[PATCH 01/26] cifs: Fix duplicate fscache cookie warnings

David Howells
2024-03-28T16:34:49Z

fscache emits a lot of duplicate cookie warnings with cifs because the
index key for the fscache cookies does not include everything that the
cifs_find_inode() function does. The latter is used with iget5_locked() to
distinguish between inodes in the local inode cache.

Fix this by adding the creation time and file type to the fscache cookie
key.

Additionally, add a couple of comments to note that if one is changed the
other must be also.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
fs/smb/client/fscache.c | 16 +++++++++++++++-
fs/smb/client/inode.c | 2 ++
2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/fscache.c b/fs/smb/client/fscache.c
index c4a3cb736881..340efce8f052 100644
--- a/fs/smb/client/fscache.c
+++ b/fs/smb/client/fscache.c
@@ -12,6 +12,16 @@
#include "cifs_fs_sb.h"
#include "cifsproto.h"

+/*
+ * Key for fscache inode. [!] Contents must match comparisons in cifs_find_inode().
+ */
+struct cifs_fscache_inode_key {
+
+ __le64 uniqueid; /* server inode number */
+ __le64 createtime; /* creation time on server */
+ u8 type; /* S_IFMT file type */
+} __packed;
+
static void cifs_fscache_fill_volume_coherency(
struct cifs_tcon *tcon,
struct cifs_fscache_volume_coherency_data *cd)
@@ -97,15 +107,19 @@ void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
void cifs_fscache_get_inode_cookie(struct inode *inode)
{
struct cifs_fscache_inode_coherency_data cd;
+ struct cifs_fscache_inode_key key;
struct cifsInodeInfo *cifsi = CIFS_I(inode);
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);

+ key.uniqueid = cpu_to_le64(cifsi->uniqueid);
+ key.createtime = cpu_to_le64(cifsi->createtime);
+ key.type = (inode->i_mode & S_IFMT) >> 12;
cifs_fscache_fill_coherency(&cifsi->netfs.inode, &cd);

cifsi->netfs.cache =
fscache_acquire_cookie(tcon->fscache, 0,
- &cifsi->uniqueid, sizeof(cifsi->uniqueid),
+ &key, sizeof(key),
&cd, sizeof(cd),
i_size_read(&cifsi->netfs.inode));
if (cifsi->netfs.cache)
diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index d28ab0af6049..91b07ef9e25c 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -1351,6 +1351,8 @@ cifs_find_inode(struct inode *inode, void *opaque)
{
struct cifs_fattr *fattr = opaque;

+ /* [!] The compared values must be the same in struct cifs_fscache_inode_key. */
+
/* don't match inode with different uniqueid */
if (CIFS_I(inode)->uniqueid != fattr->cf_uniqueid)
return 0;