xattr: extract simple_xattr code from tmpfs
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>
diff --git a/mm/shmem.c b/mm/shmem.c
index d4e184e..d375211 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -77,13 +77,6 @@
/* 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 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 @@
} 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 @@
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) {
@@ -2060,28 +2049,6 @@
*/
/*
- * 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.
*/
static int shmem_initxattrs(struct inode *inode,
@@ -2090,11 +2057,11 @@
{
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 @@
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 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 @@
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 @@
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 @@
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 */