On Thu 30-07-15 13:48:04, Dongsheng Yang wrote:
> This commit introduce a file of fs/dev.c at first. This is
> a internal file shared by block_dev and char_dev. There is
> only one function in it __lookup_dev which will be wrapped
> to be lookup_bdev and loopup_cdev.
>
> We will put more code in this file which is shared by
> block_dev and char_dev.
>
> Signed-off-by: Dongsheng Yang <yangds.fnst@xxxxxxxxxxxxxx>
> ---
> fs/Makefile | 2 +-
> fs/block_dev.c | 26 ++------------------
> fs/dev.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> fs/internal.h | 14 +++++++++++
> 4 files changed, 94 insertions(+), 25 deletions(-)
> create mode 100644 fs/dev.c
>
...
> +/**
> + * __lookup_dev - lookup a block_device or cdev by name
> + * @pathname: special file representing the device
> + * @cdevp: cdev would be returned by cdevp
> + * @bdevp: block_device would be returned by bdevp
> + *
> + * Get a reference to the block_deivce or cdev at @pathname in
> + * the current namespace if possible and return it.
> + */
> +int __lookup_dev(const char *pathname, struct cdev **cdevp,
> + struct block_device **bdevp)
> +{
> + struct inode *inode;
> + struct path path;
> + int error = 0;
> +
> + if (!pathname || !*pathname)
> + return -EINVAL;
> +
> + error = kern_path(pathname, LOOKUP_FOLLOW, &path);
> + if (error)
> + return error;
> +
> + inode = d_backing_inode(path.dentry);
> +
> + /**
> + * We need at least one of bdevp and cdevp to be NULL,
> + * but cdevp and bdevp can not be both NULL.
> + */
> + error = -EINVAL;
> + if (!(cdevp || bdevp) || (cdevp && bdevp))
> + goto out;
Why don't you allow both cdevp and bdevp to be set and in that case accept
both block & character device and just set appropriate pointer and the
other one to NULL? Then quota code wouldn't have to search twice...
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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