Re: [PATCH] smb3: extend fscache mount volume coherency check

[Steve French <smfrench@gmail.com>]

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slightly updated to fix a sparse endian warning


On Fri, Jun 5, 2020 at 5:24 PM Steve French <smfrench@gmail.com> wrote:
>
> It is better to check volume id and creation time, not just
> the root inode number to verify if the volume has changed
> when remounting.
>
> Reviewed-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Steve French <stfrench@microsoft.com>
>
>
> --
> Thanks,
>
> Steve



-- 
Thanks,

Steve

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From 5865985416ebb5a0c198a819a098b5cc300ac8a4 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Fri, 5 Jun 2020 17:19:46 -0500
Subject: [PATCH] smb3: extend fscache mount volume coherency check

It is better to check volume id and creation time, not just
the root inode number to verify if the volume has changed
when remounting.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cache.c   |  9 ++-------
 fs/cifs/fscache.c | 17 +++++++++++++++--
 fs/cifs/fscache.h |  9 +++++++++
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/fs/cifs/cache.c b/fs/cifs/cache.c
index b7420e605b28..0f2adecb94f2 100644
--- a/fs/cifs/cache.c
+++ b/fs/cifs/cache.c
@@ -53,13 +53,6 @@ const struct fscache_cookie_def cifs_fscache_server_index_def = {
 	.type = FSCACHE_COOKIE_TYPE_INDEX,
 };
 
-/*
- * Auxiliary data attached to CIFS superblock within the cache
- */
-struct cifs_fscache_super_auxdata {
-	u64	resource_id;		/* unique server resource id */
-};
-
 char *extract_sharename(const char *treename)
 {
 	const char *src;
@@ -98,6 +91,8 @@ fscache_checkaux cifs_fscache_super_check_aux(void *cookie_netfs_data,
 
 	memset(&auxdata, 0, sizeof(auxdata));
 	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
 
 	if (memcmp(data, &auxdata, datalen) != 0)
 		return FSCACHE_CHECKAUX_OBSOLETE;
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index ea6ace9c2417..da688185403c 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -96,6 +96,7 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 {
 	struct TCP_Server_Info *server = tcon->ses->server;
 	char *sharename;
+	struct cifs_fscache_super_auxdata auxdata;
 
 	sharename = extract_sharename(tcon->treeName);
 	if (IS_ERR(sharename)) {
@@ -104,11 +105,16 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 		return;
 	}
 
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
+
 	tcon->fscache =
 		fscache_acquire_cookie(server->fscache,
 				       &cifs_fscache_super_index_def,
 				       sharename, strlen(sharename),
-				       &tcon->resource_id, sizeof(tcon->resource_id),
+				       &auxdata, sizeof(auxdata),
 				       tcon, 0, true);
 	kfree(sharename);
 	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
@@ -117,8 +123,15 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 
 void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
 {
+	struct cifs_fscache_super_auxdata auxdata;
+
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
+
 	cifs_dbg(FYI, "%s: (0x%p)\n", __func__, tcon->fscache);
-	fscache_relinquish_cookie(tcon->fscache, &tcon->resource_id, false);
+	fscache_relinquish_cookie(tcon->fscache, &auxdata, false);
 	tcon->fscache = NULL;
 }
 
diff --git a/fs/cifs/fscache.h b/fs/cifs/fscache.h
index 8c0862e41306..1091633d2adb 100644
--- a/fs/cifs/fscache.h
+++ b/fs/cifs/fscache.h
@@ -27,6 +27,15 @@
 
 #ifdef CONFIG_CIFS_FSCACHE
 
+/*
+ * Auxiliary data attached to CIFS superblock within the cache
+ */
+struct cifs_fscache_super_auxdata {
+	u64	resource_id;		/* unique server resource id */
+	__le64	vol_create_time;
+	u32	vol_serial_number;
+} __packed;
+
 /*
  * Auxiliary data attached to CIFS inode within the cache
  */
-- 
2.25.1