Re: [PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
Looks good, Reviewed-by: Johannes Thumshirn
Re: [PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
On Sun, Jul 26, 2020 at 12:06:39PM -0700, Minchan Kim wrote: > > @@ -528,8 +530,7 @@ static ssize_t backing_dev_store(struct device *dev, > > * freely but in fact, IO is going on so finally could cause > > * use-after-free when the IO is really done. > > */ > > - zram->disk->queue->backing_dev_info->capabilities &= > > - ~BDI_CAP_SYNCHRONOUS_IO; > > + zram->disk->fops = _wb_devops; > > up_write(>init_lock); > > For zram, regardless of BDI_CAP_SYNCHRONOUS_IO, it have used rw_page > every time on read/write path. This one with next patch will make zram > use bio instead of rw_page when it's declared !BDI_CAP_SYNCHRONOUS_IO, > which introduce regression for performance. It really should not matter, as the overhead of setting up a bio is minimal. It also is only used in the legacy mpage buffered I/O code outside of the swap code, which has so many performance issues on its own that even if this made a difference it wouldn't matter. If you want magic treatment for your zram swap code you really need to integrate it with the swap code instead of burding the block layer with all this mess.
Re: [PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
On Sun, Jul 26, 2020 at 05:03:29PM +0200, Christoph Hellwig wrote:
> BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to
> decided if ->rw_page can be used on a block device. Just check up for
> the method instead. The only complication is that zram needs a second
> set of block_device_operations as it can switch between modes that
> actually support ->rw_page and those who don't.
>
> Signed-off-by: Christoph Hellwig
> ---
> drivers/block/brd.c | 1 -
> drivers/block/zram/zram_drv.c | 19 +--
> drivers/nvdimm/btt.c | 2 --
> drivers/nvdimm/pmem.c | 1 -
> include/linux/backing-dev.h | 9 -
> mm/swapfile.c | 2 +-
> 6 files changed, 14 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index 2723a70eb85593..cc49a921339f77 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -403,7 +403,6 @@ static struct brd_device *brd_alloc(int i)
> disk->flags = GENHD_FL_EXT_DEVT;
> sprintf(disk->disk_name, "ram%d", i);
> set_capacity(disk, rd_size * 2);
> - brd->brd_queue->backing_dev_info->capabilities |=
> BDI_CAP_SYNCHRONOUS_IO;
>
> /* Tell the block layer that this is not a rotational device */
> blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 9100ac36670afc..d73ddf018fa65f 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -52,6 +52,9 @@ static unsigned int num_devices = 1;
> */
> static size_t huge_class_size;
>
> +static const struct block_device_operations zram_devops;
> +static const struct block_device_operations zram_wb_devops;
> +
> static void zram_free_page(struct zram *zram, size_t index);
> static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
> u32 index, int offset, struct bio *bio);
> @@ -408,8 +411,7 @@ static void reset_bdev(struct zram *zram)
> zram->backing_dev = NULL;
> zram->old_block_size = 0;
> zram->bdev = NULL;
> - zram->disk->queue->backing_dev_info->capabilities |=
> - BDI_CAP_SYNCHRONOUS_IO;
> + zram->disk->fops = _devops;
> kvfree(zram->bitmap);
> zram->bitmap = NULL;
> }
> @@ -528,8 +530,7 @@ static ssize_t backing_dev_store(struct device *dev,
>* freely but in fact, IO is going on so finally could cause
>* use-after-free when the IO is really done.
>*/
> - zram->disk->queue->backing_dev_info->capabilities &=
> - ~BDI_CAP_SYNCHRONOUS_IO;
> + zram->disk->fops = _wb_devops;
> up_write(>init_lock);
For zram, regardless of BDI_CAP_SYNCHRONOUS_IO, it have used rw_page
every time on read/write path. This one with next patch will make zram
use bio instead of rw_page when it's declared !BDI_CAP_SYNCHRONOUS_IO,
which introduce regression for performance.
In the swap code, BDI_CAP_SYNCHRONOUS_IO is used to avoid swap cache
when the page was private. bdev_read_page is not designed to rely on
synchronous operation. That's why this patch breaks the old behavior.
