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configfs updates for Linux 5.13

Browse Source 
- fix a memleak in configfs_release_bin_file (Chung-Chiang Cheng)
  - implement the .read_iter and .write_iter (Bart Van Assche)
  - minor cleanups (Bart Van Assche, me)
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Merge tag 'configfs-5.13' of git://git.infradead.org/users/hch/configfs

Pull configfs updates from Christoph Hellwig:

 - fix a memleak in configfs_release_bin_file (Chung-Chiang Cheng)

 - implement the .read_iter and .write_iter (Bart Van Assche)

 - minor cleanups (Bart Van Assche, me)

* tag 'configfs-5.13' of git://git.infradead.org/users/hch/configfs:
  configfs: simplify configfs_release_bin_file
  configfs: fix memleak in configfs_release_bin_file
  configfs: implement the .read_iter and .write_iter methods
  configfs: drop pointless kerneldoc comments
  configfs: fix the kerneldoc comment for configfs_create_bin_file
This commit is contained in:
Linus Torvalds 2021-07-02 14:13:21 -07:00
commit ced4cca754
1 changed files with 51 additions and 130 deletions
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181
fs/configfs/file.c
View File

@ -14,7 +14,7 @@
#include <linux/mutex.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/configfs.h>
#include "configfs_internal.h"
@ -77,28 +77,9 @@ static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
return 0;
}
/**
* configfs_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 item is in the directory's
* ->d_fsdata.
*
* We call fill_read_buffer() to allocate and fill the buffer from the
* item'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 item 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
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0;
@ -108,43 +89,24 @@ configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *pp
if (retval)
goto out;
}
pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n",
__func__, count, *ppos, buffer->page);
retval = simple_read_from_buffer(buf, count, ppos, buffer->page,
buffer->count);
pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
__func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
retval = copy_to_iter(buffer->page, buffer->count, to);
iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
out:
mutex_unlock(&buffer->mutex);
return retval;
}
/**
* configfs_read_bin_file - read a binary attribute.
* @file: file pointer.
* @buf: buffer to fill.
* @count: number of bytes to read.
* @ppos: starting offset in file.
*
* Userspace wants to read a binary attribute file. The attribute
* descriptor is in the file's ->d_fsdata. The target item is in the
* directory's ->d_fsdata.
*
* We check whether we need to refill the buffer. If so we will
* call the attributes' attr->read() twice. The first time we
* will pass a NULL as a buffer pointer, which the attributes' method
* will use to return the size of the buffer required. If no error
* occurs we will allocate the buffer using vmalloc and call
* attr->read() again passing that buffer as an argument.
* Then we just copy to user-space using simple_read_from_buffer.
*/
static ssize_t
configfs_read_bin_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct configfs_fragment *frag = to_frag(file);
struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0;
ssize_t len = min_t(size_t, count, PAGE_SIZE);
ssize_t len;
mutex_lock(&buffer->mutex);
@ -200,42 +162,31 @@ configfs_read_bin_file(struct file *file, char __user *buf,
buffer->needs_read_fill = 0;
}
retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
buffer->bin_buffer_size);
retval = copy_to_iter(buffer->bin_buffer, buffer->bin_buffer_size, to);
iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
out:
mutex_unlock(&buffer->mutex);
return retval;
}
/**
* fill_write_buffer - copy buffer from userspace.
* @buffer: data buffer for file.
* @buf: 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 configfs_buffer * buffer, const char __user * buf, size_t count)
static int fill_write_buffer(struct configfs_buffer *buffer,
struct iov_iter *from)
{
int error;
int copied;
if (!buffer->page)
buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
if (!buffer->page)
return -ENOMEM;
if (count >= SIMPLE_ATTR_SIZE)
count = SIMPLE_ATTR_SIZE - 1;
error = copy_from_user(buffer->page,buf,count);
copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
buffer->needs_read_fill = 1;
/* if buf is assumed to contain a string, terminate it by \0,
