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Subject[PATCH 24/26] sysfs: Make sysfs_rename_link atomic
From: Eric W. Biederman <ebiederm@xmission.com>

Use the existing sysfs_rename to make sysfs_rename_link an atomic
operation that does less work. While I am at add additional sanity
checking to ensure it is a symlink I am renaming.

Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
---
fs/sysfs/symlink.c | 26 ++++++++++++++++++++++++--
1 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index fc5fc86..39d050b 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -106,8 +106,30 @@ void sysfs_remove_link(struct kobject * kobj, const char * name)
int sysfs_rename_link(struct kobject *kobj, struct kobject *targ,
const char *old, const char *new)
{
- sysfs_remove_link(kobj, old);
- return sysfs_create_link(kobj, targ, new);
+ struct sysfs_dirent *parent_sd, *sd = NULL;
+ int result;
+
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
+ parent_sd = kobj->sd;
+
+ result = -ENOENT;
+ sd = sysfs_get_dirent(parent_sd, old);
+ if (!sd)
+ goto out;
+
+ result = -EINVAL;
+ if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
+ goto out;
+ if (sd->s_symlink.target_sd->s_dir.kobj != targ)
+ goto out;
+
+ result = sysfs_rename(sd, parent_sd, new);
+
+out:
+ sysfs_put(sd);
+ return result;
}

static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
--
1.6.3.1.54.g99dd.dirty


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