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sysfs, kernfs: move file core code to fs/kernfs/file.c

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Move core file code to fs/kernfs/file.c.  fs/sysfs/file.c now contains
sysfs kernfs_ops callbacks, sysfs wrappers around kernfs interfaces,
and sysfs_schedule_callback().  The respective declarations in
fs/sysfs/sysfs.h are moved to fs/kernfs/kernfs-internal.h.

This is pure relocation.

v2: Refreshed on top of the v2 of "sysfs, kernfs: prepare read path
    for kernfs".

v3: Refreshed on top of the v3 of "sysfs, kernfs: prepare read path
    for kernfs".

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2013-11-28 14:54:34 -05:00 committed by Greg Kroah-Hartman
parent fd7b9f7b97
commit 414985ae23
4 changed files with 813 additions and 805 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

805
fs/kernfs/file.c
View File

@ -7,3 +7,808 @@
*
* This file is released under the GPLv2.
*/
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include "kernfs-internal.h"
/*
* There's one sysfs_open_file for each open file and one sysfs_open_dirent
* for each sysfs_dirent with one or more open files.
*
* sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open is
* protected by sysfs_open_dirent_lock.
*
* filp->private_data points to seq_file whose ->private points to
* sysfs_open_file. sysfs_open_files are chained at
* sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
*/
static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
static DEFINE_MUTEX(sysfs_open_file_mutex);
struct sysfs_open_dirent {
atomic_t refcnt;
atomic_t event;
wait_queue_head_t poll;
struct list_head files; /* goes through sysfs_open_file.list */
};
static struct sysfs_open_file *sysfs_of(struct file *file)
{
return ((struct seq_file *)file->private_data)->private;
}
/*
* Determine the kernfs_ops for the given sysfs_dirent. This function must
* be called while holding an active reference.
*/
static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
{
if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
lockdep_assert_held(sd);
return sd->s_attr.ops;
}
static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd))
return ERR_PTR(-ENODEV);
ops = kernfs_ops(of->sd);
if (ops->seq_start) {
return ops->seq_start(sf, ppos);
} else {
/*
* The same behavior and code as single_open(). Returns
* !NULL if pos is at the beginning; otherwise, NULL.
*/
return NULL + !*ppos;
}
}
static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops = kernfs_ops(of->sd);
if (ops->seq_next) {
return ops->seq_next(sf, v, ppos);
} else {
/*
* The same behavior and code as single_open(), always
* terminate after the initial read.
*/
++*ppos;
return NULL;
}
}
static void kernfs_seq_stop(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops = kernfs_ops(of->sd);
if (ops->seq_stop)
ops->seq_stop(sf, v);
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
}
static int kernfs_seq_show(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
of->event = atomic_read(&of->sd->s_attr.open->event);
return of->sd->s_attr.ops->seq_show(sf, v);
}
static const struct seq_operations kernfs_seq_ops = {
.start = kernfs_seq_start,
.next = kernfs_seq_next,
.stop = kernfs_seq_stop,
.show = kernfs_seq_show,
};
/*
* As reading a bin file can have side-effects, the exact offset and bytes
* specified in read(2) call should be passed to the read callback making
* it difficult to use seq_file. Implement simplistic custom buffering for
* bin files.
*/
static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
char __user *user_buf, size_t count,
loff_t *ppos)
{
ssize_t len = min_t(size_t, count, PAGE_SIZE);
const struct kernfs_ops *ops;
char *buf;
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
len = -ENODEV;
mutex_unlock(&of->mutex);
goto out_free;
}
ops = kernfs_ops(of->sd);
if (ops->read)
len = ops->read(of, buf, len, *ppos);
else
len = -EINVAL;
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len < 0)
goto out_free;
if (copy_to_user(user_buf, buf, len)) {
len = -EFAULT;
goto out_free;
}
*ppos += len;
out_free:
kfree(buf);
return len;
}
/**
* kernfs_file_read - kernfs vfs read callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*/
static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
return seq_read(file, user_buf, count, ppos);
else
return kernfs_file_direct_read(of, user_buf, count, ppos);
}
/**
* kernfs_file_write - kernfs vfs write callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Copy data in from userland and pass it to the matching kernfs write
* operation.
*
* There is no easy way for us to know if userspace is only doing a partial
* write, so we don't support them. We expect the entire buffer to come on
* the first write. Hint: if you're writing a value, first read the file,
* modify only the the value you're changing, then write entire buffer
* back.
