Commit 420405ec authored by Bart Van Assche's avatar Bart Van Assche Committed by Christoph Hellwig
Browse files

configfs: fix the read and write iterators 



Commit 7fe1e79b ("configfs: implement the .read_iter and .write_iter
methods") changed the simple_read_from_buffer() calls into copy_to_iter()
calls and the simple_write_to_buffer() calls into copy_from_iter() calls.
The simple*buffer() methods update the file offset (*ppos) but the read
and write iterators not yet. Make the read and write iterators update the
file offset (iocb->ki_pos).

This patch has been tested as follows:

 # modprobe target_core_user
 # dd if=/sys/kernel/config/target/dbroot bs=1
/var/target
12+0 records in
12+0 records out
12 bytes copied, 9.5539e-05 s, 126 kB/s

 # cd /sys/kernel/config/acpi/table
 # mkdir test
 # cd test
 # dmesg -c >/dev/null; printf 'SSDT\x8\0\0\0abcdefghijklmnopqrstuvwxyz' | dd of=aml bs=1; dmesg -c
34+0 records in
34+0 records out
34 bytes copied, 0.010627 s, 3.2 kB/s
[  261.056551] ACPI configfs: invalid table length

Reported-by: default avatarYanko Kaneti <yaneti@declera.com>
Cc: Yanko Kaneti <yaneti@declera.com>
Fixes: 7fe1e79b ("configfs: implement the .read_iter and .write_iter methods")
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 7fef2edf

fs/configfs/file.c

+22 −7
Original line number Diff line number Diff line
@@ -91,7 +91,10 @@ static ssize_t configfs_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	}

	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);

	if (iocb->ki_pos >= buffer->count)

		goto out;

	retval = copy_to_iter(buffer->page + iocb->ki_pos,

			      buffer->count - iocb->ki_pos, to);

	iocb->ki_pos += retval;

	if (retval == 0)

		retval = -EFAULT;
@@ -162,7 +165,10 @@ static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to) 
		buffer->needs_read_fill = 0;

	}



	retval = copy_to_iter(buffer->bin_buffer, buffer->bin_buffer_size, to);

	if (iocb->ki_pos >= buffer->bin_buffer_size)

		goto out;

	retval = copy_to_iter(buffer->bin_buffer + iocb->ki_pos,

			      buffer->bin_buffer_size - iocb->ki_pos, to);

	iocb->ki_pos += retval;

	if (retval == 0)

		retval = -EFAULT;
@@ -171,21 +177,28 @@ static ssize_t configfs_bin_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	return retval;

}



static int fill_write_buffer(struct configfs_buffer *buffer,

/* Fill [buffer, buffer + pos) with data coming from @from. */

static int fill_write_buffer(struct configfs_buffer *buffer, loff_t pos,

			     struct iov_iter *from)

{

	loff_t to_copy;

	int copied;

	u8 *to;



	if (!buffer->page)

		buffer->page = (char *)__get_free_pages(GFP_KERNEL, 0);

	if (!buffer->page)

		return -ENOMEM;



	copied = copy_from_iter(buffer->page, SIMPLE_ATTR_SIZE - 1, from);

	to_copy = SIMPLE_ATTR_SIZE - 1 - pos;

	if (to_copy <= 0)

		return 0;

	to = buffer->page + pos;

	copied = copy_from_iter(to, to_copy, 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[copied] = 0;

	to[copied] = 0;

	return copied ? : -EFAULT;

}
@@ -217,7 +230,7 @@ static ssize_t configfs_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	ssize_t len;



	mutex_lock(&buffer->mutex);

	len = fill_write_buffer(buffer, from);

	len = fill_write_buffer(buffer, iocb->ki_pos, from);

	if (len > 0)

		len = flush_write_buffer(file, buffer, len);

	if (len > 0)
@@ -272,7 +285,9 @@ static ssize_t configfs_bin_write_iter(struct kiocb *iocb, 
		buffer->bin_buffer_size = end_offset;

	}



	len = copy_from_iter(buffer->bin_buffer, buffer->bin_buffer_size, from);

	len = copy_from_iter(buffer->bin_buffer + iocb->ki_pos,

			     buffer->bin_buffer_size - iocb->ki_pos, from);

	iocb->ki_pos += len;

out:

	mutex_unlock(&buffer->mutex);

	return len ? : -EFAULT;