[PATCH v3 0/29] block: Make blkdev_get_by_*() return handle

[PATCH v3 0/29] block: Make blkdev_get_by_*() return handle

[Jan Kara]

Hello,

this is a v3 of the patch series which implements the idea of blkdev_get_by_*()
calls returning bdev_handle which is then passed to blkdev_put() [1]. This
makes the get and put calls for bdevs more obviously matching and allows us to
propagate context from get to put without having to modify all the users
(again!). In particular I need to propagate used open flags to blkdev_put() to
be able count writeable opens and add support for blocking writes to mounted
block devices. I'll send that series separately.

The series is based on Christian's vfs tree as of today as there is quite
some overlap. Patches have passed some reasonable testing - I've tested block
changes, md, dm, bcache, xfs, btrfs, ext4, swap. More testing or review is
always welcome. Thanks! I've pushed out the full branch to:

git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git bdev_handle

to ease review / testing. Since there were not many comments for v2 and
Christoph has acked the series I think we should start discussing how to merge
the series. Most collisions with this series seem to happen in the filesystems
area so VFS tree would seem as the least painful way to merge this. Jens,
are you OK with that?

Changes since v2:
* Rebased on top of current vfs tree
* Added some acks
* Reflected minor nits from Christoph
* Added missing conversion of blkdev_put() calls in cramfs and erofs
* Fixed possible leak of bdev handle in xfs if logdev is the same as fs dev

Changes since v1:
* Rebased on top of current vfs tree
* Renamed final functions to bdev_open_by_*() and bdev_release()
* Fixed detection of exclusive open in blkdev_ioctl() and blkdev_fallocate()
* Fixed swap conversion to properly reinitialize swap_info->bdev_handle
* Fixed xfs conversion to not oops with rtdev without logdev
* Couple other minor fixups

								Honza

[1] https://lore.kernel.org/all/ZJGNsVDhZx0Xgs2H@infradead.org

CC: Alasdair Kergon <agk@redhat.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Anna Schumaker <anna@kernel.org>
CC: Chao Yu <chao@kernel.org>
CC: Christian Borntraeger <borntraeger@linux.ibm.com>
CC: Coly Li <colyli@suse.de
CC: "Darrick J. Wong" <djwong@kernel.org>
CC: Dave Kleikamp <shaggy@kernel.org>
CC: David Sterba <dsterba@suse.com>
CC: dm-devel@redhat.com
CC: drbd-dev@lists.linbit.com
CC: Gao Xiang <xiang@kernel.org>
CC: Jack Wang <jinpu.wang@ionos.com>
CC: Jaegeuk Kim <jaegeuk@kernel.org>
CC: jfs-discussion@lists.sourceforge.net
CC: Joern Engel <joern@lazybastard.org>
CC: Joseph Qi <joseph.qi@linux.alibaba.com>
CC: Kent Overstreet <kent.overstreet@gmail.com>
CC: linux-bcache@vger.kernel.org
CC: linux-btrfs@vger.kernel.org
CC: linux-erofs@lists.ozlabs.org
CC: <linux-ext4@vger.kernel.org>
CC: linux-f2fs-devel@lists.sourceforge.net
CC: linux-mm@kvack.org
CC: linux-mtd@lists.infradead.org
CC: linux-nfs@vger.kernel.org
CC: linux-nilfs@vger.kernel.org
CC: linux-nvme@lists.infradead.org
CC: linux-pm@vger.kernel.org
CC: linux-raid@vger.kernel.org
CC: linux-s390@vger.kernel.org
CC: linux-scsi@vger.kernel.org
CC: linux-xfs@vger.kernel.org
CC: "Md. Haris Iqbal" <haris.iqbal@ionos.com>
CC: Mike Snitzer <snitzer@kernel.org>
CC: Minchan Kim <minchan@kernel.org>
CC: ocfs2-devel@oss.oracle.com
CC: reiserfs-devel@vger.kernel.org
CC: Sergey Senozhatsky <senozhatsky@chromium.org>
CC: Song Liu <song@kernel.org>
CC: Sven Schnelle <svens@linux.ibm.com>
CC: target-devel@vger.kernel.org
CC: Ted Tso <tytso@mit.edu>
CC: Trond Myklebust <trond.myklebust@hammerspace.com>
CC: xen-devel@lists.xenproject.org

Previous versions:
Link: http://lore.kernel.org/r/20230629165206.383-1-jack@suse.cz # v1
Link: http://lore.kernel.org/r/20230810171429.31759-1-jack@suse.cz # v2

[PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Jan Kara]

Convert bcache to use bdev_open_by_path() and pass the handle around.

CC: linux-bcache@vger.kernel.org
CC: Coly Li <colyli@suse.de
CC: Kent Overstreet <kent.overstreet@gmail.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/md/bcache/bcache.h |  2 +
 drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
 2 files changed, 43 insertions(+), 37 deletions(-)

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 5a79bb3c272f..2aa3f2c1f719 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -299,6 +299,7 @@ struct cached_dev {
 	struct list_head	list;
 	struct bcache_device	disk;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct cache_sb		sb;
 	struct cache_sb_disk	*sb_disk;
@@ -421,6 +422,7 @@ struct cache {
 
 	struct kobject		kobj;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct task_struct	*alloc_thread;
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 0ae2b3676293..c11ac86be72b 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
 	if (dc->sb_disk)
 		put_page(virt_to_page(dc->sb_disk));
 
-	if (!IS_ERR_OR_NULL(dc->bdev))
-		blkdev_put(dc->bdev, dc);
+	if (dc->bdev_handle)
+		bdev_release(dc->bdev_handle);
 
 	wake_up(&unregister_wait);
 
@@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
 /* Cached device - bcache superblock */
 
 static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				 struct block_device *bdev,
+				 struct bdev_handle *bdev_handle,
 				 struct cached_dev *dc)
 {
 	const char *err = "cannot allocate memory";
@@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 	int ret = -ENOMEM;
 
 	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
-	dc->bdev = bdev;
+	dc->bdev_handle = bdev_handle;
+	dc->bdev = bdev_handle->bdev;
 	dc->sb_disk = sb_disk;
 
 	if (cached_dev_init(dc, sb->block_size << 9))
 		goto err;
 
 	err = "error creating kobject";
-	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
+	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
 		goto err;
 	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
 		goto err;
@@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
 	if (ca->sb_disk)
 		put_page(virt_to_page(ca->sb_disk));
 
-	if (!IS_ERR_OR_NULL(ca->bdev))
-		blkdev_put(ca->bdev, ca);
+	if (ca->bdev_handle)
+		bdev_release(ca->bdev_handle);
 
 	kfree(ca);
 	module_put(THIS_MODULE);
@@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
 }
 
 static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				struct block_device *bdev, struct cache *ca)
+				struct bdev_handle *bdev_handle,
+				struct cache *ca)
 {
 	const char *err = NULL; /* must be set for any error case */
 	int ret = 0;
 
 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
-	ca->bdev = bdev;
+	ca->bdev_handle = bdev_handle;
+	ca->bdev = bdev_handle->bdev;
 	ca->sb_disk = sb_disk;
 
-	if (bdev_max_discard_sectors((bdev)))
+	if (bdev_max_discard_sectors((bdev_handle->bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
 	ret = cache_alloc(ca);
@@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		/*
 		 * If we failed here, it means ca->kobj is not initialized yet,
 		 * kobject_put() won't be called and there is no chance to
-		 * call blkdev_put() to bdev in bch_cache_release(). So we
-		 * explicitly call blkdev_put() here.
+		 * call bdev_release() to bdev in bch_cache_release(). So
+		 * we explicitly call bdev_release() here.
 		 */
-		blkdev_put(bdev, ca);
+		bdev_release(bdev_handle);
 		if (ret == -ENOMEM)
 			err = "cache_alloc(): -ENOMEM";
 		else if (ret == -EPERM)
@@ -2367,7 +2370,7 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto err;
 	}
 
-	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
+	if (kobject_add(&ca->kobj, bdev_kobj(bdev_handle->bdev), "bcache")) {
 		err = "error calling kobject_add";
 		ret = -ENOMEM;
 		goto out;
@@ -2382,14 +2385,14 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto out;
 	}
 
-	pr_info("registered cache device %pg\n", ca->bdev);
+	pr_info("registered cache device %pg\n", ca->bdev_handle->bdev);
 
 out:
 	kobject_put(&ca->kobj);
 
 err:
 	if (err)
-		pr_notice("error %pg: %s\n", ca->bdev, err);
+		pr_notice("error %pg: %s\n", ca->bdev_handle->bdev, err);
 
 	return ret;
 }
@@ -2445,7 +2448,7 @@ struct async_reg_args {
 	char *path;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev;
+	struct bdev_handle *bdev_handle;
 	void *holder;
 };
 
@@ -2456,8 +2459,8 @@ static void register_bdev_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	mutex_lock(&bch_register_lock);
-	if (register_bdev(args->sb, args->sb_disk, args->bdev, args->holder)
-	    < 0)
+	if (register_bdev(args->sb, args->sb_disk, args->bdev_handle,
+			  args->holder) < 0)
 		fail = true;
 	mutex_unlock(&bch_register_lock);
 
