Commit 30d7030b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'configfs-for-5.3' of git://git.infradead.org/users/hch/configfs

Pull configfs fixes from Christoph Hellwig:
 "Late configfs fixes from Al that fix pretty nasty removal vs attribute
  access races"

* tag 'configfs-for-5.3' of git://git.infradead.org/users/hch/configfs:
  configfs: provide exclusion between IO and removals
  configfs: new object reprsenting tree fragments
  configfs_register_group() shouldn't be (and isn't) called in rmdirable parts
  configfs: stash the data we need into configfs_buffer at open time
parents 76f5e9f8 b0841eef
......@@ -20,6 +20,15 @@
#include <linux/list.h>
#include <linux/spinlock.h>
struct configfs_fragment {
atomic_t frag_count;
struct rw_semaphore frag_sem;
bool frag_dead;
};
void put_fragment(struct configfs_fragment *);
struct configfs_fragment *get_fragment(struct configfs_fragment *);
struct configfs_dirent {
atomic_t s_count;
int s_dependent_count;
......@@ -34,6 +43,7 @@ struct configfs_dirent {
#ifdef CONFIG_LOCKDEP
int s_depth;
#endif
struct configfs_fragment *s_frag;
};
#define CONFIGFS_ROOT 0x0001
......@@ -61,8 +71,8 @@ extern int configfs_create(struct dentry *, umode_t mode, void (*init)(struct in
extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
extern int configfs_create_bin_file(struct config_item *,
const struct configfs_bin_attribute *);
extern int configfs_make_dirent(struct configfs_dirent *,
struct dentry *, void *, umode_t, int);
extern int configfs_make_dirent(struct configfs_dirent *, struct dentry *,
void *, umode_t, int, struct configfs_fragment *);
extern int configfs_dirent_is_ready(struct configfs_dirent *);
extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
......@@ -137,6 +147,7 @@ static inline void release_configfs_dirent(struct configfs_dirent * sd)
{
if (!(sd->s_type & CONFIGFS_ROOT)) {
kfree(sd->s_iattr);
put_fragment(sd->s_frag);
kmem_cache_free(configfs_dir_cachep, sd);
}
}
......
......@@ -151,11 +151,38 @@ configfs_adjust_dir_dirent_depth_after_populate(struct configfs_dirent *sd)
#endif /* CONFIG_LOCKDEP */
static struct configfs_fragment *new_fragment(void)
{
struct configfs_fragment *p;
p = kmalloc(sizeof(struct configfs_fragment), GFP_KERNEL);
if (p) {
atomic_set(&p->frag_count, 1);
init_rwsem(&p->frag_sem);
p->frag_dead = false;
}
return p;
}
void put_fragment(struct configfs_fragment *frag)
{
if (frag && atomic_dec_and_test(&frag->frag_count))
kfree(frag);
}
struct configfs_fragment *get_fragment(struct configfs_fragment *frag)
{
if (likely(frag))
atomic_inc(&frag->frag_count);
return frag;
}
/*
* Allocates a new configfs_dirent and links it to the parent configfs_dirent
*/
static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *parent_sd,
void *element, int type)
void *element, int type,
struct configfs_fragment *frag)
{
struct configfs_dirent * sd;
......@@ -175,6 +202,7 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent *paren
kmem_cache_free(configfs_dir_cachep, sd);
return ERR_PTR(-ENOENT);
}
sd->s_frag = get_fragment(frag);
list_add(&sd->s_sibling, &parent_sd->s_children);
spin_unlock(&configfs_dirent_lock);
......@@ -209,11 +237,11 @@ static int configfs_dirent_exists(struct configfs_dirent *parent_sd,
int configfs_make_dirent(struct configfs_dirent * parent_sd,
struct dentry * dentry, void * element,
umode_t mode, int type)
umode_t mode, int type, struct configfs_fragment *frag)
{
struct configfs_dirent * sd;
sd = configfs_new_dirent(parent_sd, element, type);
sd = configfs_new_dirent(parent_sd, element, type, frag);
if (IS_ERR(sd))
return PTR_ERR(sd);
......@@ -260,7 +288,8 @@ static void init_symlink(struct inode * inode)
* until it is validated by configfs_dir_set_ready()
*/
static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
static int configfs_create_dir(struct config_item *item, struct dentry *dentry,
struct configfs_fragment *frag)
{
int error;
umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
......@@ -273,7 +302,8 @@ static int configfs_create_dir(struct config_item *item, struct dentry *dentry)
return error;
error = configfs_make_dirent(p->d_fsdata, dentry, item, mode,
CONFIGFS_DIR | CONFIGFS_USET_CREATING);
CONFIGFS_DIR | CONFIGFS_USET_CREATING,
frag);
if (unlikely(error))
