swap: use bdev_read_page() / bdev_write_page()
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>
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1 changed files with 20 additions and 1 deletions
21
mm/page_io.c
21
mm/page_io.c
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@ -248,11 +248,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc)
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return ret;
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}
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static sector_t swap_page_sector(struct page *page)
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{
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return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
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}
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int __swap_writepage(struct page *page, struct writeback_control *wbc,
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void (*end_write_func)(struct bio *, int))
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{
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struct bio *bio;
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int ret = 0, rw = WRITE;
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int ret, rw = WRITE;
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struct swap_info_struct *sis = page_swap_info(page);
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if (sis->flags & SWP_FILE) {
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@ -297,6 +302,13 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
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return ret;
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}
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ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);
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if (!ret) {
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count_vm_event(PSWPOUT);
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return 0;
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}
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ret = 0;
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bio = get_swap_bio(GFP_NOIO, page, end_write_func);
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if (bio == NULL) {
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set_page_dirty(page);
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@ -338,6 +350,13 @@ int swap_readpage(struct page *page)
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return ret;
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}
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ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
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if (!ret) {
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count_vm_event(PSWPIN);
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return 0;
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}
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ret = 0;
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bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
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if (bio == NULL) {
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unlock_page(page);
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