@@ -2477,7 +2480,8 @@ static void register_cache_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	/* blkdev_put() will be called in bch_cache_release() */
-	if (register_cache(args->sb, args->sb_disk, args->bdev, args->holder))
+	if (register_cache(args->sb, args->sb_disk, args->bdev_handle,
+			   args->holder))
 		fail = true;
 
 	if (fail)
@@ -2514,7 +2518,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	char *path = NULL;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev, *bdev2;
+	struct bdev_handle *bdev_handle, *bdev_handle2;
 	void *holder = NULL;
 	ssize_t ret;
 	bool async_registration = false;
@@ -2547,15 +2551,15 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	ret = -EINVAL;
 	err = "failed to open device";
-	bdev = blkdev_get_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
-	if (IS_ERR(bdev))
+	bdev_handle = bdev_open_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
+	if (IS_ERR(bdev_handle))
 		goto out_free_sb;
 
 	err = "failed to set blocksize";
-	if (set_blocksize(bdev, 4096))
+	if (set_blocksize(bdev_handle->bdev, 4096))
 		goto out_blkdev_put;
 
-	err = read_super(sb, bdev, &sb_disk);
+	err = read_super(sb, bdev_handle->bdev, &sb_disk);
 	if (err)
 		goto out_blkdev_put;
 
@@ -2567,13 +2571,13 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	}
 
 	/* Now reopen in exclusive mode with proper holder */
-	bdev2 = blkdev_get_by_dev(bdev->bd_dev, BLK_OPEN_READ | BLK_OPEN_WRITE,
-				  holder, NULL);
-	blkdev_put(bdev, NULL);
-	bdev = bdev2;
-	if (IS_ERR(bdev)) {
-		ret = PTR_ERR(bdev);
-		bdev = NULL;
+	bdev_handle2 = bdev_open_by_dev(bdev_handle->bdev->bd_dev,
+			BLK_OPEN_READ | BLK_OPEN_WRITE, holder, NULL);
+	bdev_release(bdev_handle);
+	bdev_handle = bdev_handle2;
+	if (IS_ERR(bdev_handle)) {
+		ret = PTR_ERR(bdev_handle);
+		bdev_handle = NULL;
 		if (ret == -EBUSY) {
 			dev_t dev;
 
@@ -2608,7 +2612,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		args->path	= path;
 		args->sb	= sb;
 		args->sb_disk	= sb_disk;
-		args->bdev	= bdev;
+		args->bdev_handle	= bdev_handle;
 		args->holder	= holder;
 		register_device_async(args);
 		/* No wait and returns to user space */
@@ -2617,14 +2621,14 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	if (SB_IS_BDEV(sb)) {
 		mutex_lock(&bch_register_lock);
-		ret = register_bdev(sb, sb_disk, bdev, holder);
+		ret = register_bdev(sb, sb_disk, bdev_handle, holder);
 		mutex_unlock(&bch_register_lock);
 		/* blkdev_put() will be called in cached_dev_free() */
 		if (ret < 0)
 			goto out_free_sb;
 	} else {
 		/* blkdev_put() will be called in bch_cache_release() */
-		ret = register_cache(sb, sb_disk, bdev, holder);
+		ret = register_cache(sb, sb_disk, bdev_handle, holder);
 		if (ret)
 			goto out_free_sb;
 	}
@@ -2640,8 +2644,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 out_put_sb_page:
 	put_page(virt_to_page(sb_disk));
 out_blkdev_put:
-	if (bdev)
-		blkdev_put(bdev, holder);
+	if (bdev_handle)
+		bdev_release(bdev_handle);
 out_free_sb:
 	kfree(sb);
 out_free_path:
-- 
2.35.3

Re: [PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Christian Brauner]

On Wed, Aug 23, 2023 at 12:48:20PM +0200, Jan Kara wrote:
> Convert bcache to use bdev_open_by_path() and pass the handle around.
> 
> CC: linux-bcache@vger.kernel.org
> CC: Coly Li <colyli@suse.de
> CC: Kent Overstreet <kent.overstreet@gmail.com>
> Acked-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Coly Li <colyli@suse.de>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---

Looks good to me,
Acked-by: Christian Brauner <brauner@kernel.org>

> -	if (!IS_ERR_OR_NULL(dc->bdev))
> -		blkdev_put(dc->bdev, dc);
> +	if (dc->bdev_handle)
> +		bdev_release(dc->bdev_handle);

Fwiw, these conversions confused me a little as the old check gave the
impression that this could be set to an error pointer somehow.

Re: [PATCH v3 0/29] block: Make blkdev_get_by_*() return handle

[Christian Brauner]

On Wed, Aug 23, 2023 at 12:48:11PM +0200, Jan Kara wrote:
> Hello,
> 
> this is a v3 of the patch series which implements the idea of blkdev_get_by_*()
> calls returning bdev_handle which is then passed to blkdev_put() [1]. This
> makes the get and put calls for bdevs more obviously matching and allows us to
> propagate context from get to put without having to modify all the users
> (again!). In particular I need to propagate used open flags to blkdev_put() to
> be able count writeable opens and add support for blocking writes to mounted
> block devices. I'll send that series separately.
> 
> The series is based on Christian's vfs tree as of today as there is quite
> some overlap. Patches have passed some reasonable testing - I've tested block
> changes, md, dm, bcache, xfs, btrfs, ext4, swap. More testing or review is
> always welcome. Thanks! I've pushed out the full branch to:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git bdev_handle
> 
> to ease review / testing. Since there were not many comments for v2 and
> Christoph has acked the series I think we should start discussing how to merge
> the series. Most collisions with this series seem to happen in the filesystems
> area so VFS tree would seem as the least painful way to merge this. Jens,

I really do like this series especially struct bdev_handle and moving
the mode bits in there. I'll happily take this. So far there have only
been minor things that can easily be fixed.

Re: [PATCH v3 0/29] block: Make blkdev_get_by_*() return handle

[Jan Kara]

On Fri 25-08-23 15:32:47, Christian Brauner wrote:
> On Wed, Aug 23, 2023 at 12:48:11PM +0200, Jan Kara wrote:
> > Hello,
> > 
> > this is a v3 of the patch series which implements the idea of blkdev_get_by_*()
> > calls returning bdev_handle which is then passed to blkdev_put() [1]. This
> > makes the get and put calls for bdevs more obviously matching and allows us to
> > propagate context from get to put without having to modify all the users
> > (again!). In particular I need to propagate used open flags to blkdev_put() to
> > be able count writeable opens and add support for blocking writes to mounted
> > block devices. I'll send that series separately.
> > 
> > The series is based on Christian's vfs tree as of today as there is quite
> > some overlap. Patches have passed some reasonable testing - I've tested block
> > changes, md, dm, bcache, xfs, btrfs, ext4, swap. More testing or review is
> > always welcome. Thanks! I've pushed out the full branch to:
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git bdev_handle
> > 
> > to ease review / testing. Since there were not many comments for v2 and
> > Christoph has acked the series I think we should start discussing how to merge
> > the series. Most collisions with this series seem to happen in the filesystems
> > area so VFS tree would seem as the least painful way to merge this. Jens,
> 
> I really do like this series especially struct bdev_handle and moving
> the mode bits in there. I'll happily take this. So far there have only
> been minor things that can easily be fixed.

Thanks. Since Al is fine with just doing a potential conversion to 'struct
file' as a handle on top of this series (it will be dumb Coccinelle
replacement) I think we can go ahead with the series as is. As you said
there will be some conflicts in btrfs and I've learned about f2fs conflicts
as well so I can rebase & repost the series on top of rc1 to make life
easier for you.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v3 0/29] block: Make blkdev_get_by_*() return handle

[Christian Brauner]

> replacement) I think we can go ahead with the series as is. As you said
> there will be some conflicts in btrfs and I've learned about f2fs conflicts
> as well so I can rebase & repost the series on top of rc1 to make life
> easier for you.

That is be much appreciated. Thank you!

[PATCH v4 0/29] block: Make blkdev_get_by_*() return handle

[Jan Kara]

Hello,

this is a v3 of the patch series which implements the idea of blkdev_get_by_*()
calls returning bdev_handle which is then passed to blkdev_put() [1]. This
makes the get and put calls for bdevs more obviously matching and allows us to
propagate context from get to put without having to modify all the users
(again!). In particular I need to propagate used open flags to blkdev_put() to
be able count writeable opens and add support for blocking writes to mounted
block devices. I'll send that series separately.

The series is based on Btrfs tree's for-next branch [2] as of today as the
series depends on Christoph's changes to btrfs device handling.  Patches have
passed some reasonable testing - I've tested block changes, md, dm, bcache,
xfs, btrfs, ext4, swap. More testing or review is always welcome. Thanks! I've
pushed out the full branch to:

git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git bdev_handle

to ease review / testing. Christian, can you pull the patches to your tree
to get some exposure in linux-next as well? Thanks!

