linux-stable/fs/libfs.c
Linus Torvalds 590dce2d49 Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs 'statx()' update from Al Viro.

This adds the new extended stat() interface that internally subsumes our
previous stat interfaces, and allows user mode to specify in more detail
what kind of information it wants.

It also allows for some explicit synchronization information to be
passed to the filesystem, which can be relevant for network filesystems:
is the cached value ok, or do you need open/close consistency, or what?

From David Howells.

Andreas Dilger points out that the first version of the extended statx
interface was posted June 29, 2010:

    https://www.spinics.net/lists/linux-fsdevel/msg33831.html

* 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  statx: Add a system call to make enhanced file info available
2017-03-03 11:38:56 -08:00

1213 lines
30 KiB
C

/*
* fs/libfs.c
* Library for filesystems writers.
*/
#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/quotaops.h>
#include <linux/mutex.h>
#include <linux/namei.h>
#include <linux/exportfs.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h> /* sync_mapping_buffers */
#include <linux/uaccess.h>
#include "internal.h"
int simple_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct inode *inode = d_inode(path->dentry);
generic_fillattr(inode, stat);
stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9);
return 0;
}
EXPORT_SYMBOL(simple_getattr);
int simple_statfs(struct dentry *dentry, struct kstatfs *buf)
{
buf->f_type = dentry->d_sb->s_magic;
buf->f_bsize = PAGE_SIZE;
buf->f_namelen = NAME_MAX;
return 0;
}
EXPORT_SYMBOL(simple_statfs);
/*
* Retaining negative dentries for an in-memory filesystem just wastes
* memory and lookup time: arrange for them to be deleted immediately.
*/
int always_delete_dentry(const struct dentry *dentry)
{
return 1;
}
EXPORT_SYMBOL(always_delete_dentry);
const struct dentry_operations simple_dentry_operations = {
.d_delete = always_delete_dentry,
};
EXPORT_SYMBOL(simple_dentry_operations);
/*
* Lookup the data. This is trivial - if the dentry didn't already
* exist, we know it is negative. Set d_op to delete negative dentries.
*/
struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
if (dentry->d_name.len > NAME_MAX)
return ERR_PTR(-ENAMETOOLONG);
if (!dentry->d_sb->s_d_op)
d_set_d_op(dentry, &simple_dentry_operations);
d_add(dentry, NULL);
return NULL;
}
EXPORT_SYMBOL(simple_lookup);
int dcache_dir_open(struct inode *inode, struct file *file)
{
file->private_data = d_alloc_cursor(file->f_path.dentry);
return file->private_data ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(dcache_dir_open);
int dcache_dir_close(struct inode *inode, struct file *file)
{
dput(file->private_data);
return 0;
}
EXPORT_SYMBOL(dcache_dir_close);
/* parent is locked at least shared */
static struct dentry *next_positive(struct dentry *parent,
struct list_head *from,
int count)
{
unsigned *seq = &parent->d_inode->i_dir_seq, n;
struct dentry *res;
struct list_head *p;
bool skipped;
int i;
retry:
i = count;
skipped = false;
n = smp_load_acquire(seq) & ~1;
res = NULL;
rcu_read_lock();
for (p = from->next; p != &parent->d_subdirs; p = p->next) {
struct dentry *d = list_entry(p, struct dentry, d_child);
if (!simple_positive(d)) {
skipped = true;
} else if (!--i) {
res = d;
break;
}
}
rcu_read_unlock();
if (skipped) {
smp_rmb();
if (unlikely(*seq != n))
goto retry;
}
return res;
}
static void move_cursor(struct dentry *cursor, struct list_head *after)
{
