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[PATCH] get_user_pages: kill get_page_map 

Since its birth, get_user_pages has been calling a misguided get_page_map
function.  follow_page has already returned NULL if the pfn is invalid, we
cannot reach an invalid pfn from a validated struct page.

Remove get_page_map, and the messy rewind in get_user_pages to cope with
its failure.  Oh, and could we please call that "struct page *page" like
everywhere else, instead of "struct page *map"?

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hugh Dickins 2005-06-21 17:15:10 -07:00 committed by Linus Torvalds
parent 7c2f3fda56
commit 08ef472937
1 changed files with 10 additions and 35 deletions
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45
mm/memory.c
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@ -840,23 +840,8 @@ check_user_page_readable(struct mm_struct *mm, unsigned long address)
{
return __follow_page(mm, address, /*read*/1, /*write*/0) != NULL;
}
EXPORT_SYMBOL(check_user_page_readable);
/*
* Given a physical address, is there a useful struct page pointing to
* it? This may become more complex in the future if we start dealing
* with IO-aperture pages for direct-IO.
*/
static inline struct page *get_page_map(struct page *page)
{
if (!pfn_valid(page_to_pfn(page)))
return NULL;
return page;
}
static inline int
untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
unsigned long address)
@ -887,7 +872,6 @@ untouched_anonymous_page(struct mm_struct* mm, struct vm_area_struct *vma,
return 0;
}
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int len, int write, int force,
struct page **pages, struct vm_area_struct **vmas)
@ -951,21 +935,21 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
}
spin_lock(&mm->page_table_lock);
do {
struct page *map;
struct page *page;
int lookup_write = write;
cond_resched_lock(&mm->page_table_lock);
while (!(map = follow_page(mm, start, lookup_write))) {
while (!(page = follow_page(mm, start, lookup_write))) {
/*
* Shortcut for anonymous pages. We don't want
* to force the creation of pages tables for
* insanly big anonymously mapped areas that
* insanely big anonymously mapped areas that
* nobody touched so far. This is important
* for doing a core dump for these mappings.
*/
if (!lookup_write &&
untouched_anonymous_page(mm,vma,start)) {
map = ZERO_PAGE(start);
page = ZERO_PAGE(start);
break;
}
spin_unlock(&mm->page_table_lock);
@ -994,30 +978,21 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
spin_lock(&mm->page_table_lock);
}
if (pages) {
pages[i] = get_page_map(map);
if (!pages[i]) {
spin_unlock(&mm->page_table_lock);
while (i--)
page_cache_release(pages[i]);
i = -EFAULT;
goto out;
}
flush_dcache_page(pages[i]);
if (!PageReserved(pages[i]))
page_cache_get(pages[i]);
pages[i] = page;
flush_dcache_page(page);
if (!PageReserved(page))
page_cache_get(page);
}
if (vmas)
vmas[i] = vma;
i++;
start += PAGE_SIZE;
len--;
} while(len && start < vma->vm_end);
} while (len && start < vma->vm_end);
spin_unlock(&mm->page_table_lock);
} while(len);
out:
} while (len);
return i;
}
EXPORT_SYMBOL(get_user_pages);
static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd,