[PATCH 4/9] pagemap: remove open-coded sizeof(unsigned long)

Dave Hansen
2007-08-22T23:18:10Z

I think the code gets easier to read when we give symbolic names
to some of the operations we're performing. I was sure we needed
this when I saw the header being built like this:

...
buf[2] = sizeof(unsigned long)
buf[3] = sizeof(unsigned long)

I really couldn't remember what either field did ;(

This particular use is gone (because of removing the header, but
this patch is still a really good idea to clarify the code).

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

lxc-dave/fs/proc/task_mmu.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff -puN fs/proc/task_mmu.c~pagemap-use-ENTRY_SIZE fs/proc/task_mmu.c
--- lxc/fs/proc/task_mmu.c~pagemap-use-ENTRY_SIZE 2007-08-22 16:16:52.000000000 -0700
+++ lxc-dave/fs/proc/task_mmu.c 2007-08-22 16:16:52.000000000 -0700
@@ -508,14 +508,16 @@ struct pagemapread {
unsigned long __user *out;
};

+#define PM_ENTRY_BYTES sizeof(unsigned long)
+
static int add_to_pagemap(unsigned long addr, unsigned long pfn,
struct pagemapread *pm)
{
__put_user(pfn, pm->out);
pm->out++;
- pm->pos += sizeof(unsigned long);
- pm->count -= sizeof(unsigned long);
pm->next = addr + PAGE_SIZE;
+ pm->pos += PM_ENTRY_BYTES;
+ pm->count -= PM_ENTRY_BYTES;
return 0;
}

@@ -601,13 +603,13 @@ static ssize_t pagemap_read(struct file
goto out;

ret = -EIO;
- svpfn = src / sizeof(unsigned long);
+ svpfn = src / PM_ENTRY_BYTES;
addr = PAGE_SIZE * svpfn;
- if (svpfn * sizeof(unsigned long) != src)
+ if (svpfn * PM_ENTRY_BYTES != src)
goto out;
evpfn = min((src + count) / sizeof(unsigned long) - 1,
((~0UL) >> PAGE_SHIFT) + 1);
- count = (evpfn - svpfn) * sizeof(unsigned long);
+ count = (evpfn - svpfn) * PM_ENTRY_BYTES;
end = PAGE_SIZE * evpfn;
//printk("src %ld svpfn %d evpfn %d count %d\n", src, svpfn, evpfn, count);