return error;
......@@ -338,9 +368,10 @@ int configfs_create_link(struct configfs_symlink *sl,
{
int err = 0;
umode_t mode = S_IFLNK | S_IRWXUGO;
struct configfs_dirent *p = parent->d_fsdata;
err = configfs_make_dirent(parent->d_fsdata, dentry, sl, mode,
CONFIGFS_ITEM_LINK);
err = configfs_make_dirent(p, dentry, sl, mode,
CONFIGFS_ITEM_LINK, p->s_frag);
if (!err) {
err = configfs_create(dentry, mode, init_symlink);
if (err) {
......@@ -599,7 +630,8 @@ static int populate_attrs(struct config_item *item)
static int configfs_attach_group(struct config_item *parent_item,
struct config_item *item,
struct dentry *dentry);
struct dentry *dentry,
struct configfs_fragment *frag);
static void configfs_detach_group(struct config_item *item);
static void detach_groups(struct config_group *group)
......@@ -647,7 +679,8 @@ static void detach_groups(struct config_group *group)
* try using vfs_mkdir. Just a thought.
*/
static int create_default_group(struct config_group *parent_group,
struct config_group *group)
struct config_group *group,
struct configfs_fragment *frag)
{
int ret;
struct configfs_dirent *sd;
......@@ -663,7 +696,7 @@ static int create_default_group(struct config_group *parent_group,
d_add(child, NULL);
ret = configfs_attach_group(&parent_group->cg_item,
&group->cg_item, child);
&group->cg_item, child, frag);
if (!ret) {
sd = child->d_fsdata;
sd->s_type |= CONFIGFS_USET_DEFAULT;
......@@ -677,13 +710,14 @@ static int create_default_group(struct config_group *parent_group,
return ret;
}
static int populate_groups(struct config_group *group)
static int populate_groups(struct config_group *group,
struct configfs_fragment *frag)
{
struct config_group *new_group;
int ret = 0;
list_for_each_entry(new_group, &group->default_groups, group_entry) {
ret = create_default_group(group, new_group);
ret = create_default_group(group, new_group, frag);
if (ret) {
detach_groups(group);
break;
......@@ -797,11 +831,12 @@ static void link_group(struct config_group *parent_group, struct config_group *g
*/
static int configfs_attach_item(struct config_item *parent_item,
struct config_item *item,
struct dentry *dentry)
struct dentry *dentry,
struct configfs_fragment *frag)
{
int ret;
ret = configfs_create_dir(item, dentry);
ret = configfs_create_dir(item, dentry, frag);
if (!ret) {
ret = populate_attrs(item);
if (ret) {
......@@ -831,12 +866,13 @@ static void configfs_detach_item(struct config_item *item)
static int configfs_attach_group(struct config_item *parent_item,
struct config_item *item,
struct dentry *dentry)
struct dentry *dentry,
struct configfs_fragment *frag)
{
int ret;
struct configfs_dirent *sd;
ret = configfs_attach_item(parent_item, item, dentry);
ret = configfs_attach_item(parent_item, item, dentry, frag);
if (!ret) {
sd = dentry->d_fsdata;
sd->s_type |= CONFIGFS_USET_DIR;
......@@ -852,7 +888,7 @@ static int configfs_attach_group(struct config_item *parent_item,
*/
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
configfs_adjust_dir_dirent_depth_before_populate(sd);
ret = populate_groups(to_config_group(item));
ret = populate_groups(to_config_group(item), frag);
if (ret) {
configfs_detach_item(item);
d_inode(dentry)->i_flags |= S_DEAD;
......@@ -1247,6 +1283,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
struct configfs_dirent *sd;
const struct config_item_type *type;
struct module *subsys_owner = NULL, *new_item_owner = NULL;
struct configfs_fragment *frag;
char *name;
sd = dentry->d_parent->d_fsdata;
......@@ -1265,6 +1302,12 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
goto out;
}
frag = new_fragment();
if (!frag) {
ret = -ENOMEM;
goto out;
}
/* Get a working ref for the duration of this function */
parent_item = configfs_get_config_item(dentry->d_parent);
type = parent_item->ci_type;
......@@ -1367,9 +1410,9 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
spin_unlock(&configfs_dirent_lock);
if (group)
ret = configfs_attach_group(parent_item, item, dentry);
ret = configfs_attach_group(parent_item, item, dentry, frag);
else
ret = configfs_attach_item(parent_item, item, dentry);
ret = configfs_attach_item(parent_item, item, dentry, frag);
spin_lock(&configfs_dirent_lock);
sd->s_type &= ~CONFIGFS_USET_IN_MKDIR;
......@@ -1406,6 +1449,7 @@ out_put:
* reference.
