dax: for truncate/hole-punch, do zeroing through the driver if possible

[karo-tx-linux.git] / fs / dax.c

diff --git a/fs/dax.c b/fs/dax.c
index d602410d8e52c6fea96735c88e9eb1463f273279..0b9a1693401700da996e192a508565ea7c389d9e 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -87,38 +87,6 @@ struct page *read_dax_sector(struct block_device *bdev, sector_t n)
        return page;
 }
 
-/*
- * dax_clear_sectors() is called from within transaction context from XFS,
- * and hence this means the stack from this point must follow GFP_NOFS
- * semantics for all operations.
- */
-int dax_clear_sectors(struct block_device *bdev, sector_t _sector, long _size)
-{
-       struct blk_dax_ctl dax = {
-               .sector = _sector,
-               .size = _size,
-       };
-
-       might_sleep();
-       do {
-               long count, sz;
-
-               count = dax_map_atomic(bdev, &dax);
-               if (count < 0)
-                       return count;
-               sz = min_t(long, count, SZ_128K);
-               clear_pmem(dax.addr, sz);
-               dax.size -= sz;
-               dax.sector += sz / 512;
-               dax_unmap_atomic(bdev, &dax);
-               cond_resched();
-       } while (dax.size);
-
-       wmb_pmem();
-       return 0;
-}
-EXPORT_SYMBOL_GPL(dax_clear_sectors);
-
 static bool buffer_written(struct buffer_head *bh)
 {
        return buffer_mapped(bh) && !buffer_unwritten(bh);
@@ -979,6 +947,43 @@ int dax_pfn_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 }
 EXPORT_SYMBOL_GPL(dax_pfn_mkwrite);
 
+static bool dax_range_is_aligned(struct block_device *bdev,
+                                unsigned int offset, unsigned int length)
+{
+       unsigned short sector_size = bdev_logical_block_size(bdev);
+
+       if (!IS_ALIGNED(offset, sector_size))
+               return false;
+       if (!IS_ALIGNED(length, sector_size))
+               return false;
+
+       return true;
+}
+
+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_range_is_aligned(bdev, offset, length)) {
+               sector_t start_sector = dax.sector + (offset >> 9);
+
+               return blkdev_issue_zeroout(bdev, start_sector,
+                               length >> 9, 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;
+}
+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
@@ -1014,23 +1019,11 @@ 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);