Changes since v3:
* Rebased on top on btrfs tree

Changes since v2:
* Rebased on top of current vfs tree
* Added some acks
* Reflected minor nits from Christoph
* Added missing conversion of blkdev_put() calls in cramfs and erofs
* Fixed possible leak of bdev handle in xfs if logdev is the same as fs dev

Changes since v1:
* Rebased on top of current vfs tree
* Renamed final functions to bdev_open_by_*() and bdev_release()
* Fixed detection of exclusive open in blkdev_ioctl() and blkdev_fallocate()
* Fixed swap conversion to properly reinitialize swap_info->bdev_handle
* Fixed xfs conversion to not oops with rtdev without logdev
* Couple other minor fixups

								Honza

[1] https://lore.kernel.org/all/ZJGNsVDhZx0Xgs2H@infradead.org
[2] git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next

CC: Alasdair Kergon <agk@redhat.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Anna Schumaker <anna@kernel.org>
CC: Chao Yu <chao@kernel.org>
CC: Christian Borntraeger <borntraeger@linux.ibm.com>
CC: Coly Li <colyli@suse.de
CC: "Darrick J. Wong" <djwong@kernel.org>
CC: Dave Kleikamp <shaggy@kernel.org>
CC: David Sterba <dsterba@suse.com>
CC: dm-devel@redhat.com
CC: drbd-dev@lists.linbit.com
CC: Gao Xiang <xiang@kernel.org>
CC: Jack Wang <jinpu.wang@ionos.com>
CC: Jaegeuk Kim <jaegeuk@kernel.org>
CC: jfs-discussion@lists.sourceforge.net
CC: Joern Engel <joern@lazybastard.org>
CC: Joseph Qi <joseph.qi@linux.alibaba.com>
CC: Kent Overstreet <kent.overstreet@gmail.com>
CC: linux-bcache@vger.kernel.org
CC: linux-btrfs@vger.kernel.org
CC: linux-erofs@lists.ozlabs.org
CC: <linux-ext4@vger.kernel.org>
CC: linux-f2fs-devel@lists.sourceforge.net
CC: linux-mm@kvack.org
CC: linux-mtd@lists.infradead.org
CC: linux-nfs@vger.kernel.org
CC: linux-nilfs@vger.kernel.org
CC: linux-nvme@lists.infradead.org
CC: linux-pm@vger.kernel.org
CC: linux-raid@vger.kernel.org
CC: linux-s390@vger.kernel.org
CC: linux-scsi@vger.kernel.org
CC: linux-xfs@vger.kernel.org
CC: "Md. Haris Iqbal" <haris.iqbal@ionos.com>
CC: Mike Snitzer <snitzer@kernel.org>
CC: Minchan Kim <minchan@kernel.org>
CC: ocfs2-devel@oss.oracle.com
CC: reiserfs-devel@vger.kernel.org
CC: Sergey Senozhatsky <senozhatsky@chromium.org>
CC: Song Liu <song@kernel.org>
CC: Sven Schnelle <svens@linux.ibm.com>
CC: target-devel@vger.kernel.org
CC: Ted Tso <tytso@mit.edu>
CC: Trond Myklebust <trond.myklebust@hammerspace.com>
CC: xen-devel@lists.xenproject.org

Previous versions:
Link: http://lore.kernel.org/r/20230629165206.383-1-jack@suse.cz # v1
Link: http://lore.kernel.org/r/20230810171429.31759-1-jack@suse.cz # v2

[PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Jan Kara]

Convert bcache to use bdev_open_by_path() and pass the handle around.

CC: linux-bcache@vger.kernel.org
CC: Coly Li <colyli@suse.de
CC: Kent Overstreet <kent.overstreet@gmail.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/md/bcache/bcache.h |  2 +
 drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
 2 files changed, 43 insertions(+), 37 deletions(-)

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 5a79bb3c272f..2aa3f2c1f719 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -299,6 +299,7 @@ struct cached_dev {
 	struct list_head	list;
 	struct bcache_device	disk;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct cache_sb		sb;
 	struct cache_sb_disk	*sb_disk;
@@ -421,6 +422,7 @@ struct cache {
 
 	struct kobject		kobj;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct task_struct	*alloc_thread;
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 0ae2b3676293..c11ac86be72b 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
 	if (dc->sb_disk)
 		put_page(virt_to_page(dc->sb_disk));
 
-	if (!IS_ERR_OR_NULL(dc->bdev))
-		blkdev_put(dc->bdev, dc);
+	if (dc->bdev_handle)
+		bdev_release(dc->bdev_handle);
 
 	wake_up(&unregister_wait);
 
@@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
 /* Cached device - bcache superblock */
 
 static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				 struct block_device *bdev,
+				 struct bdev_handle *bdev_handle,
 				 struct cached_dev *dc)
 {
 	const char *err = "cannot allocate memory";
@@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 	int ret = -ENOMEM;
 
 	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
-	dc->bdev = bdev;
+	dc->bdev_handle = bdev_handle;
+	dc->bdev = bdev_handle->bdev;
 	dc->sb_disk = sb_disk;
 
 	if (cached_dev_init(dc, sb->block_size << 9))
 		goto err;
 
 	err = "error creating kobject";
-	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
+	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
 		goto err;
 	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
 		goto err;
@@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
 	if (ca->sb_disk)
 		put_page(virt_to_page(ca->sb_disk));
 
-	if (!IS_ERR_OR_NULL(ca->bdev))
-		blkdev_put(ca->bdev, ca);
+	if (ca->bdev_handle)
+		bdev_release(ca->bdev_handle);
 
 	kfree(ca);
 	module_put(THIS_MODULE);
@@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
 }
 
 static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				struct block_device *bdev, struct cache *ca)
+				struct bdev_handle *bdev_handle,
+				struct cache *ca)
 {
 	const char *err = NULL; /* must be set for any error case */
 	int ret = 0;
 
 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
-	ca->bdev = bdev;
+	ca->bdev_handle = bdev_handle;
+	ca->bdev = bdev_handle->bdev;
 	ca->sb_disk = sb_disk;
 
-	if (bdev_max_discard_sectors((bdev)))
+	if (bdev_max_discard_sectors((bdev_handle->bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
 	ret = cache_alloc(ca);
@@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		/*
 		 * If we failed here, it means ca->kobj is not initialized yet,
 		 * kobject_put() won't be called and there is no chance to
-		 * call blkdev_put() to bdev in bch_cache_release(). So we
-		 * explicitly call blkdev_put() here.
+		 * call bdev_release() to bdev in bch_cache_release(). So
+		 * we explicitly call bdev_release() here.
 		 */
-		blkdev_put(bdev, ca);
+		bdev_release(bdev_handle);
 		if (ret == -ENOMEM)
 			err = "cache_alloc(): -ENOMEM";
 		else if (ret == -EPERM)
@@ -2367,7 +2370,7 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto err;
 	}
 
-	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
+	if (kobject_add(&ca->kobj, bdev_kobj(bdev_handle->bdev), "bcache")) {
 		err = "error calling kobject_add";
 		ret = -ENOMEM;
 		goto out;
@@ -2382,14 +2385,14 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto out;
 	}
 
-	pr_info("registered cache device %pg\n", ca->bdev);
+	pr_info("registered cache device %pg\n", ca->bdev_handle->bdev);
 
 out:
 	kobject_put(&ca->kobj);
 
 err:
 	if (err)
-		pr_notice("error %pg: %s\n", ca->bdev, err);
+		pr_notice("error %pg: %s\n", ca->bdev_handle->bdev, err);
 
 	return ret;
 }
@@ -2445,7 +2448,7 @@ struct async_reg_args {
 	char *path;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev;
+	struct bdev_handle *bdev_handle;
 	void *holder;
 };
 
@@ -2456,8 +2459,8 @@ static void register_bdev_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	mutex_lock(&bch_register_lock);
-	if (register_bdev(args->sb, args->sb_disk, args->bdev, args->holder)
-	    < 0)
+	if (register_bdev(args->sb, args->sb_disk, args->bdev_handle,
+			  args->holder) < 0)
 		fail = true;
 	mutex_unlock(&bch_register_lock);
 
@@ -2477,7 +2480,8 @@ static void register_cache_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	/* blkdev_put() will be called in bch_cache_release() */
-	if (register_cache(args->sb, args->sb_disk, args->bdev, args->holder))
+	if (register_cache(args->sb, args->sb_disk, args->bdev_handle,
+			   args->holder))
 		fail = true;
 
 	if (fail)
@@ -2514,7 +2518,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	char *path = NULL;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev, *bdev2;
+	struct bdev_handle *bdev_handle, *bdev_handle2;
 	void *holder = NULL;
 	ssize_t ret;
 	bool async_registration = false;
@@ -2547,15 +2551,15 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	ret = -EINVAL;
 	err = "failed to open device";
-	bdev = blkdev_get_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
-	if (IS_ERR(bdev))
+	bdev_handle = bdev_open_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
+	if (IS_ERR(bdev_handle))
 		goto out_free_sb;
 
 	err = "failed to set blocksize";
-	if (set_blocksize(bdev, 4096))
+	if (set_blocksize(bdev_handle->bdev, 4096))
 		goto out_blkdev_put;
 
-	err = read_super(sb, bdev, &sb_disk);
+	err = read_super(sb, bdev_handle->bdev, &sb_disk);
 	if (err)
 		goto out_blkdev_put;
 
@@ -2567,13 +2571,13 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	}
 
 	/* Now reopen in exclusive mode with proper holder */
-	bdev2 = blkdev_get_by_dev(bdev->bd_dev, BLK_OPEN_READ | BLK_OPEN_WRITE,
-				  holder, NULL);
-	blkdev_put(bdev, NULL);
-	bdev = bdev2;
-	if (IS_ERR(bdev)) {
-		ret = PTR_ERR(bdev);
-		bdev = NULL;
+	bdev_handle2 = bdev_open_by_dev(bdev_handle->bdev->bd_dev,
+			BLK_OPEN_READ | BLK_OPEN_WRITE, holder, NULL);
+	bdev_release(bdev_handle);
+	bdev_handle = bdev_handle2;
+	if (IS_ERR(bdev_handle)) {
+		ret = PTR_ERR(bdev_handle);
+		bdev_handle = NULL;
 		if (ret == -EBUSY) {
 			dev_t dev;
 
