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kernfs: don't set dentry->d_fsdata 

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.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Shaohua Li 2017-07-12 11:49:49 -07:00 committed by Jens Axboe
parent ba16b2846a
commit 319ba91d35
6 changed files with 27 additions and 31 deletions
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25
fs/kernfs/dir.c
View File

@ -566,7 +566,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
if (d_really_is_negative(dentry)) if (d_really_is_negative(dentry))
goto out_bad_unlocked; goto out_bad_unlocked;
kn = dentry->d_fsdata; kn = kernfs_dentry_node(dentry);
mutex_lock(&kernfs_mutex); mutex_lock(&kernfs_mutex);
/* The kernfs node has been deactivated */ /* The kernfs node has been deactivated */
@ -574,7 +574,7 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
goto out_bad; goto out_bad;
/* The kernfs node has been moved? */ /* 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; goto out_bad;
/* The kernfs node has been renamed */ /* The kernfs node has been renamed */
@ -594,14 +594,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
return 0; return 0;
} }
static void kernfs_dop_release(struct dentry *dentry)
{
kernfs_put(dentry->d_fsdata);
}
const struct dentry_operations kernfs_dops = { const struct dentry_operations kernfs_dops = {
.d_revalidate = kernfs_dop_revalidate, .d_revalidate = kernfs_dop_revalidate,
.d_release = kernfs_dop_release,
}; };
/** /**
@ -617,8 +611,9 @@ const struct dentry_operations kernfs_dops = {
*/ */
struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
{ {
if (dentry->d_sb->s_op == &kernfs_sops) if (dentry->d_sb->s_op == &kernfs_sops &&
return dentry->d_fsdata; !d_really_is_negative(dentry))
return kernfs_dentry_node(dentry);
return NULL; return NULL;
} }
@ -1056,7 +1051,7 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
unsigned int flags) unsigned int flags)
{ {
struct dentry *ret; struct dentry *ret;
struct kernfs_node *parent = dentry->d_parent->d_fsdata; struct kernfs_node *parent = dir->i_private;
struct kernfs_node *kn; struct kernfs_node *kn;
struct inode *inode; struct inode *inode;
const void *ns = NULL; const void *ns = NULL;
@ -1073,8 +1068,6 @@ static struct dentry *kernfs_iop_lookup(struct inode *dir,
ret = NULL; ret = NULL;
goto out_unlock; goto out_unlock;
} }
kernfs_get(kn);
dentry->d_fsdata = kn;
/* attach dentry and inode */ /* attach dentry and inode */
inode = kernfs_get_inode(dir->i_sb, kn); inode = kernfs_get_inode(dir->i_sb, kn);
@ -1111,7 +1104,7 @@ static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry,
static int kernfs_iop_rmdir(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; struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
int ret; int ret;
@ -1131,7 +1124,7 @@ static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry, struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags) 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_node *new_parent = new_dir->i_private;
struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops;
int ret; int ret;
@ -1644,7 +1637,7 @@ static struct kernfs_node *kernfs_dir_next_pos(const void *ns,
static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
{ {
struct dentry *dentry = file->f_path.dentry; 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; struct kernfs_node *pos = file->private_data;
const void *ns = NULL; const void *ns = NULL;

6
fs/kernfs/file.c
View File

@ -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) 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 = inode->i_private;
struct kernfs_root *root = kernfs_root(kn); struct kernfs_root *root = kernfs_root(kn);
const struct kernfs_ops *ops; const struct kernfs_ops *ops;
struct kernfs_open_file *of; 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) 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 = inode->i_private;
struct kernfs_open_file *of = kernfs_of(filp); struct kernfs_open_file *of = kernfs_of(filp);
if (kn->flags & KERNFS_HAS_RELEASE) { 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) static unsigned int kernfs_fop_poll(struct file *filp, poll_table *wait)
{ {
struct kernfs_open_file *of = kernfs_of(filp); 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; struct kernfs_open_node *on = kn->attr.open;
if (!kernfs_get_active(kn)) if (!kernfs_get_active(kn))

