[PATCH V5 0/9] block: use right accessor to read nr_sects

[PATCH V5 0/9] block: use right accessor to read nr_sects

[Chaitanya Kulkarni]

Hi,

In the blk-zoned, bcache, f2fs, target-pscsi, xen and blktrace
implementation block device->hd_part->number of sectors field is
accessed directly without any appropriate locking or accessor function. 
There is an existing accessor function present in the in 
include/linux/genhd.h which should be used to read the
bdev->hd_part->nr_sects.

From ${KERN_DIR}/include/linux/genhd.h:-
<snip>
714 /*
715  * Any access of part->nr_sects which is not protected by partition
716  * bd_mutex or gendisk bdev bd_mutex, should be done using this
717  * accessor function.
718  *
719  * Code written along the lines of i_size_read() and i_size_write().
720  * CONFIG_PREEMPT case optimizes the case of UP kernel with preemption
721  * on.
722  */
723 static inline sector_t part_nr_sects_read(struct hd_struct *part)
724 {
<snip>

This patch series introduces a helper function on the top of the
part_nr_sects_read() and removes the all direct accesses to the
bdev->hd_part->nr_sects.

This series is based on :-

1. Repo :-
   git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git.
2. Branch :- for-next.

Changes from V4:-

1. Adjust code for latest branch.

Chaitanya Kulkarni (9):
  block: add a helper function to read nr_setcs
  blk-zoned: update blkdev_nr_zones() with helper
  blk-zoned: update blkdev_report_zone() with helper
  blk-zoned: update blkdev_reset_zones() with helper
  bcache: update cached_dev_init() with helper
  f2fs: use helper in init_blkz_info()
  blktrace: use helper in blk_trace_setup_lba()
  target/pscsi: use helper in pscsi_get_blocks()
  xen/blkback: use helper in vbd_sz()

 block/blk-zoned.c                  | 12 ++++++------
 drivers/block/xen-blkback/common.h |  2 +-
 drivers/md/bcache/super.c          |  2 +-
 drivers/target/target_core_pscsi.c |  2 +-
 fs/f2fs/super.c                    |  2 +-
 include/linux/blkdev.h             |  5 +++++
 kernel/trace/blktrace.c            |  2 +-
 7 files changed, 16 insertions(+), 11 deletions(-)

-- 
2.17.0

[PATCH V5 1/9] block: add a helper function to read nr_setcs

[Chaitanya Kulkarni]

This patch introduces helper function to read the number of sectors
from struct block_device->bd_part member. For more details Please refer
to the comment in the include/linux/genhd.h for part_nr_sects_read().

Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 include/linux/blkdev.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4798bb25f1ee..aa5801c8ff73 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1468,6 +1468,11 @@ static inline void put_dev_sector(Sector p)
 	put_page(p.v);
 }
 
+static inline sector_t bdev_nr_sects(struct block_device *bdev)
+{
+	return part_nr_sects_read(bdev->bd_part);
+}
+
 int kblockd_schedule_work(struct work_struct *work);
 int kblockd_schedule_work_on(int cpu, struct work_struct *work);
 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, unsigned long delay);
-- 
2.17.0

[PATCH V5 2/9] blk-zoned: update blkdev_nr_zones() with helper

[Chaitanya Kulkarni]

This patch updates the blkdev_nr_zones() with newly introduced helper
function to read the nr_sects from block device's hd_parts with the
help if part_nr_sects_read().

Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 block/blk-zoned.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 4bc5f260248a..3f5e9bf03486 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -93,7 +93,7 @@ unsigned int blkdev_nr_zones(struct block_device *bdev)
 	if (!blk_queue_is_zoned(q))
 		return 0;
 
-	return __blkdev_nr_zones(q, bdev->bd_part->nr_sects);
+	return __blkdev_nr_zones(q, bdev_nr_sects(bdev));
 }
 EXPORT_SYMBOL_GPL(blkdev_nr_zones);
 
-- 
2.17.0

[PATCH V5 3/9] blk-zoned: update blkdev_report_zone() with helper

[Chaitanya Kulkarni]

This patch updates the blkdev_report_zone(s)() with newly introduced
helper function to read the nr_sects from block device's hd_parts with
the help of part_nr_sects_read().

Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 block/blk-zoned.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 3f5e9bf03486..7e0c0b54d194 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -109,7 +109,7 @@ static bool blkdev_report_zone(struct block_device *bdev, struct blk_zone *rep)
 		return false;
 
 	rep->start -= offset;
-	if (rep->start + rep->len > bdev->bd_part->nr_sects)
+	if (rep->start + rep->len > bdev_nr_sects(bdev))
 		return false;
 
 	if (rep->type == BLK_ZONE_TYPE_CONVENTIONAL)
@@ -178,13 +178,13 @@ int blkdev_report_zones(struct block_device *bdev, sector_t sector,
 	if (WARN_ON_ONCE(!bdev->bd_disk->fops->report_zones))
 		return -EOPNOTSUPP;
 
-	if (!*nr_zones || sector >= bdev->bd_part->nr_sects) {
+	if (!*nr_zones || sector >= bdev_nr_sects(bdev)) {
 		*nr_zones = 0;
 		return 0;
 	}
 
 	nrz = min(*nr_zones,
-		  __blkdev_nr_zones(q, bdev->bd_part->nr_sects - sector));
+		  __blkdev_nr_zones(q, bdev_nr_sects(bdev) - sector));
 	ret = blk_report_zones(bdev->bd_disk, get_start_sect(bdev) + sector,
 			       zones, &nrz);
 	if (ret)
-- 
2.17.0

[PATCH V5 4/9] blk-zoned: update blkdev_reset_zones() with helper

[Chaitanya Kulkarni]

This patch updates the blkdev_reset_zones() with newly introduced
helper function to read the nr_sects from block device's hd_parts with
the help of part_nr_sects_read().

Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 block/blk-zoned.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 7e0c0b54d194..53f9df376cfb 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -267,7 +267,7 @@ int blkdev_reset_zones(struct block_device *bdev,
 	if (bdev_read_only(bdev))
 		return -EPERM;
 
-	if (!nr_sectors || end_sector > bdev->bd_part->nr_sects)
+	if (!nr_sectors || end_sector > bdev_nr_sects(bdev))
 		/* Out of range */
 		return -EINVAL;
 
@@ -280,7 +280,7 @@ int blkdev_reset_zones(struct block_device *bdev,
 		return -EINVAL;
 
 	if ((nr_sectors & (zone_sectors - 1)) &&
-	    end_sector != bdev->bd_part->nr_sects)
+	    end_sector != bdev_nr_sects(bdev))
 		return -EINVAL;
 
 	blk_start_plug(&plug);
-- 
2.17.0

[PATCH V5 5/9] bcache: update cached_dev_init() with helper

[Chaitanya Kulkarni]

In the bcache when initializing the cached device we don't actually
use any sort of locking when reading the number of sectors from the
part. This patch updates the cached_dev_init() with newly introduced
helper function to read the nr_sects from block device's hd_parts with
the help of part_nr_sects_read().

Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 drivers/md/bcache/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 20ed838e9413..79c848fa5912 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1305,7 +1305,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
 			q->limits.raid_partial_stripes_expensive;
 
 	ret = bcache_device_init(&dc->disk, block_size,
-			 dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
+			 bdev_nr_sects(dc->bdev) - dc->sb.data_offset);
 	if (ret)
 		return ret;
 
-- 
2.17.0

[PATCH V5 6/9] f2fs: use helper in init_blkz_info()

[Chaitanya Kulkarni]

This patch updates the init_blkz_info() with newly introduced helper
function to read the nr_sects from block device's hd_parts with the
help of part_nr_sects_read().

