fs/9p: Add p9_debug(VFS) in d_revalidate

This was a useful debugging / validation aid, and can explain why a
GETATTR request is made.

Signed-off-by: Tingmao Wang <[email protected]>
Message-ID: <00829a99549e33d26139fa4d756c466629f13e00.1743956147.git.m@maowtm.org>
Signed-off-by: Dominique Martinet <[email protected]>

Author: micromaomao

fs/9p/vfs_dentry.c

@@ -85,8 +85,13 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 		struct v9fs_session_info *v9ses;
 
 		fid = v9fs_fid_lookup(dentry);
-		if (IS_ERR(fid))
+		if (IS_ERR(fid)) {
+			p9_debug(
+				P9_DEBUG_VFS,
+				"v9fs_fid_lookup: dentry = %pd (%p), got error %pe\n",
+				dentry, dentry, fid);
 			return PTR_ERR(fid);
+		}
 
 		v9ses = v9fs_inode2v9ses(inode);
 		if (v9fs_proto_dotl(v9ses))
@@ -95,14 +100,25 @@ static int __v9fs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 			retval = v9fs_refresh_inode(fid, inode);
 		p9_fid_put(fid);
 
-		if (retval == -ENOENT)
+		if (retval == -ENOENT) {
+			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to ENOENT\n",
+				 dentry, dentry);
 			return 0;
-		if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR)
+		}
+		if (v9inode->cache_validity & V9FS_INO_INVALID_ATTR) {
+			p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) invalidated due to type change\n",
+				 dentry, dentry);
 			return 0;
-		if (retval < 0)
+		}
+		if (retval < 0) {
+			p9_debug(P9_DEBUG_VFS,
+				"refresh inode: dentry = %pd (%p), got error %pe\n",
+				dentry, dentry, ERR_PTR(retval));
 			return retval;
+		}
 	}
 out_valid:
+	p9_debug(P9_DEBUG_VFS, "dentry: %pd (%p) is valid\n", dentry, dentry);
 	return 1;
 }