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xattr: extract simple_xattr code from tmpfs

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Extract in-memory xattr APIs from tmpfs. Will be used by cgroup.

$ size vmlinux.o
   text    data     bss     dec     hex filename
4658782  880729 5195032 10734543         a3cbcf vmlinux.o
$ size vmlinux.o
   text    data     bss     dec     hex filename
4658957  880729 5195032 10734718         a3cc7e vmlinux.o

v7:
- checkpatch warnings fixed
- Implement the changes requested by Hugh Dickins:
	- make simple_xattrs_init and simple_xattrs_free inline
	- get rid of locking and list reinitialization in simple_xattrs_free,
	  they're not needed
v6:
- no changes
v5:
- no changes
v4:
- move simple_xattrs_free() to fs/xattr.c
v3:
- in kmem_xattrs_free(), reinitialize the list
- use simple_xattr_* prefix
- introduce simple_xattr_add() to prevent direct list usage

Original-patch-by: Li Zefan <lizefan@huawei.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Lennart Poettering <lpoetter@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Aristeu Rozanski 2012-08-23 16:53:28 -04:00 committed by Tejun Heo
parent fea7a08acb
commit 38f3865744
4 changed files with 229 additions and 159 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

166
fs/xattr.c
View file

@ -791,3 +791,169 @@ EXPORT_SYMBOL(generic_getxattr);
EXPORT_SYMBOL(generic_listxattr);
EXPORT_SYMBOL(generic_setxattr);
EXPORT_SYMBOL(generic_removexattr);
/*
* Allocate new xattr and copy in the value; but leave the name to callers.
*/
struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
{
struct simple_xattr *new_xattr;
size_t len;
/* wrap around? */
len = sizeof(*new_xattr) + size;
if (len <= sizeof(*new_xattr))
return NULL;
new_xattr = kmalloc(len, GFP_KERNEL);
if (!new_xattr)
return NULL;
new_xattr->size = size;
memcpy(new_xattr->value, value, size);
return new_xattr;
}
/*
* xattr GET operation for in-memory/pseudo filesystems
*/
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
void *buffer, size_t size)
{
struct simple_xattr *xattr;
int ret = -ENODATA;
spin_lock(&xattrs->lock);
list_for_each_entry(xattr, &xattrs->head, list) {
if (strcmp(name, xattr->name))
continue;
ret = xattr->size;
if (buffer) {
if (size < xattr->size)
ret = -ERANGE;
else
memcpy(buffer, xattr->value, xattr->size);
}
break;
}
spin_unlock(&xattrs->lock);
return ret;
}
static int __simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags)
{
struct simple_xattr *xattr;
struct simple_xattr *new_xattr = NULL;
int err = 0;
/* value == NULL means remove */
if (value) {
new_xattr = simple_xattr_alloc(value, size);
if (!new_xattr)
return -ENOMEM;
new_xattr->name = kstrdup(name, GFP_KERNEL);
if (!new_xattr->name) {
kfree(new_xattr);
return -ENOMEM;
}
}
spin_lock(&xattrs->lock);
list_for_each_entry(xattr, &xattrs->head, list) {
if (!strcmp(name, xattr->name)) {
if (flags & XATTR_CREATE) {
xattr = new_xattr;
err = -EEXIST;
} else if (new_xattr) {
list_replace(&xattr->list, &new_xattr->list);
} else {
list_del(&xattr->list);
}
goto out;
}
}
if (flags & XATTR_REPLACE) {
xattr = new_xattr;
err = -ENODATA;
} else {
list_add(&new_xattr->list, &xattrs->head);
xattr = NULL;
}
out:
spin_unlock(&xattrs->lock);
if (xattr) {
kfree(xattr->name);
kfree(xattr);
}
return err;
}
/*
* xattr SET operation for in-memory/pseudo filesystems
*/
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags)
{
if (size == 0)
value = ""; /* empty EA, do not remove */
return __simple_xattr_set(xattrs, name, value, size, flags);
}
/*
* xattr REMOVE operation for in-memory/pseudo filesystems
*/
int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name)
{
return __simple_xattr_set(xattrs, name, NULL, 0, XATTR_REPLACE);
}
static bool xattr_is_trusted(const char *name)
{
return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
}
/*
* xattr LIST operation for in-memory/pseudo filesystems
*/
ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
size_t size)
{
bool trusted = capable(CAP_SYS_ADMIN);
struct simple_xattr *xattr;
size_t used = 0;
spin_lock(&xattrs->lock);
list_for_each_entry(xattr, &xattrs->head, list) {
size_t len;
/* skip "trusted." attributes for unprivileged callers */
if (!trusted && xattr_is_trusted(xattr->name))
continue;
len = strlen(xattr->name) + 1;
used += len;
if (buffer) {
if (size < used) {
used = -ERANGE;
break;
}
memcpy(buffer, xattr->name, len);
buffer += len;
}
}
spin_unlock(&xattrs->lock);
return used;
}
void simple_xattr_list_add(struct simple_xattrs *xattrs,
struct simple_xattr *new_xattr)
{
spin_lock(&xattrs->lock);
list_add(&new_xattr->list, &xattrs->head);
spin_unlock(&xattrs->lock);
}

