[PATCH v2 13/33] ext2, ext4, xfs: retrieve dax_device for iomap operations

From: Dan Williams
Date: Fri Apr 14 2017 - 22:40:10 EST


In preparation for converting fs/dax.c to use dax_direct_access()
instead of bdev_direct_access(), add the plumbing to retrieve the
dax_device associated with a given block_device.

Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
fs/ext2/inode.c | 9 ++++++++-
fs/ext4/inode.c | 9 ++++++++-
fs/xfs/xfs_iomap.c | 10 ++++++++++
include/linux/iomap.h | 1 +
4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 128cce540645..4c9d2d44e879 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -799,6 +799,7 @@ int ext2_get_block(struct inode *inode, sector_t iblock,
static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
unsigned flags, struct iomap *iomap)
{
+ struct block_device *bdev;
unsigned int blkbits = inode->i_blkbits;
unsigned long first_block = offset >> blkbits;
unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
@@ -812,8 +813,13 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
return ret;

iomap->flags = 0;
- iomap->bdev = inode->i_sb->s_bdev;
+ bdev = inode->i_sb->s_bdev;
+ iomap->bdev = bdev;
iomap->offset = (u64)first_block << blkbits;
+ if (blk_queue_dax(bdev->bd_queue))
+ iomap->dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+ else
+ iomap->dax_dev = NULL;

if (ret == 0) {
iomap->type = IOMAP_HOLE;
@@ -835,6 +841,7 @@ static int
ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
ssize_t written, unsigned flags, struct iomap *iomap)
{
+ put_dax(iomap->dax_dev);
if (iomap->type == IOMAP_MAPPED &&
written < length &&
(flags & IOMAP_WRITE))
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4247d8d25687..2cb2634daa99 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3305,6 +3305,7 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
unsigned flags, struct iomap *iomap)
{
+ struct block_device *bdev;
unsigned int blkbits = inode->i_blkbits;
unsigned long first_block = offset >> blkbits;
unsigned long last_block = (offset + length - 1) >> blkbits;
@@ -3373,7 +3374,12 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}

iomap->flags = 0;
- iomap->bdev = inode->i_sb->s_bdev;
+ bdev = inode->i_sb->s_bdev;
+ iomap->bdev = bdev;
+ if (blk_queue_dax(bdev->bd_queue))
+ iomap->dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+ else
+ iomap->dax_dev = NULL;
iomap->offset = first_block << blkbits;

if (ret == 0) {
@@ -3406,6 +3412,7 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
int blkbits = inode->i_blkbits;
bool truncate = false;

+ put_dax(iomap->dax_dev);
if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
return 0;

diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 288ee5b840d7..4b47403f8089 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -976,6 +976,7 @@ xfs_file_iomap_begin(
int nimaps = 1, error = 0;
bool shared = false, trimmed = false;
unsigned lockmode;
+ struct block_device *bdev;

if (XFS_FORCED_SHUTDOWN(mp))
return -EIO;
@@ -1063,6 +1064,14 @@ xfs_file_iomap_begin(
}

xfs_bmbt_to_iomap(ip, iomap, &imap);
+
+ /* optionally associate a dax device with the iomap bdev */
+ bdev = iomap->bdev;
+ if (blk_queue_dax(bdev->bd_queue))
+ iomap->dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+ else
+ iomap->dax_dev = NULL;
+
if (shared)
iomap->flags |= IOMAP_F_SHARED;
return 0;
@@ -1140,6 +1149,7 @@ xfs_file_iomap_end(
unsigned flags,
struct iomap *iomap)
{
+ put_dax(iomap->dax_dev);
if ((flags & IOMAP_WRITE) && iomap->type == IOMAP_DELALLOC)
return xfs_file_iomap_end_delalloc(XFS_I(inode), offset,
length, written, iomap);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 7291810067eb..f753e788da31 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -41,6 +41,7 @@ struct iomap {
u16 type; /* type of mapping */
u16 flags; /* flags for mapping */
struct block_device *bdev; /* block device for I/O */
+ struct dax_device *dax_dev; /* dax_dev for dax operations */
};

/*