From: Dan Williams <dan.j.williams@intel.com> To: linux-block@vger.kernel.org Cc: linux-nvdimm@lists.01.org, Dave Chinner <david@fromorbit.com>, linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>, axboe@fb.com, Jeff Moyer <jmoyer@redhat.com>, Jan Kara <jack@suse.com>, linux-fsdevel@vger.kernel.org, Matthew Wilcox <willy@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Ross Zwisler <ross.zwisler@linux.intel.com> Subject: [PATCH v2] block: use DAX for partition table reads Date: Fri, 29 Jan 2016 16:33:50 -0800 [thread overview] Message-ID: <20160130003125.6392.17801.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <20160129151846.18752.48460.stgit@dwillia2-desk3.amr.corp.intel.com> Avoid populating pagecache when the block device is in DAX mode. Otherwise these page cache entries collide with the fsync/msync implementation and break data durability guarantees. Cc: Jan Kara <jack@suse.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Andrew Morton <akpm@linux-foundation.org> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- Changes in v2: 1/ Switch from __page_cache_alloc to alloc_pages (Jens) 2/ Move read_dax_sector() declaration to include/linux/dax.h (Willy) 3/ Collect Reviewed-by and Tested-by tags from Willy and Ross. block/partition-generic.c | 18 +++++++++++++++--- fs/dax.c | 20 ++++++++++++++++++++ include/linux/dax.h | 11 +++++++++++ 3 files changed, 46 insertions(+), 3 deletions(-) diff --git a/block/partition-generic.c b/block/partition-generic.c index 746935a5973c..fefd01b496a0 100644 --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -16,6 +16,7 @@ #include <linux/kmod.h> #include <linux/ctype.h> #include <linux/genhd.h> +#include <linux/dax.h> #include <linux/blktrace_api.h> #include "partitions/check.h" @@ -550,13 +551,24 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev) return 0; } -unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p) +static struct page *read_pagecache_sector(struct block_device *bdev, sector_t n) { struct address_space *mapping = bdev->bd_inode->i_mapping; + + return read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)), + NULL); +} + +unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p) +{ struct page *page; - page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)), - NULL); + /* don't populate page cache for dax capable devices */ + if (IS_DAX(bdev->bd_inode)) + page = read_dax_sector(bdev, n); + else + page = read_pagecache_sector(bdev, n); + if (!IS_ERR(page)) { if (PageError(page)) goto fail; diff --git a/fs/dax.c b/fs/dax.c index 4fd6b0c5c6b5..e0e9358baf35 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -58,6 +58,26 @@ static void dax_unmap_atomic(struct block_device *bdev, blk_queue_exit(bdev->bd_queue); } +struct page *read_dax_sector(struct block_device *bdev, sector_t n) +{ + struct page *page = alloc_pages(GFP_KERNEL, 0); + struct blk_dax_ctl dax = { + .size = PAGE_SIZE, + .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), + }; + long rc; + + if (!page) + return ERR_PTR(-ENOMEM); + + rc = dax_map_atomic(bdev, &dax); + if (rc < 0) + return ERR_PTR(rc); + memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); + dax_unmap_atomic(bdev, &dax); + return page; +} + /* * dax_clear_blocks() is called from within transaction context from XFS, * and hence this means the stack from this point must follow GFP_NOFS diff --git a/include/linux/dax.h b/include/linux/dax.h index 8204c3dc3800..818e45078929 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -14,6 +14,17 @@ int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, dax_iodone_t); int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, dax_iodone_t); + +#ifdef CONFIG_FS_DAX +struct page *read_dax_sector(struct block_device *bdev, sector_t n); +#else +static inline struct page *read_dax_sector(struct block_device *bdev, + sector_t n) +{ + return ERR_PTR(-ENXIO); +} +#endif + #ifdef CONFIG_TRANSPARENT_HUGEPAGE int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *, unsigned int flags, get_block_t, dax_iodone_t);
