sysfs: Fix locking and factor out sysfs_sd_setattr

Cleanly separate the work that is specific to setting the
attributes of a sysfs_dirent from what is needed to update
the attributes of a vfs inode.

Additionally grab the sysfs_mutex to keep any nasties from
surprising us when updating the sysfs_dirent.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 86fb230..76e977c 100644 (file)
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -65,30 +65,14 @@ static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
        return attrs;
 }
 
-int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
+int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
 {
-       struct inode * inode = dentry->d_inode;
-       struct sysfs_dirent * sd = dentry->d_fsdata;
        struct sysfs_inode_attrs *sd_attrs;
        struct iattr *iattrs;
        unsigned int ia_valid = iattr->ia_valid;
-       int error;
-
-       if (!sd)
-               return -EINVAL;
 
        sd_attrs = sd->s_iattr;
 
-       error = inode_change_ok(inode, iattr);
-       if (error)
-               return error;
-
-       iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
-
-       error = inode_setattr(inode, iattr);
-       if (error)
-               return error;
-
        if (!sd_attrs) {
                /* setting attributes for the first time, allocate now */
                sd_attrs = sysfs_init_inode_attrs(sd);
@@ -111,12 +95,39 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
                        iattrs->ia_ctime = iattr->ia_ctime;
                if (ia_valid & ATTR_MODE) {
                        umode_t mode = iattr->ia_mode;
-
-                       if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
-                               mode &= ~S_ISGID;
                        iattrs->ia_mode = sd->s_mode = mode;
                }
        }
+       return 0;
+}
+
+int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+       struct inode *inode = dentry->d_inode;
+       struct sysfs_dirent *sd = dentry->d_fsdata;
+       int error;
+
+       if (!sd)
+               return -EINVAL;
+
+       error = inode_change_ok(inode, iattr);
+       if (error)
+               return error;
+
+       iattr->ia_valid &= ~ATTR_SIZE; /* ignore size changes */
+       if (iattr->ia_valid & ATTR_MODE) {
+               if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+                       iattr->ia_mode &= ~S_ISGID;
+       }
+
+       error = inode_setattr(inode, iattr);
+       if (error)
+               return error;
+
+       mutex_lock(&sysfs_mutex);
+       error = sysfs_sd_setattr(sd, iattr);
+       mutex_unlock(&sysfs_mutex);
+
        return error;
 }
 

diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index af4c4e7..a96d967 100644 (file)
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -155,6 +155,7 @@ 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_setattr(struct dentry *dentry, struct iattr *iattr);
 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
                size_t size, int flags);