Merge branch 'work.lookup' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache lookup cleanups from Al Viro:
 "Cleaning ->lookup() instances up - mostly d_splice_alias() conversions"

* 'work.lookup' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (29 commits)
  switch the rest of procfs lookups to d_splice_alias()
  procfs: switch instantiate_t to d_splice_alias()
  don't bother with tid_fd_revalidate() in lookups
  proc_lookupfd_common(): don't bother with instantiate unless the file is open
  procfs: get rid of ancient BS in pid_revalidate() uses
  cifs_lookup(): switch to d_splice_alias()
  cifs_lookup(): cifs_get_inode_...() never returns 0 with *inode left NULL
  9p: unify paths in v9fs_vfs_lookup()
  ncp_lookup(): use d_splice_alias()
  hfsplus: switch to d_splice_alias()
  hfs: don't allow mounting over .../rsrc
  hfs: use d_splice_alias()
  omfs_lookup(): report IO errors, use d_splice_alias()
  orangefs_lookup: simplify
  openpromfs: switch to d_splice_alias()
  xfs_vn_lookup: simplify a bit
  adfs_lookup: do not fail with ENOENT on negatives, use d_splice_alias()
  adfs_lookup_byname: .. *is* taken care of in fs/namei.c
  romfs_lookup: switch to d_splice_alias()
  qnx6_lookup: switch to d_splice_alias()
  ...

6 files changed, 158 insertions, 162 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 4e35593..33ed174 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1807,15 +1807,22 @@ int pid_getattr(const struct path *path, struct kstat *stat,
 /* dentry stuff */
 
 /*
- *	Exceptional case: normally we are not allowed to unhash a busy
- * directory. In this case, however, we can do it - no aliasing problems
- * due to the way we treat inodes.
- *
+ * Set <pid>/... inode ownership (can change due to setuid(), etc.)
+ */
+void pid_update_inode(struct task_struct *task, struct inode *inode)
+{
+	task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
+
+	inode->i_mode &= ~(S_ISUID | S_ISGID);
+	security_task_to_inode(task, inode);
+}
+
+/*
  * Rewrite the inode's ownerships here because the owning task may have
  * performed a setuid(), etc.
  *
  */
-int pid_revalidate(struct dentry *dentry, unsigned int flags)
+static int pid_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct inode *inode;
 	struct task_struct *task;
@@ -1827,10 +1834,7 @@ int pid_revalidate(struct dentry *dentry, unsigned int flags)
 	task = get_proc_task(inode);
 
 	if (task) {
-		task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
-
-		inode->i_mode &= ~(S_ISUID | S_ISGID);
-		security_task_to_inode(task, inode);
+		pid_update_inode(task, inode);
 		put_task_struct(task);
 		return 1;
 	}
@@ -1878,8 +1882,8 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 	struct dentry *child, *dir = file->f_path.dentry;
 	struct qstr qname = QSTR_INIT(name, len);
 	struct inode *inode;
-	unsigned type;
-	ino_t ino;
+	unsigned type = DT_UNKNOWN;
+	ino_t ino = 1;
 
 	child = d_hash_and_lookup(dir, &qname);
 	if (!child) {
@@ -1888,22 +1892,23 @@ bool proc_fill_cache(struct file *file, struct dir_context *ctx,
 		if (IS_ERR(child))
 			goto end_instantiate;
 		if (d_in_lookup(child)) {
-			int err = instantiate(d_inode(dir), child, task, ptr);
+			struct dentry *res;
+			res = instantiate(child, task, ptr);
 			d_lookup_done(child);
-			if (err < 0) {
-				dput(child);
+			if (IS_ERR(res))
 				goto end_instantiate;
+			if (unlikely(res)) {
+				dput(child);
+				child = res;
 			}
 		}
 	}
 	inode = d_inode(child);
 	ino = inode->i_ino;
 	type = inode->i_mode >> 12;
+end_instantiate:
 	dput(child);
 	return dir_emit(ctx, name, len, ino, type);
-
-end_instantiate:
-	return dir_emit(ctx, name, len, 1, DT_UNKNOWN);
 }
 
 /*
@@ -2065,19 +2070,19 @@ static const struct inode_operations proc_map_files_link_inode_operations = {
 	.setattr	= proc_setattr,
 };
 