* so e.g. sscanf() can scan the string easily */
buffer->page[count] = 0;
return error ? -EFAULT : count;
buffer->page[copied] = 0;
return copied ? : -EFAULT;
}
static int
@ -252,58 +203,36 @@ flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t cou
}
/**
* configfs_write_file - write an attribute.
* @file: file pointer
* @buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Similar to configfs_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 config_item 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 value you're changing, then write entire buffer back.
/*
* 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 value
* you're changing, then write entire buffer back.
*/
static ssize_t
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data;
ssize_t len;
mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count);
len = fill_write_buffer(buffer, from);
if (len > 0)
len = flush_write_buffer(file, buffer, len);
if (len > 0)
*ppos += len;
iocb->ki_pos += len;
mutex_unlock(&buffer->mutex);
return len;
}
/**
* configfs_write_bin_file - write a binary attribute.
* @file: file pointer
* @buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Writing to a binary attribute file is similar to a normal read.
* We buffer the consecutive writes (binary attribute files do not
* support lseek) in a continuously growing buffer, but we don't
* commit until the close of the file.
*/
static ssize_t
configfs_write_bin_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data;
void *tbuf = NULL;
size_t end_offset;
ssize_t len;
mutex_lock(&buffer->mutex);
@ -316,15 +245,14 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
buffer->write_in_progress = true;
/* buffer grows? */
if (*ppos + count > buffer->bin_buffer_size) {
if (buffer->cb_max_size &&
*ppos + count > buffer->cb_max_size) {
end_offset = iocb->ki_pos + iov_iter_count(from);
if (end_offset > buffer->bin_buffer_size) {
if (buffer->cb_max_size && end_offset > buffer->cb_max_size) {
len = -EFBIG;
goto out;
}
tbuf = vmalloc(*ppos + count);
tbuf = vmalloc(end_offset);
if (tbuf == NULL) {
len = -ENOMEM;
goto out;
@ -339,16 +267,15 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
/* clear the new area */
memset(tbuf + buffer->bin_buffer_size, 0,
*ppos + count - buffer->bin_buffer_size);
end_offset - buffer->bin_buffer_size);
buffer->bin_buffer = tbuf;
buffer->bin_buffer_size = *ppos + count;
buffer->bin_buffer_size = end_offset;
}
len = simple_write_to_buffer(buffer->bin_buffer,
buffer->bin_buffer_size, ppos, buf, count);
len = copy_from_iter(buffer->bin_buffer, buffer->bin_buffer_size, from);
out:
mutex_unlock(&buffer->mutex);
return len;
return len ? : -EFAULT;
}
static int __configfs_open_file(struct inode *inode, struct file *file, int type)
@ -466,11 +393,8 @@ static int configfs_release_bin_file(struct inode *inode, struct file *file)
{
struct configfs_buffer *buffer = file->private_data;
buffer->read_in_progress = false;
if (buffer->write_in_progress) {
struct configfs_fragment *frag = to_frag(file);
buffer->write_in_progress = false;
down_read(&frag->frag_sem);
if (!frag->frag_dead) {
@ -480,29 +404,26 @@ static int configfs_release_bin_file(struct inode *inode, struct file *file)
buffer->bin_buffer_size);
}
up_read(&frag->frag_sem);
/* vfree on NULL is safe */
vfree(buffer->bin_buffer);
buffer->bin_buffer = NULL;
buffer->bin_buffer_size = 0;
buffer->needs_read_fill = 1;
}
vfree(buffer->bin_buffer);
configfs_release(inode, file);
return 0;
}
const struct file_operations configfs_file_operations = {
.read = configfs_read_file,
.write = configfs_write_file,
.read_iter = configfs_read_iter,
.write_iter = configfs_write_iter,
.llseek = generic_file_llseek,
.open = configfs_open_file,
.release = configfs_release,
};
const struct file_operations configfs_bin_file_operations = {
.read = configfs_read_bin_file,
.write = configfs_write_bin_file,
.read_iter = configfs_bin_read_iter,
.write_iter = configfs_bin_write_iter,
.llseek = NULL, /* bin file is not seekable */
.open = configfs_open_bin_file,
.release = configfs_release_bin_file,
@ -532,7 +453,7 @@ int configfs_create_file(struct config_item * item, const struct configfs_attrib
/**
* configfs_create_bin_file - create a binary attribute file for an item.
* @item: item we're creating for.
* @attr: atrribute descriptor.
* @bin_attr: atrribute descriptor.
*/
int configfs_create_bin_file(struct config_item *item,