From: Vishal Verma Subject: [PATCH v7 4/6] dax: export a low-level __dax_zero_page_range helper Date: Wed, 11 May 2016 15:08:50 -0600 Message-ID: <1463000932-31680-5-git-send-email-vishal.l.verma@intel.com> References: <1463000932-31680-1-git-send-email-vishal.l.verma@intel.com> Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, xfs@oss.sgi.com, linux-ext4@vger.kernel.org, linux-mm@kvack.org, Ross Zwisler , Dan Williams , Dave Chinner , Jan Kara , Jens Axboe , Andrew Morton , linux-kernel@vger.kernel.org, Christoph Hellwig , Jeff Moyer , Boaz Harrosh To: linux-nvdimm@lists.01.org Return-path: In-Reply-To: <1463000932-31680-1-git-send-email-vishal.l.verma@intel.com> Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org From: Christoph Hellwig This allows XFS to perform zeroing using the iomap infrastructure and avoid buffer heads. [vishal: fix conflicts with dax-error-handling] Signed-off-by: Christoph Hellwig --- fs/dax.c | 35 ++++++++++++++++++++--------------- include/linux/dax.h | 7 +++++++ 2 files changed, 27 insertions(+), 15 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 0abbbb6..651d4b1 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -947,6 +947,23 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) } EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); +int __dax_zero_page_range(struct block_device *bdev, sector_t sector, + unsigned int offset, unsigned int length) +{ + struct blk_dax_ctl dax = { + .sector = sector, + .size = PAGE_SIZE, + }; + + if (dax_map_atomic(bdev, &dax) < 0) + return PTR_ERR(dax.addr); + clear_pmem(dax.addr + offset, length); + wmb_pmem(); + dax_unmap_atomic(bdev, &dax); + return 0; +} +EXPORT_SYMBOL_GPL(__dax_zero_page_range); + /** * dax_zero_page_range - zero a range within a page of a DAX file * @inode: The file being truncated @@ -982,23 +999,11 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, bh.b_bdev = inode->i_sb->s_bdev; bh.b_size = PAGE_SIZE; err = get_block(inode, index, &bh, 0); - if (err < 0) + if (err < 0 || !buffer_written(&bh)) return err; - if (buffer_written(&bh)) { - struct block_device *bdev = bh.b_bdev; - struct blk_dax_ctl dax = { - .sector = to_sector(&bh, inode), - .size = PAGE_SIZE, - }; - if (dax_map_atomic(bdev, &dax) < 0) - return PTR_ERR(dax.addr); - clear_pmem(dax.addr + offset, length); - wmb_pmem(); - dax_unmap_atomic(bdev, &dax); - } - - return 0; + return __dax_zero_page_range(bh.b_bdev, to_sector(&bh, inode), + offset, length); } EXPORT_SYMBOL_GPL(dax_zero_page_range); diff --git a/include/linux/dax.h b/include/linux/dax.h index 7f853ff..90fbc99 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -14,12 +14,19 @@ int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t); #ifdef CONFIG_FS_DAX struct page *read_dax_sector(struct block_device *bdev, sector_t n); +int __dax_zero_page_range(struct block_device *bdev, sector_t sector, + unsigned int offset, unsigned int length); #else static inline struct page *read_dax_sector(struct block_device *bdev, sector_t n) { return ERR_PTR(-ENXIO); } +static inline int __dax_zero_page_range(struct block_device *bdev, + sector_t sector, unsigned int offset, unsigned int length) +{ + return -ENXIO; +} #endif #ifdef CONFIG_TRANSPARENT_HUGEPAGE -- 2.5.5 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org