Introduce DAX_OP_NORMAL and DAX_OP_RECOVERY operation modes to
{dax_direct_access, dax_copy_from_iter, dax_copy_to_iter}.
DAX_OP_NORMAL is the default or the existing mode, and
DAX_OP_RECOVERY is a new mode for data recovery purpose.

When dax-FS suspects dax media error might be encountered
on a read or write, it can enact the recovery mode read or write
by setting DAX_OP_RECOVERY in the aforementioned APIs. A read
in recovery mode attempts to fetch as much data as possible
until the first poisoned page is encountered. A write in recovery
mode attempts to clear poison(s) in a page-aligned range and
then write the user provided data over.

DAX_OP_NORMAL should be used for all non-recovery code path.

Signed-off-by: Jane Chu <[email protected]>
---
 drivers/dax/super.c             | 15 +++++++++------
 drivers/md/dm-linear.c          | 14 ++++++++------
 drivers/md/dm-log-writes.c      | 19 +++++++++++--------
 drivers/md/dm-stripe.c          | 14 ++++++++------
 drivers/md/dm-target.c          |  2 +-
 drivers/md/dm-writecache.c      |  8 +++++---
 drivers/md/dm.c                 | 14 ++++++++------
 drivers/nvdimm/pmem.c           | 11 ++++++-----
 drivers/nvdimm/pmem.h           |  2 +-
 drivers/s390/block/dcssblk.c    | 13 ++++++++-----
 fs/dax.c                        | 14 ++++++++------
 fs/fuse/dax.c                   |  4 ++--
 fs/fuse/virtio_fs.c             | 12 ++++++++----
 include/linux/dax.h             | 18 +++++++++++-------
 include/linux/device-mapper.h   |  5 +++--
 tools/testing/nvdimm/pmem-dax.c |  2 +-
 16 files changed, 98 insertions(+), 69 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index c0910687fbcb..90cae9d84b9c 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -110,6 +110,7 @@ enum dax_device_flags {
  * @dax_dev: a dax_device instance representing the logical memory range
  * @pgoff: offset in pages from the start of the device to translate
  * @nr_pages: number of consecutive pages caller can handle relative to @pfn
+ * @mode: indicate whether dax operation is in normal or recovery mode
  * @kaddr: output parameter that returns a virtual address mapping of pfn
  * @pfn: output parameter that returns an absolute pfn translation of @pgoff
  *
@@ -117,7 +118,7 @@ enum dax_device_flags {
  * pages accessible at the device relative @pgoff.
  */
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long 
nr_pages,
-               void **kaddr, pfn_t *pfn)
+               int mode, void **kaddr, pfn_t *pfn)
 {
        long avail;
 
@@ -131,7 +132,7 @@ long dax_direct_access(struct dax_device *dax_dev, pgoff_t 
pgoff, long nr_pages,
                return -EINVAL;
 
        avail = dax_dev->ops->direct_access(dax_dev, pgoff, nr_pages,
-                       kaddr, pfn);
+                       mode, kaddr, pfn);
        if (!avail)
                return -ERANGE;
        return min(avail, nr_pages);
@@ -139,22 +140,24 @@ long dax_direct_access(struct dax_device *dax_dev, 
pgoff_t pgoff, long nr_pages,
 EXPORT_SYMBOL_GPL(dax_direct_access);
 
 size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void 
*addr,
-               size_t bytes, struct iov_iter *i)
+               size_t bytes, struct iov_iter *i, int mode)
 {
        if (!dax_alive(dax_dev))
                return 0;
 
-       return dax_dev->ops->copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_dev->ops->copy_from_iter(dax_dev, pgoff, addr, bytes, i,
+                                               mode);
 }
 EXPORT_SYMBOL_GPL(dax_copy_from_iter);
 
 size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
-               size_t bytes, struct iov_iter *i)
+               size_t bytes, struct iov_iter *i, int mode)
 {
        if (!dax_alive(dax_dev))
                return 0;
 
-       return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i,
+                                               mode);
 }
 EXPORT_SYMBOL_GPL(dax_copy_to_iter);
 