@@ -2608,7 +2612,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		args->path	= path;
 		args->sb	= sb;
 		args->sb_disk	= sb_disk;
-		args->bdev	= bdev;
+		args->bdev_handle	= bdev_handle;
 		args->holder	= holder;
 		register_device_async(args);
 		/* No wait and returns to user space */
@@ -2617,14 +2621,14 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	if (SB_IS_BDEV(sb)) {
 		mutex_lock(&bch_register_lock);
-		ret = register_bdev(sb, sb_disk, bdev, holder);
+		ret = register_bdev(sb, sb_disk, bdev_handle, holder);
 		mutex_unlock(&bch_register_lock);
 		/* blkdev_put() will be called in cached_dev_free() */
 		if (ret < 0)
 			goto out_free_sb;
 	} else {
 		/* blkdev_put() will be called in bch_cache_release() */
-		ret = register_cache(sb, sb_disk, bdev, holder);
+		ret = register_cache(sb, sb_disk, bdev_handle, holder);
 		if (ret)
 			goto out_free_sb;
 	}
@@ -2640,8 +2644,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 out_put_sb_page:
 	put_page(virt_to_page(sb_disk));
 out_blkdev_put:
-	if (bdev)
-		blkdev_put(bdev, holder);
+	if (bdev_handle)
+		bdev_release(bdev_handle);
 out_free_sb:
 	kfree(sb);
 out_free_path:
-- 
2.35.3

Re: [PATCH v4 0/29] block: Make blkdev_get_by_*() return handle

[Jens Axboe]

On Wed, Sep 27, 2023 at 3:34?AM Jan Kara <jack@suse.cz> wrote:
>
> Hello,
>
> this is a v3 of the patch series which implements the idea of blkdev_get_by_*()

v4?

> calls returning bdev_handle which is then passed to blkdev_put() [1]. This
> makes the get and put calls for bdevs more obviously matching and allows us to
> propagate context from get to put without having to modify all the users
> (again!). In particular I need to propagate used open flags to blkdev_put() to
> be able count writeable opens and add support for blocking writes to mounted
> block devices. I'll send that series separately.
>
> The series is based on Btrfs tree's for-next branch [2] as of today as the
> series depends on Christoph's changes to btrfs device handling.  Patches have
> passed some reasonable testing - I've tested block changes, md, dm, bcache,
> xfs, btrfs, ext4, swap. More testing or review is always welcome. Thanks! I've
> pushed out the full branch to:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git bdev_handle
>
> to ease review / testing. Christian, can you pull the patches to your tree
> to get some exposure in linux-next as well? Thanks!

For the block bits:

Acked-by: Jens Axboe <axboe@kernel.dk>

-- 
Jens Axboe

Re: [PATCH v4 0/29] block: Make blkdev_get_by_*() return handle

[Christian Brauner]

On Wed, 27 Sep 2023 11:34:07 +0200, Jan Kara wrote:
> Create struct bdev_handle that contains all parameters that need to be
> passed to blkdev_put() and provide bdev_open_* functions that return
> this structure instead of plain bdev pointer. This will eventually allow
> us to pass one more argument to blkdev_put() (renamed to bdev_release())
> without too much hassle.
> 
> 
> [...]

> to ease review / testing. Christian, can you pull the patches to your tree
> to get some exposure in linux-next as well? Thanks!

Yep. So I did it slighly differently. I pulled in the btrfs prereqs and
then applied your series on top of it so we get all the Link: tags right.
I'm running tests right now. Please double-check.

---

Applied to the vfs.super branch of the vfs/vfs.git tree.
Patches in the vfs.super branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.super

[01/29] block: Provide bdev_open_* functions
       https://git.kernel.org/vfs/vfs/c/b7c828aa0b3c
[02/29] block: Use bdev_open_by_dev() in blkdev_open()
        https://git.kernel.org/vfs/vfs/c/d4e36f27b45a
[03/29] block: Use bdev_open_by_dev() in disk_scan_partitions() and blkdev_bszset()
        https://git.kernel.org/vfs/vfs/c/5f9bd6764c7a
[04/29] drdb: Convert to use bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/0220ca8e443d
[05/29] pktcdvd: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/7af10b889789
[06/29] rnbd-srv: Convert to use bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/3d27892a4be7
[07/29] xen/blkback: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/26afb0ed10b3
[08/29] zram: Convert to use bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/efc8e3f4c6dc
[09/29] bcache: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/dc893f51d24a
[10/29] dm: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/80c2267c6d07
[11/29] md: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/15db36126ca6
[12/29] mtd: block2mtd: Convert to bdev_open_by_dev/path()
        https://git.kernel.org/vfs/vfs/c/4c27234bf3ce
[13/29] nvmet: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/70cffddcc300
[14/29] s390/dasd: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/5581d03457f8
[15/29] scsi: target: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/43de7d844d47
[16/29] PM: hibernate: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/105ea4a2fd18
[17/29] PM: hibernate: Drop unused snapshot_test argument
        https://git.kernel.org/vfs/vfs/c/b589a66e3688
[18/29] mm/swap: Convert to use bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/615af8e29233
[19/29] fs: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/5173192bcfe6
[20/29] btrfs: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/8cf64782764f
[21/29] erofs: Convert to use bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/4d41880bf249
[22/29] ext4: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/f7507612395e
[23/29] f2fs: Convert to bdev_open_by_dev/path()
        https://git.kernel.org/vfs/vfs/c/d9ff8e3b6498
[24/29] jfs: Convert to bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/459dc6376338
[25/29] nfs/blocklayout: Convert to use bdev_open_by_dev/path()
        https://git.kernel.org/vfs/vfs/c/5b1df9a40929
[26/29] ocfs2: Convert to use bdev_open_by_dev()
        https://git.kernel.org/vfs/vfs/c/b6b95acbd943
[27/29] reiserfs: Convert to bdev_open_by_dev/path()
        https://git.kernel.org/vfs/vfs/c/7e3615ff6119
[28/29] xfs: Convert to bdev_open_by_path()
        https://git.kernel.org/vfs/vfs/c/176ccb99e207
[29/29] block: Remove blkdev_get_by_*() functions
        https://git.kernel.org/vfs/vfs/c/953863a5a2ff

Re: [PATCH v4 0/29] block: Make blkdev_get_by_*() return handle

[Jan Kara]

On Wed 27-09-23 18:21:19, Christian Brauner wrote:
> On Wed, 27 Sep 2023 11:34:07 +0200, Jan Kara wrote:
> > Create struct bdev_handle that contains all parameters that need to be
> > passed to blkdev_put() and provide bdev_open_* functions that return
> > this structure instead of plain bdev pointer. This will eventually allow
> > us to pass one more argument to blkdev_put() (renamed to bdev_release())
> > without too much hassle.
> > 
> > 
> > [...]
> 
> > to ease review / testing. Christian, can you pull the patches to your tree
> > to get some exposure in linux-next as well? Thanks!
> 
> Yep. So I did it slighly differently. I pulled in the btrfs prereqs and
> then applied your series on top of it so we get all the Link: tags right.
> I'm running tests right now. Please double-check.

Thanks for picking patches up! I've checked the branch and it looks good to
me. 

								Honza

> 
> ---
> 
> Applied to the vfs.super branch of the vfs/vfs.git tree.
> Patches in the vfs.super branch should appear in linux-next soon.
> 
> Please report any outstanding bugs that were missed during review in a
> new review to the original patch series allowing us to drop it.
> 
> It's encouraged to provide Acked-bys and Reviewed-bys even though the
> patch has now been applied. If possible patch trailers will be updated.
> 
> Note that commit hashes shown below are subject to change due to rebase,
> trailer updates or similar. If in doubt, please check the listed branch.
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
> branch: vfs.super
> 
> [01/29] block: Provide bdev_open_* functions
>        https://git.kernel.org/vfs/vfs/c/b7c828aa0b3c
> [02/29] block: Use bdev_open_by_dev() in blkdev_open()
>         https://git.kernel.org/vfs/vfs/c/d4e36f27b45a
> [03/29] block: Use bdev_open_by_dev() in disk_scan_partitions() and blkdev_bszset()
>         https://git.kernel.org/vfs/vfs/c/5f9bd6764c7a
> [04/29] drdb: Convert to use bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/0220ca8e443d
> [05/29] pktcdvd: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/7af10b889789
> [06/29] rnbd-srv: Convert to use bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/3d27892a4be7
> [07/29] xen/blkback: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/26afb0ed10b3
> [08/29] zram: Convert to use bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/efc8e3f4c6dc
> [09/29] bcache: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/dc893f51d24a
> [10/29] dm: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/80c2267c6d07
> [11/29] md: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/15db36126ca6
> [12/29] mtd: block2mtd: Convert to bdev_open_by_dev/path()
>         https://git.kernel.org/vfs/vfs/c/4c27234bf3ce
> [13/29] nvmet: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/70cffddcc300
> [14/29] s390/dasd: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/5581d03457f8
> [15/29] scsi: target: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/43de7d844d47
> [16/29] PM: hibernate: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/105ea4a2fd18
> [17/29] PM: hibernate: Drop unused snapshot_test argument
>         https://git.kernel.org/vfs/vfs/c/b589a66e3688
> [18/29] mm/swap: Convert to use bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/615af8e29233
> [19/29] fs: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/5173192bcfe6
> [20/29] btrfs: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/8cf64782764f
> [21/29] erofs: Convert to use bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/4d41880bf249
> [22/29] ext4: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/f7507612395e
> [23/29] f2fs: Convert to bdev_open_by_dev/path()
>         https://git.kernel.org/vfs/vfs/c/d9ff8e3b6498
> [24/29] jfs: Convert to bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/459dc6376338
> [25/29] nfs/blocklayout: Convert to use bdev_open_by_dev/path()
>         https://git.kernel.org/vfs/vfs/c/5b1df9a40929
> [26/29] ocfs2: Convert to use bdev_open_by_dev()
>         https://git.kernel.org/vfs/vfs/c/b6b95acbd943
> [27/29] reiserfs: Convert to bdev_open_by_dev/path()
>         https://git.kernel.org/vfs/vfs/c/7e3615ff6119
> [28/29] xfs: Convert to bdev_open_by_path()
>         https://git.kernel.org/vfs/vfs/c/176ccb99e207
> [29/29] block: Remove blkdev_get_by_*() functions
>         https://git.kernel.org/vfs/vfs/c/953863a5a2ff
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Coly Li]

