John Groves wrote: > From: John Groves <[email protected]> > > fsdev: Add dax_operations for use by famfs > > - These methods are based on pmem_dax_ops from drivers/nvdimm/pmem.c > - fsdev_dax_direct_access() returns the hpa, pfn and kva. The kva was > newly stored as dev_dax->virt_addr by dev_dax_probe(). > - The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used > for read/write (dax_iomap_rw())
I thought this driver did not support mmap? > - fsdev_dax_recovery_write() and dev_dax_zero_page_range() have not been > tested yet. I'm looking for suggestions as to how to test those. > - dax-private.h: add dev_dax->cached_size, which fsdev needs to > remember. The dev_dax size cannot change while a driver is bound > (dev_dax_resize returns -EBUSY if dev->driver is set). Caching the size > at probe time allows fsdev's direct_access path can use it without > acquiring dax_dev_rwsem (which isn't exported anyway). > None of the above explains exactly why this code is needed. Rather it just explains what it does. I'm not 100% clear on why this is needed in the driver and why this is not a layering violation which is going to bite us later? Ira > Signed-off-by: John Groves <[email protected]> > --- > drivers/dax/dax-private.h | 1 + > drivers/dax/fsdev.c | 85 +++++++++++++++++++++++++++++++++++++++ > 2 files changed, 86 insertions(+) > > diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h > index 4ae4d829d3ee..092f4ae024ea 100644 > --- a/drivers/dax/dax-private.h > +++ b/drivers/dax/dax-private.h > @@ -83,6 +83,7 @@ struct dev_dax { > struct dax_region *region; > struct dax_device *dax_dev; > void *virt_addr; > + u64 cached_size; > unsigned int align; > int target_node; > bool dyn_id; > diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c > index 72f78f606e06..5d17ad39227f 100644 > --- a/drivers/dax/fsdev.c > +++ b/drivers/dax/fsdev.c > @@ -28,6 +28,86 @@ > * - No mmap support - all access is through fs-dax/iomap > */ > > +static void fsdev_write_dax(void *pmem_addr, struct page *page, > + unsigned int off, unsigned int len) > +{ > + while (len) { > + void *mem = kmap_local_page(page); > + unsigned int chunk = min_t(unsigned int, len, PAGE_SIZE - off); > + > + memcpy_flushcache(pmem_addr, mem + off, chunk); > + kunmap_local(mem); > + len -= chunk; > + off = 0; > + page++; > + pmem_addr += chunk; > + } > +} > + > +static long __fsdev_dax_direct_access(struct dax_device *dax_dev, pgoff_t > pgoff, > + long nr_pages, enum dax_access_mode mode, void **kaddr, > + unsigned long *pfn) > +{ > + struct dev_dax *dev_dax = dax_get_private(dax_dev); > + size_t size = nr_pages << PAGE_SHIFT; > + size_t offset = pgoff << PAGE_SHIFT; > + void *virt_addr = dev_dax->virt_addr + offset; > + phys_addr_t phys; > + unsigned long local_pfn; > + > + WARN_ON(!dev_dax->virt_addr); > + > + phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT); > + if (phys == -1) { > + dev_dbg(&dev_dax->dev, > + "pgoff (%#lx) out of range\n", pgoff); > + return -ERANGE; > + } > + > + if (kaddr) > + *kaddr = virt_addr; > + > + local_pfn = PHYS_PFN(phys); > + if (pfn) > + *pfn = local_pfn; > + > + /* > + * Use cached_size which was computed at probe time. The size cannot > + * change while the driver is bound (resize returns -EBUSY). > + */ > + return PHYS_PFN(min(size, dev_dax->cached_size - offset)); > +} > + > +static int fsdev_dax_zero_page_range(struct dax_device *dax_dev, > + pgoff_t pgoff, size_t nr_pages) > +{ > + void *kaddr; > + > + WARN_ONCE(nr_pages > 1, "%s: nr_pages > 1\n", __func__); > + __fsdev_dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS, &kaddr, NULL); > + fsdev_write_dax(kaddr, ZERO_PAGE(0), 0, PAGE_SIZE); > + return 0; > +} > + > +static long fsdev_dax_direct_access(struct dax_device *dax_dev, > + pgoff_t pgoff, long nr_pages, enum dax_access_mode mode, > + void **kaddr, unsigned long *pfn) > +{ > + return __fsdev_dax_direct_access(dax_dev, pgoff, nr_pages, mode, > + kaddr, pfn); > +} > + > +static size_t fsdev_dax_recovery_write(struct dax_device *dax_dev, pgoff_t > pgoff, > + void *addr, size_t bytes, struct iov_iter *i) > +{ > + return _copy_from_iter_flushcache(addr, bytes, i); > +} > + > +static const struct dax_operations dev_dax_ops = { > + .direct_access = fsdev_dax_direct_access, > + .zero_page_range = fsdev_dax_zero_page_range, > + .recovery_write = fsdev_dax_recovery_write, > +}; > > static void fsdev_cdev_del(void *cdev) > { > @@ -163,6 +243,11 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax) > } > } > > + /* Cache size now; it cannot change while driver is bound */ > + dev_dax->cached_size = 0; > + for (i = 0; i < dev_dax->nr_range; i++) > + dev_dax->cached_size += range_len(&dev_dax->ranges[i].range); > + > /* > * FS-DAX compatible mode: Use MEMORY_DEVICE_FS_DAX type and > * do NOT set vmemmap_shift. This leaves folios at order-0, > -- > 2.52.0 > > >
