sysfs, kernfs: prepare write path for kernfs
We're in the process of separating out core sysfs functionality into kernfs which will deal with sysfs_dirents directly. This patch rearranges write path so that the kernfs and sysfs parts are separate. kernfs_file_write() handles all boilerplate work including buffer management and locking and invokes sysfs_kf_write() or sysfs_kf_bin_write() depending on the file type which deals with the interaction with kobj store or bin_attribute write method. While this patch changes the order of some operations, it shouldn't change any visible behavior. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Родитель
c2b19daf67
Коммит
50b38ca086
109
fs/sysfs/file.c
109
fs/sysfs/file.c
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@ -267,61 +267,50 @@ static ssize_t kernfs_file_read(struct file *file, char __user *user_buf,
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return seq_read(file, user_buf, count, ppos);
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}
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/**
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* flush_write_buffer - push buffer to kobject
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* @of: open file
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* @buf: data buffer for file
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* @off: file offset to write to
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* @count: number of bytes
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*
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* Get the correct pointers for the kobject and the attribute we're dealing
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* with, then call the store() method for it with @buf.
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*/
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static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
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size_t count)
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/* kernfs write callback for regular sysfs files */
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static ssize_t sysfs_kf_write(struct sysfs_open_file *of, char *buf,
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size_t count, loff_t pos)
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{
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const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
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struct kobject *kobj = of->sd->s_parent->priv;
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int rc = 0;
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/*
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* Need @of->sd for attr and ops, its parent for kobj. @of->mutex
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* nests outside active ref and is just to ensure that the ops
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* aren't called concurrently for the same open file.
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*/
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mutex_lock(&of->mutex);
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if (!sysfs_get_active(of->sd)) {
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mutex_unlock(&of->mutex);
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return -ENODEV;
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if (!count)
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return 0;
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return ops->store(kobj, of->sd->priv, buf, count);
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}
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/* kernfs write callback for bin sysfs files */
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static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
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size_t count, loff_t pos)
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{
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struct bin_attribute *battr = of->sd->priv;
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struct kobject *kobj = of->sd->s_parent->priv;
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loff_t size = file_inode(of->file)->i_size;
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if (size) {
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if (size <= pos)
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return 0;
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count = min_t(ssize_t, count, size - pos);
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}
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if (!count)
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return 0;
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if (sysfs_is_bin(of->sd)) {
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struct bin_attribute *battr = of->sd->priv;
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if (!battr->write)
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return -EIO;
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rc = -EIO;
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if (battr->write)
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rc = battr->write(of->file, kobj, battr, buf, off,
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count);
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} else {
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const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
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rc = ops->store(kobj, of->sd->priv, buf, count);
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}
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sysfs_put_active(of->sd);
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mutex_unlock(&of->mutex);
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return rc;
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return battr->write(of->file, kobj, battr, buf, pos, count);
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}
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/**
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* sysfs_write_file - write an attribute
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* kernfs_file_write - kernfs vfs write callback
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* @file: file pointer
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* @user_buf: data to write
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* @count: number of bytes
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* @ppos: starting offset
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*
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* Copy data in from userland and pass it to the matching
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* sysfs_ops->store() by invoking flush_write_buffer().
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* Copy data in from userland and pass it to the matching kernfs write
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* operation.
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*
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* There is no easy way for us to know if userspace is only doing a partial
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* write, so we don't support them. We expect the entire buffer to come on
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@ -329,23 +318,13 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
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* modify only the the value you're changing, then write entire buffer
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* back.
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*/
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static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
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size_t count, loff_t *ppos)
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static ssize_t kernfs_file_write(struct file *file, const char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct sysfs_open_file *of = sysfs_of(file);
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ssize_t len = min_t(size_t, count, PAGE_SIZE);
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loff_t size = file_inode(file)->i_size;
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char *buf;
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if (sysfs_is_bin(of->sd) && size) {
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if (size <= *ppos)
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return 0;
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len = min_t(ssize_t, len, size - *ppos);
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}
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if (!len)
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return 0;
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buf = kmalloc(len + 1, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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@ -356,7 +335,25 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
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}
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buf[len] = '\0'; /* guarantee string termination */
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len = flush_write_buffer(of, buf, *ppos, len);
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/*
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* @of->mutex nests outside active ref and is just to ensure that
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* the ops aren't called concurrently for the same open file.
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*/
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mutex_lock(&of->mutex);
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if (!sysfs_get_active(of->sd)) {
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mutex_unlock(&of->mutex);
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len = -ENODEV;
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goto out_free;
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}
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if (sysfs_is_bin(of->sd))
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len = sysfs_kf_bin_write(of, buf, len, *ppos);
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else
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len = sysfs_kf_write(of, buf, len, *ppos);
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sysfs_put_active(of->sd);
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mutex_unlock(&of->mutex);
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if (len > 0)
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*ppos += len;
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out_free:
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@ -878,7 +875,7 @@ EXPORT_SYMBOL_GPL(sysfs_notify);
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const struct file_operations sysfs_file_operations = {
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.read = kernfs_file_read,
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.write = sysfs_write_file,
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.write = kernfs_file_write,
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.llseek = generic_file_llseek,
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.open = sysfs_open_file,
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.release = sysfs_release,
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@ -887,7 +884,7 @@ const struct file_operations sysfs_file_operations = {
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const struct file_operations sysfs_bin_operations = {
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.read = kernfs_file_read,
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.write = sysfs_write_file,
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.write = kernfs_file_write,
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.llseek = generic_file_llseek,
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.mmap = sysfs_bin_mmap,
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.open = sysfs_open_file,
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