struct dentry *parent = cursor->d_parent;
unsigned n, *seq = &parent->d_inode->i_dir_seq;
spin_lock(&parent->d_lock);
for (;;) {
n = *seq;
if (!(n & 1) && cmpxchg(seq, n, n + 1) == n)
break;
cpu_relax();
}
__list_del(cursor->d_child.prev, cursor->d_child.next);
if (after)
list_add(&cursor->d_child, after);
else
list_add_tail(&cursor->d_child, &parent->d_subdirs);
smp_store_release(seq, n + 2);
spin_unlock(&parent->d_lock);
}
loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence)
{
struct dentry *dentry = file->f_path.dentry;
switch (whence) {
case 1:
offset += file->f_pos;
case 0:
if (offset >= 0)
break;
default:
return -EINVAL;
}
if (offset != file->f_pos) {
file->f_pos = offset;
if (file->f_pos >= 2) {
struct dentry *cursor = file->private_data;
struct dentry *to;
loff_t n = file->f_pos - 2;
inode_lock_shared(dentry->d_inode);
to = next_positive(dentry, &dentry->d_subdirs, n);
move_cursor(cursor, to ? &to->d_child : NULL);
inode_unlock_shared(dentry->d_inode);
}
}
return offset;
}
EXPORT_SYMBOL(dcache_dir_lseek);
/* Relationship between i_mode and the DT_xxx types */
static inline unsigned char dt_type(struct inode *inode)
{
return (inode->i_mode >> 12) & 15;
}
/*
* Directory is locked and all positive dentries in it are safe, since
* for ramfs-type trees they can't go away without unlink() or rmdir(),
* both impossible due to the lock on directory.
*/
int dcache_readdir(struct file *file, struct dir_context *ctx)
{
struct dentry *dentry = file->f_path.dentry;
struct dentry *cursor = file->private_data;
struct list_head *p = &cursor->d_child;
struct dentry *next;
bool moved = false;
if (!dir_emit_dots(file, ctx))
return 0;
if (ctx->pos == 2)
p = &dentry->d_subdirs;
while ((next = next_positive(dentry, p, 1)) != NULL) {
if (!dir_emit(ctx, next->d_name.name, next->d_name.len,
d_inode(next)->i_ino, dt_type(d_inode(next))))
break;
moved = true;
p = &next->d_child;
ctx->pos++;
}
if (moved)
move_cursor(cursor, p);
return 0;
}
EXPORT_SYMBOL(dcache_readdir);
ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos)
{
return -EISDIR;
}
EXPORT_SYMBOL(generic_read_dir);
const struct file_operations simple_dir_operations = {
.open = dcache_dir_open,
.release = dcache_dir_close,
.llseek = dcache_dir_lseek,
.read = generic_read_dir,
.iterate_shared = dcache_readdir,
.fsync = noop_fsync,
};
EXPORT_SYMBOL(simple_dir_operations);
const struct inode_operations simple_dir_inode_operations = {
.lookup = simple_lookup,
};
EXPORT_SYMBOL(simple_dir_inode_operations);
static const struct super_operations simple_super_operations = {
.statfs = simple_statfs,
};
/*
* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that
* will never be mountable)
*/
struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name,
const struct super_operations *ops, const struct xattr_handler **xattr,
const struct dentry_operations *dops, unsigned long magic)
{
struct super_block *s;
struct dentry *dentry;
struct inode *root;
struct qstr d_name = QSTR_INIT(name, strlen(name));
s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER,
&init_user_ns, NULL);
if (IS_ERR(s))
return ERR_CAST(s);
s->s_maxbytes = MAX_LFS_FILESIZE;
s->s_blocksize = PAGE_SIZE;
s->s_blocksize_bits = PAGE_SHIFT;
s->s_magic = magic;
s->s_op = ops ? ops : &simple_super_operations;
s->s_xattr = xattr;
s->s_time_gran = 1;
root = new_inode(s);
if (!root)
goto Enomem;
/*
* since this is the first inode, make it number 1. New inodes created
* after this must take care not to collide with it (by passing
* max_reserved of 1 to iunique).
