[PATCH 4/5] kernfs: don't set dentry->d_fsdata
From: Shaohua Li
Date: Mon May 22 2017 - 18:53:43 EST
When working on adding exportfs operations in kernfs, I found it's hard
to initialize dentry->d_fsdata in the exportfs operations. Looks there
is no way to do it without race condition. Look at the kernfs code
closely, there is no point to set dentry->d_fsdata. inode->i_private
already points to kernfs_node, and we can get inode from a dentry. So
this patch just delete the d_fsdata usage.
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
fs/kernfs/dir.c | 22 +++++++---------------
fs/kernfs/file.c | 6 +++---
fs/kernfs/inode.c | 6 +++---
fs/kernfs/kernfs-internal.h | 2 ++
fs/kernfs/mount.c | 8 ++------
fs/kernfs/symlink.c | 2 +-
6 files changed, 18 insertions(+), 28 deletions(-)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 4c86e4c..d5721c8 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -562,7 +562,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
if (d_really_is_negative(dentry))
goto out_bad_unlocked;
- kn = dentry->d_fsdata;
+ kn = kernfs_dentry_node(dentry);
mutex_lock(&kernfs_mutex);
/* The kernfs node has been deactivated */
@@ -570,7 +570,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
goto out_bad;
/* The kernfs node has been moved? */
- if (dentry->d_parent->d_fsdata != kn->parent)
+ if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
goto out_bad;
/* The kernfs node has been renamed */
@@ -590,14 +590,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
return 0;
}
-static void kernfs_dop_release(struct dentry *dentry)
-{
- kernfs_put(dentry->d_fsdata);
-}
-
const struct dentry_operations kernfs_dops = {
.d_revalidate = kernfs_dop_revalidate,
- .d_release = kernfs_dop_release,
};
/**
@@ -614,7 +608,7 @@ const struct dentry_operations kernfs_dops = {
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
{
if (dentry->d_sb->s_op == &kernfs_sops)
- return dentry->d_fsdata;
+ return kernfs_dentry_node(dentry);
return NULL;
}
@@ -1028,7 +1022,7 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
unsigned int flags)
{
struct dentry *ret;
- struct kernfs_node *parent = dentry->d_parent->d_fsdata;
+ struct kernfs_node *parent = kernfs_dentry_node(dentry->d_parent);
struct kernfs_node *kn;
struct inode *inode;
const void *ns = NULL;
@@ -1045,8 +1039,6 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
ret = NULL;
goto out_unlock;
}
- kernfs_get(kn);
- dentry->d_fsdata = kn;
/* attach dentry and inode */
inode = kernfs_get_inode(dir->i_sb, kn);
@@ -1083,7 +1075,7 @@ static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry)
{
- struct kernfs_node *kn = dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(dentry);
struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
int ret;
@@ -1103,7 +1095,7 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- struct kernfs_node *kn = old_dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(old_dentry);
struct kernfs_node *new_parent = new_dir->i_private;
struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
int ret;
@@ -1616,7 +1608,7 @@ static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
{
struct dentry *dentry = file->f_path.dentry;
- struct kernfs_node *parent = dentry->d_fsdata;
+ struct kernfs_node *parent = kernfs_dentry_node(dentry);
struct kernfs_node *pos = file->private_data;
const void *ns = NULL;
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index ac2dfe0..4a795ba 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -616,7 +616,7 @@ static void kernfs_put_open_node(struct kernfs_node *kn,
static int kernfs_fop_open(struct inode *inode, struct file *file)
{
- struct kernfs_node *kn = file->f_path.dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(file->f_path.dentry);
struct kernfs_root *root = kernfs_root(kn);
const struct kernfs_ops *ops;
struct kernfs_open_file *of;
@@ -768,7 +768,7 @@ static void kernfs_release_file(struct kernfs_node *kn,
static int kernfs_fop_release(struct inode *inode, struct file *filp)
{
- struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry);
struct kernfs_open_file *of = kernfs_of(filp);
if (kn->flags & KERNFS_HAS_RELEASE) {
@@ -835,7 +835,7 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait)
{
struct kernfs_open_file *of = kernfs_of(filp);
- struct kernfs_node *kn = filp->f_path.dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(filp->f_path.dentry);
struct kernfs_open_node *on = kn->attr.open;
if (!kernfs_get_active(kn))
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 79cdae4..4c8b510 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -112,7 +112,7 @@ int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
{
struct inode *inode = d_inode(dentry);
- struct kernfs_node *kn = dentry->d_fsdata;
+ struct kernfs_node *kn = inode->i_private;
int error;
if (!kn)
@@ -154,7 +154,7 @@ static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
{
- struct kernfs_node *kn = dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(dentry);
struct kernfs_iattrs *attrs;
attrs = kernfs_iattrs(kn);
@@ -203,8 +203,8 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags)
{
- struct kernfs_node *kn = path->dentry->d_fsdata;
struct inode *inode = d_inode(path->dentry);
+ struct kernfs_node *kn = inode->i_private;
mutex_lock(&kernfs_mutex);
kernfs_refresh_inode(kn, inode);
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 3534cfe..82e11fa 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -70,6 +70,8 @@ struct kernfs_super_info {
};
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
+#define kernfs_dentry_node(d) ((d_inode(d))->i_private)
+
extern const struct super_operations kernfs_sops;
extern struct kmem_cache *kernfs_node_cache;
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 343dfeb..462a40c 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -33,7 +33,7 @@ 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 +43,7 @@ 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;
@@ -176,8 +176,6 @@ 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 +281,6 @@ 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 +292,6 @@ void kernfs_kill_sb(struct super_block *sb)
*/
kill_anon_super(sb);
kfree(info);
- kernfs_put(root_kn);
}
/**
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 1684af4..efcfd7a 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -100,7 +100,7 @@ static int kernfs_get_target_path(struct kernfs_node *parent,
static int kernfs_getlink(struct dentry *dentry, char *path)
{
- struct kernfs_node *kn = dentry->d_fsdata;
+ struct kernfs_node *kn = kernfs_dentry_node(dentry);
struct kernfs_node *parent = kn->parent;
struct kernfs_node *target = kn->symlink.target_kn;
int error;
--
2.9.3