[Drbd-dev] [PATCH 10/14] bdi: remove BDI_CAP_SYNCHRONOUS_IO
Christoph Hellwig
hch at lst.de
Mon Jul 20 09:51:44 CEST 2020
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 <hch at lst.de>
---
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(&zram->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 0x00000001
#define BDI_CAP_NO_WRITEBACK 0x00000002
@@ -132,7 +129,6 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
#define BDI_CAP_STABLE_WRITES 0x00000008
#define BDI_CAP_STRICTLIMIT 0x00000010
#define BDI_CAP_CGROUP_WRITEBACK 0x00000020
-#define BDI_CAP_SYNCHRONOUS_IO 0x00000040
#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
@@ -174,11 +170,6 @@ static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
long congestion_wait(int sync, long timeout);
long wait_iff_congested(int sync, long timeout);
-static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi)
-{
- return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;
-}
-
static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
{
return bdi->capabilities & BDI_CAP_STABLE_WRITES;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6c26916e95fd4a..18eac97b10e502 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3230,7 +3230,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (bdi_cap_stable_pages_required(inode_to_bdi(inode)))
p->flags |= SWP_STABLE_WRITES;
- if (bdi_cap_synchronous_io(inode_to_bdi(inode)))
+ if (p->bdev && p->bdev->bd_disk->fops->rw_page)
p->flags |= SWP_SYNCHRONOUS_IO;
if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
--
2.27.0
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