| Message ID | 5727b1be956278e3a6c4cf7b728ee4f8f037ae51.1708709155.git.john@groves.net (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | Introduce the famfs shared-memory file system | expand |
On Fri, 23 Feb 2024 11:41:49 -0600 John Groves <John@Groves.net> wrote: > Notes about this commit: > > * These methods are based somewhat loosely on pmem_dax_ops from > drivers/nvdimm/pmem.c > > * dev_dax_direct_access() is 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()) > > * dev_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. > > Signed-off-by: John Groves <john@groves.net> > --- > drivers/dax/bus.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 107 insertions(+) > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > index 664e8c1b9930..06fcda810674 100644 > --- a/drivers/dax/bus.c > +++ b/drivers/dax/bus.c > @@ -10,6 +10,12 @@ > #include "dax-private.h" > #include "bus.h" > > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > +#include <linux/backing-dev.h> > +#include <linux/pfn_t.h> > +#include <linux/range.h> > +#endif > + Is it worth avoiding includes based on config? Probably not. > static DEFINE_MUTEX(dax_bus_lock); > > #define DAX_NAME_LEN 30 > @@ -1349,6 +1355,101 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, > } > EXPORT_SYMBOL_GPL(dax_pgoff_to_phys); > > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > + > + > +static long __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, > + long nr_pages, enum dax_access_mode mode, void **kaddr, > + pfn_t *pfn) > +{ > + struct dev_dax *dev_dax = dax_get_private(dax_dev); > + size_t dax_size = dev_dax_size(dev_dax); > + size_t size = nr_pages << PAGE_SHIFT; > + size_t offset = pgoff << PAGE_SHIFT; > + phys_addr_t phys; > + u64 virt_addr = dev_dax->virt_addr + offset; > + pfn_t local_pfn; > + u64 flags = PFN_DEV|PFN_MAP; > + > + WARN_ON(!dev_dax->virt_addr); /* virt_addr must be saved for direct_access */ Fair enough, but from local code point of view, does it make sense to check this if !kaddr as we won't use this. > + > + phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT); > + > + if (kaddr) > + *kaddr = (void *)virt_addr; Back to earlier comment on virt_addr as a void *. Definitely looking like that would be more accurate and simpler! Also not much point in computing virt_addr unless kaddr is good. > + > + local_pfn = phys_to_pfn_t(phys, flags); /* are flags correct? */ If you aren't going to do anything with it for !pfn, move it under the if (pfn). > + if (pfn) > + *pfn = local_pfn; > + > + /* This the valid size at the specified address */ > + return PHYS_PFN(min_t(size_t, size, dax_size - offset)); > +} > + > + > +static const struct dax_operations dev_dax_ops = { > + .direct_access = dev_dax_direct_access, > + .zero_page_range = dev_dax_zero_page_range, > + .recovery_write = dev_dax_recovery_write, > +}; > + > +#endif /* IS_ENABLED(CONFIG_DEV_DAX_IOMAP) */ > + > struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) > { > struct dax_region *dax_region = data->dax_region; > @@ -1404,11 +1505,17 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) > } > } > If we were to make this if (IS_ENABLED(CONFIG_DEV_DAX_IOMAP)) etc can we avoid the ifdef stuff above and let dead code removal deal with it? Might need a few stubs - I haven't tried. > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > + /* holder_ops currently populated separately in a slightly hacky way */ > + dax_dev = alloc_dax(dev_dax, &dev_dax_ops); > +#else > /* > * No dax_operations since there is no access to this device outside of > * mmap of the resulting character device. > */ > dax_dev = alloc_dax(dev_dax, NULL); > +#endif > + > if (IS_ERR(dax_dev)) { > rc = PTR_ERR(dax_dev); > goto err_alloc_dax;
