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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>, Coly Li <colyli@suse.de>,
	Song Liu <song@kernel.org>,
	dm-devel@redhat.com, linux-bcache@vger.kernel.org,
	linux-raid@vger.kernel.org, linux-s390@vger.kernel.org,
	linux-block@vger.kernel.org
Subject: [PATCH 8/9] block: remove DISK_PITER_REVERSE
Date: Tue,  1 Dec 2020 17:54:23 +0100	[thread overview]
Message-ID: <20201201165424.2030647-9-hch@lst.de> (raw)
In-Reply-To: <20201201165424.2030647-1-hch@lst.de>

There is good reason to iterate backwards when deleting all partitions in
del_gendisk, just like we don't in blk_drop_partitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c         | 34 ++++------------------------------
 include/linux/genhd.h |  1 -
 2 files changed, 4 insertions(+), 31 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 65dba32df5474f..7730ddabebba92 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -182,24 +182,13 @@ static struct block_device *__disk_get_part(struct gendisk *disk, int partno)
 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 			  unsigned int flags)
 {
-	struct disk_part_tbl *ptbl;
-
-	rcu_read_lock();
-	ptbl = rcu_dereference(disk->part_tbl);
-
 	piter->disk = disk;
 	piter->part = NULL;
-
-	if (flags & DISK_PITER_REVERSE)
-		piter->idx = ptbl->len - 1;
-	else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
+	if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
 		piter->idx = 0;
 	else
 		piter->idx = 1;
-
 	piter->flags = flags;
-
-	rcu_read_unlock();
 }
 
 /**
@@ -214,7 +203,6 @@ void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 {
 	struct disk_part_tbl *ptbl;
-	int inc, end;
 
 	/* put the last partition */
 	disk_part_iter_exit(piter);
@@ -223,21 +211,8 @@ struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 	rcu_read_lock();
 	ptbl = rcu_dereference(piter->disk->part_tbl);
 
-	/* determine iteration parameters */
-	if (piter->flags & DISK_PITER_REVERSE) {
-		inc = -1;
-		if (piter->flags & (DISK_PITER_INCL_PART0 |
-				    DISK_PITER_INCL_EMPTY_PART0))
-			end = -1;
-		else
-			end = 0;
-	} else {
-		inc = 1;
-		end = ptbl->len;
-	}
-
 	/* iterate to the next partition */
-	for (; piter->idx != end; piter->idx += inc) {
+	for (; piter->idx != ptbl->len; piter->idx += 1) {
 		struct block_device *part;
 
 		part = rcu_dereference(ptbl->part[piter->idx]);
@@ -252,7 +227,7 @@ struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 		piter->part = bdgrab(part);
 		if (!piter->part)
 			continue;
-		piter->idx += inc;
+		piter->idx += 1;
 		break;
 	}
 
@@ -776,8 +751,7 @@ void del_gendisk(struct gendisk *disk)
 	down_write(&bdev_lookup_sem);
 
 	/* invalidate stuff */
-	disk_part_iter_init(&piter, disk,
-			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
+	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
 	while ((part = disk_part_iter_next(&piter))) {
 		invalidate_partition(part);
 		delete_partition(part);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 191f5e4ae4e93b..425956ac9315fa 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -217,7 +217,6 @@ void disk_uevent(struct gendisk *disk, enum kobject_action action);
 /*
  * Smarter partition iterator without context limits.
  */
-#define DISK_PITER_REVERSE	(1 << 0) /* iterate in the reverse direction */
 #define DISK_PITER_INCL_EMPTY	(1 << 1) /* include 0-sized parts */
 #define DISK_PITER_INCL_PART0	(1 << 2) /* include partition 0 */
 #define DISK_PITER_INCL_EMPTY_PART0 (1 << 3) /* include empty partition 0 */
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: linux-s390@vger.kernel.org, linux-bcache@vger.kernel.org,
	Coly Li <colyli@suse.de>,
	linux-raid@vger.kernel.org, Song Liu <song@kernel.org>,
	dm-devel@redhat.com, linux-block@vger.kernel.org,
	Tejun Heo <tj@kernel.org>
Subject: [dm-devel] [PATCH 8/9] block: remove DISK_PITER_REVERSE
Date: Tue,  1 Dec 2020 17:54:23 +0100	[thread overview]
Message-ID: <20201201165424.2030647-9-hch@lst.de> (raw)
In-Reply-To: <20201201165424.2030647-1-hch@lst.de>

