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configfs: implement the .read_iter and .write_iter methods

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Configfs is one of the few filesystems that does not yet support the
.read_iter and .write_iter callbacks. This patch adds support for these
methods in configfs.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[hch: split out a separate fix]
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Bart Van Assche 2021-05-25 10:30:21 +02:00 committed by Christoph Hellwig
parent 44b9a000df
commit 7fe1e79b59
1 changed files with 42 additions and 42 deletions
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84
fs/configfs/file.c
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@ -14,7 +14,7 @@
#include <linux/mutex.h> #include <linux/mutex.h>
#include <linux/vmalloc.h> #include <linux/vmalloc.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/configfs.h> #include <linux/configfs.h>
#include "configfs_internal.h" #include "configfs_internal.h"
@ -77,9 +77,9 @@ static int fill_read_buffer(struct file *file, struct configfs_buffer *buffer)
return 0; return 0;
} }
static ssize_t static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{ {
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data; struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0; ssize_t retval = 0;
@ -89,23 +89,24 @@ configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *pp
if (retval) if (retval)
goto out; goto out;
} }
pr_debug("%s: count = %zd, ppos = %lld, buf = %s\n", pr_debug("%s: count = %zd, pos = %lld, buf = %s\n",
__func__, count, *ppos, buffer->page); __func__, iov_iter_count(to), iocb->ki_pos, buffer->page);
retval = simple_read_from_buffer(buf, count, ppos, buffer->page, retval = copy_to_iter(buffer->page, buffer->count, to);
buffer->count); iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
out: out:
mutex_unlock(&buffer->mutex); mutex_unlock(&buffer->mutex);
return retval; return retval;
} }
static ssize_t static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to)
configfs_read_bin_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{ {
struct file *file = iocb->ki_filp;
struct configfs_fragment *frag = to_frag(file); struct configfs_fragment *frag = to_frag(file);
struct configfs_buffer *buffer = file->private_data; struct configfs_buffer *buffer = file->private_data;
ssize_t retval = 0; ssize_t retval = 0;
ssize_t len = min_t(size_t, count, PAGE_SIZE); ssize_t len;
mutex_lock(&buffer->mutex); mutex_lock(&buffer->mutex);
@ -161,31 +162,31 @@ configfs_read_bin_file(struct file *file, char __user *buf,
buffer->needs_read_fill = 0; buffer->needs_read_fill = 0;
} }
retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer, retval = copy_to_iter(buffer->bin_buffer, buffer->bin_buffer_size, to);
buffer->bin_buffer_size); iocb->ki_pos += retval;
if (retval == 0)
retval = -EFAULT;
out: out:
mutex_unlock(&buffer->mutex); mutex_unlock(&buffer->mutex);
return retval; return retval;
} }
static int static int fill_write_buffer(struct configfs_buffer *buffer,
fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count) struct iov_iter *from)
{ {
int error; int copied;
if (!buffer->page) if (!buffer->page)
buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0); buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);
if (!buffer->page) if (!buffer->page)
return -ENOMEM; return -ENOMEM;
if (count >= SIMPLE_ATTR_SIZE) copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);
count = SIMPLE_ATTR_SIZE - 1;
error = copy_from_user(buffer->page,buf,count);
buffer->needs_read_fill = 1; buffer->needs_read_fill = 1;
/* if buf is assumed to contain a string, terminate it by \0, /* if buf is assumed to contain a string, terminate it by \0,
* so e.g. sscanf() can scan the string easily */ * so e.g. sscanf() can scan the string easily */
buffer->page[count] = 0; buffer->page[copied] = 0;
return error ? -EFAULT : count; return copied ? : -EFAULT;
} }
static int static int
@ -209,28 +210,29 @@ flush_write_buffer(struct file *file, struct configfs_buffer *buffer, size_t cou
* Hint: if you're writing a value, first read the file, modify only the value * Hint: if you're writing a value, first read the file, modify only the value
* you're changing, then write entire buffer back. * you're changing, then write entire buffer back.