*/
config_item_put(parent_item);
put_fragment(frag);
out:
return ret;
......@@ -1417,6 +1461,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
struct config_item *item;
struct configfs_subsystem *subsys;
struct configfs_dirent *sd;
struct configfs_fragment *frag;
struct module *subsys_owner = NULL, *dead_item_owner = NULL;
int ret;
......@@ -1474,6 +1519,16 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
}
} while (ret == -EAGAIN);
frag = sd->s_frag;
if (down_write_killable(&frag->frag_sem)) {
spin_lock(&configfs_dirent_lock);
configfs_detach_rollback(dentry);
spin_unlock(&configfs_dirent_lock);
return -EINTR;
}
frag->frag_dead = true;
up_write(&frag->frag_sem);
/* Get a working ref for the duration of this function */
item = configfs_get_config_item(dentry);
......@@ -1574,7 +1629,7 @@ static int configfs_dir_open(struct inode *inode, struct file *file)
*/
err = -ENOENT;
if (configfs_dirent_is_ready(parent_sd)) {
file->private_data = configfs_new_dirent(parent_sd, NULL, 0);
file->private_data = configfs_new_dirent(parent_sd, NULL, 0, NULL);
if (IS_ERR(file->private_data))
err = PTR_ERR(file->private_data);
else
......@@ -1732,8 +1787,13 @@ int configfs_register_group(struct config_group *parent_group,
{
struct configfs_subsystem *subsys = parent_group->cg_subsys;
struct dentry *parent;
struct configfs_fragment *frag;
int ret;
frag = new_fragment();
if (!frag)
return -ENOMEM;
mutex_lock(&subsys->su_mutex);
link_group(parent_group, group);
mutex_unlock(&subsys->su_mutex);
......@@ -1741,7 +1801,7 @@ int configfs_register_group(struct config_group *parent_group,
parent = parent_group->cg_item.ci_dentry;
inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
ret = create_default_group(parent_group, group);
ret = create_default_group(parent_group, group, frag);
if (ret)
goto err_out;
......@@ -1749,12 +1809,14 @@ int configfs_register_group(struct config_group *parent_group,
configfs_dir_set_ready(group->cg_item.ci_dentry->d_fsdata);
spin_unlock(&configfs_dirent_lock);
inode_unlock(d_inode(parent));
put_fragment(frag);
return 0;
err_out:
inode_unlock(d_inode(parent));
mutex_lock(&subsys->su_mutex);
unlink_group(group);
mutex_unlock(&subsys->su_mutex);
put_fragment(frag);
return ret;
}
EXPORT_SYMBOL(configfs_register_group);
......@@ -1770,16 +1832,12 @@ void configfs_unregister_group(struct config_group *group)
struct configfs_subsystem *subsys = group->cg_subsys;
struct dentry *dentry = group->cg_item.ci_dentry;
struct dentry *parent = group->cg_item.ci_parent->ci_dentry;
struct configfs_dirent *sd = dentry->d_fsdata;
struct configfs_fragment *frag = sd->s_frag;
mutex_lock(&subsys->su_mutex);
if (!group->cg_item.ci_parent->ci_group) {
/*
* The parent has already been unlinked and detached
* due to a rmdir.
