs, we found an Assertion
>
> failed error: inode_lookup >= nlookup, which was caused by the
>
> nlookup value in the kernel being greater than that in the FUSE
>
> file system.The issue was introduced by fuse_direntplus_link,
>
> where in the function, fuse_iget increments nlookup, and if
>
> d_splice_alias returns failure, fuse_direntplus_link returns
>
> failure without decrementing nlookup
>
> https://github.com/gluster/glusterfs/pull/4081
>
>
> Signed-off-by: ruanmeisi <[email protected]>

Thanks. Patch looks good.

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Thanks,
Miklos

2023-08-11 07:29:47

by ruan.meisi

Subject:  [PATCH] nlookup missing decrement in fuse_direntplus_link

From 53aad83672123dbe01bcef9f9026becc4e93ee9f Mon Sep 17 00:00:00 2001
From: ruanmeisi <[email protected]>
Date: Tue, 25 Apr 2023 19:13:54 +0800
Subject: [PATCH] nlookup missing decrement in fuse_direntplus_link

During our debugging of glusterfs, we found an Assertion
failed error: inode_lookup >= nlookup, which was caused by the
nlookup value in the kernel being greater than that in the FUSE
file system.The issue was introduced by fuse_direntplus_link,
where in the function, fuse_iget increments nlookup, and if
d_splice_alias returns failure, fuse_direntplus_link returns
failure without decrementing nlookup
https://github.com/gluster/glusterfs/pull/4081

Signed-off-by: ruanmeisi <[email protected]>
---
fs/fuse/readdir.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
index dc603479b30e..b3d498163f97 100644
--- a/fs/fuse/readdir.c
+++ b/fs/fuse/readdir.c
@@ -243,8 +243,16 @@ static int fuse_direntplus_link(struct file *file,
dput(dentry);
dentry = alias;
}
- if (IS_ERR(dentry))
+ if (IS_ERR(dentry)) {
+ if (!IS_ERR(inode)) {
+ struct fuse_inode *fi = get_fuse_inode(inode);
+
+ spin_lock(&fi->lock);
+ fi->nlookup--;
+ spin_unlock(&fi->lock);
+ }
return PTR_ERR(dentry);
+ }
}
if (fc->readdirplus_auto)
set_bit(FUSE_I_INIT_RDPLUS, &get_fuse_inode(inode)->state);
--
2.27.0