UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

fs: provide simple rcu-walk generic_check_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.

This could easily be extended to put acls under RCU and check them
under seqlock, if need be. But this implementation is enough to show
the rcu-walk aware permissions code for path lookups is working, and
will handle cases where there are no ACLs or ACLs in just the final
element.

This patch implicity converts tmpfs to rcu-aware permission check.
Subsequent patches onvert ext*, xfs, and, btrfs. Each of these uses
acl/permission code in a different way, so convert them all to provide
templates and proof of concept.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
This commit is contained in:
Nick Piggin 2011-01-07 17:49:59 +11:00
parent b74c79e993
commit 1e1743ebe3
2 changed files with 30 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
fs/generic_acl.c
View File

@ -192,16 +192,18 @@ generic_acl_chmod(struct inode *inode)
int
generic_check_acl(struct inode *inode, int mask, unsigned int flags)
{
struct posix_acl *acl;
if (flags & IPERM_FLAG_RCU) {
if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
return -ECHILD;
} else {
struct posix_acl *acl;
if (flags & IPERM_FLAG_RCU)
return -ECHILD;
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;
}

19
include/linux/posix_acl.h
View File

@ -108,6 +108,25 @@ static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
return acl;
}
static inline int negative_cached_acl(struct inode *inode, int type)
{
struct posix_acl **p, *acl;
switch (type) {
case ACL_TYPE_ACCESS:
p = &inode->i_acl;
break;
case ACL_TYPE_DEFAULT:
p = &inode->i_default_acl;
break;
default:
BUG();
}
acl = ACCESS_ONCE(*p);
if (acl)
return 0;
return 1;
}
static inline void set_cached_acl(struct inode *inode,
int type,
struct posix_acl *acl)