*/
static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
ssize_t len = min_t(size_t, count, PAGE_SIZE);
const struct kernfs_ops *ops;
char *buf;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, len)) {
len = -EFAULT;
goto out_free;
}
buf[len] = '\0'; /* guarantee string termination */
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
mutex_unlock(&of->mutex);
len = -ENODEV;
goto out_free;
}
ops = kernfs_ops(of->sd);
if (ops->write)
len = ops->write(of, buf, len, *ppos);
else
len = -EINVAL;
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len > 0)
*ppos += len;
out_free:
kfree(buf);
return len;
}
static void kernfs_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
if (!of->vm_ops)
return;
if (!sysfs_get_active(of->sd))
return;
if (of->vm_ops->open)
of->vm_ops->open(vma);
sysfs_put_active(of->sd);
}
static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
if (of->vm_ops->fault)
ret = of->vm_ops->fault(vma, vmf);
sysfs_put_active(of->sd);
return ret;
}
static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = 0;
if (of->vm_ops->page_mkwrite)
ret = of->vm_ops->page_mkwrite(vma, vmf);
else
file_update_time(file);
sysfs_put_active(of->sd);
return ret;
}
static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return -EINVAL;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = -EINVAL;
if (of->vm_ops->access)
ret = of->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(of->sd);
return ret;
}
#ifdef CONFIG_NUMA
static int kernfs_vma_set_policy(struct vm_area_struct *vma,
struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return 0;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = 0;
if (of->vm_ops->set_policy)
ret = of->vm_ops->set_policy(vma, new);
sysfs_put_active(of->sd);
return ret;
}
static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
struct mempolicy *pol;
if (!of->vm_ops)
return vma->vm_policy;
if (!sysfs_get_active(of->sd))
return vma->vm_policy;
pol = vma->vm_policy;
if (of->vm_ops->get_policy)
pol = of->vm_ops->get_policy(vma, addr);
sysfs_put_active(of->sd);
return pol;
}
static int kernfs_vma_migrate(struct vm_area_struct *vma,
const nodemask_t *from, const nodemask_t *to,
unsigned long flags)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return 0;
if (!sysfs_get_active(of->sd))
return 0;
ret = 0;
if (of->vm_ops->migrate)
ret = of->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active(of->sd);
return ret;
}
#endif
static const struct vm_operations_struct kernfs_vm_ops = {
.open = kernfs_vma_open,
.fault = kernfs_vma_fault,
.page_mkwrite = kernfs_vma_page_mkwrite,
.access = kernfs_vma_access,
#ifdef CONFIG_NUMA
.set_policy = kernfs_vma_set_policy,
.get_policy = kernfs_vma_get_policy,
.migrate = kernfs_vma_migrate,
#endif
};
static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct sysfs_open_file *of = sysfs_of(file);
const struct kernfs_ops *ops;
int rc;
mutex_lock(&of->mutex);
rc = -ENODEV;
if (!sysfs_get_active(of->sd))
goto out_unlock;
ops = kernfs_ops(of->sd);
if (ops->mmap)
rc = ops->mmap(of, vma);
if (rc)
goto out_put;
/*
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
* to satisfy versions of X which crash if the mmap fails: that
* substitutes a new vm_file, and we don't then want bin_vm_ops.
*/
if (vma->vm_file != file)
goto out_put;
rc = -EINVAL;
if (of->mmapped && of->vm_ops != vma->vm_ops)
goto out_put;
/*
* It is not possible to successfully wrap close.
* So error if someone is trying to use close.
*/
rc = -EINVAL;
if (vma->vm_ops && vma->vm_ops->close)
goto out_put;
rc = 0;
of->mmapped = 1;
of->vm_ops = vma->vm_ops;
vma->vm_ops = &kernfs_vm_ops;
out_put:
sysfs_put_active(of->sd);
out_unlock:
mutex_unlock(&of->mutex);
return rc;
}
/**
* sysfs_get_open_dirent - get or create sysfs_open_dirent
* @sd: target sysfs_dirent
* @of: sysfs_open_file for this instance of open
*
* If @sd->s_attr.open exists, increment its reference count;
* otherwise, create one. @of is chained to the files list.
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* 0 on success, -errno on failure.
*/
static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_file *of)
{
struct sysfs_open_dirent *od, *new_od = NULL;
retry:
mutex_lock(&sysfs_open_file_mutex);
spin_lock_irq(&sysfs_open_dirent_lock);
if (!sd->s_attr.open && new_od) {
sd->s_attr.open = new_od;
new_od = NULL;
}
od = sd->s_attr.open;
if (od) {
atomic_inc(&od->refcnt);
list_add_tail(&of->list, &od->files);
}
spin_unlock_irq(&sysfs_open_dirent_lock);
mutex_unlock(&sysfs_open_file_mutex);
if (od) {
kfree(new_od);
return 0;
}
/* not there, initialize a new one and retry */
new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
if (!new_od)
return -ENOMEM;
atomic_set(&new_od->refcnt, 0);
atomic_set(&new_od->event, 1);
init_waitqueue_head(&new_od->poll);
INIT_LIST_HEAD(&new_od->files);
goto retry;
}
/**
* sysfs_put_open_dirent - put sysfs_open_dirent
* @sd: target sysfs_dirent
* @of: associated sysfs_open_file
*
* Put @sd->s_attr.open and unlink @of from the files list. If
* reference count reaches zero, disassociate and free it.