There is good reason to iterate backwards when deleting all partitions in
del_gendisk, just like we don't in blk_drop_partitions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c         | 34 ++++------------------------------
 include/linux/genhd.h |  1 -
 2 files changed, 4 insertions(+), 31 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 65dba32df5474f..7730ddabebba92 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -182,24 +182,13 @@ static struct block_device *__disk_get_part(struct gendisk *disk, int partno)
 void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 			  unsigned int flags)
 {
-	struct disk_part_tbl *ptbl;
-
-	rcu_read_lock();
-	ptbl = rcu_dereference(disk->part_tbl);
-
 	piter->disk = disk;
 	piter->part = NULL;
-
-	if (flags & DISK_PITER_REVERSE)
-		piter->idx = ptbl->len - 1;
-	else if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
+	if (flags & (DISK_PITER_INCL_PART0 | DISK_PITER_INCL_EMPTY_PART0))
 		piter->idx = 0;
 	else
 		piter->idx = 1;
-
 	piter->flags = flags;
-
-	rcu_read_unlock();
 }
 
 /**
@@ -214,7 +203,6 @@ void disk_part_iter_init(struct disk_part_iter *piter, struct gendisk *disk,
 struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 {
 	struct disk_part_tbl *ptbl;
-	int inc, end;
 
 	/* put the last partition */
 	disk_part_iter_exit(piter);
@@ -223,21 +211,8 @@ struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 	rcu_read_lock();
 	ptbl = rcu_dereference(piter->disk->part_tbl);
 
-	/* determine iteration parameters */
-	if (piter->flags & DISK_PITER_REVERSE) {
-		inc = -1;
-		if (piter->flags & (DISK_PITER_INCL_PART0 |
-				    DISK_PITER_INCL_EMPTY_PART0))
-			end = -1;
-		else
-			end = 0;
-	} else {
-		inc = 1;
-		end = ptbl->len;
-	}
-
 	/* iterate to the next partition */
-	for (; piter->idx != end; piter->idx += inc) {
+	for (; piter->idx != ptbl->len; piter->idx += 1) {
 		struct block_device *part;
 
 		part = rcu_dereference(ptbl->part[piter->idx]);
@@ -252,7 +227,7 @@ struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
 		piter->part = bdgrab(part);
 		if (!piter->part)
 			continue;
-		piter->idx += inc;
+		piter->idx += 1;
 		break;
 	}
 
@@ -776,8 +751,7 @@ void del_gendisk(struct gendisk *disk)
 	down_write(&bdev_lookup_sem);
 
 	/* invalidate stuff */
-	disk_part_iter_init(&piter, disk,
-			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
+	disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
 	while ((part = disk_part_iter_next(&piter))) {
 		invalidate_partition(part);
 		delete_partition(part);
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 191f5e4ae4e93b..425956ac9315fa 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -217,7 +217,6 @@ void disk_uevent(struct gendisk *disk, enum kobject_action action);
 /*
  * Smarter partition iterator without context limits.
  */
-#define DISK_PITER_REVERSE	(1 << 0) /* iterate in the reverse direction */
 #define DISK_PITER_INCL_EMPTY	(1 << 1) /* include 0-sized parts */
 #define DISK_PITER_INCL_PART0	(1 << 2) /* include partition 0 */
 #define DISK_PITER_INCL_EMPTY_PART0 (1 << 3) /* include empty partition 0 */
-- 
2.29.2