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 90de42f6743a..c73ac6b98801 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -173,27 +173,29 @@ static struct dax_device *linear_dax_pgoff(struct 
dm_target *ti, pgoff_t *pgoff)
 }
 
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
-       return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
+       return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 }
 
 static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
-       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
-       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index df3cd78223fb..1e9847f904ef 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -959,16 +959,18 @@ static struct dax_device *log_writes_dax_pgoff(struct 
dm_target *ti,
 }
 
 static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-                                        long nr_pages, void **kaddr, pfn_t 
*pfn)
+                                        long nr_pages, int mode,
+                                        void **kaddr, pfn_t *pfn)
 {
        struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
-       return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
+       return dax_direct_access(dax_dev, pgoff, nr_pages, mode, 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)
+                                           pgoff_t pgoff, void *addr,
+                                           size_t bytes, struct iov_iter *i,
+                                           int mode)
 {
        struct log_writes_c *lc = ti->private;
        sector_t sector = pgoff * PAGE_SECTORS;
@@ -985,16 +987,17 @@ static size_t log_writes_dax_copy_from_iter(struct 
dm_target *ti,
                return 0;
        }
 dax_copy:
-       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
-                                         pgoff_t pgoff, void *addr, size_t 
bytes,
-                                         struct iov_iter *i)
+                                         pgoff_t pgoff, void *addr,
+                                         size_t bytes, struct iov_iter *i,
+                                         int mode)
 {
        struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
-       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 50dba3f39274..4c098452268b 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -317,27 +317,29 @@ static struct dax_device *stripe_dax_pgoff(struct 
dm_target *ti, pgoff_t *pgoff)
 }
 
 static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 
-       return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
+       return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
 }
 
 static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 
-       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        struct dax_device *dax_dev = stripe_dax_pgoff(ti, &pgoff);
 
-       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i, mode);
 }
 
 static int stripe_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
diff --git a/drivers/md/dm-target.c b/drivers/md/dm-target.c
index 64dd0b34fcf4..2de1073dbad6 100644
--- a/drivers/md/dm-target.c
+++ b/drivers/md/dm-target.c
@@ -142,7 +142,7 @@ static void io_err_release_clone_rq(struct request *clone,
 }
 
 static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        return -EIO;
 }
diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 0af464a863fe..b2e4ff922fe2 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -286,7 +286,8 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 
        id = dax_read_lock();
 
-       da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, 
&wc->memory_map, &pfn);
+       da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, DAX_OP_NORMAL,
+                               &wc->memory_map, &pfn);
        if (da < 0) {
                wc->memory_map = NULL;
                r = da;
@@ -308,8 +309,9 @@ static int persistent_memory_claim(struct dm_writecache *wc)
                i = 0;
                do {
                        long daa;
-                       daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + 
i, p - i,
-                                               NULL, &pfn);
+                       daa = dax_direct_access(wc->ssd_dev->dax_dev,
+                                               offset + i, p - i,
+                                               DAX_OP_NORMAL, NULL, &pfn);
                        if (daa <= 0) {
                                r = daa ? daa : -EINVAL;
                                goto err3;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 282008afc465..dc354db22ef9 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1001,7 +1001,8 @@ static struct dm_target *dm_dax_get_live_target(struct 
mapped_device *md,
 }
 
 static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
-                                long nr_pages, void **kaddr, pfn_t *pfn)
+                                long nr_pages, int mode, void **kaddr,
+                                pfn_t *pfn)
 {
        struct mapped_device *md = dax_get_private(dax_dev);
        sector_t sector = pgoff * PAGE_SECTORS;
@@ -1019,7 +1020,7 @@ static long dm_dax_direct_access(struct dax_device 
*dax_dev, pgoff_t pgoff,
        if (len < 1)
                goto out;
        nr_pages = min(len, nr_pages);
-       ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn);
+       ret = ti->type->direct_access(ti, pgoff, nr_pages, mode, kaddr, pfn);
 
  out:
        dm_put_live_table(md, srcu_idx);
@@ -1028,7 +1029,8 @@ static long dm_dax_direct_access(struct dax_device 
*dax_dev, pgoff_t pgoff,
 }
 