*
* LOCKING:
* None.
*/
static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_file *of)
{
struct sysfs_open_dirent *od = sd->s_attr.open;
unsigned long flags;
mutex_lock(&sysfs_open_file_mutex);
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
if (of)
list_del(&of->list);
if (atomic_dec_and_test(&od->refcnt))
sd->s_attr.open = NULL;
else
od = NULL;
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
mutex_unlock(&sysfs_open_file_mutex);
kfree(od);
}
static int kernfs_file_open(struct inode *inode, struct file *file)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
const struct kernfs_ops *ops;
struct sysfs_open_file *of;
bool has_read, has_write, has_mmap;
int error = -EACCES;
if (!sysfs_get_active(attr_sd))
return -ENODEV;
ops = kernfs_ops(attr_sd);
has_read = ops->seq_show || ops->read || ops->mmap;
has_write = ops->write || ops->mmap;
has_mmap = ops->mmap;
/* check perms and supported operations */
if ((file->f_mode & FMODE_WRITE) &&
(!(inode->i_mode & S_IWUGO) || !has_write))
goto err_out;
if ((file->f_mode & FMODE_READ) &&
(!(inode->i_mode & S_IRUGO) || !has_read))
goto err_out;
/* allocate a sysfs_open_file for the file */
error = -ENOMEM;
of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
if (!of)
goto err_out;
/*
* The following is done to give a different lockdep key to
* @of->mutex for files which implement mmap. This is a rather
* crude way to avoid false positive lockdep warning around
* mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
* reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
* which mm->mmap_sem nests, while holding @of->mutex. As each
* open file has a separate mutex, it's okay as long as those don't
* happen on the same file. At this point, we can't easily give
* each file a separate locking class. Let's differentiate on
* whether the file has mmap or not for now.
*/
if (has_mmap)
mutex_init(&of->mutex);
else
mutex_init(&of->mutex);
of->sd = attr_sd;
of->file = file;
/*
* Always instantiate seq_file even if read access doesn't use
* seq_file or is not requested. This unifies private data access
* and readable regular files are the vast majority anyway.
*/
if (ops->seq_show)
error = seq_open(file, &kernfs_seq_ops);
else
error = seq_open(file, NULL);
if (error)
goto err_free;
((struct seq_file *)file->private_data)->private = of;
/* seq_file clears PWRITE unconditionally, restore it if WRITE */
if (file->f_mode & FMODE_WRITE)
file->f_mode |= FMODE_PWRITE;
/* make sure we have open dirent struct */
error = sysfs_get_open_dirent(attr_sd, of);
if (error)
goto err_close;
/* open succeeded, put active references */
sysfs_put_active(attr_sd);
return 0;
err_close:
seq_release(inode, file);
err_free:
kfree(of);
err_out:
sysfs_put_active(attr_sd);
return error;
}
static int kernfs_file_release(struct inode *inode, struct file *filp)
{
struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
struct sysfs_open_file *of = sysfs_of(filp);
sysfs_put_open_dirent(sd, of);
seq_release(inode, filp);
kfree(of);
return 0;
}
void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
struct sysfs_open_file *of;
if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
return;
spin_lock_irq(&sysfs_open_dirent_lock);
od = sd->s_attr.open;
if (od)
atomic_inc(&od->refcnt);
spin_unlock_irq(&sysfs_open_dirent_lock);
if (!od)
return;
mutex_lock(&sysfs_open_file_mutex);
list_for_each_entry(of, &od->files, list) {
struct inode *inode = file_inode(of->file);
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
mutex_unlock(&sysfs_open_file_mutex);
sysfs_put_open_dirent(sd, NULL);
}
/* Sysfs attribute files are pollable. The idea is that you read
* the content and then you use 'poll' or 'select' to wait for
* the content to change. When the content changes (assuming the
* manager for the kobject supports notification), poll will
* return POLLERR|POLLPRI, and select will return the fd whether
* it is waiting for read, write, or exceptions.
* Once poll/select indicates that the value has changed, you
* need to close and re-open the file, or seek to 0 and read again.
* Reminder: this only works for attributes which actively support
* it, and it is not possible to test an attribute from userspace
* to see if it supports poll (Neither 'poll' nor 'select' return
* an appropriate error code). When in doubt, set a suitable timeout value.
