From: Dan Williams <dan.j.williams@intel.com> To: akpm@linux-foundation.org Cc: Jan Kara <jack@suse.cz>, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig <hch@lst.de> Subject: [PATCH 10/13] filesystem-dax: Make mount time pfn validation a debug check Date: Wed, 04 Jul 2018 23:49:56 -0700 [thread overview] Message-ID: <153077339595.40830.16578300356324475234.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <153077334130.40830.2714147692560185329.stgit@dwillia2-desk3.amr.corp.intel.com> Do not ask for dax_direct_access() to retrieve a pfn in the DAX_DRIVER_DEBUG=n case. This avoids an early call to memmap_sync() in the driver. Now that QUEUE_FLAG_DAX usage has been fixed the validation of the pfn is only useful for dax driver developers. It is safe to assume that pmem, dcssblk, and device-mapper-dax are correct with respect to dax operation, so only retrieve the pfn for debug builds when qualifying a new dax driver, if one ever arrives. The moves the first consumption of a pfn from ->direct_access() to the first dax mapping fault, rather than initial filesystem mount. I.e. more time for memmap init to run in the background. Cc: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- drivers/dax/Kconfig | 10 ++++++++ drivers/dax/super.c | 64 ++++++++++++++++++++++++++++++++------------------- 2 files changed, 50 insertions(+), 24 deletions(-) diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index e0700bf4893a..b32f8827b983 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -9,6 +9,16 @@ menuconfig DAX if DAX +config DAX_DRIVER_DEBUG + bool "DAX: driver debug" + help + Enable validation of the page frame objects returned from a + driver's 'direct_access' operation. This validation is + performed relative to the requirements of the FS_DAX and + FS_DAX_LIMITED configuration options. If you are validating + the implementation of a dax device driver say Y otherwise + say N. + config DEV_DAX tristate "Device DAX: direct access mapping device" depends on TRANSPARENT_HUGEPAGE diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 903d9c473749..87b1c55b7c7a 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -72,6 +72,41 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); #endif +static bool validate_dax_pfn(pfn_t *pfn) +{ + bool dax_enabled = false; + + /* + * Unless debugging a new dax driver, or new dax architecture + * support there is no need to check the pfn. Delay the kernel's + * first need for a dax pfn until first userspace dax fault. + */ + if (!pfn) + return true; + + if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(*pfn)) { + /* + * An arch that has enabled the pmem api should also + * have its drivers support pfn_t_devmap() + * + * This is a developer warning and should not trigger in + * production. dax_flush() will crash since it depends + * 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)) { + 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); + } + + return dax_enabled; +} + /** * __bdev_dax_supported() - Check if the device supports dax for filesystem * @bdev: block device to check @@ -85,11 +120,10 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); bool __bdev_dax_supported(struct block_device *bdev, int blocksize) { struct dax_device *dax_dev; - bool dax_enabled = false; + pfn_t _pfn, *pfn; pgoff_t pgoff; int err, id; void *kaddr; - pfn_t pfn; long len; char buf[BDEVNAME_SIZE]; @@ -113,8 +147,10 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) return false; } + pfn = IS_ENABLED(DAX_DRIVER_DEBUG) ? &_pfn : NULL; + id = dax_read_lock(); - len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); + len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, pfn); dax_read_unlock(id); put_dax(dax_dev); @@ -125,27 +161,7 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) return false; } - if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) { - /* - * An arch that has enabled the pmem api should also - * have its drivers support pfn_t_devmap() - * - * This is a developer warning and should not trigger in - * production. dax_flush() will crash since it depends - * 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)) { - 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) { + if (!validate_dax_pfn(pfn)) { pr_debug("%s: error: dax support not enabled\n", bdevname(bdev, buf)); return false; _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: akpm@linux-foundation.org Cc: Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>, Ross Zwisler <ross.zwisler@linux.intel.com>, vishal.l.verma@intel.com, linux-nvdimm@lists.01.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 10/13] filesystem-dax: Make mount time pfn validation a debug check Date: Wed, 04 Jul 2018 23:49:56 -0700 [thread overview] Message-ID: <153077339595.40830.16578300356324475234.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <153077334130.40830.2714147692560185329.stgit@dwillia2-desk3.amr.corp.intel.com> Do not ask for dax_direct_access() to retrieve a pfn in the DAX_DRIVER_DEBUG=n case. This avoids an early call to memmap_sync() in the driver. Now that QUEUE_FLAG_DAX usage has been fixed the validation of the pfn is only useful for dax driver developers. It is safe to assume that pmem, dcssblk, and device-mapper-dax are correct with respect to dax operation, so only retrieve the pfn for debug builds when qualifying a new dax driver, if one ever arrives. The moves the first consumption of a pfn from ->direct_access() to the first dax mapping fault, rather than initial filesystem mount. I.e. more time for memmap init to run in the background. Cc: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- drivers/dax/Kconfig | 10 ++++++++ drivers/dax/super.c | 64 ++++++++++++++++++++++++++++++++------------------- 2 files changed, 50 insertions(+), 