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Date: Sun, 30 Mar 2008 11:54:42 -0500
From: James Bottomley <James.Bottomley@...senPartnership.com>
To: Greg KH <greg@...ah.com>
Cc: Hannes Reinecke <hare@...e.de>, Kay Sievers <kay.sievers@...y.org>,
linux-scsi <linux-scsi@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] sysfs: allow the group is_visible() method to
return a mode and add an update API
On Sat, 2008-03-22 at 13:02 -0500, James Bottomley wrote:
> On Fri, 2008-03-21 at 15:26 -0700, Greg KH wrote:
> > On Fri, Mar 21, 2008 at 04:27:12PM -0500, James Bottomley wrote:
> > > We have a problem in scsi_transport_spi in that we need to customise
> > > not only the visibility of the attributes, but also their mode. Fix
> > > this by making the is_visible() callback return a mode, with 0
> > > indicating is not visible.
> > >
> > > Also add a sysfs_update_group() API to allow us to change either the
> > > visibility or mode of the files at any time on the fly.
> > >
> > > Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>
> > > ---
> > >
> > > Greg, can I take this through SCSI, please ... assuming it's OK? We
> > > need this to fix up the SPI transport class.
> >
> > Sure. But can you document that "update" field a bit more so we can
> > remember what it means in the future?
>
> How about this? I also added docbook for create and update attribute
> group.
Can I get an ACK from someone from sysfs for this, please?
James
> James
>
> ---
>
> From: James Bottomley <James.Bottomley@...senPartnership.com>
> Date: Thu, 20 Mar 2008 20:47:52 -0500
> Subject: [SCSI] sysfs: make group is_valid return a mode_t
>
> We have a problem in scsi_transport_spi in that we need to customise
> not only the visibility of the attributes, but also their mode. Fix
> this by making the is_visible() callback return a mode, with 0
> indicating is not visible.
>
> Also add a sysfs_update_group() API to allow us to change either the
> visibility or mode of the files at any time on the fly.
>
> Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>
> ---
> fs/sysfs/file.c | 14 ++++++--
> fs/sysfs/group.c | 77 +++++++++++++++++++++++++++++++++++++++++-------
> fs/sysfs/sysfs.h | 2 +
> include/linux/sysfs.h | 4 ++-
> 4 files changed, 80 insertions(+), 17 deletions(-)
>
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index 6f5954a..8f7ee10 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -490,11 +490,10 @@ const struct file_operations sysfs_file_operations = {
> .poll = sysfs_poll,
> };
>
> -
> -int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
> - int type)
> +int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
> + const struct attribute *attr, int type, mode_t amode)
> {
> - umode_t mode = (attr->mode & S_IALLUGO) | S_IFREG;
> + umode_t mode = (amode & S_IALLUGO) | S_IFREG;
> struct sysfs_addrm_cxt acxt;
> struct sysfs_dirent *sd;
> int rc;
> @@ -515,6 +514,13 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
> }
>
>
> +int sysfs_add_file(struct sysfs_dirent *dir_sd, const struct attribute *attr,
> + int type)
> +{
> + return sysfs_add_file_mode(dir_sd, attr, type, attr->mode);
> +}
> +
> +
> /**
> * sysfs_create_file - create an attribute file for an object.
> * @kobj: object we're creating for.
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index 4779049..dac9383 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -23,30 +23,41 @@ static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
> int i;
>
> for (i = 0, attr = grp->attrs; *attr; i++, attr++)
> - if (!grp->is_visible ||
> - grp->is_visible(kobj, *attr, i))
> - sysfs_hash_and_remove(dir_sd, (*attr)->name);
> + sysfs_hash_and_remove(dir_sd, (*attr)->name);
> }
>
> static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
> - const struct attribute_group *grp)
> + const struct attribute_group *grp, int update)
> {
> struct attribute *const* attr;
> int error = 0, i;
>
> - for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++)
> - if (!grp->is_visible ||
> - grp->is_visible(kobj, *attr, i))
> - error |=
> - sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
> + for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
> + mode_t mode = 0;
> +
> + /* in update mode, we're changing the permissions or
> + * visibility. Do this by first removing then
> + * re-adding (if required) the file */
> + if (update)
> + sysfs_hash_and_remove(dir_sd, (*attr)->name);
> + if (grp->is_visible) {
> + mode = grp->is_visible(kobj, *attr, i);
> + if (!mode)
> + continue;
> + }
> + error = sysfs_add_file_mode(dir_sd, *attr, SYSFS_KOBJ_ATTR,
> + (*attr)->mode | mode);
> + if (unlikely(error))
> + break;
> + }
> if (error)
> remove_files(dir_sd, kobj, grp);
> return error;
> }
>
>
> -int sysfs_create_group(struct kobject * kobj,
> - const struct attribute_group * grp)
> +static int internal_create_group(struct kobject *kobj, int update,
> + const struct attribute_group *grp)
> {
> struct sysfs_dirent *sd;
> int error;
> @@ -60,7 +71,7 @@ int sysfs_create_group(struct kobject * kobj,
> } else
> sd = kobj->sd;
> sysfs_get(sd);
> - error = create_files(sd, kobj, grp);
> + error = create_files(sd, kobj, grp, update);
> if (error) {
> if (grp->name)
> sysfs_remove_subdir(sd);
> @@ -69,6 +80,47 @@ int sysfs_create_group(struct kobject * kobj,
> return error;
> }
>
> +/**
> + * sysfs_create_group - given a directory kobject, create an attribute group
> + * @kobj: The kobject to create the group on
> + * @grp: The attribute group to create
> + *
> + * This function creates a group for the first time. It will explicitly
> + * warn and error if any of the attribute files being created already exist.
> + *
> + * Returns 0 on success or error.
> + */
> +int sysfs_create_group(struct kobject *kobj,
> + const struct attribute_group *grp)
> +{
> + return internal_create_group(kobj, 0, grp);
> +}
> +
> +/**
> + * sysfs_update_group - given a directory kobject, create an attribute group
> + * @kobj: The kobject to create the group on
> + * @grp: The attribute group to create
> + *
> + * This function updates an attribute group. Unlike
> + * sysfs_create_group(), it will explicitly not warn or error if any
> + * of the attribute files being created already exist. Furthermore,
> + * if the visibility of the files has changed through the is_visible()
> + * callback, it will update the permissions and add or remove the
> + * relevant files.
> + *
> + * The primary use for this function is to call it after making a change
> + * that affects group visibility.
> + *
> + * Returns 0 on success or error.
> + */
> +int sysfs_update_group(struct kobject *kobj,
> + const struct attribute_group *grp)
> +{
> + return internal_create_group(kobj, 1, grp);
> +}
> +
> +
> +
> void sysfs_remove_group(struct kobject * kobj,
> const struct attribute_group * grp)
> {
> @@ -95,4 +147,5 @@ void sysfs_remove_group(struct kobject * kobj,
>
>
> EXPORT_SYMBOL_GPL(sysfs_create_group);
> +EXPORT_SYMBOL_GPL(sysfs_update_group);
> EXPORT_SYMBOL_GPL(sysfs_remove_group);
> diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
> index 52aaa8c..2915959 100644
> --- a/fs/sysfs/sysfs.h
> +++ b/fs/sysfs/sysfs.h
> @@ -155,6 +155,8 @@ extern const struct file_operations sysfs_file_operations;
> int sysfs_add_file(struct sysfs_dirent *dir_sd,
> const struct attribute *attr, int type);
>
> +int sysfs_add_file_mode(struct sysfs_dirent *dir_sd,
> + const struct attribute *attr, int type, mode_t amode);
> /*
> * bin.c
> */
> diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> index 0f388af..07d9c12 100644
> --- a/include/linux/sysfs.h
> +++ b/include/linux/sysfs.h
> @@ -32,7 +32,7 @@ struct attribute {
>
> struct attribute_group {
> const char *name;
> - int (*is_visible)(struct kobject *,
> + mode_t (*is_visible)(struct kobject *,
> struct attribute *, int);
> struct attribute **attrs;
> };
> @@ -105,6 +105,8 @@ void sysfs_remove_link(struct kobject *kobj, const char *name);
>
> int __must_check sysfs_create_group(struct kobject *kobj,
> const struct attribute_group *grp);
> +int sysfs_update_group(struct kobject *kobj,
> + const struct attribute_group *grp);
> void sysfs_remove_group(struct kobject *kobj,
> const struct attribute_group *grp);
> int sysfs_add_file_to_group(struct kobject *kobj,
--
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