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com> To: linux-block@vger.kernel.org Cc: linux-nvdimm@ml01.01.org, Dave Chinner <david@fromorbit.com>, linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>, axboe@fb.com, Jeff Moyer <jmoyer@redhat.com>, Jan Kara <jack@suse.com>, linux-fsdevel@vger.kernel.org, Matthew Wilcox <willy@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Ross Zwisler <ross.zwisler@linux.intel.com> Subject: [PATCH v2] block: use DAX for partition table reads Date: Fri, 29 Jan 2016 16:33:50 -0800 [thread overview] Message-ID: <20160130003125.6392.17801.stgit@dwillia2-desk3.amr.corp.intel.com> (raw) In-Reply-To: <20160129151846.18752.48460.stgit@dwillia2-desk3.amr.corp.intel.com> Avoid populating pagecache when the block device is in DAX mode. Otherwise these page cache entries collide with the fsync/msync implementation and break data durability guarantees. Cc: Jan Kara <jack@suse.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Andrew Morton <akpm@linux-foundation.org> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com> Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- Changes in v2: 1/ Switch from __page_cache_alloc to alloc_pages (Jens) 2/ Move read_dax_sector() declaration to include/linux/dax.h (Willy) 3/ Collect Reviewed-by and Tested-by tags from Willy and Ross. block/partition-generic.c | 18 +++++++++++++++--- fs/dax.c | 20 ++++++++++++++++++++ include/linux/dax.h | 11 +++++++++++ 3 files changed, 46 insertions(+), 3 deletions(-) diff --git a/block/partition-generic.c b/block/partition-generic.c index 746935a5973c..fefd01b496a0 100644 --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -16,6 +16,7 @@ #include <linux/kmod.h> #include <linux/ctype.h> #include <linux/genhd.h> +#include <linux/dax.h> #include <linux/blktrace_api.h> #include "partitions/check.h" @@ -550,13 +551,24 @@ int invalidate_partitions(struct gendisk *disk, struct block_device *bdev) return 0; } -unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p) +static struct page *read_pagecache_sector(struct block_device *bdev, sector_t n) { struct address_space *mapping = bdev->bd_inode->i_mapping; + + return read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)), + NULL); +} + +unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p) +{ struct page *page; - page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)), - NULL); + /* don't populate page cache for dax capable devices */ + if (IS_DAX(bdev->bd_inode)) + page = read_dax_sector(bdev, n); + else + page = read_pagecache_sector(bdev, n); + if (!IS_ERR(page)) { if (PageError(page)) goto fail; diff --git a/fs/dax.c b/fs/dax.c index 4fd6b0c5c6b5..e0e9358baf35 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -58,6 +58,26 @@ static void dax_unmap_atomic(struct block_device *bdev, blk_queue_exit(bdev->bd_queue); } +struct page *read_dax_sector(struct block_device *bdev, sector_t n) +{ + struct page *page = alloc_pages(GFP_KERNEL, 0); + struct blk_dax_ctl dax = { + .size = PAGE_SIZE, + .sector = n & ~((((int) PAGE_SIZE) / 512) - 1), + }; + long rc; + + if (!page) + return ERR_PTR(-ENOMEM); + + rc = dax_map_atomic(bdev, &dax); + if (rc < 0) + return ERR_PTR(rc); + memcpy_from_pmem(page_address(page), dax.addr, PAGE_SIZE); + dax_unmap_atomic(bdev, &dax); + return page; +} + /* * dax_clear_blocks() is called from within transaction context from XFS, * and hence this means the stack from this point must follow GFP_NOFS diff --git a/include/linux/dax.h b/include/linux/dax.h index 8204c3dc3800..818e45078929 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -14,6 +14,17 @@ int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, dax_iodone_t); int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t, dax_iodone_t); + +#ifdef CONFIG_FS_DAX +struct page *read_dax_sector(struct block_device *bdev, sector_t n); +#else +static inline struct page *read_dax_sector(struct block_device *bdev, + sector_t n) +{ + return ERR_PTR(-ENXIO); +} +#endif + #ifdef CONFIG_TRANSPARENT_HUGEPAGE int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *, unsigned int flags, get_block_t, dax_iodone_t);
next prev parent reply other threads:[~2016-01-30 0:33 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-29 15:18 [PATCH 0/2] block: fix raw block device dax support Dan Williams 2016-01-29 15:18 ` Dan Williams 2016-01-29 15:18 ` [PATCH 1/2] block: revert runtime dax control of the raw block device Dan Williams 2016-01-29 15:18 ` Dan Williams 2016-01-29 17:54 ` Ross Zwisler 2016-01-29 17:54 ` Ross Zwisler 2016-01-29 15:18 ` [PATCH 2/2] block: use DAX for partition table reads Dan Williams 2016-01-29 15:18 ` Dan Williams 2016-01-29 17:46 ` Jens Axboe 2016-01-29 17:46 ` Jens Axboe 2016-01-29 17:46 ` Jens Axboe 2016-01-29 17:54 ` Dan Williams 2016-01-29 17:54 ` Dan Williams 2016-01-29 19:24 ` Ross Zwisler 2016-01-29 19:24 ` Ross Zwisler 2016-01-29 22:45 ` Matthew Wilcox 2016-01-29 22:45 ` Matthew Wilcox 2016-01-30 0:33 ` Dan Williams [this message] 2016-01-30 0:33 ` [PATCH v2] " Dan Williams
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