[PATCH 01/29] block: Provide bdev_open_* functions

Jan Kara
2023-09-27T09:34:48Z

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.

Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
block/bdev.c | 48 ++++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 10 +++++++++
2 files changed, 58 insertions(+)

diff --git a/block/bdev.c b/block/bdev.c
index f3b13aa1b7d4..bdc7d739882b 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -829,6 +829,25 @@ struct block_device *blkdev_get_by_dev(dev_t dev, blk_mode_t mode, void *holder,
}
EXPORT_SYMBOL(blkdev_get_by_dev);

+struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
+ const struct blk_holder_ops *hops)
+{
+ struct bdev_handle *handle = kmalloc(sizeof(*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)) {
+ kfree(handle);
+ return ERR_CAST(bdev);
+ }
+ handle->bdev = bdev;
+ handle->holder = holder;
+ return handle;
+}
+EXPORT_SYMBOL(bdev_open_by_dev);
+
/**
* blkdev_get_by_path - open a block device by name
* @path: path to the block device to open
@@ -867,6 +886,28 @@ struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
}
EXPORT_SYMBOL(blkdev_get_by_path);

+struct bdev_handle *bdev_open_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 = bdev_open_by_dev(dev, mode, holder, hops);
+ if (!IS_ERR(handle) && (mode & BLK_OPEN_WRITE) &&
+ bdev_read_only(handle->bdev)) {
+ bdev_release(handle);
+ return ERR_PTR(-EACCES);
+ }
+
+ return handle;
+}
+EXPORT_SYMBOL(bdev_open_by_path);
+
void blkdev_put(struct block_device *bdev, void *holder)
{
struct gendisk *disk = bdev->bd_disk;
@@ -903,6 +944,13 @@ void blkdev_put(struct block_device *bdev, void *holder)
}
EXPORT_SYMBOL(blkdev_put);

+void bdev_release(struct bdev_handle *handle)
+{
+ blkdev_put(handle->bdev, handle->holder);
+ kfree(handle);
+}
+EXPORT_SYMBOL(bdev_release);
+
/**
* 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 eef450f25982..03d3adc3ff34 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1479,14 +1479,24 @@ extern const struct blk_holder_ops fs_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 *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
+ const struct blk_holder_ops *hops);
+struct bdev_handle *bdev_open_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 bdev_release(struct bdev_handle *handle);

/* just for blk-cgroup, don't use elsewhere */
struct block_device *blkdev_get_no_open(dev_t dev);
--
2.35.3