*/ */
static ssize_t static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{ {
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data; struct configfs_buffer *buffer = file->private_data;
ssize_t len; ssize_t len;
mutex_lock(&buffer->mutex); mutex_lock(&buffer->mutex);
len = fill_write_buffer(buffer, buf, count); len = fill_write_buffer(buffer, from);
if (len > 0) if (len > 0)
len = flush_write_buffer(file, buffer, len); len = flush_write_buffer(file, buffer, len);
if (len > 0) if (len > 0)
*ppos += len; iocb->ki_pos += len;
mutex_unlock(&buffer->mutex); mutex_unlock(&buffer->mutex);
return len; return len;
} }
static ssize_t static ssize_t configfs_bin_write_iter(struct kiocb *iocb,
configfs_write_bin_file(struct file *file, const char __user *buf, struct iov_iter *from)
size_t count, loff_t *ppos)
{ {
struct file *file = iocb->ki_filp;
struct configfs_buffer *buffer = file->private_data; struct configfs_buffer *buffer = file->private_data;
void *tbuf = NULL; void *tbuf = NULL;
size_t end_offset;
ssize_t len; ssize_t len;
mutex_lock(&buffer->mutex); mutex_lock(&buffer->mutex);
@ -243,15 +245,14 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
buffer->write_in_progress = true; buffer->write_in_progress = true;
/* buffer grows? */ /* buffer grows? */
if (*ppos + count > buffer->bin_buffer_size) { end_offset = iocb->ki_pos + iov_iter_count(from);
if (end_offset > buffer->bin_buffer_size) {
if (buffer->cb_max_size && if (buffer->cb_max_size && end_offset > buffer->cb_max_size) {
*ppos + count > buffer->cb_max_size) {
len = -EFBIG; len = -EFBIG;
goto out; goto out;
} }
tbuf = vmalloc(*ppos + count); tbuf = vmalloc(end_offset);
if (tbuf == NULL) { if (tbuf == NULL) {
len = -ENOMEM; len = -ENOMEM;
goto out; goto out;
@ -266,16 +267,15 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
/* clear the new area */ /* clear the new area */
memset(tbuf + buffer->bin_buffer_size, 0, 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 = tbuf;
buffer->bin_buffer_size = *ppos + count; buffer->bin_buffer_size = end_offset;
} }
len = simple_write_to_buffer(buffer->bin_buffer, len = copy_from_iter(buffer->bin_buffer, buffer->bin_buffer_size, from);
buffer->bin_buffer_size, ppos, buf, count);
out: out:
mutex_unlock(&buffer->mutex); mutex_unlock(&buffer->mutex);
return len; return len ? : -EFAULT;
} }
static int __configfs_open_file(struct inode *inode, struct file *file, int type) static int __configfs_open_file(struct inode *inode, struct file *file, int type)
@ -420,16 +420,16 @@ static int configfs_release_bin_file(struct inode *inode, struct file *file)
const struct file_operations configfs_file_operations = { const struct file_operations configfs_file_operations = {
.read = configfs_read_file, .read_iter = configfs_read_iter,
.write = configfs_write_file, .write_iter = configfs_write_iter,
.llseek = generic_file_llseek, .llseek = generic_file_llseek,
.open = configfs_open_file, .open = configfs_open_file,
.release = configfs_release, .release = configfs_release,
}; };
const struct file_operations configfs_bin_file_operations = { const struct file_operations configfs_bin_file_operations = {
.read = configfs_read_bin_file, .read_iter = configfs_bin_read_iter,
.write = configfs_write_bin_file, .write_iter = configfs_bin_write_iter,
.llseek = NULL, /* bin file is not seekable */ .llseek = NULL, /* bin file is not seekable */
.open = configfs_open_bin_file, .open = configfs_open_bin_file,
.release = configfs_release_bin_file, .release = configfs_release_bin_file,