[PATCH 01/32] block: Provide blkdev_get_handle_* functions

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Create struct bdev_handle that contains all parameters that need to be
passed to blkdev_put() and provide blkdev_get_handle_* functions that
return this structure instead of plain bdev pointer. This will
eventually allow us to pass one more argument to blkdev_put() without
too much hassle.

CC: Alasdair Kergon <agk@xxxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Anna Schumaker <anna@xxxxxxxxxx>
CC: Chao Yu <chao@xxxxxxxxxx>
CC: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
CC: Coly Li <colyli@xxxxxxx
CC: "Darrick J. Wong" <djwong@xxxxxxxxxx>
CC: Dave Kleikamp <shaggy@xxxxxxxxxx>
CC: David Sterba <dsterba@xxxxxxxx>
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CC: drbd-dev@xxxxxxxxxxxxxxxx
CC: Gao Xiang <xiang@xxxxxxxxxx>
CC: Jack Wang <jinpu.wang@xxxxxxxxx>
CC: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
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CC: Joern Engel <joern@xxxxxxxxxxxxxxx>
CC: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
CC: Kent Overstreet <kent.overstreet@xxxxxxxxx>
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CC: <linux-ext4@xxxxxxxxxxxxxxx>
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CC: "Md. Haris Iqbal" <haris.iqbal@xxxxxxxxx>
CC: Mike Snitzer <snitzer@xxxxxxxxxx>
CC: Minchan Kim <minchan@xxxxxxxxxx>
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CC: reiserfs-devel@xxxxxxxxxxxxxxx
CC: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
CC: Song Liu <song@xxxxxxxxxx>
CC: Sven Schnelle <svens@xxxxxxxxxxxxx>
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CC: Ted Tso <tytso@xxxxxxx>
CC: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
CC: xen-devel@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
 block/bdev.c           | 47 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/blkdev.h | 10 +++++++++
 2 files changed, 57 insertions(+)

diff --git a/block/bdev.c b/block/bdev.c
index 979e28a46b98..c75de5cac2bc 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -846,6 +846,24 @@ struct block_device *blkdev_get_by_dev(dev_t dev, blk_mode_t mode, void *holder,
+struct bdev_handle *blkdev_get_handle_by_dev(dev_t dev, blk_mode_t mode,
+		void *holder, const struct blk_holder_ops *hops)
+	struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle),
+					     GFP_KERNEL);
+	struct block_device *bdev;
+	if (!handle)
+		return ERR_PTR(-ENOMEM);
+	bdev = blkdev_get_by_dev(dev, mode, holder, hops);
+	if (IS_ERR(bdev))
+		return ERR_CAST(bdev);
+	handle->bdev = bdev;
+	handle->holder = holder;
+	return handle;
  * blkdev_get_by_path - open a block device by name
  * @path: path to the block device to open
@@ -884,6 +902,28 @@ struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
+struct bdev_handle *blkdev_get_handle_by_path(const char *path, blk_mode_t mode,
+		void *holder, const struct blk_holder_ops *hops)
+	struct bdev_handle *handle;
+	dev_t dev;
+	int error;
+	error = lookup_bdev(path, &dev);
+	if (error)
+		return ERR_PTR(error);
+	handle = blkdev_get_handle_by_dev(dev, mode, holder, hops);
+	if (!IS_ERR(handle) && (mode & BLK_OPEN_WRITE) &&
+	    bdev_read_only(handle->bdev)) {
+		blkdev_handle_put(handle);
+		return ERR_PTR(-EACCES);
+	}
+	return handle;
 void blkdev_put(struct block_device *bdev, void *holder)
 	struct gendisk *disk = bdev->bd_disk;
@@ -920,6 +960,13 @@ void blkdev_put(struct block_device *bdev, void *holder)
+void blkdev_handle_put(struct bdev_handle *handle)
+	blkdev_put(handle->bdev, handle->holder);
+	kfree(handle);
  * lookup_bdev() - Look up a struct block_device by name.
  * @pathname: Name of the block device in the filesystem.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ed44a997f629..a910e9997ddd 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1471,14 +1471,24 @@ struct blk_holder_ops {
 #define sb_open_mode(flags) \
 	(BLK_OPEN_READ | (((flags) & SB_RDONLY) ? 0 : BLK_OPEN_WRITE))
+struct bdev_handle {
+	struct block_device *bdev;
+	void *holder;
 struct block_device *blkdev_get_by_dev(dev_t dev, blk_mode_t mode, void *holder,
 		const struct blk_holder_ops *hops);
 struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
 		void *holder, const struct blk_holder_ops *hops);
+struct bdev_handle *blkdev_get_handle_by_dev(dev_t dev, blk_mode_t mode,
+		void *holder, const struct blk_holder_ops *hops);
+struct bdev_handle *blkdev_get_handle_by_path(const char *path, blk_mode_t mode,
+		void *holder, const struct blk_holder_ops *hops);
 int bd_prepare_to_claim(struct block_device *bdev, void *holder,
 		const struct blk_holder_ops *hops);
 void bd_abort_claiming(struct block_device *bdev, void *holder);
 void blkdev_put(struct block_device *bdev, void *holder);
+void blkdev_handle_put(struct bdev_handle *handle);
 /* just for blk-cgroup, don't use elsewhere */
 struct block_device *blkdev_get_no_open(dev_t dev);

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