>
> pr_info("setup backing device %s\n", file_name);
> @@ -1819,6 +1820,13 @@ static const struct block_device_operations
> zram_devops = {
> .owner = THIS_MODULE
> };
>
> +static const struct block_device_operations zram_wb_devops = {
> + .open = zram_open,
> + .submit_bio = zram_submit_bio,
> + .swap_slot_free_notify = zram_slot_free_notify,
> + .owner = THIS_MODULE
> +};
> +
> static DEVICE_ATTR_WO(compact);
> static DEVICE_ATTR_RW(disksize);
> static DEVICE_ATTR_RO(initstate);
> @@ -1946,8 +1954,7 @@ static int zram_add(void)
> if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
> blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
>
> - zram->disk->queue->backing_dev_info->capabilities |=
> - (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
> + zram->disk->queue->backing_dev_info->capabilities |=
> BDI_CAP_STABLE_WRITES;
> device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
>
> strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
> diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
> index 412d21d8f64351..b4184dc9b41eb4 100644
> --- a/drivers/nvdimm/btt.c
> +++ b/drivers/nvdimm/btt.c
> @@ -1540,8 +1540,6 @@ static int btt_blk_init(struct btt *btt)
> btt->btt_disk->private_data = btt;
> btt->btt_disk->queue = btt->btt_queue;
> btt->btt_disk->flags = GENHD_FL_EXT_DEVT;
> - btt->btt_disk->queue->backing_dev_info->capabilities |=
> - BDI_CAP_SYNCHRONOUS_IO;
>
> blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
> blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index
[PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to
decided if ->rw_page can be used on a block device. Just check up for
the method instead. The only complication is that zram needs a second
set of block_device_operations as it can switch between modes that
actually support ->rw_page and those who don't.
Signed-off-by: Christoph Hellwig
---
drivers/block/brd.c | 1 -
drivers/block/zram/zram_drv.c | 19 +--
drivers/nvdimm/btt.c | 2 --
drivers/nvdimm/pmem.c | 1 -
include/linux/backing-dev.h | 9 -
mm/swapfile.c | 2 +-
6 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 2723a70eb85593..cc49a921339f77 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -403,7 +403,6 @@ static struct brd_device *brd_alloc(int i)
disk->flags = GENHD_FL_EXT_DEVT;
sprintf(disk->disk_name, "ram%d", i);
set_capacity(disk, rd_size * 2);
- brd->brd_queue->backing_dev_info->capabilities |=
BDI_CAP_SYNCHRONOUS_IO;
/* Tell the block layer that this is not a rotational device */
blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9100ac36670afc..d73ddf018fa65f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -52,6 +52,9 @@ static unsigned int num_devices = 1;
*/
static size_t huge_class_size;
+static const struct block_device_operations zram_devops;
+static const struct block_device_operations zram_wb_devops;
+
static void zram_free_page(struct zram *zram, size_t index);
static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
u32 index, int offset, struct bio *bio);
@@ -408,8 +411,7 @@ static void reset_bdev(struct zram *zram)
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
- zram->disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _devops;
kvfree(zram->bitmap);
zram->bitmap = NULL;
}
@@ -528,8 +530,7 @@ static ssize_t backing_dev_store(struct device *dev,
* freely but in fact, IO is going on so finally could cause
* use-after-free when the IO is really done.
*/
- zram->disk->queue->backing_dev_info->capabilities &=
- ~BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _wb_devops;
up_write(>init_lock);
pr_info("setup backing device %s\n", file_name);
@@ -1819,6 +1820,13 @@ static const struct block_device_operations zram_devops
= {
.owner = THIS_MODULE
};
+static const struct block_device_operations zram_wb_devops = {
+ .open = zram_open,
+ .submit_bio = zram_submit_bio,
+ .swap_slot_free_notify = zram_slot_free_notify,
+ .owner = THIS_MODULE
+};
+
static DEVICE_ATTR_WO(compact);
static DEVICE_ATTR_RW(disksize);
static DEVICE_ATTR_RO(initstate);
@@ -1946,8 +1954,7 @@ static int zram_add(void)
if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
- zram->disk->queue->backing_dev_info->capabilities |=
- (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
+ zram->disk->queue->backing_dev_info->capabilities |=
BDI_CAP_STABLE_WRITES;
device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 412d21d8f64351..b4184dc9b41eb4 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1540,8 +1540,6 @@ static int btt_blk_init(struct btt *btt)
btt->btt_disk->private_data = btt;
btt->btt_disk->queue = btt->btt_queue;
btt->btt_disk->flags = GENHD_FL_EXT_DEVT;
- btt->btt_disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 94790e6e0e4ce1..436b83fb24ad61 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -478,7 +478,6 @@ static int pmem_attach_disk(struct device *dev,
disk->queue = q;
disk->flags = GENHD_FL_EXT_DEVT;
disk->private_data = pmem;
- disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
nvdimm_namespace_disk_name(ndns, disk->disk_name);
set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
/ 512);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 52583b6f2ea05d..860ea33571bce5 100644
---
[PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to
decided if ->rw_page can be used on a block device. Just check up for
the method instead. The only complication is that zram needs a second
set of block_device_operations as it can switch between modes that
actually support ->rw_page and those who don't.
Signed-off-by: Christoph Hellwig
---
drivers/block/brd.c | 1 -
drivers/block/zram/zram_drv.c | 19 +--
drivers/nvdimm/btt.c | 2 --
drivers/nvdimm/pmem.c | 1 -
include/linux/backing-dev.h | 9 -
mm/swapfile.c | 2 +-
6 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 2723a70eb85593..cc49a921339f77 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -403,7 +403,6 @@ static struct brd_device *brd_alloc(int i)
disk->flags = GENHD_FL_EXT_DEVT;
sprintf(disk->disk_name, "ram%d", i);
set_capacity(disk, rd_size * 2);
- brd->brd_queue->backing_dev_info->capabilities |=
BDI_CAP_SYNCHRONOUS_IO;
/* Tell the block layer that this is not a rotational device */
blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9100ac36670afc..d73ddf018fa65f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -52,6 +52,9 @@ static unsigned int num_devices = 1;
*/
static size_t huge_class_size;
+static const struct block_device_operations zram_devops;
+static const struct block_device_operations zram_wb_devops;
+
static void zram_free_page(struct zram *zram, size_t index);
static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
u32 index, int offset, struct bio *bio);
@@ -408,8 +411,7 @@ static void reset_bdev(struct zram *zram)
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
- zram->disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _devops;
kvfree(zram->bitmap);
zram->bitmap = NULL;
}
@@ -528,8 +530,7 @@ static ssize_t backing_dev_store(struct device *dev,
* freely but in fact, IO is going on so finally could cause
* use-after-free when the IO is really done.
*/
- zram->disk->queue->backing_dev_info->capabilities &=
- ~BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _wb_devops;
up_write(>init_lock);
pr_info("setup backing device %s\n", file_name);
@@ -1819,6 +1820,13 @@ static const struct block_device_operations zram_devops
= {
.owner = THIS_MODULE
};
+static const struct block_device_operations zram_wb_devops = {
+ .open = zram_open,
+ .submit_bio = zram_submit_bio,
+ .swap_slot_free_notify = zram_slot_free_notify,
+ .owner = THIS_MODULE
+};
+
static DEVICE_ATTR_WO(compact);
static DEVICE_ATTR_RW(disksize);
static DEVICE_ATTR_RO(initstate);
@@ -1946,8 +1954,7 @@ static int zram_add(void)
if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
- zram->disk->queue->backing_dev_info->capabilities |=
- (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
+ zram->disk->queue->backing_dev_info->capabilities |=
BDI_CAP_STABLE_WRITES;
device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 412d21d8f64351..b4184dc9b41eb4 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1540,8 +1540,6 @@ static int btt_blk_init(struct btt *btt)
btt->btt_disk->private_data = btt;
btt->btt_disk->queue = btt->btt_queue;
btt->btt_disk->flags = GENHD_FL_EXT_DEVT;
- btt->btt_disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 94790e6e0e4ce1..436b83fb24ad61 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -478,7 +478,6 @@ static int pmem_attach_disk(struct device *dev,
disk->queue = q;
disk->flags = GENHD_FL_EXT_DEVT;
disk->private_data = pmem;
- disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
nvdimm_namespace_disk_name(ndns, disk->disk_name);
set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
/ 512);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 52583b6f2ea05d..860ea33571bce5 100644
---
[PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to
decided if ->rw_page can be used on a block device. Just check up for
the method instead. The only complication is that zram needs a second
set of block_device_operations as it can switch between modes that
actually support ->rw_page and those who don't.
