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configfs: consistent attribute size

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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: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
This commit is contained in:
Joel Becker
2007-06-22 13:07:02 -07:00
committed by Mark Fasheh
parent 4c75f7416f
commit b23cdde4c6
1 changed files with 10 additions and 3 deletions
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13
fs/configfs/file.c
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@@ -33,6 +33,13 @@
#include <linux/configfs.h> #include <linux/configfs.h>
#include "configfs_internal.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 { struct configfs_buffer {
size_t count; 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); count = ops->show_attribute(item,attr,buffer->page);
buffer->needs_read_fill = 0; buffer->needs_read_fill = 0;
BUG_ON(count > (ssize_t)PAGE_SIZE); BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
if (count >= 0) if (count >= 0)
buffer->count = count; buffer->count = count;
else else
@@ -137,8 +144,8 @@ fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size
if (!buffer->page) if (!buffer->page)
return -ENOMEM; return -ENOMEM;
if (count >= PAGE_SIZE) if (count >= SIMPLE_ATTR_SIZE)
count = PAGE_SIZE - 1; count = SIMPLE_ATTR_SIZE - 1;
error = copy_from_user(buffer->page,buf,count); 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,