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Diffstat (limited to 'fs/kernfs/mount.c')
-rw-r--r--fs/kernfs/mount.c94
1 files changed, 87 insertions, 7 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index d5b149a45be1..95a7c88baed9 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -16,6 +16,7 @@
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/seq_file.h>
+#include <linux/exportfs.h>
#include "kernfs-internal.h"
@@ -33,7 +34,7 @@ static int kernfs_sop_remount_fs(struct super_block *sb, int *flags, char *data)
static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
{
- struct kernfs_root *root = kernfs_root(dentry->d_fsdata);
+ struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
struct kernfs_syscall_ops *scops = root->syscall_ops;
if (scops && scops->show_options)
@@ -43,7 +44,7 @@ static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
{
- struct kernfs_node *node = dentry->d_fsdata;
+ struct kernfs_node *node = kernfs_dentry_node(dentry);
struct kernfs_root *root = kernfs_root(node);
struct kernfs_syscall_ops *scops = root->syscall_ops;
@@ -64,6 +65,78 @@ const struct super_operations kernfs_sops = {
.show_path = kernfs_sop_show_path,
};
+/*
+ * Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
+ * number and generation
+ */
+struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
+ const union kernfs_node_id *id)
+{
+ struct kernfs_node *kn;
+
+ kn = kernfs_find_and_get_node_by_ino(root, id->ino);
+ if (!kn)
+ return NULL;
+ if (kn->id.generation != id->generation) {
+ kernfs_put(kn);
+ return NULL;
+ }
+ return kn;
+}
+
+static struct inode *kernfs_fh_get_inode(struct super_block *sb,
+ u64 ino, u32 generation)
+{
+ struct kernfs_super_info *info = kernfs_info(sb);
+ struct inode *inode;
+ struct kernfs_node *kn;
+
+ if (ino == 0)
+ return ERR_PTR(-ESTALE);
+
+ kn = kernfs_find_and_get_node_by_ino(info->root, ino);
+ if (!kn)
+ return ERR_PTR(-ESTALE);
+ inode = kernfs_get_inode(sb, kn);
+ kernfs_put(kn);
+ if (!inode)
+ return ERR_PTR(-ESTALE);
+
+ if (generation && inode->i_generation != generation) {
+ /* we didn't find the right inode.. */
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+ return inode;
+}
+
+static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
+ kernfs_fh_get_inode);
+}
+
+static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ return generic_fh_to_parent(sb, fid, fh_len, fh_type,
+ kernfs_fh_get_inode);
+}
+
+static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
+{
+ struct kernfs_node *kn = kernfs_dentry_node(child);
+
+ return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
+}
+
+static const struct export_operations kernfs_export_ops = {
+ .fh_to_dentry = kernfs_fh_to_dentry,
+ .fh_to_parent = kernfs_fh_to_parent,
+ .get_parent = kernfs_get_parent_dentry,
+};
+
/**
* kernfs_root_from_sb - determine kernfs_root associated with a super_block
* @sb: the super_block in question
@@ -159,6 +232,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
sb->s_magic = magic;
sb->s_op = &kernfs_sops;
sb->s_xattr = kernfs_xattr_handlers;
+ if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
+ sb->s_export_op = &kernfs_export_ops;
sb->s_time_gran = 1;
/* get root inode, initialize and unlock it */
@@ -176,8 +251,6 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
pr_debug("%s: could not get root dentry!\n", __func__);
return -ENOMEM;
}
- kernfs_get(info->root->kn);
- root->d_fsdata = info->root->kn;
sb->s_root = root;
sb->s_d_op = &kernfs_dops;
return 0;
@@ -283,7 +356,6 @@ struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
void kernfs_kill_sb(struct super_block *sb)
{
struct kernfs_super_info *info = kernfs_info(sb);
- struct kernfs_node *root_kn = sb->s_root->d_fsdata;
mutex_lock(&kernfs_mutex);
list_del(&info->node);
@@ -295,7 +367,6 @@ void kernfs_kill_sb(struct super_block *sb)
*/
kill_anon_super(sb);
kfree(info);
- kernfs_put(root_kn);
}
/**
@@ -330,7 +401,16 @@ struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns)
void __init kernfs_init(void)
{
+
+ /*
+ * the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
+ * can access the slab lock free. This could introduce stale nodes,
+ * please see how kernfs_find_and_get_node_by_ino filters out stale
+ * nodes.
+ */
kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
sizeof(struct kernfs_node),
- 0, SLAB_PANIC, NULL);
+ 0,
+ SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
+ NULL);
}