*/
root->i_ino = 1;
root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
root->i_atime = root->i_mtime = root->i_ctime = current_time(root);
dentry = __d_alloc(s, &d_name);
if (!dentry) {
iput(root);
goto Enomem;
}
d_instantiate(dentry, root);
s->s_root = dentry;
s->s_d_op = dops;
s->s_flags |= MS_ACTIVE;
return dget(s->s_root);
Enomem:
deactivate_locked_super(s);
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(mount_pseudo_xattr);
int simple_open(struct inode *inode, struct file *file)
{
if (inode->i_private)
file->private_data = inode->i_private;
return 0;
}
EXPORT_SYMBOL(simple_open);
int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(old_dentry);
inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
inc_nlink(inode);
ihold(inode);
dget(dentry);
d_instantiate(dentry, inode);
return 0;
}
EXPORT_SYMBOL(simple_link);
int simple_empty(struct dentry *dentry)
{
struct dentry *child;
int ret = 0;
spin_lock(&dentry->d_lock);
list_for_each_entry(child, &dentry->d_subdirs, d_child) {
spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
if (simple_positive(child)) {
spin_unlock(&child->d_lock);
goto out;
}
spin_unlock(&child->d_lock);
}
ret = 1;
out:
spin_unlock(&dentry->d_lock);
return ret;
}
EXPORT_SYMBOL(simple_empty);
int simple_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
drop_nlink(inode);
dput(dentry);
return 0;
}
EXPORT_SYMBOL(simple_unlink);
int simple_rmdir(struct inode *dir, struct dentry *dentry)
{
if (!simple_empty(dentry))
return -ENOTEMPTY;
drop_nlink(d_inode(dentry));
simple_unlink(dir, dentry);
drop_nlink(dir);
return 0;
}
EXPORT_SYMBOL(simple_rmdir);
int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
struct inode *inode = d_inode(old_dentry);
int they_are_dirs = d_is_dir(old_dentry);
if (flags & ~RENAME_NOREPLACE)
return -EINVAL;
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
if (d_really_is_positive(new_dentry)) {
simple_unlink(new_dir, new_dentry);
if (they_are_dirs) {
drop_nlink(d_inode(new_dentry));
drop_nlink(old_dir);
}
} else if (they_are_dirs) {
drop_nlink(old_dir);
inc_nlink(new_dir);
}
old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime =
new_dir->i_mtime = inode->i_ctime = current_time(old_dir);
return 0;
}
EXPORT_SYMBOL(simple_rename);
/**
* simple_setattr - setattr for simple filesystem
* @dentry: dentry
* @iattr: iattr structure
*
* Returns 0 on success, -error on failure.
*
* simple_setattr is a simple ->setattr implementation without a proper
* implementation of size changes.
*
* It can either be used for in-memory filesystems or special files
* on simple regular filesystems. Anything that needs to change on-disk
* or wire state on size changes needs its own setattr method.
*/
int simple_setattr(struct dentry *dentry, struct iattr *iattr)
{
struct inode *inode = d_inode(dentry);
int error;
error = setattr_prepare(dentry, iattr);
if (error)
return error;
if (iattr->ia_valid & ATTR_SIZE)
truncate_setsize(inode, iattr->ia_size);
setattr_copy(inode, iattr);
mark_inode_dirty(inode);
return 0;
}
EXPORT_SYMBOL(simple_setattr);
int simple_readpage(struct file *file, struct page *page)
{
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
unlock_page(page);
return 0;
}
EXPORT_SYMBOL(simple_readpage);
int simple_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
struct page *page;
pgoff_t index;
index = pos >> PAGE_SHIFT;
page = grab_cache_page_write_begin(mapping, index, flags);
if (!page)
return -ENOMEM;
*pagep = page;
if (!PageUptodate(page) && (len != PAGE_SIZE)) {
unsigned from = pos & (PAGE_SIZE - 1);
zero_user_segments(page, 0, from, from + len, PAGE_SIZE);
}
return 0;
}
EXPORT_SYMBOL(simple_write_begin);
/**
* simple_write_end - .write_end helper for non-block-device FSes
* @available: See .write_end of address_space_operations
* @file: "
* @mapping: "
* @pos: "
* @len: "
* @copied: "
* @page: "
* @fsdata: "
*
* simple_write_end does the minimum needed for updating a page after writing is
* done. It has the same API signature as the .write_end of
* address_space_operations vector. So it can just be set onto .write_end for
* FSes that don't need any other processing. i_mutex is assumed to be held.
