[PATCH] block: set S_IFBLK for block devices instead of S_IFCHR

[Jules Maselbas]

On Fri, Mar 04, 2022 at 10:28:05AM +0100, Ahmad Fatoum wrote:
> In barebox, block devices are a special case of character devices.
> Nevertheless, differentiation can be useful to allow scripts iterating
> over all block devices without accounting for naming, e.g.
> 
>   for dev in /dev/*; do
> 	test -b $dev && echo $dev: blockdevice
>   done
> 
> Add the necessary support. This will break scripts that assume
> test -c blockdevice to be true, but that's a quite improbable check.
> 
> Signed-off-by: Ahmad Fatoum <ahmad at a3f.at>

Tested-by: Jules Maselbas <jmaselbas at kalray.eu>

> ---
>  commands/memtester/memtester.c | 2 +-
>  common/block.c                 | 8 ++++++++
>  fs/devfs.c                     | 7 ++++++-
>  fs/legacy.c                    | 1 +
>  include/block.h                | 2 ++
>  5 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/commands/memtester/memtester.c b/commands/memtester/memtester.c
> index 130dc97c8334..f4adbfc855cb 100644
> --- a/commands/memtester/memtester.c
> +++ b/commands/memtester/memtester.c
> @@ -113,7 +113,7 @@ static int do_memtester(int argc, char **argv) {
>                              strerror(errno));
>                      return COMMAND_ERROR_USAGE;
>                  } else {
> -                    if (!S_ISCHR(statbuf.st_mode)) {
> +                    if (!S_ISCHR(statbuf.st_mode) && !S_ISBLK(statbuf.st_mode)) {
>                          printf("can not mmap non-char device %s\n",
>                                  optarg);
>                          return COMMAND_ERROR_USAGE;
> diff --git a/common/block.c b/common/block.c
> index 1d386edcfd49..a48016d8dcbd 100644
> --- a/common/block.c
> +++ b/common/block.c
> @@ -361,6 +361,14 @@ static struct cdev_operations block_ops = {
>  	.discard_range = block_op_discard_range,
>  };
>  
> +struct block_device *cdev_get_block_device(struct cdev *cdev)
> +{
> +	if (cdev->ops != &block_ops)
> +		return NULL;
> +
> +	return container_of(cdev, struct block_device, cdev);
> +}
> +
>  int blockdevice_register(struct block_device *blk)
>  {
>  	loff_t size = (loff_t)blk->num_blocks * BLOCKSIZE(blk);
> diff --git a/fs/devfs.c b/fs/devfs.c
> index deb244feeab6..49cd48f6d84e 100644
> --- a/fs/devfs.c
> +++ b/fs/devfs.c
> @@ -29,6 +29,7 @@
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/mtd-abi.h>
>  #include <partition.h>
> +#include <block.h>
>  
>  struct devfs_inode {
>  	struct inode inode;
> @@ -231,6 +232,7 @@ static struct inode *devfs_get_inode(struct super_block *sb, const struct inode
>  	default:
>  		return NULL;
>  	case S_IFCHR:
> +	case S_IFBLK:
>  		inode->i_op = &devfs_file_inode_operations;
>  		inode->i_fop = &devfs_file_operations;
>  		break;
> @@ -250,12 +252,15 @@ static struct dentry *devfs_lookup(struct inode *dir, struct dentry *dentry,
>  	struct devfs_inode *dinode;
>  	struct inode *inode;
>  	struct cdev *cdev;
> +	umode_t mode;
>  
>  	cdev = cdev_by_name(dentry->name);
>  	if (!cdev)
>  		return ERR_PTR(-ENOENT);
>  
> -	inode = devfs_get_inode(dir->i_sb, dir, S_IFCHR);
> +	mode = cdev_get_block_device(cdev) ? S_IFBLK : S_IFCHR;
> +
> +	inode = devfs_get_inode(dir->i_sb, dir, mode);
>  	if (!inode)
>  		return ERR_PTR(-ENOMEM);
>  
> diff --git a/fs/legacy.c b/fs/legacy.c
> index fc6a18f408ed..779f54629440 100644
> --- a/fs/legacy.c
> +++ b/fs/legacy.c
> @@ -288,6 +288,7 @@ static struct inode *legacy_get_inode(struct super_block *sb, const struct inode
>  		return NULL;
>  	case S_IFREG:
>  	case S_IFCHR:
> +	case S_IFBLK:
>  		inode->i_op = &legacy_file_inode_operations;
>  		break;
>  	case S_IFDIR:
> diff --git a/include/block.h b/include/block.h
> index d3a154bf73c0..06c15a71b58a 100644
> --- a/include/block.h
> +++ b/include/block.h
> @@ -49,4 +49,6 @@ static inline int block_flush(struct block_device *blk)
>  	return cdev_flush(&blk->cdev);
>  }
>  
> +struct block_device *cdev_get_block_device(struct cdev *cdev);
> +
>  #endif /* __BLOCK_H */
> -- 
> 2.34.1
> 
> 
> 
> To declare a filtering error, please use the following link : https://www.security-mail.net/reporter.php?mid=10200.6221dbab.9d886.0&r=jmaselbas%40kalray.eu&s=ahmad%40a3f.at&o=%5BPATCH%5D+block%3A+set+S_IFBLK+for+block+devices+instead+of+S_IFCHR&verdict=C&c=87f89e12ce86b52361dd00e3bf70cf47f37c754f
>