Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
new file mode 100644
index 0000000..352f966a
--- /dev/null
+++ b/fs/sysfs/file.c
@@ -0,0 +1,447 @@
+/*
+ * file.c - operations for regular (text) files.
+ */
+
+#include <linux/module.h>
+#include <linux/dnotify.h>
+#include <linux/kobject.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include "sysfs.h"
+
+#define to_subsys(k) container_of(k,struct subsystem,kset.kobj)
+#define to_sattr(a) container_of(a,struct subsys_attribute,attr)
+
+/**
+ * Subsystem file operations.
+ * These operations allow subsystems to have files that can be
+ * read/written.
+ */
+static ssize_t
+subsys_attr_show(struct kobject * kobj, struct attribute * attr, char * page)
+{
+ struct subsystem * s = to_subsys(kobj);
+ struct subsys_attribute * sattr = to_sattr(attr);
+ ssize_t ret = 0;
+
+ if (sattr->show)
+ ret = sattr->show(s,page);
+ return ret;
+}
+
+static ssize_t
+subsys_attr_store(struct kobject * kobj, struct attribute * attr,
+ const char * page, size_t count)
+{
+ struct subsystem * s = to_subsys(kobj);
+ struct subsys_attribute * sattr = to_sattr(attr);
+ ssize_t ret = 0;
+
+ if (sattr->store)
+ ret = sattr->store(s,page,count);
+ return ret;
+}
+
+static struct sysfs_ops subsys_sysfs_ops = {
+ .show = subsys_attr_show,
+ .store = subsys_attr_store,
+};
+
+
+struct sysfs_buffer {
+ size_t count;
+ loff_t pos;
+ char * page;
+ struct sysfs_ops * ops;
+ struct semaphore sem;
+ int needs_read_fill;
+};
+
+
+/**
+ * fill_read_buffer - allocate and fill buffer from object.
+ * @dentry: dentry pointer.
+ * @buffer: data buffer for file.
+ *
+ * Allocate @buffer->page, if it hasn't been already, then call the
+ * kobject'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 sysfs_buffer * buffer)
+{
+ struct attribute * attr = to_attr(dentry);
+ struct kobject * kobj = to_kobj(dentry->d_parent);
+ struct sysfs_ops * ops = buffer->ops;
+ int ret = 0;
+ ssize_t count;
+
+ if (!buffer->page)
+ buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
+ if (!buffer->page)
+ return -ENOMEM;
+
+ count = ops->show(kobj,attr,buffer->page);
+ buffer->needs_read_fill = 0;
+ BUG_ON(count > (ssize_t)PAGE_SIZE);
+ if (count >= 0)
+ buffer->count = count;
+ else
+ ret = count;
+ return ret;
+}
+
+
+/**
+ * flush_read_buffer - push buffer to userspace.
+ * @buffer: data buffer for file.
+ * @userbuf: user-passed buffer.
+ * @count: number of bytes requested.
+ * @ppos: file position.
+ *
+ * Copy the buffer we filled in fill_read_buffer() to userspace.
+ * This is done at the reader's leisure, copying and advancing
+ * the amount they specify each time.
+ * This may be called continuously until the buffer is empty.
+ */
+static int flush_read_buffer(struct sysfs_buffer * buffer, char __user * buf,
+ size_t count, loff_t * ppos)
+{
+ int error;
+
+ if (*ppos > buffer->count)
+ return 0;
+
+ if (count > (buffer->count - *ppos))
+ count = buffer->count - *ppos;
+
+ error = copy_to_user(buf,buffer->page + *ppos,count);
+ if (!error)
+ *ppos += count;
+ return error ? -EFAULT : count;
+}
+
+/**
+ * sysfs_read_file - read an attribute.
+ * @file: file pointer.
+ * @buf: buffer to fill.
+ * @count: number of bytes to read.
+ * @ppos: starting offset in file.
+ *
+ * Userspace wants to read an attribute file. The attribute descriptor
+ * is in the file's ->d_fsdata. The target object is in the directory's
+ * ->d_fsdata.
+ *
+ * We call fill_read_buffer() to allocate and fill the buffer from the
+ * object's show() method exactly once (if the read is happening from
+ * the beginning of the file). That should fill the entire buffer with
+ * all the data the object has to offer for that attribute.
+ * We then call flush_read_buffer() to copy the buffer to userspace
+ * in the increments specified.
