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Commit b23cdde4 authored by Joel Becker's avatar Joel Becker Committed by Mark Fasheh
Browse files

configfs: consistent attribute size 



The attribute store/show code currently limits attributes at PAGE_SIZE.
This code comes from sysfs, where it still works that way.

However, PAGE_SIZE is not constant.  A 16k attribute string works on
ia64 but not on x86.  Really a subsystem shouldn't allow different
attribute sizes based on platform.

As such, limit all simple attributes to 4k.  This works on all
platforms, and is consistent with all current code.

Signed-off-by: default avatarJoel Becker <joel.becker@oracle.com>
Signed-off-by: default avatarMark Fasheh <mark.fasheh@oracle.com>
parent 4c75f741

fs/configfs/file.c

+10 −3
Original line number Diff line number Diff line
@@ -33,6 +33,13 @@ 
#include <linux/configfs.h>

#include "configfs_internal.h"



/*

 * A simple attribute can only be 4096 characters.  Why 4k?  Because the

 * original code limited it to PAGE_SIZE.  That's a bad idea, though,

 * because an attribute of 16k on ia64 won't work on x86.  So we limit to

 * 4k, our minimum common page size.

 */

#define SIMPLE_ATTR_SIZE 4096



struct configfs_buffer {

	size_t			count;
@@ -69,7 +76,7 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf 


	count = ops->show_attribute(item,attr,buffer->page);

	buffer->needs_read_fill = 0;

	BUG_ON(count > (ssize_t)PAGE_SIZE);

	BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);

	if (count >= 0)

		buffer->count = count;

	else
@@ -137,8 +144,8 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size 
	if (!buffer->page)

		return -ENOMEM;



	if (count >= PAGE_SIZE)

		count = PAGE_SIZE - 1;

	if (count >= SIMPLE_ATTR_SIZE)

		count = SIMPLE_ATTR_SIZE - 1;

	error = copy_from_user(buffer->page,buf,count);

	buffer->needs_read_fill = 1;

	/* if buf is assumed to contain a string, terminate it by \0,