On 24/02/26 12:32PM, Jonathan Cameron wrote: > On Fri, 23 Feb 2024 11:41:49 -0600 > John Groves <John@Groves.net> wrote: > > > Notes about this commit: > > > > * These methods are based somewhat loosely on pmem_dax_ops from > > drivers/nvdimm/pmem.c > > > > * dev_dax_direct_access() is 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()) > > > > * dev_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. > > > > Signed-off-by: John Groves <john@groves.net> > > --- > > drivers/dax/bus.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 107 insertions(+) > > > > diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c > > index 664e8c1b9930..06fcda810674 100644 > > --- a/drivers/dax/bus.c > > +++ b/drivers/dax/bus.c > > @@ -10,6 +10,12 @@ > > #include "dax-private.h" > > #include "bus.h" > > > > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > > +#include <linux/backing-dev.h> > > +#include <linux/pfn_t.h> > > +#include <linux/range.h> > > +#endif > > + > > Is it worth avoiding includes based on config? Probably not. Just trying to demonstrate that I can be tedious :D I'll drop the #if unless somebody disagrees. > > > static DEFINE_MUTEX(dax_bus_lock); > > > > #define DAX_NAME_LEN 30 > > @@ -1349,6 +1355,101 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, > > } > > EXPORT_SYMBOL_GPL(dax_pgoff_to_phys); > > > > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > > + > > > + > > +static long __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, > > + long nr_pages, enum dax_access_mode mode, void **kaddr, > > + pfn_t *pfn) > > +{ > > + struct dev_dax *dev_dax = dax_get_private(dax_dev); > > + size_t dax_size = dev_dax_size(dev_dax); > > + size_t size = nr_pages << PAGE_SHIFT; > > + size_t offset = pgoff << PAGE_SHIFT; > > + phys_addr_t phys; > > + u64 virt_addr = dev_dax->virt_addr + offset; > > + pfn_t local_pfn; > > + u64 flags = PFN_DEV|PFN_MAP; > > + > > + WARN_ON(!dev_dax->virt_addr); /* virt_addr must be saved for direct_access */ > Fair enough, but from local code point of view, does it make sense to check this > if !kaddr as we won't use this. Hmm. This gets called with kaddr=NULL for mmap faults, and with non-NULL kaddr for read/write (which need the virt_addr to do a memcpy variant). If dev_dax->virt-addr is NULL, mmap will work but read/write will hork. I lean toward keeping the warning. With these updates, it's broken if read/write are broken. > > + > > + phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT); > > + > > + if (kaddr) > > + *kaddr = (void *)virt_addr; > > Back to earlier comment on virt_addr as a void *. Definitely looking like > that would be more accurate and simpler! Also not much point in computing > virt_addr unless kaddr is good. Yes, done (the void *). the computation is copied directly from drivers/nvdimm/__pmem_direct_access() - which does not warn if virt_addr is null. Actually I suppose this code should just trust that dev_dax_probe sets virt_addr, and not warn? So I'm now contradicting myself above... > > > + > > + local_pfn = phys_to_pfn_t(phys, flags); /* are flags correct? */ > If you aren't going to do anything with it for !pfn, move it under the if (pfn). > > > + if (pfn) > > + *pfn = local_pfn; > > + > > + /* This the valid size at the specified address */ > > + return PHYS_PFN(min_t(size_t, size, dax_size - offset)); > > +} > > + > > > + > > +static const struct dax_operations dev_dax_ops = { > > + .direct_access = dev_dax_direct_access, > > + .zero_page_range = dev_dax_zero_page_range, > > + .recovery_write = dev_dax_recovery_write, > > +}; > > + > > +#endif /* IS_ENABLED(CONFIG_DEV_DAX_IOMAP) */ > > + > > struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) > > { > > struct dax_region *dax_region = data->dax_region; > > @@ -1404,11 +1505,17 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) > > } > > } > > > > If we were to make this > > if (IS_ENABLED(CONFIG_DEV_DAX_IOMAP)) > > etc can we avoid the ifdef stuff above and let dead code removal deal with it? > Might need a few stubs - I haven't tried. Better, thanks. No stubs needed. > > > +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) > > + /* holder_ops currently populated separately in a slightly hacky way */ > > + dax_dev = alloc_dax(dev_dax, &dev_dax_ops); > > +#else > > /* > > * No dax_operations since there is no access to this device outside of > > * mmap of the resulting character device. > > */ > > dax_dev = alloc_dax(dev_dax, NULL); > > +#endif Thanks! John