6
fs/kernfs/inode.c
View File

@ -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) int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
{ {
struct inode *inode = d_inode(dentry); struct inode *inode = d_inode(dentry);
struct kernfs_node *kn = dentry->d_fsdata; struct kernfs_node *kn = inode->i_private;
int error; int error;
if (!kn) 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) 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; struct kernfs_iattrs *attrs;
attrs = kernfs_iattrs(kn); 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, int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int query_flags) u32 request_mask, unsigned int query_flags)
{ {
struct kernfs_node *kn = path->dentry->d_fsdata;
struct inode *inode = d_inode(path->dentry); struct inode *inode = d_inode(path->dentry);
struct kernfs_node *kn = inode->i_private;
mutex_lock(&kernfs_mutex); mutex_lock(&kernfs_mutex);
kernfs_refresh_inode(kn, inode); kernfs_refresh_inode(kn, inode);

7
fs/kernfs/kernfs-internal.h
View File

@ -70,6 +70,13 @@ struct kernfs_super_info {
}; };
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info)) #define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry)
{
if (d_really_is_negative(dentry))
return NULL;
return d_inode(dentry)->i_private;
}
extern const struct super_operations kernfs_sops; extern const struct super_operations kernfs_sops;
extern struct kmem_cache *kernfs_node_cache; extern struct kmem_cache *kernfs_node_cache;

8
fs/kernfs/mount.c
View File

@ -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) 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; struct kernfs_syscall_ops *scops = root->syscall_ops;
if (scops && scops->show_options) 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) 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_root *root = kernfs_root(node);
struct kernfs_syscall_ops *scops = root->syscall_ops; 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__); pr_debug("%s: could not get root dentry!\n", __func__);
return -ENOMEM; return -ENOMEM;
} }
kernfs_get(info->root->kn);
root->d_fsdata = info->root->kn;
sb->s_root = root; sb->s_root = root;
sb->s_d_op = &kernfs_dops; sb->s_d_op = &kernfs_dops;
return 0; 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) void kernfs_kill_sb(struct super_block *sb)
{ {
struct kernfs_super_info *info = kernfs_info(sb); struct kernfs_super_info *info = kernfs_info(sb);
struct kernfs_node *root_kn = sb->s_root->d_fsdata;
mutex_lock(&kernfs_mutex); mutex_lock(&kernfs_mutex);
list_del(&info->node); list_del(&info->node);
@ -295,7 +292,6 @@ void kernfs_kill_sb(struct super_block *sb)
*/ */
kill_anon_super(sb); kill_anon_super(sb);
kfree(info); kfree(info);
kernfs_put(root_kn);
} }
/** /**

6
fs/kernfs/symlink.c
View File

@ -98,9 +98,9 @@ static int kernfs_get_target_path(struct kernfs_node *parent,
return 0; return 0;
} }
static int kernfs_getlink(struct dentry *dentry, char *path) static int kernfs_getlink(struct inode *inode, char *path)
{ {
struct kernfs_node *kn = dentry->d_fsdata; struct kernfs_node *kn = inode->i_private;
struct kernfs_node *parent = kn->parent; struct kernfs_node *parent = kn->parent;
struct kernfs_node *target = kn->symlink.target_kn; struct kernfs_node *target = kn->symlink.target_kn;
int error; int error;
@ -124,7 +124,7 @@ static const char *kernfs_iop_get_link(struct dentry *dentry,
body = kzalloc(PAGE_SIZE, GFP_KERNEL); body = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!body) if (!body)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
error = kernfs_getlink(dentry, body); error = kernfs_getlink(inode, body);
if (unlikely(error < 0)) { if (unlikely(error < 0)) {
kfree(body); kfree(body);
return ERR_PTR(error); return ERR_PTR(error);