The actor functions get the source blocks' start address from
iomap->src_addr, and then copy these blocks to the new allocated
blocks before writing the user data.
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxxxxx>
cc: linux-nvdimm@xxxxxxxxxxxx
---
fs/dax.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 70 insertions(+)
diff --git a/fs/dax.c b/fs/dax.c
index ca0671d55aa6..28519bdecf7c 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -982,6 +982,11 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
}
+static sector_t dax_iomap_src_sector(struct iomap *iomap, loff_t pos)
+{
+ return (iomap->src_addr + (pos & PAGE_MASK) - iomap->offset) >> 9;
+}
+
static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
pfn_t *pfnp)
{
@@ -1014,6 +1019,51 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size,
return rc;
}
+static int dax_iomap_addr(struct iomap *iomap, sector_t sector, size_t size,
+ void **kaddr)
+{
+ pgoff_t pgoff;
+ int id, rc;
+ long length;
+
+ rc = bdev_dax_pgoff(iomap->bdev, sector, size, &pgoff);
+ if (rc)
+ return rc;
+
+ id = dax_read_lock();
+ length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size),
+ kaddr, NULL);
+ if (length < 0)
+ rc = length;
+ if (!*kaddr)
+ rc = -EFAULT;
+
+ dax_read_unlock(id);
+ return rc;
+}
+
+static int dax_iomap_cow_copy(struct iomap *iomap, loff_t pos, size_t size)
+{
+ void *kaddr = 0, *src_kaddr = 0;
+ int error = 0;
+ const sector_t src_sector = dax_iomap_src_sector(iomap, pos);
+ const sector_t sector = dax_iomap_sector(iomap, pos);
+
+ error = dax_iomap_addr(iomap, src_sector, size, &src_kaddr);
+ if (error < 0)
+ return error;
+ error = dax_iomap_addr(iomap, sector, size, &kaddr);
+ if (error < 0)
+ return error;
+
+ /*
+ * Copy data from source blocks to the new allocated blocks before
+ * writing user data.
+ */
+ memcpy(kaddr, src_kaddr, size);
+ return 0;
+}
+
/*
* The user has performed a load from a hole in the file. Allocating a new
* page in the file would cause excessive storage usage for workloads with
@@ -1149,6 +1199,12 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (map_len > end - pos)
map_len = end - pos;
+ if (iomap->src_addr) {
+ ret = dax_iomap_cow_copy(iomap, pos, size);
+ if (ret < 0)
+ break;
+ }
+
/*
* The userspace address for the memory copy has already been
* validated via access_ok() in either vfs_read() or
@@ -1336,6 +1392,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
major = VM_FAULT_MAJOR;
}
+
error = dax_iomap_pfn(&iomap, pos, PAGE_SIZE, &pfn);
if (error < 0)
goto error_finish_iomap;
@@ -1358,6 +1415,13 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
ret = VM_FAULT_NEEDDSYNC | major;
goto finish_iomap;
}
+
+ if (iomap.src_addr) {
+ error = dax_iomap_cow_copy(&iomap, pos, PAGE_SIZE);
+ if (error < 0)
+ goto error_finish_iomap;
+ }
+
trace_dax_insert_mapping(inode, vmf, entry);
if (write)
ret = vmf_insert_mixed_mkwrite(vma, vaddr, pfn);
@@ -1559,6 +1623,12 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto finish_iomap;
}
+ if (iomap.src_addr) {
+ error = dax_iomap_cow_copy(&iomap, pos, PMD_SIZE);
+ if (error < 0)
+ goto finish_iomap;
+ }
+
trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry);
result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn,
write);
--
2.17.0
