Quoting Eric W. Biederman (ebiederm@xxxxxxxxxxxx):
> From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>
> With the implementation of sysfs_getattr and sysfs_permission
> sysfs becomes able to lazily propogate inode attribute changes
> from the sysfs_dirents to the vfs inodes. This paves the way
> for deleting significant chunks of now unnecessary code.
>
> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxxxxxxxx>
> ---
> fs/sysfs/dir.c | 2 +
> fs/sysfs/inode.c | 64 ++++++++++++++++++++++++++++++++++++++-------------
> fs/sysfs/symlink.c | 3 ++
> fs/sysfs/sysfs.h | 2 +
> 4 files changed, 54 insertions(+), 17 deletions(-)
>
> diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> index fa37126..25d052a 100644
> --- a/fs/sysfs/dir.c
> +++ b/fs/sysfs/dir.c
> @@ -800,7 +800,9 @@ static struct dentry * sysfs_lookup(struct inode *dir, struct dentry *dentry,
>
> const struct inode_operations sysfs_dir_inode_operations = {
> .lookup = sysfs_lookup,
> + .permission = sysfs_permission,
> .setattr = sysfs_setattr,
> + .getattr = sysfs_getattr,
> .setxattr = sysfs_setxattr,
> };
>
> diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
> index fccfb55..2dcafe8 100644
> --- a/fs/sysfs/inode.c
> +++ b/fs/sysfs/inode.c
> @@ -37,7 +37,9 @@ static struct backing_dev_info sysfs_backing_dev_info = {
> };
>
> static const struct inode_operations sysfs_inode_operations ={
> + .permission = sysfs_permission,
> .setattr = sysfs_setattr,
> + .getattr = sysfs_getattr,
> .setxattr = sysfs_setxattr,
> };
>
> @@ -196,7 +198,6 @@ static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
>
> static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
> {
> - inode->i_mode = iattr->ia_mode;
> inode->i_uid = iattr->ia_uid;
> inode->i_gid = iattr->ia_gid;
> inode->i_atime = iattr->ia_atime;
> @@ -227,38 +228,56 @@ static int sysfs_count_nlink(struct sysfs_dirent *sd)
> return nr + 2;
> }
>
> +static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
> +{
> + struct sysfs_inode_attrs *iattrs = sd->s_iattr;
> +
> + inode->i_mode = sd->s_mode;
> + if (iattrs) {
> + /* sysfs_dirent has non-default attributes
> + * get them from persistent copy in sysfs_dirent
> + */
> + set_inode_attr(inode, &iattrs->ia_iattr);
> + security_inode_notifysecctx(inode,
> + iattrs->ia_secdata,
> + iattrs->ia_secdata_len);
> + }
> +
> + if (sysfs_type(sd) == SYSFS_DIR)
> + inode->i_nlink = sysfs_count_nlink(sd);
> +}
> +
> +int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
> +{
> + struct sysfs_dirent *sd = dentry->d_fsdata;
> + struct inode *inode = dentry->d_inode;
> +
> + mutex_lock(&sysfs_mutex);
> + sysfs_refresh_inode(sd, inode);
> + mutex_unlock(&sysfs_mutex);
So the inode->i_mutex is not needed?
> +
> + generic_fillattr(inode, stat);
> + return 0;
> +}
> +
> static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
> {
> struct bin_attribute *bin_attr;
> - struct sysfs_inode_attrs *iattrs;
>
> inode->i_private = sysfs_get(sd);
> inode->i_mapping->a_ops = &sysfs_aops;
> inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
> inode->i_op = &sysfs_inode_operations;
> - inode->i_ino = sd->s_ino;
> lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
>
> - iattrs = sd->s_iattr;
> - if (iattrs) {
> - /* sysfs_dirent has non-default attributes
> - * get them for the new inode from persistent copy
> - * in sysfs_dirent
> - */
> - set_inode_attr(inode, &iattrs->ia_iattr);
> - if (iattrs->ia_secdata)
> - security_inode_notifysecctx(inode,
> - iattrs->ia_secdata,
> - iattrs->ia_secdata_len);
> - } else
> - set_default_inode_attr(inode, sd->s_mode);
> + set_default_inode_attr(inode, sd->s_mode);
> + sysfs_refresh_inode(sd, inode);
>
> /* initialize inode according to type */
> switch (sysfs_type(sd)) {
> case SYSFS_DIR:
> inode->i_op = &sysfs_dir_inode_operations;
> inode->i_fop = &sysfs_dir_operations;
> - inode->i_nlink = sysfs_count_nlink(sd);
> break;
> case SYSFS_KOBJ_ATTR:
> inode->i_size = PAGE_SIZE;
> @@ -341,3 +360,14 @@ int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name)
> else
> return -ENOENT;
> }
> +
> +int sysfs_permission(struct inode *inode, int mask)
> +{
> + struct sysfs_dirent *sd = inode->i_private;
> +
> + mutex_lock(&sysfs_mutex);
> + sysfs_refresh_inode(sd, inode);
> + mutex_unlock(&sysfs_mutex);
> +
> + return generic_permission(inode, mask, NULL);
> +}
> diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
> index 1137418..c5eff49 100644
> --- a/fs/sysfs/symlink.c
> +++ b/fs/sysfs/symlink.c
> @@ -214,6 +214,9 @@ const struct inode_operations sysfs_symlink_inode_operations = {
> .readlink = generic_readlink,
> .follow_link = sysfs_follow_link,
> .put_link = sysfs_put_link,
> + .setattr = sysfs_setattr,
> + .getattr = sysfs_getattr,
> + .permission = sysfs_permission,
> };
>
>
> diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
> index a96d967..12ccc07 100644
> --- a/fs/sysfs/sysfs.h
> +++ b/fs/sysfs/sysfs.h
> @@ -156,7 +156,9 @@ static inline void __sysfs_put(struct sysfs_dirent *sd)
> struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
> void sysfs_delete_inode(struct inode *inode);
> int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr *iattr);
> +int sysfs_permission(struct inode *inode, int mask);
> int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
> +int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat);
> int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
> size_t size, int flags);
> int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
> --
> 1.6.5.2.143.g8cc62
>
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