> 2023年8月22日 02:54，Eric Wheeler <bcache@lists.ewheeler.net> 写道：
> 
> On Mon, 21 Aug 2023, Jan Kara wrote:
>> On Sun 20-08-23 18:06:01, Eric Wheeler wrote:
>>> On Fri, 11 Aug 2023, Jan Kara wrote:
>>>> Convert bcache to use bdev_open_by_path() and pass the handle around.
>>>> 
>>>> CC: linux-bcache@vger.kernel.org
>>>> CC: Coly Li <colyli@suse.de
>>>> CC: Kent Overstreet <kent.overstreet@gmail.com>
>>>> Acked-by: Coly Li <colyli@suse.de>
>>>> Signed-off-by: Jan Kara <jack@suse.cz>
>>>> ---
>>>> drivers/md/bcache/bcache.h |  2 +
>>>> drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
>>>> 2 files changed, 43 insertions(+), 37 deletions(-)
>>>> 
>>>> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
>>>> index 5a79bb3c272f..2aa3f2c1f719 100644
>>>> --- a/drivers/md/bcache/bcache.h
>>>> +++ b/drivers/md/bcache/bcache.h
>>>> @@ -299,6 +299,7 @@ struct cached_dev {
>>>> struct list_head list;
>>>> struct bcache_device disk;
>>>> struct block_device *bdev;
>>>> + struct bdev_handle *bdev_handle;
>>> 
>>> It looks like you've handled most if not all of the `block_device *bdev` 
>>> refactor.  Can we drop `block_device *bdev` and fixup any remaining 
>>> references?  More below.
>> 
>> Well, we could but it's a lot of churn - like 53 dereferences in bcache.
>> So if bcache maintainer wants to go this way, sure we can do it. But
>> preferably as a separate cleanup patch on top of this series because the
>> series generates enough conflicts as is and this will make it considerably
>> worse.
> 
> A separate cleanup patch seems reasonable, I'll defer to Coly on this one 
> since he's the maintainer.  I just wanted to point out the possible issue.  
> Thanks for your work on this.

Yes, the challenge of this series is from the block layer core, once the change in core part is accepted, the cleanup can be followed up if necessary.

Thank you all.

Coly Li

Re: [PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Eric Wheeler]

On Mon, 21 Aug 2023, Jan Kara wrote:
> On Sun 20-08-23 18:06:01, Eric Wheeler wrote:
> > On Fri, 11 Aug 2023, Jan Kara wrote:
> > > Convert bcache to use bdev_open_by_path() and pass the handle around.
> > > 
> > > CC: linux-bcache@vger.kernel.org
> > > CC: Coly Li <colyli@suse.de
> > > CC: Kent Overstreet <kent.overstreet@gmail.com>
> > > Acked-by: Coly Li <colyli@suse.de>
> > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > ---
> > >  drivers/md/bcache/bcache.h |  2 +
> > >  drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
> > >  2 files changed, 43 insertions(+), 37 deletions(-)
> > > 
> > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> > > index 5a79bb3c272f..2aa3f2c1f719 100644
> > > --- a/drivers/md/bcache/bcache.h
> > > +++ b/drivers/md/bcache/bcache.h
> > > @@ -299,6 +299,7 @@ struct cached_dev {
> > >  	struct list_head	list;
> > >  	struct bcache_device	disk;
> > >  	struct block_device	*bdev;
> > > +	struct bdev_handle	*bdev_handle;
> > 
> > It looks like you've handled most if not all of the `block_device *bdev` 
> > refactor.  Can we drop `block_device *bdev` and fixup any remaining 
> > references?  More below.
> 
> Well, we could but it's a lot of churn - like 53 dereferences in bcache.
> So if bcache maintainer wants to go this way, sure we can do it. But
> preferably as a separate cleanup patch on top of this series because the
> series generates enough conflicts as is and this will make it considerably
> worse.

A separate cleanup patch seems reasonable, I'll defer to Coly on this one 
since he's the maintainer.  I just wanted to point out the possible issue.  
Thanks for your work on this.

--
Eric Wheeler



> 
> > > @@ -421,6 +422,7 @@ struct cache {
> > >  
> > >  	struct kobject		kobj;
> > >  	struct block_device	*bdev;
> > > +	struct bdev_handle	*bdev_handle;
> > 
> > ditto.
> > 
> > >  
> > >  	struct task_struct	*alloc_thread;
> > >  
> > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> > > index 0ae2b3676293..c11ac86be72b 100644
> > > --- a/drivers/md/bcache/super.c
> > > +++ b/drivers/md/bcache/super.c
> > > @@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
> > >  	if (dc->sb_disk)
> > >  		put_page(virt_to_page(dc->sb_disk));
> > >  
> > > -	if (!IS_ERR_OR_NULL(dc->bdev))
> > > -		blkdev_put(dc->bdev, dc);
> > > +	if (dc->bdev_handle)
> > > +		bdev_release(dc->bdev_handle);
> > 
> > bdev_release does not reset dc->bdev, which could leave a hanging 
> > reference.
> 
> So after this, dc->bdev may reference freed block device that is true. But
> the original code did not cleanup dc->bdev either so things just stay as
> they were.
> 
> > > @@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
> > >  /* Cached device - bcache superblock */
> > >  
> > >  static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > > -				 struct block_device *bdev,
> > > +				 struct bdev_handle *bdev_handle,
> > >  				 struct cached_dev *dc)
> > >  {
> > >  	const char *err = "cannot allocate memory";
> > > @@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > >  	int ret = -ENOMEM;
> > >  
> > >  	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
> > > -	dc->bdev = bdev;
> > > +	dc->bdev_handle = bdev_handle;
> > > +	dc->bdev = bdev_handle->bdev;
> > 
> > If I understand correctly, this patch duplicates the dc->bdev reference to 
> > exist as dc->bdev_handle->bdev _and_ dc->bdev. (Same for changes related 
> > to `struct cache`.)
> 
> Well, dc->bdev isn't a reference anymore, just a shortcut so that people
> don't have to write the long dc->bdev_handle->bdev (plus it limits the
> churn this series generates as I've mentioned above). I can see why some
> people needn't like this duplication so sure we can clean it up if that's
> the concensus of bcache developers.
>  
> > This would mean future developers have to understand they are the same 
> > thing, and someone may not manage it correctly.
> > 
> > If block core is moving to `struct bdev_handle`, then can we drop 
> > `dc->bdev` and replace all occurances of `dc->bdev` with 
> > `bdev_handle->bdev`?  Or make an accessor macro/function like 
> > bdev_handle_get_bdev(dc->bdev_handle)?
> 
> Accessor is making things even longer and I don't see the benefit. So I'd
> just go with dc->bdev_handle->bdev.
> 
> > Unless I misunderstand something here, I would NACK this as written 
> > because it increases the liklihood of future developer error.  
> > 
> > I've added a few other comments below, but my comments are not exhaustive:
> > 
> > >  	dc->sb_disk = sb_disk;
> > >  
> > >  	if (cached_dev_init(dc, sb->block_size << 9))
> > >  		goto err;
> > >  
> > >  	err = "error creating kobject";
> > > -	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
> > > +	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
> > >  		goto err;
> > >  	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
> > >  		goto err;
> > > @@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
> > >  	if (ca->sb_disk)
> > >  		put_page(virt_to_page(ca->sb_disk));
> > >  
> > > -	if (!IS_ERR_OR_NULL(ca->bdev))
> > > -		blkdev_put(ca->bdev, ca);
> > > +	if (ca->bdev_handle)
> > > +		bdev_release(ca->bdev_handle);
> > >  
> > 
> > ca->bdev is not cleaned up
> 
> Well, same comment as with dc->bdev - the old code didn't cleanup the
> pointer either. Furthermore the structure is kfree()d in the line below so
> there is really no point in zeroing the pointer.
> 
> > >  	kfree(ca);
> > >  	module_put(THIS_MODULE);
> > > @@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
> > >  }
> > >  
> > >  static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > > -				struct block_device *bdev, struct cache *ca)
> > > +				struct bdev_handle *bdev_handle,
> > > +				struct cache *ca)
> > >  {
> > >  	const char *err = NULL; /* must be set for any error case */
> > >  	int ret = 0;
> > >  
> > >  	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
> > > -	ca->bdev = bdev;
> > > +	ca->bdev_handle = bdev_handle;
> > > +	ca->bdev = bdev_handle->bdev;
> > >  	ca->sb_disk = sb_disk;
> > >  
> > > -	if (bdev_max_discard_sectors((bdev)))
> > > +	if (bdev_max_discard_sectors((bdev_handle->bdev)))
> > >  		ca->discard = CACHE_DISCARD(&ca->sb);
> > >  
> > >  	ret = cache_alloc(ca);
> > > @@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > >  		/*
> > >  		 * If we failed here, it means ca->kobj is not initialized yet,
> > >  		 * kobject_put() won't be called and there is no chance to
> > > -		 * call blkdev_put() to bdev in bch_cache_release(). So we
> > > -		 * explicitly call blkdev_put() here.
> > > +		 * call bdev_release() to bdev in bch_cache_release(). So
> > > +		 * we explicitly call bdev_release() here.
> > >  		 */
> > > -		blkdev_put(bdev, ca);
> > > +		bdev_release(bdev_handle);
> > 
> > ca->bdev is not cleaned up
> 
> So ca->bdev doesn't really need to be cleaned up here and the original code
> wasn't cleaning it up either. So I don't see a problem here either... But
> maybe I miss something.
> 
> 								Honza
> -- 
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
> 

