From e7638488434415aa478e78435cac8f0365737638 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 16 May 2018 11:46:08 -0700 Subject: mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In preparation for fixing dax-dma-vs-unmap issues, filesystems need to be able to rely on the fact that they will get wakeups on dev_pagemap page-idle events. Introduce MEMORY_DEVICE_FS_DAX and generic_dax_page_free() as common indicator / infrastructure for dax filesytems to require. With this change there are no users of the MEMORY_DEVICE_HOST designation, so remove it. The HMM sub-system extended dev_pagemap to arrange a callback when a dev_pagemap managed page is freed. Since a dev_pagemap page is free / idle when its reference count is 1 it requires an additional branch to check the page-type at put_page() time. Given put_page() is a hot-path we do not want to incur that check if HMM is not in use, so a static branch is used to avoid that overhead when not necessary. Now, the FS_DAX implementation wants to reuse this mechanism for receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific static-key into a generic mechanism that either HMM or FS_DAX code paths can enable. For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support, care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure. However, we still need to support FS_DAX in the FS_DAX_LIMITED case implemented by the s390/dcssblk driver. Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Michal Hocko Reported-by: kbuild test robot Reported-by: Thomas Meyer Reported-by: Dave Jiang Cc: "Jérôme Glisse" Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams --- drivers/dax/super.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 2b2332b605e4..bf8bfaf5596f 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -86,6 +86,7 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize) { struct block_device *bdev = sb->s_bdev; struct dax_device *dax_dev; + bool dax_enabled = false; pgoff_t pgoff; int err, id; void *kaddr; @@ -134,14 +135,21 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize) * on being able to do (page_address(pfn_to_page())). */ WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API)); + dax_enabled = true; } else if (pfn_t_devmap(pfn)) { - /* pass */; - } else { + struct dev_pagemap *pgmap; + + pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL); + if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX) + dax_enabled = true; + put_dev_pagemap(pgmap); + } + + if (!dax_enabled) { pr_debug("VFS (%s): error: dax support not enabled\n", sb->s_id); return -EOPNOTSUPP; } - return 0; } EXPORT_SYMBOL_GPL(__bdev_dax_supported); -- cgit From b3a9a0c36e1f7b9e2e6cf965c2bb973624f2b3b9 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 2 May 2018 06:46:33 -0700 Subject: dax: Introduce a ->copy_to_iter dax operation Similar to the ->copy_from_iter() operation, a platform may want to deploy an architecture or device specific routine for handling reads from a dax_device like /dev/pmemX. On x86 this routine will point to a machine check safe version of copy_to_iter(). For now, add the plumbing to device-mapper and the dax core. Cc: Ross Zwisler Cc: Mike Snitzer Cc: Christoph Hellwig Signed-off-by: Dan Williams --- drivers/dax/super.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/dax') diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 2b2332b605e4..31b839113399 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -282,6 +282,16 @@ size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr, } 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) +{ + if (!dax_alive(dax_dev)) + return 0; + + return dax_dev->ops->copy_to_iter(dax_dev, pgoff, addr, bytes, i); +} +EXPORT_SYMBOL_GPL(dax_copy_to_iter); + #ifdef CONFIG_ARCH_HAS_PMEM_API void arch_wb_cache_pmem(void *addr, size_t size); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) -- cgit From 808c340be17dc77131fcdf9ad1eb34452d650da1 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Wed, 6 Jun 2018 10:45:14 -0600 Subject: dax: Use dax_write_cache* helpers Use dax_write_cache() and dax_write_cache_enabled() instead of open coding the bit operations. Signed-off-by: Ross Zwisler Signed-off-by: Dan Williams --- drivers/dax/super.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 2b2332b605e4..c2c46f96b18c 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -182,8 +182,7 @@ static ssize_t write_cache_show(struct device *dev, if (!dax_dev) return -ENXIO; - rc = sprintf(buf, "%d\n", !!test_bit(DAXDEV_WRITE_CACHE, - &dax_dev->flags)); + rc = sprintf(buf, "%d\n", !!dax_write_cache_enabled(dax_dev)); put_dax(dax_dev); return rc; } @@ -201,10 +200,8 @@ static ssize_t write_cache_store(struct device *dev, if (rc) len = rc; - else if (write_cache) - set_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags); else - clear_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags); + dax_write_cache(dax_dev, write_cache); put_dax(dax_dev); return len; @@ -286,7 +283,7 @@ EXPORT_SYMBOL_GPL(dax_copy_from_iter); void arch_wb_cache_pmem(void *addr, size_t size); void dax_flush(struct dax_device *dax_dev, void *addr, size_t size) { - if (unlikely(!test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags))) + if (unlikely(!dax_write_cache_enabled(dax_dev))) return; arch_wb_cache_pmem(addr, size); -- cgit