+ */
+
+static ssize_t
+sysfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ struct sysfs_buffer * buffer = file->private_data;
+ ssize_t retval = 0;
+
+ down(&buffer->sem);
+ if (buffer->needs_read_fill) {
+ if ((retval = fill_read_buffer(file->f_dentry,buffer)))
+ goto out;
+ }
+ pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
+ __FUNCTION__,count,*ppos,buffer->page);
+ retval = flush_read_buffer(buffer,buf,count,ppos);
+out:
+ up(&buffer->sem);
+ return retval;
+}
+
+
+/**
+ * fill_write_buffer - copy buffer from userspace.
+ * @buffer: data buffer for file.
+ * @userbuf: data from user.
+ * @count: number of bytes in @userbuf.
+ *
+ * Allocate @buffer->page if it hasn't been already, then
+ * copy the user-supplied buffer into it.
+ */
+
+static int
+fill_write_buffer(struct sysfs_buffer * buffer, const char __user * buf, size_t count)
+{
+ int error;
+
+ if (!buffer->page)
+ buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+ if (!buffer->page)
+ return -ENOMEM;
+
+ if (count >= PAGE_SIZE)
+ count = PAGE_SIZE - 1;
+ error = copy_from_user(buffer->page,buf,count);
+ buffer->needs_read_fill = 1;
+ return error ? -EFAULT : count;
+}
+
+
+/**
+ * flush_write_buffer - push buffer to kobject.
+ * @file: file pointer.
+ * @buffer: data buffer for file.
+ *
+ * Get the correct pointers for the kobject 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 sysfs_buffer * buffer, size_t count)
+{
+ struct attribute * attr = to_attr(dentry);
+ struct kobject * kobj = to_kobj(dentry->d_parent);
+ struct sysfs_ops * ops = buffer->ops;
+
+ return ops->store(kobj,attr,buffer->page,count);
+}
+
+
+/**
+ * sysfs_write_file - write an attribute.
+ * @file: file pointer
+ * @buf: data to write
+ * @count: number of bytes
+ * @ppos: starting offset
+ *
+ * Similar to sysfs_read_file(), though working in the opposite direction.
+ * We allocate and fill the data from the user in fill_write_buffer(),
+ * then push it to the kobject in flush_write_buffer().
+ * 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
+sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct sysfs_buffer * buffer = file->private_data;
+ ssize_t len;
+
+ down(&buffer->sem);
+ len = fill_write_buffer(buffer, buf, count);
+ if (len > 0)
+ len = flush_write_buffer(file->f_dentry, buffer, len);
+ if (len > 0)
+ *ppos += len;
+ up(&buffer->sem);
+ return len;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+ struct kobject *kobj = sysfs_get_kobject(file->f_dentry->d_parent);
+ struct attribute * attr = to_attr(file->f_dentry);
+ struct sysfs_buffer * buffer;
+ struct sysfs_ops * ops = NULL;
+ int error = 0;
+
+ if (!kobj || !attr)
+ goto Einval;
+
+ /* Grab the module reference for this attribute if we have one */
+ if (!try_module_get(attr->owner)) {
+ error = -ENODEV;
+ goto Done;
+ }
+
+ /* if the kobject has no ktype, then we assume that it is a subsystem
+ * itself, and use ops for it.
+ */
+ if (kobj->kset && kobj->kset->ktype)
+ ops = kobj->kset->ktype->sysfs_ops;
+ else if (kobj->ktype)
+ ops = kobj->ktype->sysfs_ops;
+ else
+ ops = &subsys_sysfs_ops;
+
+ /* No sysfs operations, either from having no subsystem,
+ * or the subsystem have no operations.
+ */
+ if (!ops)
+ goto Eaccess;
+
+ /* File needs write support.
+ * The inode's perms must say it's ok,
+ * and we must have a store method.
+ */
+ if (file->f_mode & FMODE_WRITE) {
+
+ if (!(inode->i_mode & S_IWUGO) || !ops->store)
+ goto Eaccess;
+
+ }
+
+ /* File needs read support.
+ * The inode's perms must say it's ok, and we there
+ * must be a show method for it.
+ */
+ if (file->f_mode & FMODE_READ) {
+ if (!(inode->i_mode & S_IRUGO) || !ops->show)
+ goto Eaccess;
+ }
+
+ /* No error? Great, allocate a buffer for the file, and store it
+ * it in file->private_data for easy access.
