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    Subject[PATCH 09/34] sysfs, kernfs: introduce kernfs_create_link()
    Date
    Separate out kernfs symlink interface - kernfs_create_link() - which
    takes and returns sysfs_dirents, from sysfs_do_create_link_sd().
    sysfs_do_create_link_sd() now just determines the parent and target
    sysfs_dirents and invokes the new interface and handles dup warning.

    This patch doesn't introduce behavior changes.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    ---
    fs/sysfs/symlink.c | 74 ++++++++++++++++++++++++++++++--------------------
    include/linux/kernfs.h | 8 ++++++
    2 files changed, 53 insertions(+), 29 deletions(-)

    diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
    index 996d861..8b8efbe 100644
    --- a/fs/sysfs/symlink.c
    +++ b/fs/sysfs/symlink.c
    @@ -21,14 +21,47 @@

    #include "sysfs.h"

    +/**
    + * kernfs_create_link - create a symlink
    + * @parent: directory to create the symlink in
    + * @name: name of the symlink
    + * @target: target node for the symlink to point to
    + *
    + * Returns the created node on success, ERR_PTR() value on error.
    + */
    +struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
    + const char *name,
    + struct sysfs_dirent *target)
    +{
    + struct sysfs_dirent *sd;
    + struct sysfs_addrm_cxt acxt;
    + int error;
    +
    + sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
    + if (!sd)
    + return ERR_PTR(-ENOMEM);
    +
    + sd->s_ns = target->s_ns;
    + sd->s_symlink.target_sd = target;
    + sysfs_get(target); /* ref owned by symlink */
    +
    + sysfs_addrm_start(&acxt);
    + error = __sysfs_add_one(&acxt, sd, parent);
    + sysfs_addrm_finish(&acxt);
    +
    + if (!error)
    + return sd;
    +
    + sysfs_put(sd);
    + return ERR_PTR(error);
    +}
    +
    +
    static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
    struct kobject *target,
    const char *name, int warn)
    {
    - struct sysfs_dirent *target_sd = NULL;
    - struct sysfs_dirent *sd = NULL;
    - struct sysfs_addrm_cxt acxt;
    - int error;
    + struct sysfs_dirent *sd, *target_sd = NULL;

    BUG_ON(!name || !parent_sd);

    @@ -40,35 +73,18 @@ static int sysfs_do_create_link_sd(struct sysfs_dirent *parent_sd,
    target_sd = sysfs_get(target->sd);
    spin_unlock(&sysfs_assoc_lock);

    - error = -ENOENT;
    if (!target_sd)
    - goto out_put;
    + return -ENOENT;

    - error = -ENOMEM;
    - sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
    - if (!sd)
    - goto out_put;
    -
    - sd->s_ns = target_sd->s_ns;
    - sd->s_symlink.target_sd = target_sd;
    - target_sd = NULL; /* reference is now owned by the symlink */
    -
    - sysfs_addrm_start(&acxt);
    - if (warn)
    - error = sysfs_add_one(&acxt, sd, parent_sd);
    - else
    - error = __sysfs_add_one(&acxt, sd, parent_sd);
    - sysfs_addrm_finish(&acxt);
    -
    - if (error)
    - goto out_put;
    + sd = kernfs_create_link(parent_sd, name, target_sd);
    + sysfs_put(target_sd);

    - return 0;
    + if (!IS_ERR(sd))
    + return 0;

    - out_put:
    - sysfs_put(target_sd);
    - sysfs_put(sd);
    - return error;
    + if (warn && PTR_ERR(sd) == -EEXIST)
    + sysfs_warn_dup(parent_sd, name);
    + return PTR_ERR(sd);
    }

    /**
    diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
    index ad0483a..03dcee3 100644
    --- a/include/linux/kernfs.h
    +++ b/include/linux/kernfs.h
    @@ -13,12 +13,20 @@ struct sysfs_dirent;

    #ifdef CONFIG_SYSFS

    +struct sysfs_dirent *kernfs_create_link(struct sysfs_dirent *parent,
    + const char *name,
    + struct sysfs_dirent *target);
    void kernfs_remove(struct sysfs_dirent *sd);
    int kernfs_remove_by_name_ns(struct sysfs_dirent *parent, const char *name,
    const void *ns);

    #else /* CONFIG_SYSFS */

    +static inline struct sysfs_dirent *
    +kernfs_create_link(struct sysfs_dirent *parent, const char *name,
    + struct sysfs_dirent *target)
    +{ return NULL; }
    +
    static inline void kernfs_remove(struct sysfs_dirent *sd) { }

    static inline int kernfs_remove_by_name_ns(struct sysfs_dirent *parent,
    --
    1.8.3.1


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