* Block based filesystems should use generic_write_end().
* NOTE: Even though i_size might get updated by this function, mark_inode_dirty
* is not called, so a filesystem that actually does store data in .write_inode
* should extend on what's done here with a call to mark_inode_dirty() in the
* case that i_size has changed.
*
* Use *ONLY* with simple_readpage()
*/
int simple_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
struct inode *inode = page->mapping->host;
loff_t last_pos = pos + copied;
/* zero the stale part of the page if we did a short copy */
if (!PageUptodate(page)) {
if (copied < len) {
unsigned from = pos & (PAGE_SIZE - 1);
zero_user(page, from + copied, len - copied);
}
SetPageUptodate(page);
}
/*
* No need to use i_size_read() here, the i_size
* cannot change under us because we hold the i_mutex.
*/
if (last_pos > inode->i_size)
i_size_write(inode, last_pos);
set_page_dirty(page);
unlock_page(page);
put_page(page);
return copied;
}
EXPORT_SYMBOL(simple_write_end);
/*
* the inodes created here are not hashed. If you use iunique to generate
* unique inode values later for this filesystem, then you must take care
* to pass it an appropriate max_reserved value to avoid collisions.
*/
int simple_fill_super(struct super_block *s, unsigned long magic,
struct tree_descr *files)
{
struct inode *inode;
struct dentry *root;
struct dentry *dentry;
int i;
s->s_blocksize = PAGE_SIZE;
s->s_blocksize_bits = PAGE_SHIFT;
s->s_magic = magic;
s->s_op = &simple_super_operations;
s->s_time_gran = 1;
inode = new_inode(s);
if (!inode)
return -ENOMEM;
/*
* because the root inode is 1, the files array must not contain an
* entry at index 1
*/
inode->i_ino = 1;
inode->i_mode = S_IFDIR | 0755;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
set_nlink(inode, 2);
root = d_make_root(inode);
if (!root)
return -ENOMEM;
for (i = 0; !files->name || files->name[0]; i++, files++) {
if (!files->name)
continue;
/* warn if it tries to conflict with the root inode */
if (unlikely(i == 1))
printk(KERN_WARNING "%s: %s passed in a files array"
"with an index of 1!\n", __func__,
s->s_type->name);
dentry = d_alloc_name(root, files->name);
if (!dentry)
goto out;
inode = new_inode(s);
if (!inode) {
dput(dentry);
goto out;
}
inode->i_mode = S_IFREG | files->mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
inode->i_fop = files->ops;
inode->i_ino = i;
d_add(dentry, inode);
}
s->s_root = root;
return 0;
out:
d_genocide(root);
shrink_dcache_parent(root);
dput(root);
return -ENOMEM;
}
EXPORT_SYMBOL(simple_fill_super);
static DEFINE_SPINLOCK(pin_fs_lock);
int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count)
{
struct vfsmount *mnt = NULL;
spin_lock(&pin_fs_lock);
if (unlikely(!*mount)) {
spin_unlock(&pin_fs_lock);
mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL);
if (IS_ERR(mnt))
return PTR_ERR(mnt);
spin_lock(&pin_fs_lock);
if (!*mount)
*mount = mnt;
}
mntget(*mount);
++*count;
spin_unlock(&pin_fs_lock);
mntput(mnt);
return 0;
}
EXPORT_SYMBOL(simple_pin_fs);
void simple_release_fs(struct vfsmount **mount, int *count)
{
struct vfsmount *mnt;
spin_lock(&pin_fs_lock);
mnt = *mount;
if (!--*count)
*mount = NULL;
spin_unlock(&pin_fs_lock);
mntput(mnt);
}
EXPORT_SYMBOL(simple_release_fs);
/**
* simple_read_from_buffer - copy data from the buffer to user space
* @to: the user space buffer to read to
* @count: the maximum number of bytes to read
* @ppos: the current position in the buffer
* @from: the buffer to read from
* @available: the size of the buffer
*
* The simple_read_from_buffer() function reads up to @count bytes from the
* buffer @from at offset @ppos into the user space address starting at @to.
