bdev: make struct bdev_handle private to the block layer

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-29-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/block/bdev.c b/block/bdev.c
index e6e46f24a89a926bf28e28ee3d177069151c98ba..8f33f160e92328f9dad30564747a6d6266c41d0c 100644 (file)
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -703,6 +703,24 @@ out_blkdev_put:
        return ret;
 }
 
+int bdev_permission(dev_t dev, blk_mode_t mode, void *holder)
+{
+       int ret;
+
+       ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
+                       MAJOR(dev), MINOR(dev),
+                       ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) |
+                       ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0));
+       if (ret)
+               return ret;
+
+       /* Blocking writes requires exclusive opener */
+       if (mode & BLK_OPEN_RESTRICT_WRITES && !holder)
+               return -EINVAL;
+
+       return 0;
+}
+
 static void blkdev_put_part(struct block_device *part)
 {
        struct block_device *whole = bdev_whole(part);
@@ -795,69 +813,43 @@ static void bdev_yield_write_access(struct block_device *bdev, blk_mode_t mode)
 }
 
 /**
- * bdev_open_by_dev - open a block device by device number
- * @dev: device number of block device to open
+ * bdev_open - open a block device
+ * @bdev: block device to open
  * @mode: open mode (BLK_OPEN_*)
  * @holder: exclusive holder identifier
  * @hops: holder operations
+ * @bdev_file: file for the block device
  *
- * Open the block device described by device number @dev. If @holder is not
- * %NULL, the block device is opened with exclusive access.  Exclusive opens may
- * nest for the same @holder.
- *
- * Use this interface ONLY if you really do not have anything better - i.e. when
- * you are behind a truly sucky interface and all you are given is a device
- * number.  Everything else should use bdev_open_by_path().
+ * Open the block device. If @holder is not %NULL, the block device is opened
+ * with exclusive access.  Exclusive opens may nest for the same @holder.
  *
  * CONTEXT:
  * Might sleep.
  *
  * RETURNS:
- * Handle with a reference to the block_device on success, ERR_PTR(-errno) on
- * failure.
+ * zero on success, -errno on failure.
  */
-struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
-                                    const struct blk_holder_ops *hops)
+int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
+             const struct blk_holder_ops *hops, struct file *bdev_file)
 {
-       struct bdev_handle *handle = kmalloc(sizeof(struct bdev_handle),
-                                            GFP_KERNEL);
-       struct block_device *bdev;
+       struct bdev_handle *handle;
        bool unblock_events = true;
-       struct gendisk *disk;
+       struct gendisk *disk = bdev->bd_disk;
        int ret;
 
+       handle = kmalloc(sizeof(struct bdev_handle), GFP_KERNEL);
        if (!handle)
-               return ERR_PTR(-ENOMEM);
-
-       ret = devcgroup_check_permission(DEVCG_DEV_BLOCK,
-                       MAJOR(dev), MINOR(dev),
-                       ((mode & BLK_OPEN_READ) ? DEVCG_ACC_READ : 0) |
-                       ((mode & BLK_OPEN_WRITE) ? DEVCG_ACC_WRITE : 0));
-       if (ret)
-               goto free_handle;
-
-       /* Blocking writes requires exclusive opener */
-       if (mode & BLK_OPEN_RESTRICT_WRITES && !holder) {
-               ret = -EINVAL;
-               goto free_handle;
-       }
-
-       bdev = blkdev_get_no_open(dev);
-       if (!bdev) {
-               ret = -ENXIO;
-               goto free_handle;
-       }
-       disk = bdev->bd_disk;
+               return -ENOMEM;
 
        if (holder) {
                mode |= BLK_OPEN_EXCL;
                ret = bd_prepare_to_claim(bdev, holder, hops);
                if (ret)
-                       goto put_blkdev;
+                       goto free_handle;
        } else {
                if (WARN_ON_ONCE(mode & BLK_OPEN_EXCL)) {
                        ret = -EIO;
-                       goto put_blkdev;
+                       goto free_handle;
                }
        }
 
@@ -902,7 +894,16 @@ struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
        handle->bdev = bdev;
        handle->holder = holder;
        handle->mode = mode;
-       return handle;
+
+       bdev_file->f_flags |= O_LARGEFILE;
+       bdev_file->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
+       if (bdev_nowait(bdev))
+               bdev_file->f_mode |= FMODE_NOWAIT;
+       bdev_file->f_mapping = handle->bdev->bd_inode->i_mapping;
+       bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping);
+       bdev_file->private_data = handle;
+
+       return 0;
 put_module:
        module_put(disk->fops->owner);
 abort_claiming:
@@ -910,11 +911,9 @@ abort_claiming:
                bd_abort_claiming(bdev, holder);
        mutex_unlock(&disk->open_mutex);
        disk_unblock_events(disk);
-put_blkdev:
-       blkdev_put_no_open(bdev);
 free_handle:
        kfree(handle);
-       return ERR_PTR(ret);
+       return ret;
 }
 
 /*
@@ -951,29 +950,33 @@ struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
                                   const struct blk_holder_ops *hops)
 {
        struct file *bdev_file;
-       struct bdev_handle *handle;
+       struct block_device *bdev;
        unsigned int flags;
+       int ret;
 