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 fs/f2fs/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 78a1b873e48a..78f8f834aa44 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2775,7 +2775,7 @@ static int init_percpu_info(struct f2fs_sb_info *sbi)
 static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
 {
 	struct block_device *bdev = FDEV(devi).bdev;
-	sector_t nr_sectors = bdev->bd_part->nr_sects;
+	sector_t nr_sectors = bdev_nr_sects(bdev);
 	sector_t sector = 0;
 	struct blk_zone *zones;
 	unsigned int i, nr_zones;
-- 
2.17.0

[PATCH V5 7/9] blktrace: use helper in blk_trace_setup_lba()

[Chaitanya Kulkarni]

This patch updates the blk_trace_setup_lba() with newly introduced
helper function to read the nr_sects from block device's hd_parts with
the help of part_nr_sects_read().

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 kernel/trace/blktrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 2d6e93ab0478..801f8c465bff 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -461,7 +461,7 @@ static void blk_trace_setup_lba(struct blk_trace *bt,
 
 	if (part) {
 		bt->start_lba = part->start_sect;
-		bt->end_lba = part->start_sect + part->nr_sects;
+		bt->end_lba = part->start_sect + bdev_nr_sects(bdev);
 	} else {
 		bt->start_lba = 0;
 		bt->end_lba = -1ULL;
-- 
2.17.0

[COMPILE TESTED PATCH V5 8/9] target/pscsi: use helper in pscsi_get_blocks()

[Chaitanya Kulkarni]

This patch updates the pscsi_get_blocks() with newly introduced helper
function to read the nr_sects from block device's hd_parts with the
help of part_nr_sects_read().

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 drivers/target/target_core_pscsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index c9d92b3e777d..da481edab2de 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -1030,7 +1030,7 @@ static sector_t pscsi_get_blocks(struct se_device *dev)
 	struct pscsi_dev_virt *pdv = PSCSI_DEV(dev);
 
 	if (pdv->pdv_bd && pdv->pdv_bd->bd_part)
-		return pdv->pdv_bd->bd_part->nr_sects;
+		return bdev_nr_sects(pdv->pdv_bd);
 
 	return 0;
 }
-- 
2.17.0

[COMPILE TESTED PATCH V5 9/9] xen/blkback: use helper in vbd_sz()

[Chaitanya Kulkarni]

This patch updates the vbd_sz() macro with newly introduced helper
function to read the nr_sects from block device's hd_parts with the
help of part_nr_sects_read().

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
 drivers/block/xen-blkback/common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 1d3002d773f7..f96cb8d1cb99 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -359,7 +359,7 @@ struct pending_req {
 
 
 #define vbd_sz(_v)	((_v)->bdev->bd_part ? \
-			 (_v)->bdev->bd_part->nr_sects : \
+			  bdev_nr_sects((_v)->bdev) : \
 			  get_capacity((_v)->bdev->bd_disk))
 
 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
-- 
2.17.0

Re: [PATCH V5 1/9] block: add a helper function to read nr_setcs

[Bart Van Assche]

On 8/20/19 11:14 PM, Chaitanya Kulkarni wrote:
> This patch introduces helper function to read the number of sectors
> from struct block_device->bd_part member. For more details Please refer
> to the comment in the include/linux/genhd.h for part_nr_sects_read().
> 
> Reviewed-by: Minwoo Im <minwoo.im.dev@gmail.com>
> Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
                                                    ^^^^^^^^^^
This looks weird.

Re: [PATCH V5 0/9] block: use right accessor to read nr_sects

[Bart Van Assche]

On 8/20/19 11:14 PM, Chaitanya Kulkarni wrote:
> In the blk-zoned, bcache, f2fs, target-pscsi, xen and blktrace
> implementation block device->hd_part->number of sectors field is
> accessed directly without any appropriate locking or accessor function.
> There is an existing accessor function present in the in
> include/linux/genhd.h which should be used to read the
> bdev->hd_part->nr_sects.

For the entire series:

Reviewed-by: Bart Van Assche <bvanassche@acm.org>