-static int
-proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
+static struct dentry *
+proc_map_files_instantiate(struct dentry *dentry,
 			   struct task_struct *task, const void *ptr)
 {
 	fmode_t mode = (fmode_t)(unsigned long)ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK |
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK |
 				    ((mode & FMODE_READ ) ? S_IRUSR : 0) |
 				    ((mode & FMODE_WRITE) ? S_IWUSR : 0));
 	if (!inode)
-		return -ENOENT;
+		return ERR_PTR(-ENOENT);
 
 	ei = PROC_I(inode);
 	ei->op.proc_get_link = map_files_get_link;
@@ -2086,9 +2091,7 @@ proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
 	inode->i_size = 64;
 
 	d_set_d_op(dentry, &tid_map_files_dentry_operations);
-	d_add(dentry, inode);
-
-	return 0;
+	return d_splice_alias(inode, dentry);
 }
 
 static struct dentry *proc_map_files_lookup(struct inode *dir,
@@ -2097,19 +2100,19 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 	unsigned long vm_start, vm_end;
 	struct vm_area_struct *vma;
 	struct task_struct *task;
-	int result;
+	struct dentry *result;
 	struct mm_struct *mm;
 
-	result = -ENOENT;
+	result = ERR_PTR(-ENOENT);
 	task = get_proc_task(dir);
 	if (!task)
 		goto out;
 
-	result = -EACCES;
+	result = ERR_PTR(-EACCES);
 	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))
 		goto out_put_task;
 
-	result = -ENOENT;
+	result = ERR_PTR(-ENOENT);
 	if (dname_to_vma_addr(dentry, &vm_start, &vm_end))
 		goto out_put_task;
 
@@ -2123,7 +2126,7 @@ static struct dentry *proc_map_files_lookup(struct inode *dir,
 		goto out_no_vma;
 
 	if (vma->vm_file)
-		result = proc_map_files_instantiate(dir, dentry, task,
+		result = proc_map_files_instantiate(dentry, task,
 				(void *)(unsigned long)vma->vm_file->f_mode);
 
 out_no_vma:
@@ -2132,7 +2135,7 @@ out_no_vma:
 out_put_task:
 	put_task_struct(task);
 out:
-	return ERR_PTR(result);
+	return result;
 }
 
 static const struct inode_operations proc_map_files_inode_operations = {
@@ -2433,16 +2436,16 @@ static const struct file_operations proc_pid_set_timerslack_ns_operations = {
 	.release	= single_release,
 };
 
-static int proc_pident_instantiate(struct inode *dir,
-	struct dentry *dentry, struct task_struct *task, const void *ptr)
+static struct dentry *proc_pident_instantiate(struct dentry *dentry,
+	struct task_struct *task, const void *ptr)
 {
 	const struct pid_entry *p = ptr;
 	struct inode *inode;
 	struct proc_inode *ei;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
+	inode = proc_pid_make_inode(dentry->d_sb, task, p->mode);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
 
 	ei = PROC_I(inode);
 	if (S_ISDIR(inode->i_mode))
@@ -2452,13 +2455,9 @@ static int proc_pident_instantiate(struct inode *dir,
 	if (p->fop)
 		inode->i_fop = p->fop;
 	ei->op = p->op;
+	pid_update_inode(task, inode);
 	d_set_d_op(dentry, &pid_dentry_operations);
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (pid_revalidate(dentry, 0))
-		return 0;
-out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 static struct dentry *proc_pident_lookup(struct inode *dir, 
@@ -2466,11 +2465,9 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
 					 const struct pid_entry *ents,
 					 unsigned int nents)
 {
-	int error;
 	struct task_struct *task = get_proc_task(dir);
 	const struct pid_entry *p, *last;
-
-	error = -ENOENT;
+	struct dentry *res = ERR_PTR(-ENOENT);
 
 	if (!task)
 		goto out_no_task;
@@ -2489,11 +2486,11 @@ static struct dentry *proc_pident_lookup(struct inode *dir,
 	if (p >= last)
 		goto out;
 
-	error = proc_pident_instantiate(dir, dentry, task, p);
+	res = proc_pident_instantiate(dentry, task, p);
 out:
 	put_task_struct(task);
 out_no_task:
-	return ERR_PTR(error);
+	return res;
 }
 
 static int proc_pident_readdir(struct file *file, struct dir_context *ctx,
@@ -3136,38 +3133,32 @@ void proc_flush_task(struct task_struct *task)
 	}
 }
 
-static int proc_pid_instantiate(struct inode *dir,
-				   struct dentry * dentry,
+static struct dentry *proc_pid_instantiate(struct dentry * dentry,
 				   struct task_struct *task, const void *ptr)
 {
 	struct inode *inode;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
 
 	inode->i_op = &proc_tgid_base_inode_operations;
 	inode->i_fop = &proc_tgid_base_operations;
 	inode->i_flags|=S_IMMUTABLE;
 
 	set_nlink(inode, nlink_tgid);
+	pid_update_inode(task, inode);
 
 	d_set_d_op(dentry, &pid_dentry_operations);
-
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (pid_revalidate(dentry, 0))
-		return 0;
-out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
 {
-	int result = -ENOENT;
 	struct task_struct *task;
 	unsigned tgid;
 	struct pid_namespace *ns;
+	struct dentry *result = ERR_PTR(-ENOENT);
 
 	tgid = name_to_int(&dentry->d_name);
 	if (tgid == ~0U)
@@ -3182,10 +3173,10 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
 	if (!task)
 		goto out;
 