*/
static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
{
struct sysfs_open_file *of = sysfs_of(filp);
struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
struct sysfs_open_dirent *od = attr_sd->s_attr.open;
/* need parent for the kobj, grab both */
if (!sysfs_get_active(attr_sd))
goto trigger;
poll_wait(filp, &od->poll, wait);
sysfs_put_active(attr_sd);
if (of->event != atomic_read(&od->event))
goto trigger;
return DEFAULT_POLLMASK;
trigger:
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}
/**
* kernfs_notify - notify a kernfs file
* @sd: file to notify
*
* Notify @sd such that poll(2) on @sd wakes up.
*/
void kernfs_notify(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
unsigned long flags;
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
od = sd->s_attr.open;
if (od) {
atomic_inc(&od->event);
wake_up_interruptible(&od->poll);
}
}
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
}
EXPORT_SYMBOL_GPL(kernfs_notify);
const struct file_operations kernfs_file_operations = {
.read = kernfs_file_read,
.write = kernfs_file_write,
.llseek = generic_file_llseek,
.mmap = kernfs_file_mmap,
.open = kernfs_file_open,
.release = kernfs_file_release,
.poll = kernfs_file_poll,
};
/**
* kernfs_create_file_ns_key - create a file
* @parent: directory to create the file in
* @name: name of the file
* @mode: mode of the file
* @size: size of the file
* @ops: kernfs operations for the file
* @priv: private data for the file
* @ns: optional namespace tag of the file
* @key: lockdep key for the file's active_ref, %NULL to disable lockdep
*
* Returns the created node on success, ERR_PTR() value on error.
*/
struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
const char *name,
umode_t mode, loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
struct lock_class_key *key)
{
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
int rc;
sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
SYSFS_KOBJ_ATTR);
if (!sd)
return ERR_PTR(-ENOMEM);
sd->s_attr.ops = ops;
sd->s_attr.size = size;
sd->s_ns = ns;
sd->priv = priv;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (key) {
lockdep_init_map(&sd->dep_map, "s_active", key, 0);
sd->s_flags |= SYSFS_FLAG_LOCKDEP;
}
#endif
/*
* sd->s_attr.ops is accesible only while holding active ref. We
* need to know whether some ops are implemented outside active
* ref. Cache their existence in flags.
*/
if (ops->seq_show)
sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
if (ops->mmap)
sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
sysfs_addrm_start(&acxt);
rc = sysfs_add_one(&acxt, sd, parent);
sysfs_addrm_finish(&acxt);
if (rc) {
kernfs_put(sd);
return ERR_PTR(rc);
}
return sd;
}

7
fs/kernfs/kernfs-internal.h
View File

@ -142,4 +142,11 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd,
void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
/*
* file.c
*/
extern const struct file_operations kernfs_file_operations;
void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
#endif /* __KERNFS_INTERNAL_H */

802
fs/sysfs/file.c
View File

@ -14,54 +14,12 @@
#include <linux/kobject.h>
#include <linux/kallsyms.h>
#include <linux/slab.h>
#include <linux/fsnotify.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/limits.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/mm.h>
#include "sysfs.h"
/*
* There's one sysfs_open_file for each open file and one sysfs_open_dirent
* for each sysfs_dirent with one or more open files.
*
* sysfs_dirent->s_attr.open points to sysfs_open_dirent. s_attr.open is
* protected by sysfs_open_dirent_lock.
*
* filp->private_data points to seq_file whose ->private points to
* sysfs_open_file. sysfs_open_files are chained at
* sysfs_open_dirent->files, which is protected by sysfs_open_file_mutex.
*/
static DEFINE_SPINLOCK(sysfs_open_dirent_lock);
static DEFINE_MUTEX(sysfs_open_file_mutex);
struct sysfs_open_dirent {
atomic_t refcnt;
atomic_t event;
wait_queue_head_t poll;
struct list_head files; /* goes through sysfs_open_file.list */
};
static struct sysfs_open_file *sysfs_of(struct file *file)
{
return ((struct seq_file *)file->private_data)->private;
}
/*
* Determine the kernfs_ops for the given sysfs_dirent. This function must
* be called while holding an active reference.
*/
static const struct kernfs_ops *kernfs_ops(struct sysfs_dirent *sd)
{
if (sd->s_flags & SYSFS_FLAG_LOCKDEP)
lockdep_assert_held(sd);
return sd->s_attr.ops;
}
#include "../kernfs/kernfs-internal.h"
/*
* Determine ktype->sysfs_ops for the given sysfs_dirent. This function
@ -143,147 +101,6 @@ static ssize_t sysfs_kf_bin_read(struct sysfs_open_file *of, char *buf,
return battr->read(of->file, kobj, battr, buf, pos, count);
}
static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd))
return ERR_PTR(-ENODEV);
ops = kernfs_ops(of->sd);
if (ops->seq_start) {
return ops->seq_start(sf, ppos);
} else {
/*
* The same behavior and code as single_open(). Returns
* !NULL if pos is at the beginning; otherwise, NULL.