Re: [PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Jan Kara]

On Sun 20-08-23 18:06:01, Eric Wheeler wrote:
> On Fri, 11 Aug 2023, Jan Kara wrote:
> > Convert bcache to use bdev_open_by_path() and pass the handle around.
> > 
> > CC: linux-bcache@vger.kernel.org
> > CC: Coly Li <colyli@suse.de
> > CC: Kent Overstreet <kent.overstreet@gmail.com>
> > Acked-by: Coly Li <colyli@suse.de>
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> >  drivers/md/bcache/bcache.h |  2 +
> >  drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
> >  2 files changed, 43 insertions(+), 37 deletions(-)
> > 
> > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> > index 5a79bb3c272f..2aa3f2c1f719 100644
> > --- a/drivers/md/bcache/bcache.h
> > +++ b/drivers/md/bcache/bcache.h
> > @@ -299,6 +299,7 @@ struct cached_dev {
> >  	struct list_head	list;
> >  	struct bcache_device	disk;
> >  	struct block_device	*bdev;
> > +	struct bdev_handle	*bdev_handle;
> 
> It looks like you've handled most if not all of the `block_device *bdev` 
> refactor.  Can we drop `block_device *bdev` and fixup any remaining 
> references?  More below.

Well, we could but it's a lot of churn - like 53 dereferences in bcache.
So if bcache maintainer wants to go this way, sure we can do it. But
preferably as a separate cleanup patch on top of this series because the
series generates enough conflicts as is and this will make it considerably
worse.

> > @@ -421,6 +422,7 @@ struct cache {
> >  
> >  	struct kobject		kobj;
> >  	struct block_device	*bdev;
> > +	struct bdev_handle	*bdev_handle;
> 
> ditto.
> 
> >  
> >  	struct task_struct	*alloc_thread;
> >  
> > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> > index 0ae2b3676293..c11ac86be72b 100644
> > --- a/drivers/md/bcache/super.c
> > +++ b/drivers/md/bcache/super.c
> > @@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
> >  	if (dc->sb_disk)
> >  		put_page(virt_to_page(dc->sb_disk));
> >  
> > -	if (!IS_ERR_OR_NULL(dc->bdev))
> > -		blkdev_put(dc->bdev, dc);
> > +	if (dc->bdev_handle)
> > +		bdev_release(dc->bdev_handle);
> 
> bdev_release does not reset dc->bdev, which could leave a hanging 
> reference.

So after this, dc->bdev may reference freed block device that is true. But
the original code did not cleanup dc->bdev either so things just stay as
they were.

> > @@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
> >  /* Cached device - bcache superblock */
> >  
> >  static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > -				 struct block_device *bdev,
> > +				 struct bdev_handle *bdev_handle,
> >  				 struct cached_dev *dc)
> >  {
> >  	const char *err = "cannot allocate memory";
> > @@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> >  	int ret = -ENOMEM;
> >  
> >  	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
> > -	dc->bdev = bdev;
> > +	dc->bdev_handle = bdev_handle;
> > +	dc->bdev = bdev_handle->bdev;
> 
> If I understand correctly, this patch duplicates the dc->bdev reference to 
> exist as dc->bdev_handle->bdev _and_ dc->bdev. (Same for changes related 
> to `struct cache`.)

Well, dc->bdev isn't a reference anymore, just a shortcut so that people
don't have to write the long dc->bdev_handle->bdev (plus it limits the
churn this series generates as I've mentioned above). I can see why some
people needn't like this duplication so sure we can clean it up if that's
the concensus of bcache developers.
 
> This would mean future developers have to understand they are the same 
> thing, and someone may not manage it correctly.
> 
> If block core is moving to `struct bdev_handle`, then can we drop 
> `dc->bdev` and replace all occurances of `dc->bdev` with 
> `bdev_handle->bdev`?  Or make an accessor macro/function like 
> bdev_handle_get_bdev(dc->bdev_handle)?

Accessor is making things even longer and I don't see the benefit. So I'd
just go with dc->bdev_handle->bdev.

> Unless I misunderstand something here, I would NACK this as written 
> because it increases the liklihood of future developer error.  
> 
> I've added a few other comments below, but my comments are not exhaustive:
> 
> >  	dc->sb_disk = sb_disk;
> >  
> >  	if (cached_dev_init(dc, sb->block_size << 9))
> >  		goto err;
> >  
> >  	err = "error creating kobject";
> > -	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
> > +	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
> >  		goto err;
> >  	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
> >  		goto err;
> > @@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
> >  	if (ca->sb_disk)
> >  		put_page(virt_to_page(ca->sb_disk));
> >  
> > -	if (!IS_ERR_OR_NULL(ca->bdev))
> > -		blkdev_put(ca->bdev, ca);
> > +	if (ca->bdev_handle)
> > +		bdev_release(ca->bdev_handle);
> >  
> 
> ca->bdev is not cleaned up

Well, same comment as with dc->bdev - the old code didn't cleanup the
pointer either. Furthermore the structure is kfree()d in the line below so
there is really no point in zeroing the pointer.

> >  	kfree(ca);
> >  	module_put(THIS_MODULE);
> > @@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
> >  }
> >  
> >  static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> > -				struct block_device *bdev, struct cache *ca)
> > +				struct bdev_handle *bdev_handle,
> > +				struct cache *ca)
> >  {
> >  	const char *err = NULL; /* must be set for any error case */
> >  	int ret = 0;
> >  
> >  	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
> > -	ca->bdev = bdev;
> > +	ca->bdev_handle = bdev_handle;
> > +	ca->bdev = bdev_handle->bdev;
> >  	ca->sb_disk = sb_disk;
> >  
> > -	if (bdev_max_discard_sectors((bdev)))
> > +	if (bdev_max_discard_sectors((bdev_handle->bdev)))
> >  		ca->discard = CACHE_DISCARD(&ca->sb);
> >  
> >  	ret = cache_alloc(ca);
> > @@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> >  		/*
> >  		 * If we failed here, it means ca->kobj is not initialized yet,
> >  		 * kobject_put() won't be called and there is no chance to
> > -		 * call blkdev_put() to bdev in bch_cache_release(). So we
> > -		 * explicitly call blkdev_put() here.
> > +		 * call bdev_release() to bdev in bch_cache_release(). So
> > +		 * we explicitly call bdev_release() here.
> >  		 */
> > -		blkdev_put(bdev, ca);
> > +		bdev_release(bdev_handle);
> 
> ca->bdev is not cleaned up

So ca->bdev doesn't really need to be cleaned up here and the original code
wasn't cleaning it up either. So I don't see a problem here either... But
maybe I miss something.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Eric Wheeler]

On Fri, 11 Aug 2023, Jan Kara wrote:
> Convert bcache to use bdev_open_by_path() and pass the handle around.
> 
> CC: linux-bcache@vger.kernel.org
> CC: Coly Li <colyli@suse.de
> CC: Kent Overstreet <kent.overstreet@gmail.com>
> Acked-by: Coly Li <colyli@suse.de>
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
>  drivers/md/bcache/bcache.h |  2 +
>  drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
>  2 files changed, 43 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
> index 5a79bb3c272f..2aa3f2c1f719 100644
> --- a/drivers/md/bcache/bcache.h
> +++ b/drivers/md/bcache/bcache.h
> @@ -299,6 +299,7 @@ struct cached_dev {
>  	struct list_head	list;
>  	struct bcache_device	disk;
>  	struct block_device	*bdev;
> +	struct bdev_handle	*bdev_handle;

It looks like you've handled most if not all of the `block_device *bdev` 
refactor.  Can we drop `block_device *bdev` and fixup any remaining 
references?  More below.

>  
>  	struct cache_sb		sb;
>  	struct cache_sb_disk	*sb_disk;
> @@ -421,6 +422,7 @@ struct cache {
>  
>  	struct kobject		kobj;
>  	struct block_device	*bdev;
> +	struct bdev_handle	*bdev_handle;

ditto.

>  
>  	struct task_struct	*alloc_thread;
>  
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 0ae2b3676293..c11ac86be72b 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
>  	if (dc->sb_disk)
>  		put_page(virt_to_page(dc->sb_disk));
>  
> -	if (!IS_ERR_OR_NULL(dc->bdev))
> -		blkdev_put(dc->bdev, dc);
> +	if (dc->bdev_handle)
> +		bdev_release(dc->bdev_handle);

bdev_release does not reset dc->bdev, which could leave a hanging 
reference.

