linux-kernel - [PATCH v2] 9p: v9fs_fid_find: also lookup by inode if not found dentry

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Date: Fri, 24 May 2024 06:00:23 +0900
From: Dominique Martinet <asmadeus@...ewreck.org>
To: Eric Van Hensbergen <ericvh@...nel.org>,
	Latchesar Ionkov <lucho@...kov.net>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Christian Schoenebeck <linux_oss@...debyte.com>
Cc: v9fs@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2] 9p: v9fs_fid_find: also lookup by inode if not found dentry

It's possible for v9fs_fid_find "find by dentry" branch to not turn up
anything despite having an entry set (because e.g. uid doesn't match),
in which case the calling code will generally make an extra lookup
to the server.

In this case we might have had better luck looking by inode, so fall
back to look up by inode if we have one and the lookup by dentry failed.

Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
---
v1 -> v2: fix build error

Sorry, shouldn't send patches without testing even if I'm not planning
to apply them for a while...

 fs/9p/fid.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/9p/fid.c b/fs/9p/fid.c
index de009a33e0e2..f84412290a30 100644
--- a/fs/9p/fid.c
+++ b/fs/9p/fid.c
@@ -131,10 +131,9 @@ static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
 			}
 		}
 		spin_unlock(&dentry->d_lock);
-	} else {
-		if (dentry->d_inode)
-			ret = v9fs_fid_find_inode(dentry->d_inode, false, uid, any);
 	}
+	if (!ret && dentry->d_inode)
+		ret = v9fs_fid_find_inode(dentry->d_inode, false, uid, any);

 	return ret;
 }
-- 
2.44.0