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authorMiklos Szeredi <mszeredi@redhat.com>2021-08-18 22:08:24 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2021-08-18 22:08:24 +0200
commit332f606b32b6291a944c8cf23b91f53a6e676525 (patch)
treec3a46cae0901eec40dd900a9a64c8ad1e51647ba /fs/overlayfs
parent0cad6246621b5887d5b33fea84219d2a71f2f99a (diff)
downloadlinux-332f606b32b6291a944c8cf23b91f53a6e676525.tar.bz2
ovl: enable RCU'd ->get_acl()
Overlayfs does not cache ACL's (to avoid double caching). Instead it just calls the underlying filesystem's i_op->get_acl(), which will return the cached value, if possible. In rcu path walk, however, get_cached_acl_rcu() is employed to get the value from the cache, which will fail on overlayfs resulting in dropping out of rcu walk mode. This can result in a big performance hit in certain situations. Fix by calling ->get_acl() with rcu=true in case of ACL_DONT_CACHE (which indicates pass-through) Reported-by: garyhuang <zjh.20052005@163.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs')
-rw-r--r--fs/overlayfs/inode.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index ea335d3e55cf..832b17589733 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -13,6 +13,7 @@
#include <linux/fiemap.h>
#include <linux/fileattr.h>
#include <linux/security.h>
+#include <linux/namei.h>
#include "overlayfs.h"
@@ -452,12 +453,12 @@ struct posix_acl *ovl_get_acl(struct inode *inode, int type, bool rcu)
const struct cred *old_cred;
struct posix_acl *acl;
- if (rcu)
- return ERR_PTR(-ECHILD);
-
if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode))
return NULL;
+ if (rcu)
+ return get_cached_acl_rcu(realinode, type);
+
old_cred = ovl_override_creds(inode->i_sb);
acl = get_acl(realinode, type);
revert_creds(old_cred);