24 deletions(-) diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index e0700bf4893a..b32f8827b983 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -9,6 +9,16 @@ menuconfig DAX if DAX +config DAX_DRIVER_DEBUG + bool "DAX: driver debug" + help + Enable validation of the page frame objects returned from a + driver's 'direct_access' operation. This validation is + performed relative to the requirements of the FS_DAX and + FS_DAX_LIMITED configuration options. If you are validating + the implementation of a dax device driver say Y otherwise + say N. + config DEV_DAX tristate "Device DAX: direct access mapping device" depends on TRANSPARENT_HUGEPAGE diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 903d9c473749..87b1c55b7c7a 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -72,6 +72,41 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev) EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); #endif +static bool validate_dax_pfn(pfn_t *pfn) +{ + bool dax_enabled = false; + + /* + * Unless debugging a new dax driver, or new dax architecture + * support there is no need to check the pfn. Delay the kernel's + * first need for a dax pfn until first userspace dax fault. + */ + if (!pfn) + return true; + + if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(*pfn)) { + /* + * An arch that has enabled the pmem api should also + * have its drivers support pfn_t_devmap() + * + * This is a developer warning and should not trigger in + * production. dax_flush() will crash since it depends + * 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)) { + 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); + } + + return dax_enabled; +} + /** * __bdev_dax_supported() - Check if the device supports dax for filesystem * @bdev: block device to check @@ -85,11 +120,10 @@ EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev); bool __bdev_dax_supported(struct block_device *bdev, int blocksize) { struct dax_device *dax_dev; - bool dax_enabled = false; + pfn_t _pfn, *pfn; pgoff_t pgoff; int err, id; void *kaddr; - pfn_t pfn; long len; char buf[BDEVNAME_SIZE]; @@ -113,8 +147,10 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) return false; } + pfn = IS_ENABLED(DAX_DRIVER_DEBUG) ? &_pfn : NULL; + id = dax_read_lock(); - len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); + len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, pfn); dax_read_unlock(id); put_dax(dax_dev); @@ -125,27 +161,7 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) return false; } - if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) { - /* - * An arch that has enabled the pmem api should also - * have its drivers support pfn_t_devmap() - * - * This is a developer warning and should not trigger in - * production. dax_flush() will crash since it depends - * 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)) { - 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) { + if (!validate_dax_pfn(pfn)) { pr_debug("%s: error: dax support not enabled\n", bdevname(bdev, buf)); return false;
next prev parent reply other threads:[~2018-07-05 6:59 UTC|newest] Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-07-05 6:49 [PATCH 00/13] mm: Asynchronous + multithreaded memmap init for ZONE_DEVICE Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 01/13] mm: Plumb dev_pagemap instead of vmem_altmap to memmap_init_zone() Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 02/13] mm: Enable asynchronous __add_pages() and vmemmap_populate_hugepages() Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 03/13] mm: Teach memmap_init_zone() to initialize ZONE_DEVICE pages Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 04/13] mm: Multithread ZONE_DEVICE initialization Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 05/13] mm: Allow an external agent to wait for memmap initialization Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 06/13] nvdimm/pmem: check the validity of the pointer pfn Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 07/13] nvdimm/pmem-dax: " Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 08/13] s390/block/dcssblk: " Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` [PATCH 09/13] fs/dax: Assign NULL to pfn of dax_direct_access if useless Dan Williams 2018-07-05 6:49 ` Dan Williams 2018-07-05 6:49 ` Dan Williams [this message] 2018-07-05 6:49 ` [PATCH 10/13] filesystem-dax: Make mount time pfn validation a debug check Dan Williams 2018-07-05 6:50 ` [PATCH 11/13] libnvdimm, pmem: Initialize the memmap in the background Dan Williams 2018-07-05 6:50 ` Dan Williams 2018-07-05 6:50 ` [PATCH 12/13] device-dax: " Dan Williams 2018-07-05 6:50 ` Dan Williams 2018-07-05 6:50 ` [PATCH 13/13] libnvdimm, namespace: Publish page structure init state / control Dan Williams 2018-07-05 6:50 ` Dan Williams 2018-07-05 8:29 ` Johannes Thumshirn 2018-07-05 8:29 ` Johannes Thumshirn 2018-07-05 8:29 ` Johannes Thumshirn 2018-07-05 14:46 ` Dan Williams 2018-07-05 14:46 ` Dan Williams 2018-07-05 14:49 ` Johannes Thumshirn 2018-07-05 14:49 ` Johannes Thumshirn 2018-07-05 14:49 ` Johannes Thumshirn 2018-07-05 20:24 ` Andrew Morton 2018-07-05 20:24 ` Andrew Morton 2018-07-05 20:34 ` Dan Williams 2018-07-05 20:34 ` Dan Williams 2018-07-06 8:18 ` Johannes Thumshirn 2018-07-06 8:18 ` Johannes Thumshirn 2018-07-06 8:18 ` Johannes Thumshirn 2018-07-05 21:00 ` Matthew Wilcox 2018-07-05 21:00 ` Matthew Wilcox 2018-07-05 19:49 ` Matthew Wilcox 2018-07-05 19:49 ` Matthew Wilcox 2018-07-05 19:52 ` Dan Williams 2018-07-05 19:52 ` Dan Williams 2018-07-05 20:00 ` Jeff Moyer 2018-07-09 12:56 ` [PATCH 00/13] mm: Asynchronous + multithreaded memmap init for ZONE_DEVICE Jan Kara 2018-07-09 12:56 ` Jan Kara 2018-07-09 16:53 ` Dan Williams
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