*
* On success, the number of bytes read is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
const void *from, size_t available)
{
loff_t pos = *ppos;
size_t ret;
if (pos < 0)
return -EINVAL;
if (pos >= available || !count)
return 0;
if (count > available - pos)
count = available - pos;
ret = copy_to_user(to, from + pos, count);
if (ret == count)
return -EFAULT;
count -= ret;
*ppos = pos + count;
return count;
}
EXPORT_SYMBOL(simple_read_from_buffer);
/**
* simple_write_to_buffer - copy data from user space to the buffer
* @to: the buffer to write to
* @available: the size of the buffer
* @ppos: the current position in the buffer
* @from: the user space buffer to read from
* @count: the maximum number of bytes to read
*
* The simple_write_to_buffer() function reads up to @count bytes from the user
* space address starting at @from into the buffer @to at offset @ppos.
*
* On success, the number of bytes written is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
const void __user *from, size_t count)
{
loff_t pos = *ppos;
size_t res;
if (pos < 0)
return -EINVAL;
if (pos >= available || !count)
return 0;
if (count > available - pos)
count = available - pos;
res = copy_from_user(to + pos, from, count);
if (res == count)
return -EFAULT;
count -= res;
*ppos = pos + count;
return count;
}
EXPORT_SYMBOL(simple_write_to_buffer);
/**
* memory_read_from_buffer - copy data from the buffer
* @to: the kernel space buffer to read to
* @count: the maximum number of bytes to read
* @ppos: the current position in the buffer
* @from: the buffer to read from
* @available: the size of the buffer
*
* The memory_read_from_buffer() function reads up to @count bytes from the
* buffer @from at offset @ppos into the kernel space address starting at @to.
*
* On success, the number of bytes read is returned and the offset @ppos is
* advanced by this number, or negative value is returned on error.
**/
ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
const void *from, size_t available)
{
loff_t pos = *ppos;
if (pos < 0)
return -EINVAL;
if (pos >= available)
return 0;
if (count > available - pos)
count = available - pos;
memcpy(to, from + pos, count);
*ppos = pos + count;
return count;
}
EXPORT_SYMBOL(memory_read_from_buffer);
/*
* Transaction based IO.
* The file expects a single write which triggers the transaction, and then
* possibly a read which collects the result - which is stored in a
* file-local buffer.
*/
void simple_transaction_set(struct file *file, size_t n)
{
struct simple_transaction_argresp *ar = file->private_data;
BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
/*
* The barrier ensures that ar->size will really remain zero until
* ar->data is ready for reading.
