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sysfs, kernfs: make super_blocks bind to different kernfs_roots

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kernfs is being updated to allow multiple sysfs_dirent hierarchies so
that it can also be used by other users.  Currently, sysfs
super_blocks are always attached to one kernfs_root - sysfs_root - and
distinguished only by their namespace tags.

This patch adds sysfs_super_info->root and update
sysfs_fill/test_super() so that super_blocks are identified by the
combination of both the associated kernfs_root and namespace tag.
This allows mounting different kernfs hierarchies.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tejun Heo 2013-11-28 14:54:42 -05:00 committed by Greg Kroah-Hartman
parent bc755553df
commit df394fb56c
2 changed files with 12 additions and 4 deletions
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10
fs/sysfs/mount.c
View file

@ -37,6 +37,7 @@ struct sysfs_dirent *sysfs_root_sd;
static int sysfs_fill_super(struct super_block *sb)
{
struct sysfs_super_info *info = sysfs_info(sb);
struct inode *inode;
struct dentry *root;
@ -48,7 +49,7 @@ static int sysfs_fill_super(struct super_block *sb)
/* get root inode, initialize and unlock it */
mutex_lock(&sysfs_mutex);
inode = sysfs_get_inode(sb, sysfs_root_sd);
inode = sysfs_get_inode(sb, info->root->sd);
mutex_unlock(&sysfs_mutex);
if (!inode) {
pr_debug("sysfs: could not get root inode\n");
@ -61,8 +62,8 @@ static int sysfs_fill_super(struct super_block *sb)
pr_debug("%s: could not get root dentry!\n", __func__);
return -ENOMEM;
}
kernfs_get(sysfs_root_sd);
root->d_fsdata = sysfs_root_sd;
kernfs_get(info->root->sd);
root->d_fsdata = info->root->sd;
sb->s_root = root;
sb->s_d_op = &sysfs_dentry_ops;
return 0;
@ -73,7 +74,7 @@ static int sysfs_test_super(struct super_block *sb, void *data)
struct sysfs_super_info *sb_info = sysfs_info(sb);
struct sysfs_super_info *info = data;
return sb_info->ns == info->ns;
return sb_info->root == info->root && sb_info->ns == info->ns;
}
static int sysfs_set_super(struct super_block *sb, void *data)
@ -110,6 +111,7 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
if (!info)
return ERR_PTR(-ENOMEM);
info->root = sysfs_root;
info->ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);

6
fs/sysfs/sysfs.h
View file

@ -19,6 +19,12 @@
*/
struct sysfs_super_info {
/*
* The root associated with this super_block. Each super_block is
* identified by the root and ns it's associated with.
*/
struct kernfs_root *root;
/*
* Each sb is associated with one namespace tag, currently the network
* namespace of the task which mounted this sysfs instance. If multiple