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linux-sg2042
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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  RCUify freeing acls, let check_acl() go ahead in RCU mode if acl is cached
  get rid of boilerplate switches in posix_acl.h
  fix block device fallout from ->fsync() changes
This commit is contained in:
Linus Torvalds 2011-08-04 16:44:40 -10:00
parent 8b6b462812 3567866bf2
commit 24f0eed266
3 changed files with 36 additions and 59 deletions
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4
fs/block_dev.c
View File

@ -388,6 +388,10 @@ int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
struct block_device *bdev = I_BDEV(bd_inode);
int error;
error = filemap_write_and_wait_range(filp->f_mapping, start, end);
if (error)
return error;
/*
* There is no need to serialise calls to blkdev_issue_flush with
* i_mutex and doing so causes performance issues with concurrent

17
fs/namei.c
View File

@ -179,19 +179,14 @@ static int check_acl(struct inode *inode, int mask)
#ifdef CONFIG_FS_POSIX_ACL
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))
acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
if (!acl)
return -EAGAIN;
return -ECHILD;
/* no ->get_acl() calls in RCU mode... */
if (acl == ACL_NOT_CACHED)
return -ECHILD;
return posix_acl_permission(inode, acl, mask);
}
acl = get_cached_acl(inode, ACL_TYPE_ACCESS);

74
include/linux/posix_acl.h
View File

@ -9,6 +9,7 @@
#define __LINUX_POSIX_ACL_H
#include <linux/slab.h>
#include <linux/rcupdate.h>
#define ACL_UNDEFINED_ID (-1)
@ -38,7 +39,10 @@ struct posix_acl_entry {
};
struct posix_acl {
atomic_t a_refcount;
union {
atomic_t a_refcount;
struct rcu_head a_rcu;
};
unsigned int a_count;
struct posix_acl_entry a_entries[0];
};
@ -65,7 +69,7 @@ static inline void
posix_acl_release(struct posix_acl *acl)
{
if (acl && atomic_dec_and_test(&acl->a_refcount))
kfree(acl);
kfree_rcu(acl, a_rcu);
}
@ -84,20 +88,22 @@ extern struct posix_acl *get_posix_acl(struct inode *, int);
extern int set_posix_acl(struct inode *, int, struct posix_acl *);
#ifdef CONFIG_FS_POSIX_ACL
static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
static inline struct posix_acl **acl_by_type(struct inode *inode, int type)
{
struct posix_acl **p, *acl;
switch (type) {
case ACL_TYPE_ACCESS:
p = &inode->i_acl;
break;
return &inode->i_acl;
case ACL_TYPE_DEFAULT:
p = &inode->i_default_acl;
break;
return &inode->i_default_acl;
default:
return ERR_PTR(-EINVAL);
BUG();
}
acl = ACCESS_ONCE(*p);
}
static inline struct posix_acl *get_cached_acl(struct inode *inode, int type)
{
struct posix_acl **p = acl_by_type(inode, type);
struct posix_acl *acl = ACCESS_ONCE(*p);
if (acl) {
spin_lock(&inode->i_lock);
acl = *p;
@ -108,41 +114,20 @@ 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)
static inline struct posix_acl *get_cached_acl_rcu(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;
return rcu_dereference(*acl_by_type(inode, type));
}
static inline void set_cached_acl(struct inode *inode,
int type,
struct posix_acl *acl)
{
struct posix_acl *old = NULL;
struct posix_acl **p = acl_by_type(inode, type);
struct posix_acl *old;
spin_lock(&inode->i_lock);
switch (type) {
case ACL_TYPE_ACCESS:
old = inode->i_acl;
inode->i_acl = posix_acl_dup(acl);
break;
case ACL_TYPE_DEFAULT:
old = inode->i_default_acl;
inode->i_default_acl = posix_acl_dup(acl);
break;
}
old = *p;
rcu_assign_pointer(*p, posix_acl_dup(acl));
spin_unlock(&inode->i_lock);
if (old != ACL_NOT_CACHED)
posix_acl_release(old);
@ -150,18 +135,11 @@ static inline void set_cached_acl(struct inode *inode,
static inline void forget_cached_acl(struct inode *inode, int type)
{
struct posix_acl *old = NULL;
struct posix_acl **p = acl_by_type(inode, type);
struct posix_acl *old;
spin_lock(&inode->i_lock);
switch (type) {
case ACL_TYPE_ACCESS:
old = inode->i_acl;
inode->i_acl = ACL_NOT_CACHED;
break;
case ACL_TYPE_DEFAULT:
old = inode->i_default_acl;
inode->i_default_acl = ACL_NOT_CACHED;
break;
}
old = *p;
*p = ACL_NOT_CACHED;
spin_unlock(&inode->i_lock);
if (old != ACL_NOT_CACHED)
posix_acl_release(old);