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Subject[PATCH 6/6] pagemap: introduce data structure for pagemap entry
Date
Currently a local variable of pagemap entry in pagemap_pte_range()
is named pfn and typed with u64, but it's not correct (pfn should
be unsigned long.)
This patch introduces special type for pagemap entry and replace
code with it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>

Changes since v4:
- Rename pme_t to pagemap_entry_t
---
fs/proc/task_mmu.c | 69 ++++++++++++++++++++++++++++-----------------------
1 files changed, 38 insertions(+), 31 deletions(-)

diff --git 3.3-rc2.orig/fs/proc/task_mmu.c 3.3-rc2/fs/proc/task_mmu.c
index de94384..7810281 100644
--- 3.3-rc2.orig/fs/proc/task_mmu.c
+++ 3.3-rc2/fs/proc/task_mmu.c
@@ -589,9 +589,13 @@ const struct file_operations proc_clear_refs_operations = {
.llseek = noop_llseek,
};

+typedef struct {
+ u64 pme;
+} pagemap_entry_t;
+
struct pagemapread {
int pos, len;
- u64 *buffer;
+ pagemap_entry_t *buffer;
};

#define PAGEMAP_WALK_SIZE (PMD_SIZE)
@@ -614,10 +618,15 @@ struct pagemapread {
#define PM_NOT_PRESENT PM_PSHIFT(PAGE_SHIFT)
#define PM_END_OF_BUFFER 1

-static int add_to_pagemap(unsigned long addr, u64 pfn,
+static inline pagemap_entry_t make_pme(u64 val)
+{
+ return (pagemap_entry_t) { .pme = val };
+}
+
+static int add_to_pagemap(unsigned long addr, pagemap_entry_t *pme,
struct pagemapread *pm)
{
- pm->buffer[pm->pos++] = pfn;
+ pm->buffer[pm->pos++] = *pme;
if (pm->pos >= pm->len)
return PM_END_OF_BUFFER;
return 0;
@@ -629,8 +638,10 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
struct pagemapread *pm = walk->private;
unsigned long addr;
int err = 0;
+ pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);
+
for (addr = start; addr < end; addr += PAGE_SIZE) {
- err = add_to_pagemap(addr, PM_NOT_PRESENT, pm);
+ err = add_to_pagemap(addr, &pme, pm);
if (err)
break;
}
@@ -643,36 +654,33 @@ static u64 swap_pte_to_pagemap_entry(pte_t pte)
return swp_type(e) | (swp_offset(e) << MAX_SWAPFILES_SHIFT);
}

-static u64 pte_to_pagemap_entry(pte_t pte)
+static void pte_to_pagemap_entry(pagemap_entry_t *pme, pte_t pte)
{
- u64 pme = 0;
if (is_swap_pte(pte))
- pme = PM_PFRAME(swap_pte_to_pagemap_entry(pte))
- | PM_PSHIFT(PAGE_SHIFT) | PM_SWAP;
+ *pme = make_pme(PM_PFRAME(swap_pte_to_pagemap_entry(pte))
+ | PM_PSHIFT(PAGE_SHIFT) | PM_SWAP);
else if (pte_present(pte))
- pme = PM_PFRAME(pte_pfn(pte))
- | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
- return pme;
+ *pme = make_pme(PM_PFRAME(pte_pfn(pte))
+ | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
+static void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
+ pmd_t pmd, int offset)
{
- u64 pme = 0;
/*
* Currently pmd for thp is always present because thp can not be
* swapped-out, migrated, or HWPOISONed (split in such cases instead.)
* This if-check is just to prepare for future implementation.
*/
if (pmd_present(pmd))
- pme = PM_PFRAME(pmd_pfn(pmd) + offset)
- | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
- return pme;
+ *pme = make_pme(PM_PFRAME(pmd_pfn(pmd) + offset)
+ | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}
#else
-static inline u64 thp_pmd_to_pagemap_entry(pmd_t pmd, int offset)
+static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme,
+ pmd_t pmd, int offset)
{
- return 0;
}
#endif

@@ -683,7 +691,7 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct pagemapread *pm = walk->private;
pte_t *pte;
int err = 0;
- u64 pfn = PM_NOT_PRESENT;
+ pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);

/* find the first VMA at or above 'addr' */
vma = find_vma(walk->mm, addr);
@@ -692,8 +700,8 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
for (; addr != end; addr += PAGE_SIZE) {
unsigned long offset = (addr & ~PAGEMAP_WALK_MASK)
>> PAGE_SHIFT;
- pfn = thp_pmd_to_pagemap_entry(*pmd, offset);
- err = add_to_pagemap(addr, pfn, pm);
+ thp_pmd_to_pagemap_entry(&pme, *pmd, offset);
+ err = add_to_pagemap(addr, &pme, pm);
if (err)
break;
}
@@ -712,11 +720,11 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
if (vma && (vma->vm_start <= addr) &&
!is_vm_hugetlb_page(vma)) {
pte = pte_offset_map(pmd, addr);
- pfn = pte_to_pagemap_entry(*pte);
+ pte_to_pagemap_entry(&pme, *pte);
/* unmap before userspace copy */
pte_unmap(pte);
}
- err = add_to_pagemap(addr, pfn, pm);
+ err = add_to_pagemap(addr, &pme, pm);
if (err)
return err;
}
@@ -727,13 +735,12 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
}

#ifdef CONFIG_HUGETLB_PAGE
-static u64 huge_pte_to_pagemap_entry(pte_t pte, int offset)
+static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme,
+ pte_t pte, int offset)
{
- u64 pme = 0;
if (pte_present(pte))
- pme = PM_PFRAME(pte_pfn(pte) + offset)
- | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
- return pme;
+ *pme = make_pme(PM_PFRAME(pte_pfn(pte) + offset)
+ | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT);
}

/* This function walks within one hugetlb entry in the single call */
@@ -743,12 +750,12 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
{
struct pagemapread *pm = walk->private;
int err = 0;
- u64 pfn;
+ pagemap_entry_t pme = make_pme(PM_NOT_PRESENT);

for (; addr != end; addr += PAGE_SIZE) {
int offset = (addr & ~hmask) >> PAGE_SHIFT;
- pfn = huge_pte_to_pagemap_entry(*pte, offset);
- err = add_to_pagemap(addr, pfn, pm);
+ huge_pte_to_pagemap_entry(&pme, *pte, offset);
+ err = add_to_pagemap(addr, &pme, pm);
if (err)
return err;
}
--
1.7.7.6


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