ext2,3,4: provide simple rcu-walk ACL implementation

This simple implementation just checks for no ACLs on the inode, and
if so, then the rcu-walk may proceed, otherwise fail it.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
index dd9bb3f..7b41805 100644 (file)
--- a/fs/ext2/acl.c
+++ b/fs/ext2/acl.c
@@ -236,8 +236,11 @@ ext2_check_acl(struct inode *inode, int mask, unsigned int flags)
 {
        struct posix_acl *acl;
 
-       if (flags & IPERM_FLAG_RCU)
-               return -ECHILD;
+       if (flags & IPERM_FLAG_RCU) {
+               if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
+                       return -ECHILD;
+               return -EAGAIN;
+       }
 
        acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
        if (IS_ERR(acl))

diff --git a/fs/ext3/acl.c b/fs/ext3/acl.c
index 9e49da8..e4fa49e 100644 (file)
--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -244,8 +244,11 @@ ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
 {
        struct posix_acl *acl;
 
-       if (flags & IPERM_FLAG_RCU)
-               return -ECHILD;
+       if (flags & IPERM_FLAG_RCU) {
+               if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
+                       return -ECHILD;
+               return -EAGAIN;
+       }
 
        acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
        if (IS_ERR(acl))

diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
index 373dcae..e0270d1 100644 (file)
--- a/fs/ext4/acl.c
+++ b/fs/ext4/acl.c
@@ -242,8 +242,11 @@ ext4_check_acl(struct inode *inode, int mask, unsigned int flags)
 {
        struct posix_acl *acl;
 
-       if (flags & IPERM_FLAG_RCU)
-               return -ECHILD;
+       if (flags & IPERM_FLAG_RCU) {
+               if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
+                       return -ECHILD;
+               return -EAGAIN;
+       }
 
        acl = ext4_get_acl(inode, ACL_TYPE_ACCESS);
        if (IS_ERR(acl))