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swap: use bdev_read_page() / bdev_write_page()

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By calling the device driver to write the page directly, we avoid
allocating a BIO, which allows us to free memory without allocating
memory.

[akpm@linux-foundation.org: fix used-uninitialized bug]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matthew Wilcox 2014-06-04 16:07:48 -07:00 committed by Linus Torvalds
parent 47a191fd38
commit dd6bd0d9c7
1 changed files with 20 additions and 1 deletions
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21
mm/page_io.c
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@ -248,11 +248,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
return ret;
}
static sector_t swap_page_sector(struct page *page)
{
return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
}
int __swap_writepage(struct page *page, struct writeback_control *wbc,
void (*end_write_func)(struct bio *, int))
{
struct bio *bio;
int ret = 0, rw = WRITE;
int ret, rw = WRITE;
struct swap_info_struct *sis = page_swap_info(page);
if (sis->flags & SWP_FILE) {
@ -297,6 +302,13 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
return ret;
}
ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
if (!ret) {
count_vm_event(PSWPOUT);
return 0;
}
ret = 0;
bio = get_swap_bio(GFP_NOIO, page, end_write_func);
if (bio == NULL) {
set_page_dirty(page);
@ -338,6 +350,13 @@ int swap_readpage(struct page *page)
return ret;
}
ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
if (!ret) {
count_vm_event(PSWPIN);
return 0;
}
ret = 0;
bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
if (bio == NULL) {
unlock_page(page);