*/
return NULL + !*ppos;
}
}
static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops = kernfs_ops(of->sd);
if (ops->seq_next) {
return ops->seq_next(sf, v, ppos);
} else {
/*
* The same behavior and code as single_open(), always
* terminate after the initial read.
*/
++*ppos;
return NULL;
}
}
static void kernfs_seq_stop(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
const struct kernfs_ops *ops = kernfs_ops(of->sd);
if (ops->seq_stop)
ops->seq_stop(sf, v);
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
}
static int kernfs_seq_show(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
of->event = atomic_read(&of->sd->s_attr.open->event);
return of->sd->s_attr.ops->seq_show(sf, v);
}
static const struct seq_operations kernfs_seq_ops = {
.start = kernfs_seq_start,
.next = kernfs_seq_next,
.stop = kernfs_seq_stop,
.show = kernfs_seq_show,
};
/*
* As reading a bin file can have side-effects, the exact offset and bytes
* specified in read(2) call should be passed to the read callback making
* it difficult to use seq_file. Implement simplistic custom buffering for
* bin files.
*/
static ssize_t kernfs_file_direct_read(struct sysfs_open_file *of,
char __user *user_buf, size_t count,
loff_t *ppos)
{
ssize_t len = min_t(size_t, count, PAGE_SIZE);
const struct kernfs_ops *ops;
char *buf;
buf = kmalloc(len, GFP_KERNEL);
if (!buf)
return -ENOMEM;
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
len = -ENODEV;
mutex_unlock(&of->mutex);
goto out_free;
}
ops = kernfs_ops(of->sd);
if (ops->read)
len = ops->read(of, buf, len, *ppos);
else
len = -EINVAL;
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len < 0)
goto out_free;
if (copy_to_user(user_buf, buf, len)) {
len = -EFAULT;
goto out_free;
}
*ppos += len;
out_free:
kfree(buf);
return len;
}
/**
* kernfs_file_read - kernfs vfs read callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*/
static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
if (of->sd->s_flags & SYSFS_FLAG_HAS_SEQ_SHOW)
return seq_read(file, user_buf, count, ppos);
else
return kernfs_file_direct_read(of, user_buf, count, ppos);
}
/* kernfs write callback for regular sysfs files */
static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
@ -319,67 +136,6 @@ static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
return battr->write(of->file, kobj, battr, buf, pos, count);
}
/**
* kernfs_file_write - kernfs vfs write callback
* @file: file pointer
* @user_buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Copy data in from userland and pass it to the matching kernfs write
* operation.
*
* There is no easy way for us to know if userspace is only doing a partial
* write, so we don't support them. We expect the entire buffer to come on
* the first write. Hint: if you're writing a value, first read the file,
* modify only the the value you're changing, then write entire buffer
* back.
*/
static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
struct sysfs_open_file *of = sysfs_of(file);
ssize_t len = min_t(size_t, count, PAGE_SIZE);
const struct kernfs_ops *ops;
char *buf;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
if (copy_from_user(buf, user_buf, len)) {
len = -EFAULT;
goto out_free;
}
buf[len] = '\0'; /* guarantee string termination */
/*
* @of->mutex nests outside active ref and is just to ensure that
* the ops aren't called concurrently for the same open file.
