[PATCH v3 6/7] dax: for truncate/hole-punch, do zeroing through the driver if possible
From: Vishal Verma <vishal.l.verma@intel.com>
Date: 2016-04-23 19:13:41
Also in:
linux-fsdevel, linux-mm, linux-xfs, lkml, nvdimm
Subsystem:
filesystem direct access (dax), filesystems (vfs and infrastructure), the rest · Maintainers:
Dan Williams, Alexander Viro, Christian Brauner, Linus Torvalds
In the truncate or hole-punch path in dax, we clear out sub-page ranges. If these sub-page ranges are sector aligned and sized, we can do the zeroing through the driver instead so that error-clearing is handled automatically. For sub-sector ranges, we still have to rely on clear_pmem and have the possibility of tripping over errors. Cc: Matthew Wilcox <redacted> Cc: Dan Williams <redacted> Cc: Ross Zwisler <redacted> Cc: Jeff Moyer <redacted> Cc: Christoph Hellwig <hch@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> --- fs/dax.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 5948d9b..d8c974e 100644
--- a/fs/dax.c
+++ b/fs/dax.c@@ -1196,6 +1196,20 @@ out: } EXPORT_SYMBOL_GPL(dax_pfn_mkwrite); +static bool dax_range_is_aligned(struct block_device *bdev, + struct blk_dax_ctl *dax, unsigned int offset, + unsigned int length) +{ + unsigned short sector_size = bdev_logical_block_size(bdev); + + if (((u64)dax->addr + offset) % sector_size) + return false; + if (length % sector_size) + return false; + + return true; +} + /** * dax_zero_page_range - zero a range within a page of a DAX file * @inode: The file being truncated
@@ -1240,11 +1254,17 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, .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); + if (dax_range_is_aligned(bdev, &dax, offset, length)) + return blkdev_issue_zeroout(bdev, dax.sector, + length / bdev_logical_block_size(bdev), + GFP_NOFS, true); + else { + 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;
--
2.5.5
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