3
include/linux/shmem_fs.h
View file

@ -5,6 +5,7 @@
#include <linux/mempolicy.h>
#include <linux/pagemap.h>
#include <linux/percpu_counter.h>
#include <linux/xattr.h>
/* inode in-kernel data */
@ -18,7 +19,7 @@ struct shmem_inode_info {
};
struct shared_policy policy; /* NUMA memory alloc policy */
struct list_head swaplist; /* chain of maybes on swap */
struct list_head xattr_list; /* list of shmem_xattr */
struct simple_xattrs xattrs; /* list of xattrs */
struct inode vfs_inode;
};

48
include/linux/xattr.h
View file

@ -59,7 +59,9 @@
#ifdef __KERNEL__
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/spinlock.h>
struct inode;
struct dentry;
@ -96,6 +98,52 @@ ssize_t vfs_getxattr_alloc(struct dentry *dentry, const char *name,
char **xattr_value, size_t size, gfp_t flags);
int vfs_xattr_cmp(struct dentry *dentry, const char *xattr_name,
const char *value, size_t size, gfp_t flags);
struct simple_xattrs {
struct list_head head;
spinlock_t lock;
};
struct simple_xattr {
struct list_head list;
char *name;
size_t size;
char value[0];
};
/*
* initialize the simple_xattrs structure
*/
static inline void simple_xattrs_init(struct simple_xattrs *xattrs)
{
INIT_LIST_HEAD(&xattrs->head);
spin_lock_init(&xattrs->lock);
}
/*
* free all the xattrs
*/
static inline void simple_xattrs_free(struct simple_xattrs *xattrs)
{
struct simple_xattr *xattr, *node;
list_for_each_entry_safe(xattr, node, &xattrs->head, list) {
kfree(xattr->name);
kfree(xattr);
}
}
struct simple_xattr *simple_xattr_alloc(const void *value, size_t size);
int simple_xattr_get(struct simple_xattrs *xattrs, const char *name,
void *buffer, size_t size);
int simple_xattr_set(struct simple_xattrs *xattrs, const char *name,
const void *value, size_t size, int flags);
int simple_xattr_remove(struct simple_xattrs *xattrs, const char *name);
ssize_t simple_xattr_list(struct simple_xattrs *xattrs, char *buffer,
size_t size);
void simple_xattr_list_add(struct simple_xattrs *xattrs,
struct simple_xattr *new_xattr);
#endif /* __KERNEL__ */
#endif /* _LINUX_XATTR_H */

