To copy source data to destance address before write. Change dax_iomap_pfn() to return the address as well in order to use it for performing a memcpy in case the type is IOMAP_COW.
dax_copy_edges() is a helper functions performs a copy from one part of the device to another for data not page aligned. Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com> Signed-off-by: Shiyang Ruan <ruansy.f...@cn.fujitsu.com> --- fs/dax.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 58 insertions(+), 6 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 68eef98cd9c4..e1f4493ce56a 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -987,8 +987,8 @@ static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos) return (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9; } -static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, - pfn_t *pfnp) +static int dax_iomap_direct_access(struct iomap *iomap, loff_t pos, size_t size, + pfn_t *pfnp, void **addr) { const sector_t sector = dax_iomap_sector(iomap, pos); pgoff_t pgoff; @@ -999,12 +999,14 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, if (rc) return rc; id = dax_read_lock(); - length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), - NULL, pfnp); + length = dax_direct_access(iomap->dax_dev, pgoff, PHYS_PFN(size), addr, + pfnp); if (length < 0) { rc = length; goto out; } + if (!pfnp) + goto out_check_addr; rc = -EINVAL; if (PFN_PHYS(length) < size) goto out; @@ -1014,6 +1016,12 @@ static int dax_iomap_pfn(struct iomap *iomap, loff_t pos, size_t size, if (length > 1 && !pfn_t_devmap(*pfnp)) goto out; rc = 0; + +out_check_addr: + if (!addr) + goto out; + if (!*addr) + rc = -EFAULT; out: dax_read_unlock(id); return rc; @@ -1056,6 +1064,48 @@ static bool dax_range_is_aligned(struct block_device *bdev, return true; } +/* + * dax_copy_edges - Copies the part of the pages not included in + * the write, but required for CoW because + * offset/offset+length are not page aligned. + */ +static int dax_copy_edges(loff_t pos, loff_t length, struct iomap *srcmap, + void *daddr, bool pmd) +{ + size_t page_size = pmd ? PMD_SIZE : PAGE_SIZE; + loff_t offset = pos & (page_size - 1); + size_t size = ALIGN(offset + length, page_size); + loff_t end = pos + length; + loff_t pg_end = round_up(end, page_size); + void *saddr = 0; + int ret = 0; + + ret = dax_iomap_direct_access(srcmap, pos, size, NULL, &saddr); + if (ret) + return ret; + /* + * Copy the first part of the page + * Note: we pass offset as length + */ + if (offset) { + if (saddr) + ret = memcpy_mcsafe(daddr, saddr, offset); + else + memset(daddr, 0, offset); + } + + /* Copy the last part of the range */ + if (end < pg_end) { + if (saddr) + ret = memcpy_mcsafe(daddr + offset + length, + saddr + offset + length, pg_end - end); + else + memset(daddr + offset + length, 0, + pg_end - end); + } + return ret; +} + int __dax_zero_page_range(struct block_device *bdev, struct dax_device *dax_dev, sector_t sector, unsigned int offset, unsigned int size) @@ -1342,7 +1392,8 @@ 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); + error = dax_iomap_direct_access(&iomap, pos, PAGE_SIZE, &pfn, + NULL); if (error < 0) goto error_finish_iomap; @@ -1560,7 +1611,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, switch (iomap.type) { case IOMAP_MAPPED: - error = dax_iomap_pfn(&iomap, pos, PMD_SIZE, &pfn); + error = dax_iomap_direct_access(&iomap, pos, PMD_SIZE, &pfn, + NULL); if (error < 0) goto finish_iomap; -- 2.23.0 _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-le...@lists.01.org