vfs: move ACL cache lookup into generic code
This moves logic for checking the cached ACL values from low-level
filesystems into generic code. The end result is a streamlined ACL
check that doesn't need to load the inode->i_op->check_acl pointer at
all for the common cached case.
The filesystems also don't need to check for a non-blocking RCU walk
case in their acl_check() functions, because that is all handled at a
VFS layer.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index 7350f53..8be8785 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -101,9 +101,6 @@
struct posix_acl *acl;
struct v9fs_session_info *v9ses;
- if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
-
v9ses = v9fs_inode2v9ses(inode);
if (((v9ses->flags & V9FS_ACCESS_MASK) != V9FS_ACCESS_CLIENT) ||
((v9ses->flags & V9FS_ACL_MASK) != V9FS_POSIX_ACL)) {
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 9f62ab2..c13ea9f 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -198,19 +198,14 @@
int btrfs_check_acl(struct inode *inode, int mask)
{
int error = -EAGAIN;
+ struct posix_acl *acl;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- error = -ECHILD;
- } else {
- struct posix_acl *acl;
- acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
- if (IS_ERR(acl))
- return PTR_ERR(acl);
- if (acl) {
- error = posix_acl_permission(inode, acl, mask);
- posix_acl_release(acl);
- }
+ acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ if (acl) {
+ error = posix_acl_permission(inode, acl, mask);
+ posix_acl_release(acl);
}
return error;
diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
index bfe651f..ced1c47 100644
--- a/fs/ext2/acl.c
+++ b/fs/ext2/acl.c
@@ -236,12 +236,6 @@
{
struct posix_acl *acl;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- return -EAGAIN;
- }
-
acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/ext3/acl.c b/fs/ext3/acl.c
index edfeb29..5326038 100644
--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -244,12 +244,6 @@
{
struct posix_acl *acl;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- return -EAGAIN;
- }
-
acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
index 60d900f..4cd9e2e 100644
--- a/fs/ext4/acl.c
+++ b/fs/ext4/acl.c
@@ -242,12 +242,6 @@
{
struct posix_acl *acl;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- return -EAGAIN;
- }
-
acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/generic_acl.c b/fs/generic_acl.c
index 70e90b4..4949473 100644
--- a/fs/generic_acl.c
+++ b/fs/generic_acl.c
@@ -192,18 +192,13 @@
int
generic_check_acl(struct inode *inode, int mask)
{
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- } else {
- struct posix_acl *acl;
+ struct posix_acl *acl;
- acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
- if (acl) {
- int error = posix_acl_permission(inode, acl, mask);
- posix_acl_release(acl);
- return error;
- }
+ acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
+ if (acl) {
+ int error = posix_acl_permission(inode, acl, mask);
+ posix_acl_release(acl);
+ return error;
}
return -EAGAIN;
}
diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
index 8ef1079..48171f4 100644
--- a/fs/gfs2/acl.c
+++ b/fs/gfs2/acl.c
@@ -80,12 +80,6 @@
struct posix_acl *acl;
int error;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- return -EAGAIN;
- }
-
acl = gfs2_acl_get(GFS2_I(inode), ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/jffs2/acl.c b/fs/jffs2/acl.c
index f9c3024..4933a8f 100644
--- a/fs/jffs2/acl.c
+++ b/fs/jffs2/acl.c
@@ -264,9 +264,6 @@
struct posix_acl *acl;
int rc;
- if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
-
acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/jfs/acl.c b/fs/jfs/acl.c
index 8a0a066..ead200e 100644
--- a/fs/jfs/acl.c
+++ b/fs/jfs/acl.c
@@ -118,9 +118,6 @@
{
struct posix_acl *acl;
- if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
-
acl = jfs_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
diff --git a/fs/namei.c b/fs/namei.c
index b7fad00..120efc7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -32,6 +32,7 @@
#include <linux/fcntl.h>
#include <linux/device_cgroup.h>
#include <linux/fs_struct.h>
+#include <linux/posix_acl.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -173,12 +174,58 @@
EXPORT_SYMBOL(putname);
#endif
+static int check_acl(struct inode *inode, int mask)
+{
+ struct posix_acl *acl;
+
+ /*
+ * Under RCU walk, we cannot even do a "get_cached_acl()",
+ * because that involves locking and getting a refcount on
+ * a cached ACL.
+ *
+ * So the only case we handle during RCU walking is the
+ * case of a cached "no ACL at all", which needs no locks
+ * or refcounts.
+ */
+ if (mask & MAY_NOT_BLOCK) {
+ if (negative_cached_acl(inode, ACL_TYPE_ACCESS))
+ return -EAGAIN;
+ return -ECHILD;
+ }
+
+ acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
+
+ /*
+ * 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 ->check_acl call.
+ *
+ * If the filesystem doesn't have a check_acl() function
+ * at all, we'll just create the negative cache entry.
+ */
+ if (acl == ACL_NOT_CACHED) {
+ if (inode->i_op->check_acl)
+ return inode->i_op->check_acl(inode, mask);
+
+ set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
+ return -EAGAIN;
+ }
+
+ if (acl) {
+ int error = posix_acl_permission(inode, acl, mask);
+ posix_acl_release(acl);
+ return error;
+ }
+
+ return -EAGAIN;
+}
+
/*
* This does basic POSIX ACL permission checking
*/
static int acl_permission_check(struct inode *inode, int mask)
{
- int (*check_acl)(struct inode *inode, int mask);
unsigned int mode = inode->i_mode;
mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK;
@@ -189,8 +236,7 @@
if (current_fsuid() == inode->i_uid)
mode >>= 6;
else {
- check_acl = inode->i_op->check_acl;
- if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) {
+ if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
int error = check_acl(inode, mask);
if (error != -EAGAIN)
return error;
diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c
index f4cf451..aff23e5 100644
--- a/fs/ocfs2/acl.c
+++ b/fs/ocfs2/acl.c
@@ -297,9 +297,6 @@
struct posix_acl *acl;
int ret = -EAGAIN;
- if (mask & MAY_NOT_BLOCK)
- return -ECHILD;
-
osb = OCFS2_SB(inode->i_sb);
if (!(osb->s_mount_opt & OCFS2_MOUNT_POSIX_ACL))
return ret;
diff --git a/fs/xfs/linux-2.6/xfs_acl.c b/fs/xfs/linux-2.6/xfs_acl.c
index cac48fe..f6d065a 100644
--- a/fs/xfs/linux-2.6/xfs_acl.c
+++ b/fs/xfs/linux-2.6/xfs_acl.c
@@ -231,16 +231,12 @@
/*
* If there is no attribute fork no ACL exists on this inode and
* we can skip the whole exercise.
+ *
+ * FIXME! Fill the cache! Locking?
*/
if (!XFS_IFORK_Q(ip))
return -EAGAIN;
- if (mask & MAY_NOT_BLOCK) {
- if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
- return -ECHILD;
- return -EAGAIN;
- }
-
acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);