*/
smp_mb();
ar->size = n;
}
EXPORT_SYMBOL(simple_transaction_set);
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
{
struct simple_transaction_argresp *ar;
static DEFINE_SPINLOCK(simple_transaction_lock);
if (size > SIMPLE_TRANSACTION_LIMIT - 1)
return ERR_PTR(-EFBIG);
ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
if (!ar)
return ERR_PTR(-ENOMEM);
spin_lock(&simple_transaction_lock);
/* only one write allowed per open */
if (file->private_data) {
spin_unlock(&simple_transaction_lock);
free_page((unsigned long)ar);
return ERR_PTR(-EBUSY);
}
file->private_data = ar;
spin_unlock(&simple_transaction_lock);
if (copy_from_user(ar->data, buf, size))
return ERR_PTR(-EFAULT);
return ar->data;
}
EXPORT_SYMBOL(simple_transaction_get);
ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
{
struct simple_transaction_argresp *ar = file->private_data;
if (!ar)
return 0;
return simple_read_from_buffer(buf, size, pos, ar->data, ar->size);
}
EXPORT_SYMBOL(simple_transaction_read);
int simple_transaction_release(struct inode *inode, struct file *file)
{
free_page((unsigned long)file->private_data);
return 0;
}
EXPORT_SYMBOL(simple_transaction_release);
/* Simple attribute files */
struct simple_attr {
int (*get)(void *, u64 *);
int (*set)(void *, u64);
char get_buf[24]; /* enough to store a u64 and "\n\0" */
char set_buf[24];
void *data;
const char *fmt; /* format for read operation */
struct mutex mutex; /* protects access to these buffers */
};
/* simple_attr_open is called by an actual attribute open file operation
* to set the attribute specific access operations. */
int simple_attr_open(struct inode *inode, struct file *file,
int (*get)(void *, u64 *), int (*set)(void *, u64),
const char *fmt)
{
struct simple_attr *attr;
attr = kmalloc(sizeof(*attr), GFP_KERNEL);
if (!attr)
return -ENOMEM;
attr->get = get;
attr->set = set;
attr->data = inode->i_private;
attr->fmt = fmt;
mutex_init(&attr->mutex);
file->private_data = attr;
return nonseekable_open(inode, file);
}
EXPORT_SYMBOL_GPL(simple_attr_open);
int simple_attr_release(struct inode *inode, struct file *file)
{
kfree(file->private_data);
return 0;
}
EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */
/* read from the buffer that is filled with the get function */
ssize_t simple_attr_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
struct simple_attr *attr;
size_t size;
ssize_t ret;
attr = file->private_data;
if (!attr->get)
return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex);
if (ret)
return ret;
if (*ppos) { /* continued read */
size = strlen(attr->get_buf);
} else { /* first read */
u64 val;
ret = attr->get(attr->data, &val);
if (ret)
goto out;
size = scnprintf(attr->get_buf, sizeof(attr->get_buf),
attr->fmt, (unsigned long long)val);
}
ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size);
out:
mutex_unlock(&attr->mutex);
return ret;
}
EXPORT_SYMBOL_GPL(simple_attr_read);
/* interpret the buffer as a number to call the set function with */
ssize_t simple_attr_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
struct simple_attr *attr;
u64 val;
size_t size;
ssize_t ret;
attr = file->private_data;
if (!attr->set)
return -EACCES;
ret = mutex_lock_interruptible(&attr->mutex);
if (ret)
return ret;
ret = -EFAULT;
size = min(sizeof(attr->set_buf) - 1, len);
if (copy_from_user(attr->set_buf, buf, size))
goto out;
attr->set_buf[size] = '\0';
val = simple_strtoll(attr->set_buf, NULL, 0);
ret = attr->set(attr->data, val);
if (ret == 0)
ret = len; /* on success, claim we got the whole input */
out:
mutex_unlock(&attr->mutex);
return ret;
}
EXPORT_SYMBOL_GPL(simple_attr_write);
/**
* generic_fh_to_dentry - generic helper for the fh_to_dentry export operation
* @sb: filesystem to do the file handle conversion on
* @fid: file handle to convert
* @fh_len: length of the file handle in bytes
* @fh_type: type of file handle
* @get_inode: filesystem callback to retrieve inode
*
* This function decodes @fid as long as it has one of the well-known
* Linux filehandle types and calls @get_inode on it to retrieve the
* inode for the object specified in the file handle.