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 664e8c1b9930..06fcda810674 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -10,6 +10,12 @@ #include "dax-private.h" #include "bus.h" +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) +#include <linux/backing-dev.h> +#include <linux/pfn_t.h> +#include <linux/range.h> +#endif + static DEFINE_MUTEX(dax_bus_lock); #define DAX_NAME_LEN 30 @@ -1349,6 +1355,101 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, } EXPORT_SYMBOL_GPL(dax_pgoff_to_phys); +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) + +static void write_dax(void *pmem_addr, struct page *page, + unsigned int off, unsigned int len) +{ + unsigned int chunk; + void *mem; + + while (len) { + mem = kmap_local_page(page); + 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 __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, + long nr_pages, enum dax_access_mode mode, void **kaddr, + pfn_t *pfn) +{ + struct dev_dax *dev_dax = dax_get_private(dax_dev); + size_t dax_size = dev_dax_size(dev_dax); + size_t size = nr_pages << PAGE_SHIFT; + size_t offset = pgoff << PAGE_SHIFT; + phys_addr_t phys; + u64 virt_addr = dev_dax->virt_addr + offset; + pfn_t local_pfn; + u64 flags = PFN_DEV|PFN_MAP; + + WARN_ON(!dev_dax->virt_addr); /* virt_addr must be saved for direct_access */ + + phys = dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT); + + if (kaddr) + *kaddr = (void *)virt_addr; + + local_pfn = phys_to_pfn_t(phys, flags); /* are flags correct? */ + if (pfn) + *pfn = local_pfn; + + /* This the valid size at the specified address */ + return PHYS_PFN(min_t(size_t, size, dax_size - offset)); +} + +static int dev_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff, + size_t nr_pages) +{ + long resid = nr_pages << PAGE_SHIFT; + long offset = pgoff << PAGE_SHIFT; + + /* Break into one write per dax region */ + while (resid > 0) { + void *kaddr; + pgoff_t poff = offset >> PAGE_SHIFT; + long len = __dev_dax_direct_access(dax_dev, poff, + nr_pages, DAX_ACCESS, &kaddr, NULL); + len = min_t(long, len, PAGE_SIZE); + write_dax(kaddr, ZERO_PAGE(0), offset, len); + + offset += len; + resid -= len; + } + return 0; +} + +static long dev_dax_direct_access(struct dax_device *dax_dev, + pgoff_t pgoff, long nr_pages, enum dax_access_mode mode, + void **kaddr, pfn_t *pfn) +{ + return __dev_dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn); +} + +static size_t dev_dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff, + void *addr, size_t bytes, struct iov_iter *i) +{ + size_t len, off; + + off = offset_in_page(addr); + len = PFN_PHYS(PFN_UP(off + bytes)); + + return _copy_from_iter_flushcache(addr, bytes, i); +} + +static const struct dax_operations dev_dax_ops = { + .direct_access = dev_dax_direct_access, + .zero_page_range = dev_dax_zero_page_range, + .recovery_write = dev_dax_recovery_write, +}; + +#endif /* IS_ENABLED(CONFIG_DEV_DAX_IOMAP) */ + struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) { struct dax_region *dax_region = data->dax_region; @@ -1404,11 +1505,17 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) } } +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) + /* holder_ops currently populated separately in a slightly hacky way */ + dax_dev = alloc_dax(dev_dax, &dev_dax_ops); +#else /* * No dax_operations since there is no access to this device outside of * mmap of the resulting character device. */ dax_dev = alloc_dax(dev_dax, NULL); +#endif + if (IS_ERR(dax_dev)) { rc = PTR_ERR(dax_dev); goto err_alloc_dax;
Notes about this commit: * These methods are based somewhat loosely on pmem_dax_ops from drivers/nvdimm/pmem.c * dev_dax_direct_access() is 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()) * dev_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. Signed-off-by: John Groves <john@groves.net> --- drivers/dax/bus.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+)