+ */
+ buffer = kmalloc(sizeof(struct sysfs_buffer),GFP_KERNEL);
+ if (buffer) {
+ memset(buffer,0,sizeof(struct sysfs_buffer));
+ init_MUTEX(&buffer->sem);
+ buffer->needs_read_fill = 1;
+ buffer->ops = ops;
+ file->private_data = buffer;
+ } else
+ error = -ENOMEM;
+ goto Done;
+
+ Einval:
+ error = -EINVAL;
+ goto Done;
+ Eaccess:
+ error = -EACCES;
+ module_put(attr->owner);
+ Done:
+ if (error && kobj)
+ kobject_put(kobj);
+ return error;
+}
+
+static int sysfs_open_file(struct inode * inode, struct file * filp)
+{
+ return check_perm(inode,filp);
+}
+
+static int sysfs_release(struct inode * inode, struct file * filp)
+{
+ struct kobject * kobj = to_kobj(filp->f_dentry->d_parent);
+ struct attribute * attr = to_attr(filp->f_dentry);
+ struct module * owner = attr->owner;
+ struct sysfs_buffer * buffer = filp->private_data;
+
+ if (kobj)
+ kobject_put(kobj);
+ /* After this point, attr should not be accessed. */
+ module_put(owner);
+
+ if (buffer) {
+ if (buffer->page)
+ free_page((unsigned long)buffer->page);
+ kfree(buffer);
+ }
+ return 0;
+}
+
+struct file_operations sysfs_file_operations = {
+ .read = sysfs_read_file,
+ .write = sysfs_write_file,
+ .llseek = generic_file_llseek,
+ .open = sysfs_open_file,
+ .release = sysfs_release,
+};
+
+
+int sysfs_add_file(struct dentry * dir, const struct attribute * attr, int type)
+{
+ struct sysfs_dirent * parent_sd = dir->d_fsdata;
+ umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
+ int error = 0;
+
+ down(&dir->d_inode->i_sem);
+ error = sysfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+ up(&dir->d_inode->i_sem);
+
+ return error;
+}
+
+
+/**
+ * sysfs_create_file - create an attribute file for an object.
+ * @kobj: object we're creating for.
+ * @attr: atrribute descriptor.
+ */
+
+int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
+{
+ BUG_ON(!kobj || !kobj->dentry || !attr);
+
+ return sysfs_add_file(kobj->dentry, attr, SYSFS_KOBJ_ATTR);
+
+}
+
+
+/**
+ * sysfs_update_file - update the modified timestamp on an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ *
+ * Also call dnotify for the dentry, which lots of userspace programs
+ * use.
+ */
+int sysfs_update_file(struct kobject * kobj, const struct attribute * attr)
+{
+ struct dentry * dir = kobj->dentry;
+ struct dentry * victim;
+ int res = -ENOENT;
+
+ down(&dir->d_inode->i_sem);
+ victim = sysfs_get_dentry(dir, attr->name);
+ if (!IS_ERR(victim)) {
+ /* make sure dentry is really there */
+ if (victim->d_inode &&
+ (victim->d_parent->d_inode == dir->d_inode)) {
+ victim->d_inode->i_mtime = CURRENT_TIME;
+ dnotify_parent(victim, DN_MODIFY);
+
+ /**
+ * Drop reference from initial sysfs_get_dentry().
+ */
+ dput(victim);
+ res = 0;
+ } else
+ d_drop(victim);
+
+ /**
+ * Drop the reference acquired from sysfs_get_dentry() above.
+ */
+ dput(victim);
+ }
+ up(&dir->d_inode->i_sem);
+
+ return res;
+}
+
+
+/**
+ * sysfs_remove_file - remove an object attribute.
+ * @kobj: object we're acting for.
+ * @attr: attribute descriptor.
+ *
+ * Hash the attribute name and kill the victim.
+ */
+
+void sysfs_remove_file(struct kobject * kobj, const struct attribute * attr)
+{
+ sysfs_hash_and_remove(kobj->dentry,attr->name);
+}
+
+
+EXPORT_SYMBOL_GPL(sysfs_create_file);
+EXPORT_SYMBOL_GPL(sysfs_remove_file);
+EXPORT_SYMBOL_GPL(sysfs_update_file);
+
