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

1 files changed, 51 insertions, 130 deletions

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index e26060dae70a..2f63bf3a7325 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -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,