sysfs: kill unnecessary attribute->owner

sysfs is now completely out of driver/module lifetime game.  After
deletion, a sysfs node doesn't access anything outside sysfs proper,
so there's no reason to hold onto the attribute owners.  Note that
often the wrong modules were accounted for as owners leading to
accessing removed modules.

This patch kills now unnecessary attribute->owner.  Note that with
this change, userland holding a sysfs node does not prevent the
backing module from being unloaded.

For more info regarding lifetime rule cleanup, please read the
following message.

  http://article.gmane.org/gmane.linux.kernel/510293

(tweaked by Greg to not delete the field just yet, to make it easier to
merge things properly.)

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

5 files changed, 10 insertions, 34 deletions

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 606128f5c927..02ca6f1e55d7 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -840,8 +840,6 @@ static int __init ecryptfs_init(void)
                 goto out;
         }
         kobj_set_kset_s(&ecryptfs_subsys, fs_subsys);
-        sysfs_attr_version.attr.owner = THIS_MODULE;
-        sysfs_attr_version_str.attr.owner = THIS_MODULE;
         rc = do_sysfs_registration();
         if (rc) {
                 printk(KERN_ERR "sysfs registration failed\n");
diff --git a/fs/ocfs2/cluster/masklog.c b/fs/ocfs2/cluster/masklog.c
index 2b205f5d5790..e9e042b93dbf 100644
--- a/fs/ocfs2/cluster/masklog.c
+++ b/fs/ocfs2/cluster/masklog.c
@@ -74,7 +74,6 @@ struct mlog_attribute {
 #define define_mask(_name) {                    \
         .attr = {                               \
                 .name = #_name,                 \
-                .owner = THIS_MODULE,           \
                 .mode = S_IRUGO | S_IWUSR,      \
         },                                      \
         .mask = ML_##_name,                     \
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 9a3a058f3553..98e0b85a9bb2 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -397,7 +397,6 @@ void add_partition(struct gendisk *disk, int part, sector_t start, sector_t len,
                 static struct attribute addpartattr = {
                         .name = "whole_disk",
                         .mode = S_IRUSR | S_IRGRP | S_IROTH,
-                        .owner = THIS_MODULE,
                 };
 
                 sysfs_create_file(&p->kobj, &addpartattr);
diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 618b8aea6a7b..3c5574a40b09 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -175,25 +175,20 @@ static int open(struct inode * inode, struct file * file)
         if (!sysfs_get_active(attr_sd))
                 return -ENODEV;
 
-        /* Grab the module reference for this attribute */
-        error = -ENODEV;
-        if (!try_module_get(attr->attr.owner))
-                goto err_sput;
-
         error = -EACCES;
         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
-                goto err_mput;
+                goto err_out;
         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
-                goto err_mput;
+                goto err_out;
 
         error = -ENOMEM;
         bb = kzalloc(sizeof(*bb), GFP_KERNEL);
         if (!bb)
-                goto err_mput;
+                goto err_out;
 
         bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
         if (!bb->buffer)
-                goto err_mput;
+                goto err_out;
 
         mutex_init(&bb->mutex);
         file->private_data = bb;
@@ -203,9 +198,7 @@ static int open(struct inode * inode, struct file * file)
         sysfs_get(attr_sd);
         return 0;
 
- err_mput:
-        module_put(attr->attr.owner);
- err_sput:
+ err_out:
         sysfs_put_active(attr_sd);
         kfree(bb);
         return error;
@@ -214,13 +207,11 @@ static int open(struct inode * inode, struct file * file)
 static int release(struct inode * inode, struct file * file)
 {
         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
         struct bin_buffer *bb = file->private_data;
 
         if (bb->mmapped)
                 sysfs_put_active_two(attr_sd);
         sysfs_put(attr_sd);
-        module_put(attr->attr.owner);
         kfree(bb->buffer);
         kfree(bb);
         return 0;
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index d673d9b5d33f..a84b734f7b29 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -241,7 +241,6 @@ sysfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t
 static int sysfs_open_file(struct inode *inode, struct file *file)
 {
         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
-        struct attribute *attr = attr_sd->s_elem.attr.attr;
         struct kobject *kobj = attr_sd->s_parent->s_elem.dir.kobj;
         struct sysfs_buffer * buffer;
         struct sysfs_ops * ops = NULL;
@@ -251,11 +250,6 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
         if (!sysfs_get_active_two(attr_sd))
                 return -ENODEV;
 
-        /* Grab the module reference for this attribute */
-        error = -ENODEV;
-        if (!try_module_get(attr->owner))
-                goto err_sput;
-
         /* if the kobject has no ktype, then we assume that it is a subsystem
          * itself, and use ops for it.
          */
@@ -272,7 +266,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
          * or the subsystem have no operations.
          */
         if (!ops)
-                goto err_mput;
+                goto err_out;
 
         /* File needs write support.
          * The inode's perms must say it's ok, 
@@ -280,7 +274,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
          */
         if (file->f_mode & FMODE_WRITE) {
                 if (!(inode->i_mode & S_IWUGO) || !ops->store)
-                        goto err_mput;
+                        goto err_out;
         }
 
         /* File needs read support.
@@ -289,7 +283,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
          */
         if (file->f_mode & FMODE_READ) {
                 if (!(inode->i_mode & S_IRUGO) || !ops->show)
-                        goto err_mput;
+                        goto err_out;
         }
 
         /* No error? Great, allocate a buffer for the file, and store it
@@ -298,7 +292,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
         error = -ENOMEM;
         buffer = kzalloc(sizeof(struct sysfs_buffer), GFP_KERNEL);
         if (!buffer)
-                goto err_mput;
+                goto err_out;
 
         init_MUTEX(&buffer->sem);
         buffer->needs_read_fill = 1;
@@ -310,9 +304,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
         sysfs_get(attr_sd);
         return 0;
 
- err_mput:
-        module_put(attr->owner);
- err_sput:
+ err_out:
         sysfs_put_active_two(attr_sd);
         return error;
 }
@@ -320,12 +312,9 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 static int sysfs_release(struct inode * inode, struct file * filp)
 {
         struct sysfs_dirent *attr_sd = filp->f_path.dentry->d_fsdata;
-        struct attribute *attr = attr_sd->s_elem.attr.attr;
         struct sysfs_buffer *buffer = filp->private_data;
 
         sysfs_put(attr_sd);
-        /* After this point, attr should not be accessed. */
-        module_put(attr->owner);
 
         if (buffer) {
                 if (buffer->page)