Commit 029085b8 authored by Chengen Du's avatar Chengen Du Committed by Trond Myklebust
Browse files

NFS: Judge the file access cache's timestamp in rcu path 



If the user's login time is newer than the cache's timestamp,
we expect the cache may be stale and need to clear.
The stale cache will remain in the list's tail if no other
users operate on that inode.
Once the user accesses the inode, the stale cache will be
returned in rcu path.

Signed-off-by: default avatarChengen Du <chengen.du@canonical.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent a6b9d2fa

fs/nfs/dir.c

+3 −0
Original line number Diff line number Diff line
@@ -3023,6 +3023,7 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre 
	 * but do it without locking.

	 */

	struct nfs_inode *nfsi = NFS_I(inode);

	u64 login_time = nfs_access_login_time(current, cred);

	struct nfs_access_entry *cache;

	int err = -ECHILD;

	struct list_head *lh;
@@ -3037,6 +3038,8 @@ static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cre 
		cache = NULL;

	if (cache == NULL)

		goto out;

	if ((s64)(login_time - cache->timestamp) > 0)

		goto out;

	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))

		goto out;

	*mask = cache->mask;