171
mm/shmem.c
View file

@ -77,13 +77,6 @@ static struct vfsmount *shm_mnt;
/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
#define SHORT_SYMLINK_LEN 128
struct shmem_xattr {
struct list_head list; /* anchored by shmem_inode_info->xattr_list */
char *name; /* xattr name */
size_t size;
char value[0];
};
/*
* shmem_fallocate and shmem_writepage communicate via inode->i_private
* (with i_mutex making sure that it has only one user at a time):
@ -636,7 +629,6 @@ static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
static void shmem_evict_inode(struct inode *inode)
{
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr, *nxattr;
if (inode->i_mapping->a_ops == &shmem_aops) {
shmem_unacct_size(info->flags, inode->i_size);
@ -650,10 +642,7 @@ static void shmem_evict_inode(struct inode *inode)
} else
kfree(info->symlink);
list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
kfree(xattr->name);
kfree(xattr);
}
simple_xattrs_free(&info->xattrs);
BUG_ON(inode->i_blocks);
shmem_free_inode(inode->i_sb);
clear_inode(inode);
@ -1377,7 +1366,7 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
spin_lock_init(&info->lock);
info->flags = flags & VM_NORESERVE;
INIT_LIST_HEAD(&info->swaplist);
INIT_LIST_HEAD(&info->xattr_list);
simple_xattrs_init(&info->xattrs);
cache_no_acl(inode);
switch (mode & S_IFMT) {
@ -2059,28 +2048,6 @@ static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *co
* filesystem level, though.
*/
/*
* Allocate new xattr and copy in the value; but leave the name to callers.
*/
static struct shmem_xattr *shmem_xattr_alloc(const void *value, size_t size)
{
struct shmem_xattr *new_xattr;
size_t len;
/* wrap around? */
len = sizeof(*new_xattr) + size;
if (len <= sizeof(*new_xattr))
return NULL;
new_xattr = kmalloc(len, GFP_KERNEL);
if (!new_xattr)
return NULL;
new_xattr->size = size;
memcpy(new_xattr->value, value, size);
return new_xattr;
}
/*
* Callback for security_inode_init_security() for acquiring xattrs.
*/
@ -2090,11 +2057,11 @@ static int shmem_initxattrs(struct inode *inode,
{
struct shmem_inode_info *info = SHMEM_I(inode);
const struct xattr *xattr;
struct shmem_xattr *new_xattr;
struct simple_xattr *new_xattr;
size_t len;
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
new_xattr = shmem_xattr_alloc(xattr->value, xattr->value_len);
new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
if (!new_xattr)
return -ENOMEM;
@ -2111,91 +2078,12 @@ static int shmem_initxattrs(struct inode *inode,
memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
xattr->name, len);
spin_lock(&info->lock);
list_add(&new_xattr->list, &info->xattr_list);
spin_unlock(&info->lock);
simple_xattr_list_add(&info->xattrs, new_xattr);
}
return 0;
}
static int shmem_xattr_get(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
struct shmem_inode_info *info;
struct shmem_xattr *xattr;
int ret = -ENODATA;
info = SHMEM_I(dentry->d_inode);
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
if (strcmp(name, xattr->name))
continue;
ret = xattr->size;
if (buffer) {
if (size < xattr->size)
ret = -ERANGE;
else
memcpy(buffer, xattr->value, xattr->size);
}
break;
}
spin_unlock(&info->lock);
return ret;
}
static int shmem_xattr_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr;
struct shmem_xattr *new_xattr = NULL;
int err = 0;
/* value == NULL means remove */
if (value) {
new_xattr = shmem_xattr_alloc(value, size);
if (!new_xattr)
return -ENOMEM;
new_xattr->name = kstrdup(name, GFP_KERNEL);
if (!new_xattr->name) {
kfree(new_xattr);
return -ENOMEM;
}
}
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
if (!strcmp(name, xattr->name)) {
if (flags & XATTR_CREATE) {
xattr = new_xattr;
err = -EEXIST;
} else if (new_xattr) {
list_replace(&xattr->list, &new_xattr->list);
} else {
list_del(&xattr->list);
}
goto out;
}
}
if (flags & XATTR_REPLACE) {
xattr = new_xattr;
err = -ENODATA;
} else {
list_add(&new_xattr->list, &info->xattr_list);
xattr = NULL;
}
out:
spin_unlock(&info->lock);
if (xattr)
kfree(xattr->name);
kfree(xattr);
return err;
}
static const struct xattr_handler *shmem_xattr_handlers[] = {
#ifdef CONFIG_TMPFS_POSIX_ACL
&generic_acl_access_handler,
@ -2226,6 +2114,7 @@ static int shmem_xattr_validate(const char *name)
static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
int err;
/*
@ -2240,12 +2129,13 @@ static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
if (err)
return err;
return shmem_xattr_get(dentry, name, buffer, size);
return simple_xattr_get(&info->xattrs, name, buffer, size);
}
static int shmem_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
int err;
/*
@ -2260,15 +2150,12 @@ static int shmem_setxattr(struct dentry *dentry, const char *name,
if (err)
return err;
if (size == 0)
value = ""; /* empty EA, do not remove */
return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
return simple_xattr_set(&info->xattrs, name, value, size, flags);
}
static int shmem_removexattr(struct dentry *dentry, const char *name)
{
struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
int err;
/*
@ -2283,45 +2170,13 @@ static int shmem_removexattr(struct dentry *dentry, const char *name)
if (err)
return err;
return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
}
static bool xattr_is_trusted(const char *name)
{
return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
return simple_xattr_remove(&info->xattrs, name);
}
static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
bool trusted = capable(CAP_SYS_ADMIN);
struct shmem_xattr *xattr;
struct shmem_inode_info *info;
size_t used = 0;
info = SHMEM_I(dentry->d_inode);
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
size_t len;
/* skip "trusted." attributes for unprivileged callers */
if (!trusted && xattr_is_trusted(xattr->name))
continue;
len = strlen(xattr->name) + 1;
used += len;
if (buffer) {
if (size < used) {
used = -ERANGE;
break;
}
memcpy(buffer, xattr->name, len);
buffer += len;
}
}
spin_unlock(&info->lock);
return used;
struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
return simple_xattr_list(&info->xattrs, buffer, size);
}
#endif /* CONFIG_TMPFS_XATTR */