*/
mutex_lock(&of->mutex);
if (!sysfs_get_active(of->sd)) {
mutex_unlock(&of->mutex);
len = -ENODEV;
goto out_free;
}
ops = kernfs_ops(of->sd);
if (ops->write)
len = ops->write(of, buf, len, *ppos);
else
len = -EINVAL;
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len > 0)
*ppos += len;
out_free:
kfree(buf);
return len;
}
static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
struct vm_area_struct *vma)
{
@ -392,490 +148,6 @@ static int sysfs_kf_bin_mmap(struct sysfs_open_file *of,
return battr->mmap(of->file, kobj, battr, vma);
}
static void kernfs_vma_open(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
if (!of->vm_ops)
return;
if (!sysfs_get_active(of->sd))
return;
if (of->vm_ops->open)
of->vm_ops->open(vma);
sysfs_put_active(of->sd);
}
static int kernfs_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = VM_FAULT_SIGBUS;
if (of->vm_ops->fault)
ret = of->vm_ops->fault(vma, vmf);
sysfs_put_active(of->sd);
return ret;
}
static int kernfs_vma_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return VM_FAULT_SIGBUS;
if (!sysfs_get_active(of->sd))
return VM_FAULT_SIGBUS;
ret = 0;
if (of->vm_ops->page_mkwrite)
ret = of->vm_ops->page_mkwrite(vma, vmf);
else
file_update_time(file);
sysfs_put_active(of->sd);
return ret;
}
static int kernfs_vma_access(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return -EINVAL;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = -EINVAL;
if (of->vm_ops->access)
ret = of->vm_ops->access(vma, addr, buf, len, write);
sysfs_put_active(of->sd);
return ret;
}
#ifdef CONFIG_NUMA
static int kernfs_vma_set_policy(struct vm_area_struct *vma,
struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return 0;
if (!sysfs_get_active(of->sd))
return -EINVAL;
ret = 0;
if (of->vm_ops->set_policy)
ret = of->vm_ops->set_policy(vma, new);
sysfs_put_active(of->sd);
return ret;
}
static struct mempolicy *kernfs_vma_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
struct mempolicy *pol;
if (!of->vm_ops)
return vma->vm_policy;
if (!sysfs_get_active(of->sd))
return vma->vm_policy;
pol = vma->vm_policy;
if (of->vm_ops->get_policy)
pol = of->vm_ops->get_policy(vma, addr);
sysfs_put_active(of->sd);
return pol;
}
static int kernfs_vma_migrate(struct vm_area_struct *vma,
const nodemask_t *from, const nodemask_t *to,
unsigned long flags)
{
struct file *file = vma->vm_file;
struct sysfs_open_file *of = sysfs_of(file);
int ret;
if (!of->vm_ops)
return 0;
if (!sysfs_get_active(of->sd))
return 0;
ret = 0;
if (of->vm_ops->migrate)
ret = of->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active(of->sd);
return ret;
}
#endif
static const struct vm_operations_struct kernfs_vm_ops = {
.open = kernfs_vma_open,
.fault = kernfs_vma_fault,
.page_mkwrite = kernfs_vma_page_mkwrite,
.access = kernfs_vma_access,
#ifdef CONFIG_NUMA
.set_policy = kernfs_vma_set_policy,
.get_policy = kernfs_vma_get_policy,
.migrate = kernfs_vma_migrate,
#endif
};
static int kernfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct sysfs_open_file *of = sysfs_of(file);
const struct kernfs_ops *ops;
int rc;
mutex_lock(&of->mutex);
rc = -ENODEV;
if (!sysfs_get_active(of->sd))
goto out_unlock;
ops = kernfs_ops(of->sd);
if (ops->mmap)
rc = ops->mmap(of, vma);
if (rc)
goto out_put;
/*
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
* to satisfy versions of X which crash if the mmap fails: that
* substitutes a new vm_file, and we don't then want bin_vm_ops.
*/
if (vma->vm_file != file)
goto out_put;
rc = -EINVAL;
if (of->mmapped && of->vm_ops != vma->vm_ops)
goto out_put;
/*
* It is not possible to successfully wrap close.
* So error if someone is trying to use close.
*/
rc = -EINVAL;
if (vma->vm_ops && vma->vm_ops->close)
goto out_put;
rc = 0;
of->mmapped = 1;
of->vm_ops = vma->vm_ops;
vma->vm_ops = &kernfs_vm_ops;
out_put:
sysfs_put_active(of->sd);
out_unlock:
mutex_unlock(&of->mutex);
return rc;
}
/**
* sysfs_get_open_dirent - get or create sysfs_open_dirent
* @sd: target sysfs_dirent
* @of: sysfs_open_file for this instance of open
*
* If @sd->s_attr.open exists, increment its reference count;
* otherwise, create one. @of is chained to the files list.
*
* LOCKING:
* Kernel thread context (may sleep).
*
* RETURNS:
* 0 on success, -errno on failure.
*/
static int sysfs_get_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_file *of)
{
struct sysfs_open_dirent *od, *new_od = NULL;
retry:
mutex_lock(&sysfs_open_file_mutex);
spin_lock_irq(&sysfs_open_dirent_lock);
if (!sd->s_attr.open && new_od) {
sd->s_attr.open = new_od;
new_od = NULL;
}
od = sd->s_attr.open;
if (od) {
atomic_inc(&od->refcnt);
list_add_tail(&of->list, &od->files);
}
spin_unlock_irq(&sysfs_open_dirent_lock);
mutex_unlock(&sysfs_open_file_mutex);
if (od) {
kfree(new_od);
return 0;
}
/* not there, initialize a new one and retry */
new_od = kmalloc(sizeof(*new_od), GFP_KERNEL);
if (!new_od)
return -ENOMEM;
atomic_set(&new_od->refcnt, 0);
atomic_set(&new_od->event, 1);
init_waitqueue_head(&new_od->poll);
INIT_LIST_HEAD(&new_od->files);
goto retry;
}
/**
* sysfs_put_open_dirent - put sysfs_open_dirent
* @sd: target sysfs_dirent
* @of: associated sysfs_open_file
*
* Put @sd->s_attr.open and unlink @of from the files list. If
* reference count reaches zero, disassociate and free it.
