block, THP: make block_device_operations.rw_page support THP

The .rw_page in struct block_device_operations is used by the swap
subsystem to read/write the page contents from/into the corresponding
swap slot in the swap device.  To support the THP (Transparent Huge
Page) swap optimization, the .rw_page is enhanced to support to
read/write THP if possible.

Link: http://lkml.kernel.org/r/20170724051840.2309-6-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@intel.com> [for brd.c, zram_drv.c, pmem.c]
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 104b71c..5d9ed06 100644 (file)
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -326,7 +326,11 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,
                       struct page *page, bool is_write)
 {
        struct brd_device *brd = bdev->bd_disk->private_data;
-       int err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector);
+       int err;
+
+       if (PageTransHuge(page))
+               return -ENOTSUPP;
+       err = brd_do_bvec(brd, page, PAGE_SIZE, 0, is_write, sector);
        page_endio(page, is_write, err);
        return err;
 }

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 4ddc18a..4a0438c 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1285,6 +1285,8 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
        struct zram *zram;
        struct bio_vec bv;
 
+       if (PageTransHuge(page))
+               return -ENOTSUPP;
        zram = bdev->bd_disk->private_data;
 
        if (!valid_io_request(zram, sector, PAGE_SIZE)) {

diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 14323fa..6049164 100644 (file)
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1241,8 +1241,10 @@ static int btt_rw_page(struct block_device *bdev, sector_t sector,
 {
        struct btt *btt = bdev->bd_disk->private_data;
        int rc;
+       unsigned int len;
 
-       rc = btt_do_bvec(btt, NULL, page, PAGE_SIZE, 0, is_write, sector);
+       len = hpage_nr_pages(page) * PAGE_SIZE;
+       rc = btt_do_bvec(btt, NULL, page, len, 0, is_write, sector);
        if (rc == 0)
                page_endio(page, is_write, 0);
 

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index f7099ad..e9aa453 100644 (file)
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -80,22 +80,40 @@ static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
 static void write_pmem(void *pmem_addr, struct page *page,
                unsigned int off, unsigned int len)
 {
-       void *mem = kmap_atomic(page);
-
-       memcpy_flushcache(pmem_addr, mem + off, len);
-       kunmap_atomic(mem);
+       unsigned int chunk;
+       void *mem;
+
+       while (len) {
+               mem = kmap_atomic(page);
+               chunk = min_t(unsigned int, len, PAGE_SIZE);
+               memcpy_flushcache(pmem_addr, mem + off, chunk);
+               kunmap_atomic(mem);
+               len -= chunk;
+               off = 0;
+               page++;
+               pmem_addr += PAGE_SIZE;
+       }
 }
 
 static blk_status_t read_pmem(struct page *page, unsigned int off,
                void *pmem_addr, unsigned int len)
 {
+       unsigned int chunk;
        int rc;
-       void *mem = kmap_atomic(page);
-
-       rc = memcpy_mcsafe(mem + off, pmem_addr, len);
-       kunmap_atomic(mem);
-       if (rc)
-               return BLK_STS_IOERR;
+       void *mem;
+
+       while (len) {
+               mem = kmap_atomic(page);
+               chunk = min_t(unsigned int, len, PAGE_SIZE);
+               rc = memcpy_mcsafe(mem + off, pmem_addr, chunk);
+               kunmap_atomic(mem);
+               if (rc)
+                       return BLK_STS_IOERR;
+               len -= chunk;
+               off = 0;
+               page++;
+               pmem_addr += PAGE_SIZE;
+       }
        return BLK_STS_OK;
 }
 
@@ -188,7 +206,8 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
        struct pmem_device *pmem = bdev->bd_queue->queuedata;
        blk_status_t rc;
 
-       rc = pmem_do_bvec(pmem, page, PAGE_SIZE, 0, is_write, sector);
+       rc = pmem_do_bvec(pmem, page, hpage_nr_pages(page) * PAGE_SIZE,
+                         0, is_write, sector);
 
        /*
         * The ->rw_page interface is subtle and tricky.  The core