*/
struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type, struct inode *(*get_inode)
(struct super_block *sb, u64 ino, u32 gen))
{
struct inode *inode = NULL;
if (fh_len < 2)
return NULL;
switch (fh_type) {
case FILEID_INO32_GEN:
case FILEID_INO32_GEN_PARENT:
inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
break;
}
return d_obtain_alias(inode);
}
EXPORT_SYMBOL_GPL(generic_fh_to_dentry);
/**
* generic_fh_to_parent - generic helper for the fh_to_parent export operation
* @sb: filesystem to do the file handle conversion on
* @fid: file handle to convert
* @fh_len: length of the file handle in bytes
* @fh_type: type of file handle
* @get_inode: filesystem callback to retrieve inode
*
* This function decodes @fid as long as it has one of the well-known
* Linux filehandle types and calls @get_inode on it to retrieve the
* inode for the _parent_ object specified in the file handle if it
* is specified in the file handle, or NULL otherwise.
*/
struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type, struct inode *(*get_inode)
(struct super_block *sb, u64 ino, u32 gen))
{
struct inode *inode = NULL;
if (fh_len <= 2)
return NULL;
switch (fh_type) {
case FILEID_INO32_GEN_PARENT:
inode = get_inode(sb, fid->i32.parent_ino,
(fh_len > 3 ? fid->i32.parent_gen : 0));
break;
}
return d_obtain_alias(inode);
}
EXPORT_SYMBOL_GPL(generic_fh_to_parent);
/**
* __generic_file_fsync - generic fsync implementation for simple filesystems
*
* @file: file to synchronize
* @start: start offset in bytes
* @end: end offset in bytes (inclusive)
* @datasync: only synchronize essential metadata if true
*
* This is a generic implementation of the fsync method for simple
* filesystems which track all non-inode metadata in the buffers list
* hanging off the address_space structure.
*/
int __generic_file_fsync(struct file *file, loff_t start, loff_t end,
int datasync)
{
struct inode *inode = file->f_mapping->host;
int err;
int ret;
err = filemap_write_and_wait_range(inode->i_mapping, start, end);
if (err)
return err;
inode_lock(inode);
ret = sync_mapping_buffers(inode->i_mapping);
if (!(inode->i_state & I_DIRTY_ALL))
goto out;
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
goto out;
err = sync_inode_metadata(inode, 1);
if (ret == 0)
ret = err;
out:
inode_unlock(inode);
return ret;
}
EXPORT_SYMBOL(__generic_file_fsync);
/**
* generic_file_fsync - generic fsync implementation for simple filesystems
* with flush
* @file: file to synchronize
* @start: start offset in bytes
* @end: end offset in bytes (inclusive)
* @datasync: only synchronize essential metadata if true
*
*/
int generic_file_fsync(struct file *file, loff_t start, loff_t end,
int datasync)
{
struct inode *inode = file->f_mapping->host;
int err;
err = __generic_file_fsync(file, start, end, datasync);
if (err)
return err;
return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
}
EXPORT_SYMBOL(generic_file_fsync);
/**
* generic_check_addressable - Check addressability of file system
* @blocksize_bits: log of file system block size
* @num_blocks: number of blocks in file system
*
* Determine whether a file system with @num_blocks blocks (and a
* block size of 2**@blocksize_bits) is addressable by the sector_t
* and page cache of the system. Return 0 if so and -EFBIG otherwise.
*/
int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
{
u64 last_fs_block = num_blocks - 1;
u64 last_fs_page =
last_fs_block >> (PAGE_SHIFT - blocksize_bits);
if (unlikely(num_blocks == 0))
return 0;
if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
return -EINVAL;
if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
(last_fs_page > (pgoff_t)(~0ULL))) {
return -EFBIG;
}
return 0;
}
EXPORT_SYMBOL(generic_check_addressable);
/*
* No-op implementation of ->fsync for in-memory filesystems.
*/
int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
return 0;
}
EXPORT_SYMBOL(noop_fsync);
/* Because kfree isn't assignment-compatible with void(void*) ;-/ */
void kfree_link(void *p)
{
kfree(p);
}
EXPORT_SYMBOL(kfree_link);
/*
* nop .set_page_dirty method so that people can use .page_mkwrite on
* anon inodes.
