linux-ext4 - [PATCH v5 12/17] dax: add dax_iomap

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Date:   Fri,  7 Oct 2016 15:08:59 -0600
From:   Ross Zwisler <ross.zwisler@...ux.intel.com>
To:     linux-kernel@...r.kernel.org
Cc:     Ross Zwisler <ross.zwisler@...ux.intel.com>,
        "Theodore Ts'o" <tytso@....edu>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-nvdimm@...ts.01.org,
        linux-xfs@...r.kernel.org
Subject: [PATCH v5 12/17] dax: add dax_iomap_sector() helper function

To be able to correctly calculate the sector from a file position and a
struct iomap there is a complex little bit of logic that currently happens
in both dax_iomap_actor() and dax_iomap_fault().  This will need to be
repeated yet again in the DAX PMD fault handler when it is added, so break
it out into a helper function.

Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
---
 fs/dax.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 982ccbb..7689ab0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1023,6 +1023,11 @@ int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
 EXPORT_SYMBOL_GPL(dax_truncate_page);
 
 #ifdef CONFIG_FS_IOMAP
+static inline sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
+{
+	return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
+}
+
 static loff_t
 dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		struct iomap *iomap)
@@ -1048,8 +1053,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		struct blk_dax_ctl dax = { 0 };
 		ssize_t map_len;
 
-		dax.sector = iomap->blkno +
-			(((pos & PAGE_MASK) - iomap->offset) >> 9);
+		dax.sector = dax_iomap_sector(iomap, pos);
 		dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
 		map_len = dax_map_atomic(iomap->bdev, &dax);
 		if (map_len < 0) {
@@ -1186,7 +1190,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 		goto unlock_entry;
 	}
 
-	sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9);
+	sector = dax_iomap_sector(&iomap, pos);
 
 	if (vmf->cow_page) {
 		switch (iomap.type) {
-- 
2.7.4

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