Signed-off-by: Christoph Hellwig
---
drivers/block/brd.c | 1 -
drivers/block/zram/zram_drv.c | 19 +--
drivers/nvdimm/btt.c | 2 --
drivers/nvdimm/pmem.c | 1 -
include/linux/backing-dev.h | 9 -
mm/swapfile.c | 2 +-
6 files changed, 14 insertions(+), 20 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 2723a70eb85593..cc49a921339f77 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -403,7 +403,6 @@ static struct brd_device *brd_alloc(int i)
disk->flags = GENHD_FL_EXT_DEVT;
sprintf(disk->disk_name, "ram%d", i);
set_capacity(disk, rd_size * 2);
- brd->brd_queue->backing_dev_info->capabilities |=
BDI_CAP_SYNCHRONOUS_IO;
/* Tell the block layer that this is not a rotational device */
blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 9100ac36670afc..d73ddf018fa65f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -52,6 +52,9 @@ static unsigned int num_devices = 1;
*/
static size_t huge_class_size;
+static const struct block_device_operations zram_devops;
+static const struct block_device_operations zram_wb_devops;
+
static void zram_free_page(struct zram *zram, size_t index);
static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
u32 index, int offset, struct bio *bio);
@@ -408,8 +411,7 @@ static void reset_bdev(struct zram *zram)
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
- zram->disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _devops;
kvfree(zram->bitmap);
zram->bitmap = NULL;
}
@@ -528,8 +530,7 @@ static ssize_t backing_dev_store(struct device *dev,
* freely but in fact, IO is going on so finally could cause
* use-after-free when the IO is really done.
*/
- zram->disk->queue->backing_dev_info->capabilities &=
- ~BDI_CAP_SYNCHRONOUS_IO;
+ zram->disk->fops = _wb_devops;
up_write(>init_lock);
pr_info("setup backing device %s\n", file_name);
@@ -1819,6 +1820,13 @@ static const struct block_device_operations zram_devops
= {
.owner = THIS_MODULE
};
+static const struct block_device_operations zram_wb_devops = {
+ .open = zram_open,
+ .submit_bio = zram_submit_bio,
+ .swap_slot_free_notify = zram_slot_free_notify,
+ .owner = THIS_MODULE
+};
+
static DEVICE_ATTR_WO(compact);
static DEVICE_ATTR_RW(disksize);
static DEVICE_ATTR_RO(initstate);
@@ -1946,8 +1954,7 @@ static int zram_add(void)
if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
- zram->disk->queue->backing_dev_info->capabilities |=
- (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
+ zram->disk->queue->backing_dev_info->capabilities |=
BDI_CAP_STABLE_WRITES;
device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 412d21d8f64351..b4184dc9b41eb4 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1540,8 +1540,6 @@ static int btt_blk_init(struct btt *btt)
btt->btt_disk->private_data = btt;
btt->btt_disk->queue = btt->btt_queue;
btt->btt_disk->flags = GENHD_FL_EXT_DEVT;
- btt->btt_disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 94790e6e0e4ce1..436b83fb24ad61 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -478,7 +478,6 @@ static int pmem_attach_disk(struct device *dev,
disk->queue = q;
disk->flags = GENHD_FL_EXT_DEVT;
disk->private_data = pmem;
- disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
nvdimm_namespace_disk_name(ndns, disk->disk_name);
set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
/ 512);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 52583b6f2ea05d..860ea33571bce5 100644
---
[PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
BDI_CAP_SYNCHRONOUS_IO is only checked in the swap code, and used to
decided if ->rw_page can be used on a block device. Just check up for
the method instead.