*
* LOCKING:
* None.
*/
static void sysfs_put_open_dirent(struct sysfs_dirent *sd,
struct sysfs_open_file *of)
{
struct sysfs_open_dirent *od = sd->s_attr.open;
unsigned long flags;
mutex_lock(&sysfs_open_file_mutex);
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
if (of)
list_del(&of->list);
if (atomic_dec_and_test(&od->refcnt))
sd->s_attr.open = NULL;
else
od = NULL;
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
mutex_unlock(&sysfs_open_file_mutex);
kfree(od);
}
static int kernfs_file_open(struct inode *inode, struct file *file)
{
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
const struct kernfs_ops *ops;
struct sysfs_open_file *of;
bool has_read, has_write, has_mmap;
int error = -EACCES;
if (!sysfs_get_active(attr_sd))
return -ENODEV;
ops = kernfs_ops(attr_sd);
has_read = ops->seq_show || ops->read || ops->mmap;
has_write = ops->write || ops->mmap;
has_mmap = ops->mmap;
/* check perms and supported operations */
if ((file->f_mode & FMODE_WRITE) &&
(!(inode->i_mode & S_IWUGO) || !has_write))
goto err_out;
if ((file->f_mode & FMODE_READ) &&
(!(inode->i_mode & S_IRUGO) || !has_read))
goto err_out;
/* allocate a sysfs_open_file for the file */
error = -ENOMEM;
of = kzalloc(sizeof(struct sysfs_open_file), GFP_KERNEL);
if (!of)
goto err_out;
/*
* The following is done to give a different lockdep key to
* @of->mutex for files which implement mmap. This is a rather
* crude way to avoid false positive lockdep warning around
* mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
* reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
* which mm->mmap_sem nests, while holding @of->mutex. As each
* open file has a separate mutex, it's okay as long as those don't
* happen on the same file. At this point, we can't easily give
* each file a separate locking class. Let's differentiate on
* whether the file has mmap or not for now.
*/
if (has_mmap)
mutex_init(&of->mutex);
else
mutex_init(&of->mutex);
of->sd = attr_sd;
of->file = file;
/*
* Always instantiate seq_file even if read access doesn't use
* seq_file or is not requested. This unifies private data access
* and readable regular files are the vast majority anyway.
*/
if (ops->seq_show)
error = seq_open(file, &kernfs_seq_ops);
else
error = seq_open(file, NULL);
if (error)
goto err_free;
((struct seq_file *)file->private_data)->private = of;
/* seq_file clears PWRITE unconditionally, restore it if WRITE */
if (file->f_mode & FMODE_WRITE)
file->f_mode |= FMODE_PWRITE;
/* make sure we have open dirent struct */
error = sysfs_get_open_dirent(attr_sd, of);
if (error)
goto err_close;
/* open succeeded, put active references */
sysfs_put_active(attr_sd);
return 0;
err_close:
seq_release(inode, file);
err_free:
kfree(of);
err_out:
sysfs_put_active(attr_sd);
return error;
}
static int kernfs_file_release(struct inode *inode, struct file *filp)
{
struct sysfs_dirent *sd = filp->f_path.dentry->d_fsdata;
struct sysfs_open_file *of = sysfs_of(filp);
sysfs_put_open_dirent(sd, of);
seq_release(inode, filp);
kfree(of);
return 0;
}
void sysfs_unmap_bin_file(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
struct sysfs_open_file *of;
if (!(sd->s_flags & SYSFS_FLAG_HAS_MMAP))
return;
spin_lock_irq(&sysfs_open_dirent_lock);
od = sd->s_attr.open;
if (od)
atomic_inc(&od->refcnt);
spin_unlock_irq(&sysfs_open_dirent_lock);
if (!od)
return;
mutex_lock(&sysfs_open_file_mutex);
list_for_each_entry(of, &od->files, list) {
struct inode *inode = file_inode(of->file);
unmap_mapping_range(inode->i_mapping, 0, 0, 1);
}
mutex_unlock(&sysfs_open_file_mutex);
sysfs_put_open_dirent(sd, NULL);
}
/* Sysfs attribute files are pollable. The idea is that you read
* the content and then you use 'poll' or 'select' to wait for
* the content to change. When the content changes (assuming the
* manager for the kobject supports notification), poll will
* return POLLERR|POLLPRI, and select will return the fd whether
* it is waiting for read, write, or exceptions.
