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Diffstat (limited to 'fs/kernfs/mount.c')
-rw-r--r--fs/kernfs/mount.c99
1 files changed, 74 insertions, 25 deletions
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index e08e8d999807..3ac52e141766 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -16,11 +16,14 @@
#include <linux/namei.h>
#include <linux/seq_file.h>
#include <linux/exportfs.h>
+#include <linux/uuid.h>
+#include <linux/statfs.h>
#include "kernfs-internal.h"
-struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
-struct kernfs_global_locks *kernfs_locks;
+struct kmem_cache *kernfs_node_cache __ro_after_init;
+struct kmem_cache *kernfs_iattrs_cache __ro_after_init;
+struct kernfs_global_locks *kernfs_locks __ro_after_init;
static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
{
@@ -45,13 +48,35 @@ static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
return 0;
}
+static int kernfs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ simple_statfs(dentry, buf);
+ buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
+ return 0;
+}
+
const struct super_operations kernfs_sops = {
- .statfs = simple_statfs,
- .drop_inode = generic_delete_inode,
+ .statfs = kernfs_statfs,
+ .drop_inode = inode_just_drop,
.evict_inode = kernfs_evict_inode,
.show_options = kernfs_sop_show_options,
.show_path = kernfs_sop_show_path,
+
+ /*
+ * sysfs is built on top of kernfs and sysfs provides the power
+ * management infrastructure to support suspend/hibernate by
+ * writing to various files in /sys/power/. As filesystems may
+ * be automatically frozen during suspend/hibernate implementing
+ * freeze/thaw support for kernfs generically will cause
+ * deadlocks as the suspending/hibernation initiating task will
+ * hold a VFS lock that it will then wait upon to be released.
+ * If freeze/thaw for kernfs is needed talk to the VFS.
+ */
+ .freeze_fs = NULL,
+ .unfreeze_fs = NULL,
+ .freeze_super = NULL,
+ .thaw_super = NULL,
};
static int kernfs_encode_fh(struct inode *inode, __u32 *fh, int *max_len,
@@ -115,9 +140,6 @@ static struct dentry *__kernfs_fh_to_dentry(struct super_block *sb,
inode = kernfs_get_inode(sb, kn);
kernfs_put(kn);
- if (!inode)
- return ERR_PTR(-ESTALE);
-
return d_obtain_alias(inode);
}
@@ -138,8 +160,10 @@ static struct dentry *kernfs_fh_to_parent(struct super_block *sb,
static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
{
struct kernfs_node *kn = kernfs_dentry_node(child);
+ struct kernfs_root *root = kernfs_root(kn);
- return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
+ guard(rwsem_read)(&root->kernfs_rwsem);
+ return d_obtain_alias(kernfs_get_inode(child->d_sb, kernfs_parent(kn)));
}
static const struct export_operations kernfs_export_ops = {
@@ -179,10 +203,10 @@ static struct kernfs_node *find_next_ancestor(struct kernfs_node *child,
return NULL;
}
- while (child->parent != parent) {
- if (!child->parent)
+ while (kernfs_parent(child) != parent) {
+ child = kernfs_parent(child);
+ if (!child)
return NULL;
- child = child->parent;
}
return child;
@@ -199,17 +223,28 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
struct super_block *sb)
{
struct dentry *dentry;
- struct kernfs_node *knparent = NULL;
+ struct kernfs_node *knparent;
+ struct kernfs_root *root;
BUG_ON(sb->s_op != &kernfs_sops);
dentry = dget(sb->s_root);
/* Check if this is the root kernfs_node */
- if (!kn->parent)
+ if (!rcu_access_pointer(kn->__parent))
return dentry;
- knparent = find_next_ancestor(kn, NULL);
+ root = kernfs_root(kn);
+ /*
+ * As long as kn is valid, its parent can not vanish. This is cgroup's
+ * kn so it can't have its parent replaced. Therefore it is safe to use
+ * the ancestor node outside of the RCU or locked section.
+ */
+ if (WARN_ON_ONCE(!(root->flags & KERNFS_ROOT_INVARIANT_PARENT)))
+ return ERR_PTR(-EINVAL);
+ scoped_guard(rcu) {
+ knparent = find_next_ancestor(kn, NULL);
+ }
if (WARN_ON(!knparent)) {
dput(dentry);
return ERR_PTR(-EINVAL);
@@ -218,17 +253,26 @@ struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
do {
struct dentry *dtmp;
struct kernfs_node *kntmp;
+ const char *name;
if (kn == knparent)
return dentry;
- kntmp = find_next_ancestor(kn, knparent);
- if (WARN_ON(!kntmp)) {
+
+ scoped_guard(rwsem_read, &root->kernfs_rwsem) {
+ kntmp = find_next_ancestor(kn, knparent);
+ if (WARN_ON(!kntmp)) {
+ dput(dentry);
+ return ERR_PTR(-EINVAL);
+ }
+ name = kstrdup(kernfs_rcu_name(kntmp), GFP_KERNEL);
+ }
+ if (!name) {
dput(dentry);
- return ERR_PTR(-EINVAL);
+ return ERR_PTR(-ENOMEM);
}
- dtmp = lookup_positive_unlocked(kntmp->name, dentry,
- strlen(kntmp->name));
+ dtmp = lookup_noperm_positive_unlocked(&QSTR(name), dentry);
dput(dentry);
+ kfree(name);
if (IS_ERR(dtmp))
return dtmp;
knparent = kntmp;
@@ -254,9 +298,10 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k
if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
sb->s_export_op = &kernfs_export_ops;
sb->s_time_gran = 1;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
/* sysfs dentries and inodes don't require IO to create */
- sb->s_shrink.seeks = 0;
+ sb->s_shrink->seeks = 0;
/* get root inode, initialize and unlock it */
down_read(&kf_root->kernfs_rwsem);
@@ -274,7 +319,7 @@ static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *k
return -ENOMEM;
}
sb->s_root = root;
- sb->s_d_op = &kernfs_dops;
+ set_default_d_op(sb, &kernfs_dops);
return 0;
}
@@ -351,9 +396,13 @@ int kernfs_get_tree(struct fs_context *fc)
}
sb->s_flags |= SB_ACTIVE;
- down_write(&root->kernfs_rwsem);
+ uuid_t uuid;
+ uuid_gen(&uuid);
+ super_set_uuid(sb, uuid.b, sizeof(uuid));
+
+ down_write(&root->kernfs_supers_rwsem);
list_add(&info->node, &info->root->supers);
- up_write(&root->kernfs_rwsem);
+ up_write(&root->kernfs_supers_rwsem);
}
fc->root = dget(sb->s_root);
@@ -380,9 +429,9 @@ void kernfs_kill_sb(struct super_block *sb)
struct kernfs_super_info *info = kernfs_info(sb);
struct kernfs_root *root = info->root;
- down_write(&root->kernfs_rwsem);
+ down_write(&root->kernfs_supers_rwsem);
list_del(&info->node);
- up_write(&root->kernfs_rwsem);
+ up_write(&root->kernfs_supers_rwsem);
/*
* Remove the superblock from fs_supers/s_instances
generated by cgit (git 2.34.1) at 2025-12-21 22:27:52 +0000