>  
>  	wake_up(&unregister_wait);
>  
> @@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
>  /* Cached device - bcache superblock */
>  
>  static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> -				 struct block_device *bdev,
> +				 struct bdev_handle *bdev_handle,
>  				 struct cached_dev *dc)
>  {
>  	const char *err = "cannot allocate memory";
> @@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
>  	int ret = -ENOMEM;
>  
>  	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
> -	dc->bdev = bdev;
> +	dc->bdev_handle = bdev_handle;
> +	dc->bdev = bdev_handle->bdev;

If I understand correctly, this patch duplicates the dc->bdev reference to 
exist as dc->bdev_handle->bdev _and_ dc->bdev. (Same for changes related 
to `struct cache`.)

This would mean future developers have to understand they are the same 
thing, and someone may not manage it correctly.

If block core is moving to `struct bdev_handle`, then can we drop 
`dc->bdev` and replace all occurances of `dc->bdev` with 
`bdev_handle->bdev`?  Or make an accessor macro/function like 
bdev_handle_get_bdev(dc->bdev_handle)?

Unless I misunderstand something here, I would NACK this as written 
because it increases the liklihood of future developer error.  

I've added a few other comments below, but my comments are not exhaustive:

>  	dc->sb_disk = sb_disk;
>  
>  	if (cached_dev_init(dc, sb->block_size << 9))
>  		goto err;
>  
>  	err = "error creating kobject";
> -	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
> +	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
>  		goto err;
>  	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
>  		goto err;
> @@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
>  	if (ca->sb_disk)
>  		put_page(virt_to_page(ca->sb_disk));
>  
> -	if (!IS_ERR_OR_NULL(ca->bdev))
> -		blkdev_put(ca->bdev, ca);
> +	if (ca->bdev_handle)
> +		bdev_release(ca->bdev_handle);
>  

ca->bdev is not cleaned up

>  	kfree(ca);
>  	module_put(THIS_MODULE);
> @@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
>  }
>  
>  static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
> -				struct block_device *bdev, struct cache *ca)
> +				struct bdev_handle *bdev_handle,
> +				struct cache *ca)
>  {
>  	const char *err = NULL; /* must be set for any error case */
>  	int ret = 0;
>  
>  	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
> -	ca->bdev = bdev;
> +	ca->bdev_handle = bdev_handle;
> +	ca->bdev = bdev_handle->bdev;
>  	ca->sb_disk = sb_disk;
>  
> -	if (bdev_max_discard_sectors((bdev)))
> +	if (bdev_max_discard_sectors((bdev_handle->bdev)))
>  		ca->discard = CACHE_DISCARD(&ca->sb);
>  
>  	ret = cache_alloc(ca);
> @@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
>  		/*
>  		 * If we failed here, it means ca->kobj is not initialized yet,
>  		 * kobject_put() won't be called and there is no chance to
> -		 * call blkdev_put() to bdev in bch_cache_release(). So we
> -		 * explicitly call blkdev_put() here.
> +		 * call bdev_release() to bdev in bch_cache_release(). So
> +		 * we explicitly call bdev_release() here.
>  		 */
> -		blkdev_put(bdev, ca);
> +		bdev_release(bdev_handle);

ca->bdev is not cleaned up

>  		if (ret == -ENOMEM)
>  			err = "cache_alloc(): -ENOMEM";
>  		else if (ret == -EPERM)
> @@ -2367,7 +2370,7 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
>  		goto err;
>  	}
>  
> -	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
> +	if (kobject_add(&ca->kobj, bdev_kobj(bdev_handle->bdev), "bcache")) {
>  		err = "error calling kobject_add";
>  		ret = -ENOMEM;
>  		goto out;
> @@ -2382,14 +2385,14 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
>  		goto out;
>  	}
>  
> -	pr_info("registered cache device %pg\n", ca->bdev);
> +	pr_info("registered cache device %pg\n", ca->bdev_handle->bdev);
>  
>  out:
>  	kobject_put(&ca->kobj);
>  
>  err:
>  	if (err)
> -		pr_notice("error %pg: %s\n", ca->bdev, err);
> +		pr_notice("error %pg: %s\n", ca->bdev_handle->bdev, err);
>  
>  	return ret;
>  }
> @@ -2445,7 +2448,7 @@ struct async_reg_args {
>  	char *path;
>  	struct cache_sb *sb;
>  	struct cache_sb_disk *sb_disk;
> -	struct block_device *bdev;
> +	struct bdev_handle *bdev_handle;
>  	void *holder;
>  };
>  
> @@ -2456,8 +2459,8 @@ static void register_bdev_worker(struct work_struct *work)
>  		container_of(work, struct async_reg_args, reg_work.work);
>  
>  	mutex_lock(&bch_register_lock);
> -	if (register_bdev(args->sb, args->sb_disk, args->bdev, args->holder)
> -	    < 0)
> +	if (register_bdev(args->sb, args->sb_disk, args->bdev_handle,
> +			  args->holder) < 0)
>  		fail = true;
>  	mutex_unlock(&bch_register_lock);
>  
> @@ -2477,7 +2480,8 @@ static void register_cache_worker(struct work_struct *work)
>  		container_of(work, struct async_reg_args, reg_work.work);
>  
>  	/* blkdev_put() will be called in bch_cache_release() */
> -	if (register_cache(args->sb, args->sb_disk, args->bdev, args->holder))
> +	if (register_cache(args->sb, args->sb_disk, args->bdev_handle,
> +			   args->holder))
>  		fail = true;
>  
>  	if (fail)
> @@ -2514,7 +2518,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  	char *path = NULL;
>  	struct cache_sb *sb;
>  	struct cache_sb_disk *sb_disk;
> -	struct block_device *bdev, *bdev2;
> +	struct bdev_handle *bdev_handle, *bdev_handle2;
>  	void *holder = NULL;
>  	ssize_t ret;
>  	bool async_registration = false;
> @@ -2547,15 +2551,15 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  
>  	ret = -EINVAL;
>  	err = "failed to open device";
> -	bdev = blkdev_get_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
> -	if (IS_ERR(bdev))
> +	bdev_handle = bdev_open_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
> +	if (IS_ERR(bdev_handle))
>  		goto out_free_sb;
>  
>  	err = "failed to set blocksize";
> -	if (set_blocksize(bdev, 4096))
> +	if (set_blocksize(bdev_handle->bdev, 4096))
>  		goto out_blkdev_put;
>  
> -	err = read_super(sb, bdev, &sb_disk);
> +	err = read_super(sb, bdev_handle->bdev, &sb_disk);
>  	if (err)
>  		goto out_blkdev_put;
>  
> @@ -2567,13 +2571,13 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  	}
>  
>  	/* Now reopen in exclusive mode with proper holder */
> -	bdev2 = blkdev_get_by_dev(bdev->bd_dev, BLK_OPEN_READ | BLK_OPEN_WRITE,
> -				  holder, NULL);
> -	blkdev_put(bdev, NULL);
> -	bdev = bdev2;
> -	if (IS_ERR(bdev)) {
> -		ret = PTR_ERR(bdev);
> -		bdev = NULL;
> +	bdev_handle2 = bdev_open_by_dev(bdev_handle->bdev->bd_dev,
> +			BLK_OPEN_READ | BLK_OPEN_WRITE, holder, NULL);
> +	bdev_release(bdev_handle);
> +	bdev_handle = bdev_handle2;
> +	if (IS_ERR(bdev_handle)) {
> +		ret = PTR_ERR(bdev_handle);
> +		bdev_handle = NULL;
>  		if (ret == -EBUSY) {
>  			dev_t dev;
>  
> @@ -2608,7 +2612,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  		args->path	= path;
>  		args->sb	= sb;
>  		args->sb_disk	= sb_disk;
> -		args->bdev	= bdev;
> +		args->bdev_handle	= bdev_handle;
>  		args->holder	= holder;
>  		register_device_async(args);
>  		/* No wait and returns to user space */
> @@ -2617,14 +2621,14 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  
>  	if (SB_IS_BDEV(sb)) {
>  		mutex_lock(&bch_register_lock);
> -		ret = register_bdev(sb, sb_disk, bdev, holder);
> +		ret = register_bdev(sb, sb_disk, bdev_handle, holder);
>  		mutex_unlock(&bch_register_lock);
>  		/* blkdev_put() will be called in cached_dev_free() */
>  		if (ret < 0)
>  			goto out_free_sb;
>  	} else {
>  		/* blkdev_put() will be called in bch_cache_release() */
> -		ret = register_cache(sb, sb_disk, bdev, holder);
> +		ret = register_cache(sb, sb_disk, bdev_handle, holder);
>  		if (ret)
>  			goto out_free_sb;
>  	}
> @@ -2640,8 +2644,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  out_put_sb_page:
>  	put_page(virt_to_page(sb_disk));
>  out_blkdev_put:
> -	if (bdev)
> -		blkdev_put(bdev, holder);
> +	if (bdev_handle)
> +		bdev_release(bdev_handle);
>  out_free_sb:
>  	kfree(sb);
>  out_free_path:
> -- 
> 2.35.3
> 
> 


--
Eric Wheeler

[PATCH 09/29] bcache: Convert to bdev_open_by_path()

[Jan Kara]

Convert bcache to use bdev_open_by_path() and pass the handle around.

