linux-kernel - [PATCH 4/4] NFSv4: Fix fscache cookie aux_data to ensure change

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Message-ID: <158897468722.1116213.9964942101141957205.stgit@warthog.procyon.org.uk>
Date:   Fri, 08 May 2020 22:51:27 +0100
From:   David Howells <dhowells@...hat.com>
To:     torvalds@...ux-foundation.org,
        Trond Myklebust <trond.myklebust@...merspace.com>
Cc:     Dave Wysochanski <dwysocha@...hat.com>, dhowells@...hat.com,
        Anna Schumaker <anna.schumaker@...app.com>,
        linux-nfs@...r.kernel.org, linux-cachefs@...hat.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] NFSv4: Fix fscache cookie aux_data to ensure change_attr
 is included

From: Dave Wysochanski <dwysocha@...hat.com>

Commit 402cb8dda949 ("fscache: Attach the index key and aux data to
the cookie") added the aux_data and aux_data_len to parameters to
fscache_acquire_cookie(), and updated the callers in the NFS client.
In the process it modified the aux_data to include the change_attr,
but missed adding change_attr to a couple places where aux_data was
used.  Specifically, when opening a file and the change_attr is not
added, the following attempt to lookup an object will fail inside
cachefiles_check_object_xattr() = -116 due to
nfs_fscache_inode_check_aux() failing memcmp on auxdata and returning
FSCACHE_CHECKAUX_OBSOLETE.

Fix this by adding nfs_fscache_update_auxdata() to set the auxdata
from all relevant fields in the inode, including the change_attr.

Fixes: 402cb8dda949 ("fscache: Attach the index key and aux data to the cookie")
Signed-off-by: Dave Wysochanski <dwysocha@...hat.com>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/nfs/fscache.c |   34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index f51718415606..a60df88efc40 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -225,6 +225,19 @@ void nfs_fscache_release_super_cookie(struct super_block *sb)
 	}
 }
 
+static void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
+				  struct nfs_inode *nfsi)
+{
+	memset(auxdata, 0, sizeof(*auxdata));
+	auxdata->mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata->mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata->ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata->ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
+
+	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
+		auxdata->change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
+}
+
 /*
  * Initialise the per-inode cache cookie pointer for an NFS inode.
  */
@@ -238,14 +251,7 @@ void nfs_fscache_init_inode(struct inode *inode)
 	if (!(nfss->fscache && S_ISREG(inode->i_mode)))
 		return;
 
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
-	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
-	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
-
-	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
-		auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
+	nfs_fscache_update_auxdata(&auxdata, nfsi);
 
 	nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
 					       &nfs_fscache_inode_object_def,
@@ -265,11 +271,7 @@ void nfs_fscache_clear_inode(struct inode *inode)
 
 	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
-	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
-	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
+	nfs_fscache_update_auxdata(&auxdata, nfsi);
 	fscache_relinquish_cookie(cookie, &auxdata, false);
 	nfsi->fscache = NULL;
 }
@@ -309,11 +311,7 @@ void nfs_fscache_open_file(struct inode *inode, struct file *filp)
 	if (!fscache_cookie_valid(cookie))
 		return;
 
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
-	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
-	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
+	nfs_fscache_update_auxdata(&auxdata, nfsi);
 
 	if (inode_is_open_for_write(inode)) {
 		dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);