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path: root/fs/nfs/nfs3acl.c
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Diffstat (limited to 'fs/nfs/nfs3acl.c')
-rw-r--r--fs/nfs/nfs3acl.c43
1 files changed, 41 insertions, 2 deletions
diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index 17c0fa1eccfa..720d92f5abfb 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -11,6 +11,38 @@
#define NFSDBG_FACILITY NFSDBG_PROC
+/*
+ * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
+ * caching get_acl results in a race-free way. See fs/posix_acl.c:get_acl()
+ * for explanations.
+ */
+static void nfs3_prepare_get_acl(struct posix_acl **p)
+{
+ struct posix_acl *sentinel = uncached_acl_sentinel(current);
+
+ if (cmpxchg(p, ACL_NOT_CACHED, sentinel) != ACL_NOT_CACHED) {
+ /* Not the first reader or sentinel already in place. */
+ }
+}
+
+static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
+{
+ struct posix_acl *sentinel = uncached_acl_sentinel(current);
+
+ /* Only cache the ACL if our sentinel is still in place. */
+ posix_acl_dup(acl);
+ if (cmpxchg(p, sentinel, acl) != sentinel)
+ posix_acl_release(acl);
+}
+
+static void nfs3_abort_get_acl(struct posix_acl **p)
+{
+ struct posix_acl *sentinel = uncached_acl_sentinel(current);
+
+ /* Remove our sentinel upon failure. */
+ cmpxchg(p, sentinel, ACL_NOT_CACHED);
+}
+
struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
{
struct nfs_server *server = NFS_SERVER(inode);
@@ -55,6 +87,11 @@ struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
if (res.fattr == NULL)
return ERR_PTR(-ENOMEM);
+ if (args.mask & NFS_ACL)
+ nfs3_prepare_get_acl(&inode->i_acl);
+ if (args.mask & NFS_DFACL)
+ nfs3_prepare_get_acl(&inode->i_default_acl);
+
status = rpc_call_sync(server->client_acl, &msg, 0);
dprintk("NFS reply getacl: %d\n", status);
@@ -89,12 +126,12 @@ struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
}
if (res.mask & NFS_ACL)
- set_cached_acl(inode, ACL_TYPE_ACCESS, res.acl_access);
+ nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
else
forget_cached_acl(inode, ACL_TYPE_ACCESS);
if (res.mask & NFS_DFACL)
- set_cached_acl(inode, ACL_TYPE_DEFAULT, res.acl_default);
+ nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
else
forget_cached_acl(inode, ACL_TYPE_DEFAULT);
@@ -108,6 +145,8 @@ struct posix_acl *nfs3_get_acl(struct inode *inode, int type)
}
getout:
+ nfs3_abort_get_acl(&inode->i_acl);
+ nfs3_abort_get_acl(&inode->i_default_acl);
posix_acl_release(res.acl_access);
posix_acl_release(res.acl_default);
nfs_free_fattr(res.fattr);