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 <[email protected]> Cc: Dan Williams <[email protected]> Cc: Ross Zwisler <[email protected]> Cc: Jeff Moyer <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Dave Chinner <[email protected]> Cc: Jan Kara <[email protected]> Signed-off-by: Vishal Verma <[email protected]> --- 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