 static size_t dm_dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-                                   void *addr, size_t bytes, struct iov_iter 
*i)
+                                   void *addr, size_t bytes,
+                                   struct iov_iter *i, int mode)
 {
        struct mapped_device *md = dax_get_private(dax_dev);
        sector_t sector = pgoff * PAGE_SECTORS;
@@ -1044,7 +1046,7 @@ static size_t dm_dax_copy_from_iter(struct dax_device 
*dax_dev, pgoff_t pgoff,
                ret = copy_from_iter(addr, bytes, i);
                goto out;
        }
-       ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i);
+       ret = ti->type->dax_copy_from_iter(ti, pgoff, addr, bytes, i, mode);
  out:
        dm_put_live_table(md, srcu_idx);
 
@@ -1052,7 +1054,7 @@ static size_t dm_dax_copy_from_iter(struct dax_device 
*dax_dev, pgoff_t pgoff,
 }
 
 static size_t dm_dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i, int mode)
 {
        struct mapped_device *md = dax_get_private(dax_dev);
        sector_t sector = pgoff * PAGE_SECTORS;
@@ -1068,7 +1070,7 @@ static size_t dm_dax_copy_to_iter(struct dax_device 
*dax_dev, pgoff_t pgoff,
                ret = copy_to_iter(addr, bytes, i);
                goto out;
        }
-       ret = ti->type->dax_copy_to_iter(ti, pgoff, addr, bytes, i);
+       ret = ti->type->dax_copy_to_iter(ti, pgoff, addr, bytes, i, mode);
  out:
        dm_put_live_table(md, srcu_idx);
 
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 0d6633987552..3dc99e0bf633 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -255,7 +255,7 @@ static int pmem_rw_page(struct block_device *bdev, sector_t 
sector,
 
 /* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
 __weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
 
@@ -294,11 +294,12 @@ static int pmem_dax_zero_page_range(struct dax_device 
*dax_dev, pgoff_t pgoff,
 }
 
 static long pmem_dax_direct_access(struct dax_device *dax_dev,
-               pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
+               pgoff_t pgoff, long nr_pages, int mode, void **kaddr,
+               pfn_t *pfn)
 {
        struct pmem_device *pmem = dax_get_private(dax_dev);
 
-       return __pmem_direct_access(pmem, pgoff, nr_pages, kaddr, pfn);
+       return __pmem_direct_access(pmem, pgoff, nr_pages, mode, kaddr, pfn);
 }
 
 /*
@@ -308,13 +309,13 @@ static long pmem_dax_direct_access(struct dax_device 
*dax_dev,
  * dax_iomap_actor()
  */
 static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i, int mode)
 {
        return _copy_from_iter_flushcache(addr, bytes, i);
 }
 
 static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i)
+               void *addr, size_t bytes, struct iov_iter *i, int mode)
 {
        return _copy_mc_to_iter(addr, bytes, i);
 }
diff --git a/drivers/nvdimm/pmem.h b/drivers/nvdimm/pmem.h
index 59cfe13ea8a8..bda6a898ba81 100644
--- a/drivers/nvdimm/pmem.h
+++ b/drivers/nvdimm/pmem.h
@@ -27,7 +27,7 @@ struct pmem_device {
 };
 
 long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn);
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn);
 
 #ifdef CONFIG_MEMORY_FAILURE
 static inline bool test_and_clear_pmem_poison(struct page *page)
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index e65e83764d1c..fb9f768e12a1 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -32,7 +32,7 @@ static int dcssblk_open(struct block_device *bdev, fmode_t 
mode);
 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
 static void dcssblk_submit_bio(struct bio *bio);
 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t 
pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn);
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -45,13 +45,15 @@ static const struct block_device_operations dcssblk_devops 
= {
 };
 
 static size_t dcssblk_dax_copy_from_iter(struct dax_device *dax_dev,
-               pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
+               pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        return copy_from_iter(addr, bytes, i);
 }
 
 static size_t dcssblk_dax_copy_to_iter(struct dax_device *dax_dev,
-               pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
+               pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i,
+               int mode)
 {
        return copy_to_iter(addr, bytes, i);
 }
@@ -62,7 +64,8 @@ static int dcssblk_dax_zero_page_range(struct dax_device 
*dax_dev,
        long rc;
        void *kaddr;
 
