[PATCH 07/12] mm: Add support for direct_IO to highmem pages
From: Mel Gorman <mgorman@suse.de>
Date: 2012-05-10 13:54:48
Also in:
linux-mm, linux-nfs, lkml
Subsystem:
memory management, memory management - core, memory management - swap, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Chris Li, Kairui Song, Linus Torvalds
The patch "mm: Add support for a filesystem to activate swap files and use direct_IO for writing swap pages" added support for using direct_IO to write swap pages but it is insufficient for highmem pages. To support highmem pages, this patch kmaps() the page before calling the direct_IO() handler. As direct_IO deals with virtual addresses an additional helper is necessary for get_kernel_pages() to lookup the struct page for a kmap virtual address. Signed-off-by: Mel Gorman <mgorman@suse.de> --- include/linux/highmem.h | 7 +++++++ mm/highmem.c | 12 ++++++++++++ mm/memory.c | 3 +-- mm/page_io.c | 3 ++- 4 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index d3999b4..e186e3c 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h@@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages; void kmap_flush_unused(void); +struct page *kmap_to_page(void *addr); + #else /* CONFIG_HIGHMEM */ static inline unsigned int nr_free_highpages(void) { return 0; } +static inline struct page *kmap_to_page(void *addr) +{ + return virt_to_page(addr); +} + #define totalhigh_pages 0UL #ifndef ARCH_HAS_KMAP
diff --git a/mm/highmem.c b/mm/highmem.c
index 57d82c6..d517cd1 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c@@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map_wait); do { spin_unlock(&kmap_lock); (void)(flags); } while (0) #endif +struct page *kmap_to_page(void *vaddr) +{ + unsigned long addr = (unsigned long)vaddr; + + if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) { + int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT; + return pte_page(pkmap_page_table[i]); + } + + return virt_to_page(addr); +} + static void flush_all_zero_pkmaps(void) { int i;
diff --git a/mm/memory.c b/mm/memory.c
index 0bc990e7..fd32a1a 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -1858,8 +1858,7 @@ int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write, if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE)) return seg; - /* virt_to_page sanity checks the PFN */ - pages[seg] = virt_to_page(kiov[seg].iov_base); + pages[seg] = kmap_to_page(kiov[seg].iov_base); page_cache_get(pages[seg]); }
diff --git a/mm/page_io.c b/mm/page_io.c
index f363261..1e39e88 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c@@ -198,7 +198,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) struct file *swap_file = sis->swap_file; struct address_space *mapping = swap_file->f_mapping; struct iovec iov = { - .iov_base = page_address(page), + .iov_base = kmap(page), .iov_len = PAGE_SIZE, };
@@ -211,6 +211,7 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) ret = mapping->a_ops->direct_IO(KERNEL_WRITE, &kiocb, &iov, kiocb.ki_pos, 1); + kunmap(page); if (ret == PAGE_SIZE) { count_vm_event(PSWPOUT); ret = 0;
--
1.7.9.2
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