Signed-off-by: Christoph Hellwig
---
drivers/block/brd.c | 1 -
drivers/block/zram/zram_drv.c | 17 +
drivers/nvdimm/btt.c | 2 --
drivers/nvdimm/pmem.c | 1 -
include/linux/backing-dev.h | 9 -
mm/swapfile.c | 2 +-
6 files changed, 2 insertions(+), 30 deletions(-)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 2723a70eb85593..cc49a921339f77 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -403,7 +403,6 @@ static struct brd_device *brd_alloc(int i)
disk->flags = GENHD_FL_EXT_DEVT;
sprintf(disk->disk_name, "ram%d", i);
set_capacity(disk, rd_size * 2);
- brd->brd_queue->backing_dev_info->capabilities |=
BDI_CAP_SYNCHRONOUS_IO;
/* Tell the block layer that this is not a rotational device */
blk_queue_flag_set(QUEUE_FLAG_NONROT, brd->brd_queue);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index f9a57f147ee1e6..f336c0d45a6f16 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -408,8 +408,6 @@ static void reset_bdev(struct zram *zram)
zram->backing_dev = NULL;
zram->old_block_size = 0;
zram->bdev = NULL;
- zram->disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
kvfree(zram->bitmap);
zram->bitmap = NULL;
}
@@ -518,18 +516,6 @@ static ssize_t backing_dev_store(struct device *dev,
zram->backing_dev = backing_dev;
zram->bitmap = bitmap;
zram->nr_pages = nr_pages;
- /*
-* With writeback feature, zram does asynchronous IO so it's no longer
-* synchronous device so let's remove synchronous io flag. Othewise,
-* upper layer(e.g., swap) could wait IO completion rather than
-* (submit and return), which will cause system sluggish.
-* Furthermore, when the IO function returns(e.g., swap_readpage),
-* upper layer expects IO was done so it could deallocate the page
-* freely but in fact, IO is going on so finally could cause
-* use-after-free when the IO is really done.
-*/
- zram->disk->queue->backing_dev_info->capabilities &=
- ~BDI_CAP_SYNCHRONOUS_IO;
up_write(>init_lock);
pr_info("setup backing device %s\n", file_name);
@@ -1946,8 +1932,7 @@ static int zram_add(void)
if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
blk_queue_max_write_zeroes_sectors(zram->disk->queue, UINT_MAX);
- zram->disk->queue->backing_dev_info->capabilities |=
- (BDI_CAP_STABLE_WRITES | BDI_CAP_SYNCHRONOUS_IO);
+ zram->disk->queue->backing_dev_info->capabilities |=
BDI_CAP_STABLE_WRITES;
device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
diff --git a/drivers/nvdimm/btt.c b/drivers/nvdimm/btt.c
index 412d21d8f64351..b4184dc9b41eb4 100644
--- a/drivers/nvdimm/btt.c
+++ b/drivers/nvdimm/btt.c
@@ -1540,8 +1540,6 @@ static int btt_blk_init(struct btt *btt)
btt->btt_disk->private_data = btt;
btt->btt_disk->queue = btt->btt_queue;
btt->btt_disk->flags = GENHD_FL_EXT_DEVT;
- btt->btt_disk->queue->backing_dev_info->capabilities |=
- BDI_CAP_SYNCHRONOUS_IO;
blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 94790e6e0e4ce1..436b83fb24ad61 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -478,7 +478,6 @@ static int pmem_attach_disk(struct device *dev,
disk->queue = q;
disk->flags = GENHD_FL_EXT_DEVT;
disk->private_data = pmem;
- disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
nvdimm_namespace_disk_name(ndns, disk->disk_name);
set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
/ 512);
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 52583b6f2ea05d..860ea33571bce5 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -122,9 +122,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi,
unsigned int max_ratio);
* BDI_CAP_NO_WRITEBACK: Don't write pages back
* BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
* BDI_CAP_STRICTLIMIT:Keep number of dirty pages below bdi threshold.
- *
- * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
- *inefficient.
*/
#define BDI_CAP_NO_ACCT_DIRTY 0x0001
#define