*/
goto unlink_group;
}
mutex_unlock(&subsys->su_mutex);
down_write(&frag->frag_sem);
frag->frag_dead = true;
up_write(&frag->frag_sem);
inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);
spin_lock(&configfs_dirent_lock);
......@@ -1796,7 +1854,6 @@ void configfs_unregister_group(struct config_group *group)
dput(dentry);
mutex_lock(&subsys->su_mutex);
unlink_group:
unlink_group(group);
mutex_unlock(&subsys->su_mutex);
}
......@@ -1853,10 +1910,17 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
struct dentry *dentry;
struct dentry *root;
struct configfs_dirent *sd;
struct configfs_fragment *frag;
frag = new_fragment();
if (!frag)
return -ENOMEM;
root = configfs_pin_fs();
if (IS_ERR(root))
if (IS_ERR(root)) {
put_fragment(frag);
return PTR_ERR(root);
}
if (!group->cg_item.ci_name)
group->cg_item.ci_name = group->cg_item.ci_namebuf;
......@@ -1872,7 +1936,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
d_add(dentry, NULL);
err = configfs_attach_group(sd->s_element, &group->cg_item,
dentry);
dentry, frag);
if (err) {
BUG_ON(d_inode(dentry));
d_drop(dentry);
......@@ -1890,6 +1954,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
unlink_group(group);
configfs_release_fs();
}
put_fragment(frag);
return err;
}
......@@ -1899,12 +1964,18 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
struct config_group *group = &subsys->su_group;
struct dentry *dentry = group->cg_item.ci_dentry;
struct dentry *root = dentry->d_sb->s_root;
struct configfs_dirent *sd = dentry->d_fsdata;
struct configfs_fragment *frag = sd->s_frag;
if (dentry->d_parent != root) {
pr_err("Tried to unregister non-subsystem!\n");
return;
}
down_write(&frag->frag_sem);
frag->frag_dead = true;
up_write(&frag->frag_sem);
inode_lock_nested(d_inode(root),
I_MUTEX_PARENT);
inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
......
......@@ -39,40 +39,44 @@ struct configfs_buffer {
bool write_in_progress;
char *bin_buffer;
int bin_buffer_size;
int cb_max_size;
struct config_item *item;
struct module *owner;
union {
struct configfs_attribute *attr;
struct configfs_bin_attribute *bin_attr;
};
};
static inline struct configfs_fragment *to_frag(struct file *file)
{
struct configfs_dirent *sd = file->f_path.dentry->d_fsdata;
/**
* fill_read_buffer - allocate and fill buffer from item.
* @dentry: dentry pointer.
* @buffer: data buffer for file.
*
* Allocate @buffer->page, if it hasn't been already, then call the
* config_item's show() method to fill the buffer with this attribute's
* data.
* This is called only once, on the file's first read.
*/
static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
return sd->s_frag;
}
static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
{
struct configfs_attribute * attr = to_attr(dentry);
struct config_item * item = to_item(dentry->d_parent);
int ret = 0;
ssize_t count;
struct configfs_fragment *frag = to_frag(file);
ssize_t count = -ENOENT;
if (!buffer->page)
buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
if (!buffer->page)
return -ENOMEM;
count = attr->show(item, buffer->page);
BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
if (count >= 0) {
buffer->needs_read_fill = 0;
buffer->count = count;
} else
ret = count;
return ret;
down_read(&frag->frag_sem);
if (!frag->frag_dead)
count = buffer->attr->show(buffer->item, buffer->page);
up_read(&frag->frag_sem);
if (count < 0)
return count;
if (WARN_ON_ONCE(count > (ssize_t)SIMPLE_ATTR_SIZE))
return -EIO;
buffer->needs_read_fill = 0;
buffer->count = count;
return 0;
}
/**
......@@ -97,12 +101,13 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
static ssize_t
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct configfs_buffer * buffer = file->private_data;
struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0;
mutex_lock(&buffer->mutex);
if (buffer->needs_read_fill) {
if ((retval = fill_read_buffer(file->f_path.dentry,buffer)))
retval = fill_read_buffer(file, buffer);
if (retval)
goto out;
}
pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
......@@ -138,10 +143,8 @@ static ssize_t