--
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dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel


  parent reply	other threads:[~2020-12-01 16:56 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-01 16:54 store a pointer to the block_device in struct bio (again) Christoph Hellwig
2020-12-01 16:54 ` [dm-devel] " Christoph Hellwig
2020-12-01 16:54 ` [PATCH 1/9] brd: remove the end of device check in brd_do_bvec Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 22:39   ` Tejun Heo
2020-12-02 22:39     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 2/9] dcssblk: " Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 22:39   ` Tejun Heo
2020-12-02 22:39     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 3/9] block: store a block_device pointer in struct bio Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 22:54   ` Tejun Heo
2020-12-02 22:54     ` [dm-devel] " Tejun Heo
2020-12-03  6:39   ` Ming Lei
2020-12-03  6:39     ` [dm-devel] " Ming Lei
2020-12-03  7:10     ` Ming Lei
2020-12-03  7:10       ` [dm-devel] " Ming Lei
2020-12-03  8:29       ` Christoph Hellwig
2020-12-03  8:29         ` [dm-devel] " Christoph Hellwig
2020-12-03  9:32         ` Ming Lei
2020-12-03  9:32           ` [dm-devel] " Ming Lei
2020-12-03 20:53   ` Keith Busch
2020-12-03 20:53     ` [dm-devel] " Keith Busch
2020-12-01 16:54 ` [PATCH 4/9] block: simplify submit_bio_checks a bit Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 22:55   ` Tejun Heo
2020-12-02 22:55     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 5/9] block: use ->bi_bdev for bio based I/O accounting Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 23:05   ` Tejun Heo
2020-12-02 23:05     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 6/9] blk-mq: use ->bi_bdev for " Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 23:06   ` Tejun Heo
2020-12-02 23:06     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 7/9] block: add a disk_uevent helper Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 23:08   ` Tejun Heo
2020-12-02 23:08     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` Christoph Hellwig [this message]
2020-12-01 16:54   ` [dm-devel] [PATCH 8/9] block: remove DISK_PITER_REVERSE Christoph Hellwig
2020-12-02 23:15   ` Tejun Heo
2020-12-02 23:15     ` [dm-devel] " Tejun Heo
2020-12-01 16:54 ` [PATCH 9/9] block: use an xarray for disk->part_tbl Christoph Hellwig
2020-12-01 16:54   ` [dm-devel] " Christoph Hellwig
2020-12-02 23:22   ` Tejun Heo
2020-12-02 23:22     ` [dm-devel] " Tejun Heo
2020-12-02 22:35 ` store a pointer to the block_device in struct bio (again) Tejun Heo
2020-12-02 22:35   ` [dm-devel] " Tejun Heo
2020-12-02 22:37   ` Tejun Heo
2020-12-02 22:37     ` [dm-devel] " Tejun Heo
2020-12-04 16:43 ` Jens Axboe
2020-12-04 16:43   ` [dm-devel] " Jens Axboe
2020-12-07 18:56 ` Qian Cai
2020-12-07 18:56   ` [dm-devel] " Qian Cai
2020-12-07 19:01   ` Christoph Hellwig
2020-12-07 19:01     ` [dm-devel] " Christoph Hellwig
2020-12-07 20:20     ` Jens Axboe
2020-12-07 20:20       ` [dm-devel] " Jens Axboe
2020-12-08 11:04   ` Christoph Hellwig
2020-12-08 11:04     ` [dm-devel] " Christoph Hellwig
2020-12-08 13:08     ` Qian Cai
2020-12-08 13:08       ` [dm-devel] " Qian Cai
2020-12-08 13:38     ` Daniel Wagner
2020-12-08 13:38       ` [dm-devel] " Daniel Wagner
2020-12-08 14:15     ` Jens Axboe
2020-12-08 14:15       ` [dm-devel] " Jens Axboe

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