1 files changed, 87 insertions, 1 deletions

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 34b9b4146021..189badbeddaf 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -10,9 +10,11 @@
 #include <linux/init.h>
 #include <linux/blkdev.h>
 #include <linux/bio.h>
+#include <linux/dax.h>
 #include <linux/slab.h>
 #include <linux/kthread.h>
 #include <linux/freezer.h>
+#include <linux/uio.h>
 
 #define DM_MSG_PREFIX "log-writes"
 
@@ -608,6 +610,51 @@ static int log_mark(struct log_writes_c *lc, char *data)
         return 0;
 }
 
+static int log_dax(struct log_writes_c *lc, sector_t sector, size_t bytes,
+                   struct iov_iter *i)
+{
+        struct pending_block *block;
+
+        if (!bytes)
+                return 0;
+
+        block = kzalloc(sizeof(struct pending_block), GFP_KERNEL);
+        if (!block) {
+                DMERR("Error allocating dax pending block");
+                return -ENOMEM;
+        }
+
+        block->data = kzalloc(bytes, GFP_KERNEL);
+        if (!block->data) {
+                DMERR("Error allocating dax data space");
+                kfree(block);
+                return -ENOMEM;
+        }
+
+        /* write data provided via the iterator */
+        if (!copy_from_iter(block->data, bytes, i)) {
+                DMERR("Error copying dax data");
+                kfree(block->data);
+                kfree(block);
+                return -EIO;
+        }
+
+        /* rewind the iterator so that the block driver can use it */
+        iov_iter_revert(i, bytes);
+
+        block->datalen = bytes;
+        block->sector = bio_to_dev_sectors(lc, sector);
+        block->nr_sectors = ALIGN(bytes, lc->sectorsize) >> lc->sectorshift;
+
+        atomic_inc(&lc->pending_blocks);
+        spin_lock_irq(&lc->blocks_lock);
+        list_add_tail(&block->list, &lc->unflushed_blocks);
+        spin_unlock_irq(&lc->blocks_lock);
+        wake_up_process(lc->log_kthread);
+
+        return 0;
+}
+
 static void log_writes_dtr(struct dm_target *ti)
 {
         struct log_writes_c *lc = ti->private;
@@ -873,9 +920,46 @@ static void log_writes_io_hints(struct dm_target *ti, struct queue_limits *limit
         limits->io_min = limits->physical_block_size;
 }
 
+static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
+                                         long nr_pages, void **kaddr, pfn_t *pfn)
+{
+        struct log_writes_c *lc = ti->private;
+        sector_t sector = pgoff * PAGE_SECTORS;
+        int ret;
+
+        ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages * PAGE_SIZE, &pgoff);
+        if (ret)
+                return ret;
+        return dax_direct_access(lc->dev->dax_dev, pgoff, nr_pages, kaddr, pfn);
+}
+
+static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
+                                            pgoff_t pgoff, void *addr, size_t bytes,
+                                            struct iov_iter *i)
+{
+        struct log_writes_c *lc = ti->private;
+        sector_t sector = pgoff * PAGE_SECTORS;
+        int err;
+
+        if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
+                return 0;
+
+        /* Don't bother doing anything if logging has been disabled */
+        if (!lc->logging_enabled)
+                goto dax_copy;
+
+        err = log_dax(lc, sector, bytes, i);
+        if (err) {
+                DMWARN("Error %d logging DAX write", err);
+                return 0;
+        }
+dax_copy:
+        return dax_copy_from_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
+}
+
 static struct target_type log_writes_target = {
         .name   = "log-writes",
-        .version = {1, 0, 0},
+        .version = {1, 1, 0},
         .module = THIS_MODULE,
         .ctr    = log_writes_ctr,
         .dtr    = log_writes_dtr,
@@ -886,6 +970,8 @@ static struct target_type log_writes_target = {
         .message = log_writes_message,
         .iterate_devices = log_writes_iterate_devices,
         .io_hints = log_writes_io_hints,
+        .direct_access = log_writes_dax_direct_access,
+        .dax_copy_from_iter = log_writes_dax_copy_from_iter,
 };
 
 static int __init dm_log_writes_init(void)