2017-08-28 03:48:46

by Dan Williams

Subject: [PATCH v2 2/2] ext2, ext4: use the super_block dax_device

The ->iomap_begin() operation is a hot path, and now that mount_bdev()
arranges for the dax_device to be populated in the super_block, we can
just reference that attribute directly rather than perform a new lookup.

Cc: Jan Kara <jack-IBi9RG/[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Andreas Dilger <[email protected]>
Reported-by: Christoph Hellwig <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
---
fs/ext2/inode.c | 10 ++--------
fs/ext4/inode.c | 10 ++--------
2 files changed, 4 insertions(+), 16 deletions(-)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 30163d007b2f..7102b77a83c6 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -800,7 +800,6 @@ 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;
@@ -814,13 +813,9 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
return ret;

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

if (ret == 0) {
iomap->type = IOMAP_HOLE;
@@ -842,7 +837,6 @@ static int
ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
ssize_t written, unsigned flags, struct iomap *iomap)
{
- fs_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 c774bdc22759..311690522366 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3404,7 +3404,6 @@ 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;
@@ -3473,12 +3472,8 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
}

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

if (ret == 0) {
@@ -3511,7 +3506,6 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
int blkbits = inode->i_blkbits;
bool truncate = false;

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

2017-08-28 08:27:24

by Jan Kara

Subject: Re: [PATCH v2 2/2] ext2, ext4: use the super_block dax_device

On Sun 27-08-17 20:48:46, Dan Williams wrote:
> The ->iomap_begin() operation is a hot path, and now that mount_bdev()
> arranges for the dax_device to be populated in the super_block, we can
> just reference that attribute directly rather than perform a new lookup.
>
> Cc: Jan Kara <jack-IBi9RG/[email protected]>
> Cc: "Theodore Ts'o" <[email protected]>
> Cc: Andreas Dilger <[email protected]>
> Reported-by: Christoph Hellwig <[email protected]>
> Signed-off-by: Dan Williams <[email protected]>

Looks good. You can add:

Reviewed-by: Jan Kara <[email protected]>

Honza


> ---
> fs/ext2/inode.c | 10 ++--------
> fs/ext4/inode.c | 10 ++--------
> 2 files changed, 4 insertions(+), 16 deletions(-)
>
> diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
> index 30163d007b2f..7102b77a83c6 100644
> --- a/fs/ext2/inode.c
> +++ b/fs/ext2/inode.c
> @@ -800,7 +800,6 @@ 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;
> @@ -814,13 +813,9 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> return ret;
>
> iomap->flags = 0;
> - bdev = inode->i_sb->s_bdev;
> - iomap->bdev = bdev;
> + iomap->bdev = inode->i_sb->s_bdev;
> iomap->offset = (u64)first_block << blkbits;
> - if (blk_queue_dax(bdev->bd_queue))
> - iomap->dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name);
> - else
> - iomap->dax_dev = NULL;
> + iomap->dax_dev = inode->i_sb->s_daxdev;
>
> if (ret == 0) {
> iomap->type = IOMAP_HOLE;
> @@ -842,7 +837,6 @@ static int
> ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
> ssize_t written, unsigned flags, struct iomap *iomap)
> {
> - fs_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 c774bdc22759..311690522366 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3404,7 +3404,6 @@ 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;
> @@ -3473,12 +3472,8 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> }
>
> iomap->flags = 0;
> - bdev = inode->i_sb->s_bdev;
> - iomap->bdev = bdev;
> - if (blk_queue_dax(bdev->bd_queue))
> - iomap->dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name);
> - else
> - iomap->dax_dev = NULL;
> + iomap->bdev = inode->i_sb->s_bdev;
> + iomap->dax_dev = inode->i_sb->s_daxdev;
> iomap->offset = first_block << blkbits;
>
> if (ret == 0) {
> @@ -3511,7 +3506,6 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
> int blkbits = inode->i_blkbits;
> bool truncate = false;
>
> - fs_put_dax(iomap->dax_dev);
> if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
> return 0;
>
>
--
Jan Kara <jack-IBi9RG/[email protected]>
SUSE Labs, CR