configfs_read_bin_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
struct configfs_fragment *frag = to_frag(file);
struct configfs_buffer *buffer = file->private_data;
struct dentry *dentry = file->f_path.dentry;
struct config_item *item = to_item(dentry->d_parent);
struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
ssize_t retval = 0;
ssize_t len = min_t(size_t, count, PAGE_SIZE);
......@@ -156,14 +159,19 @@ configfs_read_bin_file(struct file *file, char __user *buf,
if (buffer->needs_read_fill) {
/* perform first read with buf == NULL to get extent */
len = bin_attr->read(item, NULL, 0);
down_read(&frag->frag_sem);
if (!frag->frag_dead)
len = buffer->bin_attr->read(buffer->item, NULL, 0);
else
len = -ENOENT;
up_read(&frag->frag_sem);
if (len <= 0) {
retval = len;
goto out;
}
/* do not exceed the maximum value */
if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
if (buffer->cb_max_size && len > buffer->cb_max_size) {
retval = -EFBIG;
goto out;
}
......@@ -176,7 +184,13 @@ configfs_read_bin_file(struct file *file, char __user *buf,
buffer->bin_buffer_size = len;
/* perform second read to fill buffer */
len = bin_attr->read(item, buffer->bin_buffer, len);
down_read(&frag->frag_sem);
if (!frag->frag_dead)
len = buffer->bin_attr->read(buffer->item,
buffer->bin_buffer, len);
else
len = -ENOENT;
up_read(&frag->frag_sem);
if (len < 0) {
retval = len;
vfree(buffer->bin_buffer);
......@@ -226,25 +240,17 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size
return error ? -EFAULT : count;
}
/**
* flush_write_buffer - push buffer to config_item.
* @dentry: dentry to the attribute
* @buffer: data buffer for file.
* @count: number of bytes
*
* Get the correct pointers for the config_item and the attribute we're
* dealing with, then call the store() method for the attribute,
* passing the buffer that we acquired in fill_write_buffer().
*/
static int
flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t count)
{
struct configfs_attribute * attr = to_attr(dentry);
struct config_item * item = to_item(dentry->d_parent);
return attr->store(item, buffer->page, count);
struct configfs_fragment *frag = to_frag(file);
int res = -ENOENT;
down_read(&frag->frag_sem);
if (!frag->frag_dead)
res = buffer->attr->store(buffer->item, buffer->page, count);
up_read(&frag->frag_sem);
return res;
}
......@@ -268,13 +274,13 @@ flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size
static ssize_t
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct configfs_buffer * buffer = file->private_data;
struct configfs_buffer *buffer = file->private_data;
ssize_t len;
mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
len = flush_write_buffer(file->f_path.dentry, buffer, len);
len = flush_write_buffer(file, buffer, len);
if (len > 0)
*ppos += len;
mutex_unlock(&buffer->mutex);
......@@ -299,8 +305,6 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct configfs_buffer *buffer = file->private_data;
struct dentry *dentry = file->f_path.dentry;
struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
void *tbuf = NULL;
ssize_t len;
......@@ -316,8 +320,8 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
/* buffer grows? */
if (*ppos + count > buffer->bin_buffer_size) {
if (bin_attr->cb_max_size &&
*ppos + count > bin_attr->cb_max_size) {
if (buffer->cb_max_size &&
*ppos + count > buffer->cb_max_size) {
len = -EFBIG;
goto out;
}
......@@ -349,31 +353,51 @@ out:
return len;
}
static int check_perm(struct inode * inode, struct file * file, int type)
static int __configfs_open_file(struct inode *inode, struct file *file, int type)
{
struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
struct configfs_attribute * attr = to_attr(file->f_path.dentry);
struct configfs_bin_attribute *bin_attr = NULL;
struct configfs_buffer * buffer;
struct configfs_item_operations * ops = NULL;
int error = 0;
struct dentry *dentry = file->f_path.dentry;
struct configfs_fragment *frag = to_frag(file);
struct configfs_attribute *attr;
struct configfs_buffer *buffer;
int error;