-       rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL);
+       rc = dax_direct_access(dax_dev, pgoff, nr_pages, DAX_OP_NORMAL,
+                              &kaddr, NULL);
        if (rc < 0)
                return rc;
        memset(kaddr, 0, nr_pages << PAGE_SHIFT);
@@ -941,7 +944,7 @@ __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, 
pgoff_t pgoff,
 
 static long
 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 
diff --git a/fs/dax.c b/fs/dax.c
index eb715363fd66..bea6df1498c3 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -735,7 +735,8 @@ static int copy_cow_page_dax(struct block_device *bdev, 
struct dax_device *dax_d
                return rc;
 
        id = dax_read_lock();
-       rc = dax_direct_access(dax_dev, pgoff, 1, &kaddr, NULL);
+       rc = dax_direct_access(dax_dev, pgoff, 1, DAX_OP_NORMAL, &kaddr,
+                              NULL);
        if (rc < 0) {
                dax_read_unlock(id);
                return rc;
@@ -1036,7 +1037,7 @@ static int dax_iomap_pfn(const struct iomap *iomap, 
loff_t pos, size_t size,
                return rc;
        id = dax_read_lock();
        length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
-                                  NULL, pfnp);
+                                  DAX_OP_NORMAL, NULL, pfnp);
        if (length < 0) {
                rc = length;
                goto out;
@@ -1162,7 +1163,8 @@ s64 dax_iomap_zero(loff_t pos, u64 length, struct iomap 
*iomap)
        if (page_aligned)
                rc = dax_zero_page_range(iomap->dax_dev, pgoff, 1);
        else
-               rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
+               rc = dax_direct_access(iomap->dax_dev, pgoff, 1,
+                                      DAX_OP_NORMAL, &kaddr, NULL);
        if (rc < 0) {
                dax_read_unlock(id);
                return rc;
@@ -1231,7 +1233,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter 
*iomi,
                        break;
 
                map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
-                               &kaddr, NULL);
+                                           DAX_OP_NORMAL, &kaddr, NULL);
                if (map_len < 0) {
                        ret = map_len;
                        break;
@@ -1250,10 +1252,10 @@ static loff_t dax_iomap_iter(const struct iomap_iter 
*iomi,
                 */
                if (iov_iter_rw(iter) == WRITE)
                        xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr,
-                                       map_len, iter);
+                                       map_len, iter, DAX_OP_NORMAL);
                else
                        xfer = dax_copy_to_iter(dax_dev, pgoff, kaddr,
-                                       map_len, iter);
+                                       map_len, iter, DAX_OP_NORMAL);
 
                pos += xfer;
                length -= xfer;
diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index 713818d74de6..755d8d4b7d34 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -1241,8 +1241,8 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax 
*fcd)
        INIT_DELAYED_WORK(&fcd->free_work, fuse_dax_free_mem_worker);
 
        id = dax_read_lock();
-       nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size), NULL,
-                                    NULL);
+       nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size),
+                                    DAX_OP_NORMAL, NULL, NULL);
        dax_read_unlock(id);
        if (nr_pages < 0) {
                pr_debug("dax_direct_access() returned %ld\n", nr_pages);
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index b4c7c7fa987f..fb5433a37a7b 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -739,7 +739,8 @@ static void virtio_fs_cleanup_vqs(struct virtio_device 
*vdev,
  * offset.
  */
 static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
-                                   long nr_pages, void **kaddr, pfn_t *pfn)
+                                   long nr_pages, int mode, void **kaddr,
+                                   pfn_t *pfn)
 {
        struct virtio_fs *fs = dax_get_private(dax_dev);
        phys_addr_t offset = PFN_PHYS(pgoff);
@@ -755,14 +756,16 @@ static long virtio_fs_direct_access(struct dax_device 
*dax_dev, pgoff_t pgoff,
 
 static size_t virtio_fs_copy_from_iter(struct dax_device *dax_dev,
                                       pgoff_t pgoff, void *addr,
-                                      size_t bytes, struct iov_iter *i)
+                                      size_t bytes, struct iov_iter *i,
+                                      int mode)
 {
        return copy_from_iter(addr, bytes, i);
 }
 
 static size_t virtio_fs_copy_to_iter(struct dax_device *dax_dev,
                                       pgoff_t pgoff, void *addr,
-                                      size_t bytes, struct iov_iter *i)
+                                      size_t bytes, struct iov_iter *i,
+                                      int mode)
 {
        return copy_to_iter(addr, bytes, i);
 }
@@ -773,7 +776,8 @@ static int virtio_fs_zero_page_range(struct dax_device 
*dax_dev,
        long rc;
        void *kaddr;
 
