fs: add get_acl helper

Factor out the code to get an ACL either from the inode or disk from
check_acl, so that it can be used elsewhere later on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 27 insertions, 0 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 359d70b0e947..30524de49a6b 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -26,6 +26,33 @@ EXPORT_SYMBOL(posix_acl_valid);
 EXPORT_SYMBOL(posix_acl_equiv_mode);
 EXPORT_SYMBOL(posix_acl_from_mode);
 
+struct posix_acl *get_acl(struct inode *inode, int type)
+{
+	struct posix_acl *acl;
+
+	acl = get_cached_acl(inode, type);
+	if (acl != ACL_NOT_CACHED)
+		return acl;
+
+	if (!IS_POSIXACL(inode))
+		return NULL;
+
+	/*
+	 * A filesystem can force a ACL callback by just never filling the
+	 * ACL cache. But normally you'd fill the cache either at inode
+	 * instantiation time, or on the first ->get_acl call.
+	 *
+	 * If the filesystem doesn't have a get_acl() function at all, we'll
+	 * just create the negative cache entry.
+	 */
+	if (!inode->i_op->get_acl) {
+		set_cached_acl(inode, type, NULL);
+		return NULL;
+	}
+	return inode->i_op->get_acl(inode, type);
+}
+EXPORT_SYMBOL(get_acl);
+
 /*
  * Init a fresh posix_acl
  */