* Once poll/select indicates that the value has changed, you
* need to close and re-open the file, or seek to 0 and read again.
* Reminder: this only works for attributes which actively support
* it, and it is not possible to test an attribute from userspace
* to see if it supports poll (Neither 'poll' nor 'select' return
* an appropriate error code). When in doubt, set a suitable timeout value.
*/
static unsigned int kernfs_file_poll(struct file *filp, poll_table *wait)
{
struct sysfs_open_file *of = sysfs_of(filp);
struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
struct sysfs_open_dirent *od = attr_sd->s_attr.open;
/* need parent for the kobj, grab both */
if (!sysfs_get_active(attr_sd))
goto trigger;
poll_wait(filp, &od->poll, wait);
sysfs_put_active(attr_sd);
if (of->event != atomic_read(&od->event))
goto trigger;
return DEFAULT_POLLMASK;
trigger:
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}
/**
* kernfs_notify - notify a kernfs file
* @sd: file to notify
*
* Notify @sd such that poll(2) on @sd wakes up.
*/
void kernfs_notify(struct sysfs_dirent *sd)
{
struct sysfs_open_dirent *od;
unsigned long flags;
spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
if (!WARN_ON(sysfs_type(sd) != SYSFS_KOBJ_ATTR)) {
od = sd->s_attr.open;
if (od) {
atomic_inc(&od->event);
wake_up_interruptible(&od->poll);
}
}
spin_unlock_irqrestore(&sysfs_open_dirent_lock, flags);
}
EXPORT_SYMBOL_GPL(kernfs_notify);
void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
{
struct sysfs_dirent *sd = k->sd, *tmp;
@ -898,16 +170,6 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
}
EXPORT_SYMBOL_GPL(sysfs_notify);
const struct file_operations kernfs_file_operations = {
.read = kernfs_file_read,
.write = kernfs_file_write,
.llseek = generic_file_llseek,
.mmap = kernfs_file_mmap,
.open = kernfs_file_open,
.release = kernfs_file_release,
.poll = kernfs_file_poll,
};
static const struct kernfs_ops sysfs_file_kfops_empty = {
};
@ -996,68 +258,6 @@ int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
return 0;
}
/**
* kernfs_create_file_ns_key - create a file
* @parent: directory to create the file in
* @name: name of the file
* @mode: mode of the file
* @size: size of the file
* @ops: kernfs operations for the file
* @priv: private data for the file
* @ns: optional namespace tag of the file
* @key: lockdep key for the file's active_ref, %NULL to disable lockdep
*
* Returns the created node on success, ERR_PTR() value on error.
*/
struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
const char *name,
umode_t mode, loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
struct lock_class_key *key)
{
struct sysfs_addrm_cxt acxt;
struct sysfs_dirent *sd;
int rc;
sd = sysfs_new_dirent(name, (mode & S_IALLUGO) | S_IFREG,
SYSFS_KOBJ_ATTR);
if (!sd)
return ERR_PTR(-ENOMEM);
sd->s_attr.ops = ops;
sd->s_attr.size = size;
sd->s_ns = ns;
sd->priv = priv;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (key) {
lockdep_init_map(&sd->dep_map, "s_active", key, 0);
sd->s_flags |= SYSFS_FLAG_LOCKDEP;
}
#endif
/*
* sd->s_attr.ops is accesible only while holding active ref. We
* need to know whether some ops are implemented outside active
* ref. Cache their existence in flags.
*/
if (ops->seq_show)
sd->s_flags |= SYSFS_FLAG_HAS_SEQ_SHOW;
if (ops->mmap)
sd->s_flags |= SYSFS_FLAG_HAS_MMAP;
sysfs_addrm_start(&acxt);
rc = sysfs_add_one(&acxt, sd, parent);
sysfs_addrm_finish(&acxt);
if (rc) {
kernfs_put(sd);
return ERR_PTR(rc);
}
return sd;
}
int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
bool is_bin)
{

4
fs/sysfs/sysfs.h
View File

@ -41,15 +41,11 @@ void sysfs_warn_dup(struct sysfs_dirent *parent, const char *name);
/*
* file.c
*/
extern const struct file_operations kernfs_file_operations;
int sysfs_add_file(struct sysfs_dirent *dir_sd,
const struct attribute *attr, bool is_bin);
int sysfs_add_file_mode_ns(struct sysfs_dirent *dir_sd,
const struct attribute *attr, bool is_bin,
umode_t amode, const void *ns);
void sysfs_unmap_bin_file(struct sysfs_dirent *sd);
/*
* symlink.c