*/
static int anon_set_page_dirty(struct page *page)
{
return 0;
};
/*
* A single inode exists for all anon_inode files. Contrary to pipes,
* anon_inode inodes have no associated per-instance data, so we need
* only allocate one of them.
*/
struct inode *alloc_anon_inode(struct super_block *s)
{
static const struct address_space_operations anon_aops = {
.set_page_dirty = anon_set_page_dirty,
};
struct inode *inode = new_inode_pseudo(s);
if (!inode)
return ERR_PTR(-ENOMEM);
inode->i_ino = get_next_ino();
inode->i_mapping->a_ops = &anon_aops;
/*
* Mark the inode dirty from the very beginning,
* that way it will never be moved to the dirty
* list because mark_inode_dirty() will think
* that it already _is_ on the dirty list.
*/
inode->i_state = I_DIRTY;
inode->i_mode = S_IRUSR | S_IWUSR;
inode->i_uid = current_fsuid();
inode->i_gid = current_fsgid();
inode->i_flags |= S_PRIVATE;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
return inode;
}
EXPORT_SYMBOL(alloc_anon_inode);
/**
* simple_nosetlease - generic helper for prohibiting leases
* @filp: file pointer
* @arg: type of lease to obtain
* @flp: new lease supplied for insertion
* @priv: private data for lm_setup operation
*
* Generic helper for filesystems that do not wish to allow leases to be set.
* All arguments are ignored and it just returns -EINVAL.
*/
int
simple_nosetlease(struct file *filp, long arg, struct file_lock **flp,
void **priv)
{
return -EINVAL;
}
EXPORT_SYMBOL(simple_nosetlease);
const char *simple_get_link(struct dentry *dentry, struct inode *inode,
struct delayed_call *done)
{
return inode->i_link;
}
EXPORT_SYMBOL(simple_get_link);
const struct inode_operations simple_symlink_inode_operations = {
.get_link = simple_get_link,
};
EXPORT_SYMBOL(simple_symlink_inode_operations);
/*
* Operations for a permanently empty directory.
*/
static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
return ERR_PTR(-ENOENT);
}
static int empty_dir_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
struct inode *inode = d_inode(path->dentry);
generic_fillattr(inode, stat);
return 0;
}
static int empty_dir_setattr(struct dentry *dentry, struct iattr *attr)
{
return -EPERM;
}
static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size)
{
return -EOPNOTSUPP;
}
static const struct inode_operations empty_dir_inode_operations = {
.lookup = empty_dir_lookup,
.permission = generic_permission,
.setattr = empty_dir_setattr,
.getattr = empty_dir_getattr,
.listxattr = empty_dir_listxattr,
};
static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence)
{
/* An empty directory has two entries . and .. at offsets 0 and 1 */
return generic_file_llseek_size(file, offset, whence, 2, 2);
}
static int empty_dir_readdir(struct file *file, struct dir_context *ctx)
{
dir_emit_dots(file, ctx);
return 0;
}
static const struct file_operations empty_dir_operations = {
.llseek = empty_dir_llseek,
.read = generic_read_dir,
.iterate_shared = empty_dir_readdir,
.fsync = noop_fsync,
};
void make_empty_dir_inode(struct inode *inode)
{
set_nlink(inode, 2);
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
inode->i_rdev = 0;
inode->i_size = 0;
inode->i_blkbits = PAGE_SHIFT;
inode->i_blocks = 0;
inode->i_op = &empty_dir_inode_operations;
inode->i_opflags &= ~IOP_XATTR;
inode->i_fop = &empty_dir_operations;
}
bool is_empty_dir_inode(struct inode *inode)
{
return (inode->i_fop == &empty_dir_operations) &&
(inode->i_op == &empty_dir_inode_operations);
}