CC: linux-bcache@vger.kernel.org
CC: Coly Li <colyli@suse.de
CC: Kent Overstreet <kent.overstreet@gmail.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/md/bcache/bcache.h |  2 +
 drivers/md/bcache/super.c  | 78 ++++++++++++++++++++------------------
 2 files changed, 43 insertions(+), 37 deletions(-)

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index 5a79bb3c272f..2aa3f2c1f719 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -299,6 +299,7 @@ struct cached_dev {
 	struct list_head	list;
 	struct bcache_device	disk;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct cache_sb		sb;
 	struct cache_sb_disk	*sb_disk;
@@ -421,6 +422,7 @@ struct cache {
 
 	struct kobject		kobj;
 	struct block_device	*bdev;
+	struct bdev_handle	*bdev_handle;
 
 	struct task_struct	*alloc_thread;
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 0ae2b3676293..c11ac86be72b 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1368,8 +1368,8 @@ static void cached_dev_free(struct closure *cl)
 	if (dc->sb_disk)
 		put_page(virt_to_page(dc->sb_disk));
 
-	if (!IS_ERR_OR_NULL(dc->bdev))
-		blkdev_put(dc->bdev, dc);
+	if (dc->bdev_handle)
+		bdev_release(dc->bdev_handle);
 
 	wake_up(&unregister_wait);
 
@@ -1444,7 +1444,7 @@ static int cached_dev_init(struct cached_dev *dc, unsigned int block_size)
 /* Cached device - bcache superblock */
 
 static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				 struct block_device *bdev,
+				 struct bdev_handle *bdev_handle,
 				 struct cached_dev *dc)
 {
 	const char *err = "cannot allocate memory";
@@ -1452,14 +1452,15 @@ static int register_bdev(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 	int ret = -ENOMEM;
 
 	memcpy(&dc->sb, sb, sizeof(struct cache_sb));
-	dc->bdev = bdev;
+	dc->bdev_handle = bdev_handle;
+	dc->bdev = bdev_handle->bdev;
 	dc->sb_disk = sb_disk;
 
 	if (cached_dev_init(dc, sb->block_size << 9))
 		goto err;
 
 	err = "error creating kobject";
-	if (kobject_add(&dc->disk.kobj, bdev_kobj(bdev), "bcache"))
+	if (kobject_add(&dc->disk.kobj, bdev_kobj(dc->bdev), "bcache"))
 		goto err;
 	if (bch_cache_accounting_add_kobjs(&dc->accounting, &dc->disk.kobj))
 		goto err;
@@ -2216,8 +2217,8 @@ void bch_cache_release(struct kobject *kobj)
 	if (ca->sb_disk)
 		put_page(virt_to_page(ca->sb_disk));
 
-	if (!IS_ERR_OR_NULL(ca->bdev))
-		blkdev_put(ca->bdev, ca);
+	if (ca->bdev_handle)
+		bdev_release(ca->bdev_handle);
 
 	kfree(ca);
 	module_put(THIS_MODULE);
@@ -2337,16 +2338,18 @@ static int cache_alloc(struct cache *ca)
 }
 
 static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
-				struct block_device *bdev, struct cache *ca)
+				struct bdev_handle *bdev_handle,
+				struct cache *ca)
 {
 	const char *err = NULL; /* must be set for any error case */
 	int ret = 0;
 
 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
-	ca->bdev = bdev;
+	ca->bdev_handle = bdev_handle;
+	ca->bdev = bdev_handle->bdev;
 	ca->sb_disk = sb_disk;
 
-	if (bdev_max_discard_sectors((bdev)))
+	if (bdev_max_discard_sectors((bdev_handle->bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
 	ret = cache_alloc(ca);
@@ -2354,10 +2357,10 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		/*
 		 * If we failed here, it means ca->kobj is not initialized yet,
 		 * kobject_put() won't be called and there is no chance to
-		 * call blkdev_put() to bdev in bch_cache_release(). So we
-		 * explicitly call blkdev_put() here.
+		 * call bdev_release() to bdev in bch_cache_release(). So
+		 * we explicitly call bdev_release() here.
 		 */
-		blkdev_put(bdev, ca);
+		bdev_release(bdev_handle);
 		if (ret == -ENOMEM)
 			err = "cache_alloc(): -ENOMEM";
 		else if (ret == -EPERM)
@@ -2367,7 +2370,7 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto err;
 	}
 
-	if (kobject_add(&ca->kobj, bdev_kobj(bdev), "bcache")) {
+	if (kobject_add(&ca->kobj, bdev_kobj(bdev_handle->bdev), "bcache")) {
 		err = "error calling kobject_add";
 		ret = -ENOMEM;
 		goto out;
@@ -2382,14 +2385,14 @@ static int register_cache(struct cache_sb *sb, struct cache_sb_disk *sb_disk,
 		goto out;
 	}
 
-	pr_info("registered cache device %pg\n", ca->bdev);
+	pr_info("registered cache device %pg\n", ca->bdev_handle->bdev);
 
 out:
 	kobject_put(&ca->kobj);
 
 err:
 	if (err)
-		pr_notice("error %pg: %s\n", ca->bdev, err);
+		pr_notice("error %pg: %s\n", ca->bdev_handle->bdev, err);
 
 	return ret;
 }
@@ -2445,7 +2448,7 @@ struct async_reg_args {
 	char *path;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev;
+	struct bdev_handle *bdev_handle;
 	void *holder;
 };
 
@@ -2456,8 +2459,8 @@ static void register_bdev_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	mutex_lock(&bch_register_lock);
-	if (register_bdev(args->sb, args->sb_disk, args->bdev, args->holder)
-	    < 0)
+	if (register_bdev(args->sb, args->sb_disk, args->bdev_handle,
+			  args->holder) < 0)
 		fail = true;
 	mutex_unlock(&bch_register_lock);
 
@@ -2477,7 +2480,8 @@ static void register_cache_worker(struct work_struct *work)
 		container_of(work, struct async_reg_args, reg_work.work);
 
 	/* blkdev_put() will be called in bch_cache_release() */
-	if (register_cache(args->sb, args->sb_disk, args->bdev, args->holder))
+	if (register_cache(args->sb, args->sb_disk, args->bdev_handle,
+			   args->holder))
 		fail = true;
 
 	if (fail)
@@ -2514,7 +2518,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	char *path = NULL;
 	struct cache_sb *sb;
 	struct cache_sb_disk *sb_disk;
-	struct block_device *bdev, *bdev2;
+	struct bdev_handle *bdev_handle, *bdev_handle2;
 	void *holder = NULL;
 	ssize_t ret;
 	bool async_registration = false;
@@ -2547,15 +2551,15 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	ret = -EINVAL;
 	err = "failed to open device";
-	bdev = blkdev_get_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
-	if (IS_ERR(bdev))
+	bdev_handle = bdev_open_by_path(strim(path), BLK_OPEN_READ, NULL, NULL);
+	if (IS_ERR(bdev_handle))
 		goto out_free_sb;
 
 	err = "failed to set blocksize";
-	if (set_blocksize(bdev, 4096))
+	if (set_blocksize(bdev_handle->bdev, 4096))
 		goto out_blkdev_put;
 
-	err = read_super(sb, bdev, &sb_disk);
+	err = read_super(sb, bdev_handle->bdev, &sb_disk);
 	if (err)
 		goto out_blkdev_put;
 
@@ -2567,13 +2571,13 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 	}
 
 	/* Now reopen in exclusive mode with proper holder */
-	bdev2 = blkdev_get_by_dev(bdev->bd_dev, BLK_OPEN_READ | BLK_OPEN_WRITE,
-				  holder, NULL);
-	blkdev_put(bdev, NULL);
-	bdev = bdev2;
-	if (IS_ERR(bdev)) {
-		ret = PTR_ERR(bdev);
-		bdev = NULL;
+	bdev_handle2 = bdev_open_by_dev(bdev_handle->bdev->bd_dev,
+			BLK_OPEN_READ | BLK_OPEN_WRITE, holder, NULL);
+	bdev_release(bdev_handle);
+	bdev_handle = bdev_handle2;
+	if (IS_ERR(bdev_handle)) {
+		ret = PTR_ERR(bdev_handle);
+		bdev_handle = NULL;
 		if (ret == -EBUSY) {
 			dev_t dev;
 
@@ -2608,7 +2612,7 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		args->path	= path;
 		args->sb	= sb;
 		args->sb_disk	= sb_disk;
-		args->bdev	= bdev;
+		args->bdev_handle	= bdev_handle;
 		args->holder	= holder;
 		register_device_async(args);
 		/* No wait and returns to user space */
@@ -2617,14 +2621,14 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 
 	if (SB_IS_BDEV(sb)) {
 		mutex_lock(&bch_register_lock);
-		ret = register_bdev(sb, sb_disk, bdev, holder);
+		ret = register_bdev(sb, sb_disk, bdev_handle, holder);
 		mutex_unlock(&bch_register_lock);
 		/* blkdev_put() will be called in cached_dev_free() */
 		if (ret < 0)
 			goto out_free_sb;
 	} else {
 		/* blkdev_put() will be called in bch_cache_release() */
-		ret = register_cache(sb, sb_disk, bdev, holder);
+		ret = register_cache(sb, sb_disk, bdev_handle, holder);
 		if (ret)
 			goto out_free_sb;
 	}
@@ -2640,8 +2644,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 out_put_sb_page:
 	put_page(virt_to_page(sb_disk));
 out_blkdev_put:
-	if (bdev)
-		blkdev_put(bdev, holder);
+	if (bdev_handle)
+		bdev_release(bdev_handle);
 out_free_sb:
 	kfree(sb);
 out_free_path:
-- 
2.35.3