aboutsummaryrefslogtreecommitdiffstats
path: root/mm/page_io.c
diff options
context:
space:
mode:
Diffstat (limited to 'mm/page_io.c')
-rw-r--r--mm/page_io.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/mm/page_io.c b/mm/page_io.c
new file mode 100644
index 00000000..dc76b4d0
--- /dev/null
+++ b/mm/page_io.c
@@ -0,0 +1,135 @@
+/*
+ * linux/mm/page_io.c
+ *
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ *
+ * Swap reorganised 29.12.95,
+ * Asynchronous swapping added 30.12.95. Stephen Tweedie
+ * Removed race in async swapping. 14.4.1996. Bruno Haible
+ * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
+ * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
+ */
+
+#include <linux/mm.h>
+#include <linux/kernel_stat.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/swap.h>
+#include <linux/bio.h>
+#include <linux/swapops.h>
+#include <linux/writeback.h>
+#include <asm/pgtable.h>
+
+static struct bio *get_swap_bio(gfp_t gfp_flags,
+ struct page *page, bio_end_io_t end_io)
+{
+ struct bio *bio;
+
+ bio = bio_alloc(gfp_flags, 1);
+ if (bio) {
+ bio->bi_sector = map_swap_page(page, &bio->bi_bdev);
+ bio->bi_sector <<= PAGE_SHIFT - 9;
+ bio->bi_io_vec[0].bv_page = page;
+ bio->bi_io_vec[0].bv_len = PAGE_SIZE;
+ bio->bi_io_vec[0].bv_offset = 0;
+ bio->bi_vcnt = 1;
+ bio->bi_idx = 0;
+ bio->bi_size = PAGE_SIZE;
+ bio->bi_end_io = end_io;
+ }
+ return bio;
+}
+
+static void end_swap_bio_write(struct bio *bio, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct page *page = bio->bi_io_vec[0].bv_page;
+
+ if (!uptodate) {
+ SetPageError(page);
+ /*
+ * We failed to write the page out to swap-space.
+ * Re-dirty the page in order to avoid it being reclaimed.
+ * Also print a dire warning that things will go BAD (tm)
+ * very quickly.
+ *
+ * Also clear PG_reclaim to avoid rotate_reclaimable_page()
+ */
+ set_page_dirty(page);
+ printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode),
+ (unsigned long long)bio->bi_sector);
+ ClearPageReclaim(page);
+ }
+ end_page_writeback(page);
+ bio_put(bio);
+}
+
+void end_swap_bio_read(struct bio *bio, int err)
+{
+ const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+ struct page *page = bio->bi_io_vec[0].bv_page;
+
+ if (!uptodate) {
+ SetPageError(page);
+ ClearPageUptodate(page);
+ printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
+ imajor(bio->bi_bdev->bd_inode),
+ iminor(bio->bi_bdev->bd_inode),
+ (unsigned long long)bio->bi_sector);
+ } else {
+ SetPageUptodate(page);
+ }
+ unlock_page(page);
+ bio_put(bio);
+}
+
+/*
+ * We may have stale swap cache pages in memory: notice
+ * them here and get rid of the unnecessary final write.
+ */
+int swap_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct bio *bio;
+ int ret = 0, rw = WRITE;
+
+ if (try_to_free_swap(page)) {
+ unlock_page(page);
+ goto out;
+ }
+ bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
+ if (bio == NULL) {
+ set_page_dirty(page);
+ unlock_page(page);
+ ret = -ENOMEM;
+ goto out;
+ }
+ if (wbc->sync_mode == WB_SYNC_ALL)
+ rw |= REQ_SYNC;
+ count_vm_event(PSWPOUT);
+ set_page_writeback(page);
+ unlock_page(page);
+ submit_bio(rw, bio);
+out:
+ return ret;
+}
+
+int swap_readpage(struct page *page)
+{
+ struct bio *bio;
+ int ret = 0;
+
+ VM_BUG_ON(!PageLocked(page));
+ VM_BUG_ON(PageUptodate(page));
+ bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
+ if (bio == NULL) {
+ unlock_page(page);
+ ret = -ENOMEM;
+ goto out;
+ }
+ count_vm_event(PSWPIN);
+ submit_bio(READ, bio);
+out:
+ return ret;
+}