-       handle = bdev_open_by_dev(dev, mode, holder, hops);
-       if (IS_ERR(handle))
-               return ERR_CAST(handle);
+       ret = bdev_permission(dev, mode, holder);
+       if (ret)
+               return ERR_PTR(ret);
+
+       bdev = blkdev_get_no_open(dev);
+       if (!bdev)
+               return ERR_PTR(-ENXIO);
 
        flags = blk_to_file_flags(mode);
-       bdev_file = alloc_file_pseudo_noaccount(handle->bdev->bd_inode,
+       bdev_file = alloc_file_pseudo_noaccount(bdev->bd_inode,
                        blockdev_mnt, "", flags | O_LARGEFILE, &def_blk_fops);
        if (IS_ERR(bdev_file)) {
-               bdev_release(handle);
+               blkdev_put_no_open(bdev);
                return bdev_file;
        }
-       ihold(handle->bdev->bd_inode);
+       ihold(bdev->bd_inode);
 
-       bdev_file->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
-       if (bdev_nowait(handle->bdev))
-               bdev_file->f_mode |= FMODE_NOWAIT;
-
-       bdev_file->f_mapping = handle->bdev->bd_inode->i_mapping;
-       bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping);
-       bdev_file->private_data = handle;
+       ret = bdev_open(bdev, mode, holder, hops, bdev_file);
+       if (ret) {
+               blkdev_put_no_open(bdev);
+               fput(bdev_file);
+               return ERR_PTR(ret);
+       }
        return bdev_file;
 }
 EXPORT_SYMBOL(bdev_file_open_by_dev);

diff --git a/block/blk.h b/block/blk.h
index c9630774767d3717d3ac9fe3d4d1d6b3c95a1201..19b15870284f43579f80dfe5755959b82601250c 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -25,6 +25,12 @@ struct blk_flush_queue {
        struct request          *flush_rq;
 };
 
+struct bdev_handle {
+       struct block_device *bdev;
+       void *holder;
+       blk_mode_t mode;
+};
+
 bool is_flush_rq(struct request *req);
 
 struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
@@ -517,7 +523,7 @@ static inline int req_ref_read(struct request *req)
 }
 
 void bdev_release(struct bdev_handle *handle);
-struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
-               const struct blk_holder_ops *hops);
-
+int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
+             const struct blk_holder_ops *hops, struct file *bdev_file);
+int bdev_permission(dev_t dev, blk_mode_t mode, void *holder);
 #endif /* BLK_INTERNAL_H */

diff --git a/block/fops.c b/block/fops.c
index 0cf8cf72cdfa108926ae8fc7f53bce05a3225058..a1ba1a50ae7787259cbdba6740e8f8c9dde6dab4 100644 (file)
--- a/block/fops.c
+++ b/block/fops.c
@@ -599,36 +599,31 @@ blk_mode_t file_to_blk_mode(struct file *file)
 
 static int blkdev_open(struct inode *inode, struct file *filp)
 {
-       struct bdev_handle *handle;
+       struct block_device *bdev;
        blk_mode_t mode;
-
-       /*
-        * Preserve backwards compatibility and allow large file access
-        * even if userspace doesn't ask for it explicitly. Some mkfs
-        * binary needs it. We might want to drop this workaround
-        * during an unstable branch.
-        */
-       filp->f_flags |= O_LARGEFILE;
-       filp->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
+       void *holder;
+       int ret;
 
        mode = file_to_blk_mode(filp);
-       handle = bdev_open_by_dev(inode->i_rdev, mode,
-                       mode & BLK_OPEN_EXCL ? filp : NULL, NULL);
-       if (IS_ERR(handle))
-               return PTR_ERR(handle);
+       holder = mode & BLK_OPEN_EXCL ? filp : NULL;
+       ret = bdev_permission(inode->i_rdev, mode, holder);
+       if (ret)
+               return ret;
 
-       if (bdev_nowait(handle->bdev))
-               filp->f_mode |= FMODE_NOWAIT;
+       bdev = blkdev_get_no_open(inode->i_rdev);
+       if (!bdev)
+               return -ENXIO;
 
-       filp->f_mapping = handle->bdev->bd_inode->i_mapping;
-       filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
-       filp->private_data = handle;
-       return 0;
+       ret = bdev_open(bdev, mode, holder, NULL, filp);
+       if (ret)
+               blkdev_put_no_open(bdev);
+       return ret;
 }
 
 static int blkdev_release(struct inode *inode, struct file *filp)
 {
-       bdev_release(filp->private_data);
+       if (filp->private_data)
+               bdev_release(filp->private_data);
        return 0;
 }
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 495f55587207199f5c2d2e2e3e080ba94a9f4f27..2f5dbde23094a70b26030093cf3131a1f31b96f1 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1475,13 +1475,6 @@ extern const struct blk_holder_ops fs_holder_ops;
        (BLK_OPEN_READ | BLK_OPEN_RESTRICT_WRITES | \
         (((flags) & SB_RDONLY) ? 0 : BLK_OPEN_WRITE))
 
-/* @bdev_handle will be removed soon. */
-struct bdev_handle {
-       struct block_device *bdev;
-       void *holder;
-       blk_mode_t mode;
-};
-
 struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
                const struct blk_holder_ops *hops);
 struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode,

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e9291e27cc47f3fc84a8d72be415296244601e6e..6e0714d35d9b2ac6da4dfa38bb42711dab6e48ea 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1327,12 +1327,6 @@ struct super_block {
        struct list_head        s_inodes_wb;    /* writeback inodes */
 } __randomize_layout;
 
-/* Temporary helper that will go away. */
-static inline struct bdev_handle *sb_bdev_handle(struct super_block *sb)
-{
-       return sb->s_bdev_file->private_data;
-}
-
 static inline struct user_namespace *i_user_ns(const struct inode *inode)
 {
        return inode->i_sb->s_user_ns;