-       rc = dax_direct_access(dax_dev, pgoff, nr_pages, &kaddr, NULL);
+       rc = dax_direct_access(dax_dev, pgoff, nr_pages, DAX_OP_NORMAL,
+                              &kaddr, NULL);
        if (rc < 0)
                return rc;
        memset(kaddr, 0, nr_pages << PAGE_SHIFT);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 324363b798ec..931586df2905 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -9,6 +9,10 @@
 /* Flag for synchronous flush */
 #define DAXDEV_F_SYNC (1UL << 0)
 
+/* dax operation mode dynamically set by caller */
+#define        DAX_OP_NORMAL           0
+#define        DAX_OP_RECOVERY         1
+
 typedef unsigned long dax_entry_t;
 
 struct dax_device;
@@ -22,8 +26,8 @@ struct dax_operations {
         * logical-page-offset into an absolute physical pfn. Return the
         * number of pages available for DAX at that pfn.
         */
-       long (*direct_access)(struct dax_device *, pgoff_t, long,
-                       void **, pfn_t *);
+       long (*direct_access)(struct dax_device *, pgoff_t, long, int,
+                               void **, pfn_t *);
        /*
         * Validate whether this device is usable as an fsdax backing
         * device.
@@ -32,10 +36,10 @@ struct dax_operations {
                        sector_t, sector_t);
        /* copy_from_iter: required operation for fs-dax direct-i/o */
        size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t,
-                       struct iov_iter *);
+                       struct iov_iter *, int);
        /* copy_to_iter: required operation for fs-dax direct-i/o */
        size_t (*copy_to_iter)(struct dax_device *, pgoff_t, void *, size_t,
-                       struct iov_iter *);
+                       struct iov_iter *, int);
        /* zero_page_range: required operation. Zero page range   */
        int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
 };
@@ -186,11 +190,11 @@ static inline void dax_read_unlock(int id)
 bool dax_alive(struct dax_device *dax_dev);
 void *dax_get_private(struct dax_device *dax_dev);
 long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long 
nr_pages,
-               void **kaddr, pfn_t *pfn);
+               int mode, void **kaddr, pfn_t *pfn);
 size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void 
*addr,
-               size_t bytes, struct iov_iter *i);
+               size_t bytes, struct iov_iter *i, int mode);
 size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
-               size_t bytes, struct iov_iter *i);
+               size_t bytes, struct iov_iter *i, int mode);
 int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
                        size_t nr_pages);
 void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index a7df155ea49b..6596a8e0ceed 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -146,9 +146,10 @@ typedef int (*dm_busy_fn) (struct dm_target *ti);
  * >= 0 : the number of bytes accessible at the address
  */
 typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn);
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn);
 typedef size_t (*dm_dax_copy_iter_fn)(struct dm_target *ti, pgoff_t pgoff,
-               void *addr, size_t bytes, struct iov_iter *i);
+               void *addr, size_t bytes, struct iov_iter *i,
+               int mode);
 typedef int (*dm_dax_zero_page_range_fn)(struct dm_target *ti, pgoff_t pgoff,
                size_t nr_pages);
 
diff --git a/tools/testing/nvdimm/pmem-dax.c b/tools/testing/nvdimm/pmem-dax.c
index af19c85558e7..71c225630e7e 100644
--- a/tools/testing/nvdimm/pmem-dax.c
+++ b/tools/testing/nvdimm/pmem-dax.c
@@ -8,7 +8,7 @@
 #include <nd.h>
 
 long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
-               long nr_pages, void **kaddr, pfn_t *pfn)
+               long nr_pages, int mode, void **kaddr, pfn_t *pfn)
 {
        resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;
 
-- 
2.18.4


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