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sysfs, kernfs: prepare write path for kernfs

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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>
This commit is contained in:
Tejun Heo 2013-11-28 14:54:17 -05:00 committed by Greg Kroah-Hartman
parent c2b19daf67
commit 50b38ca086
1 changed files with 53 additions and 56 deletions
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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,
return seq_read(file, user_buf, count, ppos);
}
/**
* flush_write_buffer - push buffer to kobject
* @of: open file
* @buf: data buffer for file
* @off: file offset to write to
* @count: number of bytes
*
* Get the correct pointers for the kobject and the attribute we're dealing
* with, then call the store() method for it with @buf.
*/
static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
size_t count)
/* 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)
{
const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
struct kobject *kobj = of->sd->s_parent->priv;
int rc = 0;
/*
* Need @of->sd for attr and ops, its parent for kobj. @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);
return -ENODEV;
if (!count)
return 0;
return ops->store(kobj, of->sd->priv, buf, count);
}
/* kernfs write callback for bin sysfs files */
static ssize_t sysfs_kf_bin_write(struct sysfs_open_file *of, char *buf,
size_t count, loff_t pos)
{
struct bin_attribute *battr = of->sd->priv;
struct kobject *kobj = of->sd->s_parent->priv;
loff_t size = file_inode(of->file)->i_size;
if (size) {
if (size <= pos)
return 0;
count = min_t(ssize_t, count, size - pos);
}
if (!count)
return 0;
if (sysfs_is_bin(of->sd)) {
struct bin_attribute *battr = of->sd->priv;
if (!battr->write)
return -EIO;
rc = -EIO;
if (battr->write)
rc = battr->write(of->file, kobj, battr, buf, off,
count);
} else {
const struct sysfs_ops *ops = sysfs_file_ops(of->sd);
rc = ops->store(kobj, of->sd->priv, buf, count);
}
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
return rc;
return battr->write(of->file, kobj, battr, buf, pos, count);
}
/**
* sysfs_write_file - write an attribute
* 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
* sysfs_ops->store() by invoking flush_write_buffer().
* 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
@ -329,23 +318,13 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
* 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 *user_buf,
size_t count, loff_t *ppos)
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);
loff_t size = file_inode(file)->i_size;
char *buf;
if (sysfs_is_bin(of->sd) && size) {
if (size <= *ppos)
return 0;
len = min_t(ssize_t, len, size - *ppos);
}
if (!len)
return 0;
buf = kmalloc(len + 1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
@ -356,7 +335,25 @@ static ssize_t sysfs_write_file(struct file *file, const char __user *user_buf,
}
buf[len] = '\0'; /* guarantee string termination */
len = flush_write_buffer(of, buf, *ppos, len);
/*
* @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;
}
if (sysfs_is_bin(of->sd))
len = sysfs_kf_bin_write(of, buf, len, *ppos);
else
len = sysfs_kf_write(of, buf, len, *ppos);
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);
if (len > 0)
*ppos += len;
out_free:
@ -878,7 +875,7 @@ EXPORT_SYMBOL_GPL(sysfs_notify);
const struct file_operations sysfs_file_operations = {
.read = kernfs_file_read,
.write = sysfs_write_file,
.write = kernfs_file_write,
.llseek = generic_file_llseek,
.open = sysfs_open_file,
.release = sysfs_release,
@ -887,7 +884,7 @@ const struct file_operations sysfs_file_operations = {
const struct file_operations sysfs_bin_operations = {
.read = kernfs_file_read,
.write = sysfs_write_file,
.write = kernfs_file_write,
.llseek = generic_file_llseek,
.mmap = sysfs_bin_mmap,
.open = sysfs_open_file,