-	result = proc_pid_instantiate(dir, dentry, task, NULL);
+	result = proc_pid_instantiate(dentry, task, NULL);
 	put_task_struct(task);
 out:
-	return ERR_PTR(result);
+	return result;
 }
 
 /*
@@ -3433,37 +3424,32 @@ static const struct inode_operations proc_tid_base_inode_operations = {
 	.setattr	= proc_setattr,
 };
 
-static int proc_task_instantiate(struct inode *dir,
-	struct dentry *dentry, struct task_struct *task, const void *ptr)
+static struct dentry *proc_task_instantiate(struct dentry *dentry,
+	struct task_struct *task, const void *ptr)
 {
 	struct inode *inode;
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
-
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
+
 	inode->i_op = &proc_tid_base_inode_operations;
 	inode->i_fop = &proc_tid_base_operations;
-	inode->i_flags|=S_IMMUTABLE;
+	inode->i_flags |= S_IMMUTABLE;
 
 	set_nlink(inode, nlink_tid);
+	pid_update_inode(task, inode);
 
 	d_set_d_op(dentry, &pid_dentry_operations);
-
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (pid_revalidate(dentry, 0))
-		return 0;
-out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
 {
-	int result = -ENOENT;
 	struct task_struct *task;
 	struct task_struct *leader = get_proc_task(dir);
 	unsigned tid;
 	struct pid_namespace *ns;
+	struct dentry *result = ERR_PTR(-ENOENT);
 
 	if (!leader)
 		goto out_no_task;
@@ -3483,13 +3469,13 @@ static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry
 	if (!same_thread_group(leader, task))
 		goto out_drop_task;
 
-	result = proc_task_instantiate(dir, dentry, task, NULL);
+	result = proc_task_instantiate(dentry, task, NULL);
 out_drop_task:
 	put_task_struct(task);
 out:
 	put_task_struct(leader);
 out_no_task:
-	return ERR_PTR(result);
+	return result;
 }
 
 /*
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 6b80cd1..05b9893 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -81,9 +81,41 @@ static const struct file_operations proc_fdinfo_file_operations = {
 	.release	= single_release,
 };
 
+static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
+{
+	struct files_struct *files = get_files_struct(task);
+	struct file *file;
+
+	if (!files)
+		return false;
+
+	rcu_read_lock();
+	file = fcheck_files(files, fd);
+	if (file)
+		*mode = file->f_mode;
+	rcu_read_unlock();
+	put_files_struct(files);
+	return !!file;
+}
+
+static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
+				fmode_t f_mode)
+{
+	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
+
+	if (S_ISLNK(inode->i_mode)) {
+		unsigned i_mode = S_IFLNK;
+		if (f_mode & FMODE_READ)
+			i_mode |= S_IRUSR | S_IXUSR;
+		if (f_mode & FMODE_WRITE)
+			i_mode |= S_IWUSR | S_IXUSR;
+		inode->i_mode = i_mode;
+	}
+	security_task_to_inode(task, inode);
+}
+
 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 {
-	struct files_struct *files;
 	struct task_struct *task;
 	struct inode *inode;
 	unsigned int fd;
@@ -96,35 +128,11 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 	fd = proc_fd(inode);
 
 	if (task) {
-		files = get_files_struct(task);
-		if (files) {
-			struct file *file;
-
-			rcu_read_lock();
-			file = fcheck_files(files, fd);
-			if (file) {
-				unsigned f_mode = file->f_mode;
-
-				rcu_read_unlock();
-				put_files_struct(files);
-
-				task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
-
-				if (S_ISLNK(inode->i_mode)) {
-					unsigned i_mode = S_IFLNK;
-					if (f_mode & FMODE_READ)
-						i_mode |= S_IRUSR | S_IXUSR;
-					if (f_mode & FMODE_WRITE)
-						i_mode |= S_IWUSR | S_IXUSR;
-					inode->i_mode = i_mode;
-				}
-
-				security_task_to_inode(task, inode);
-				put_task_struct(task);
-				return 1;
-			}
-			rcu_read_unlock();
-			put_files_struct(files);
+		fmode_t f_mode;
+		if (tid_fd_mode(task, fd, &f_mode)) {
+			tid_fd_update_inode(task, inode, f_mode);
+			put_task_struct(task);
+			return 1;
 		}
 		put_task_struct(task);
 	}
@@ -166,34 +174,33 @@ static int proc_fd_link(struct dentry *dentry, struct path *path)
 	return ret;
 }
 
-static int
-proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
-		    struct task_struct *task, const void *ptr)
+struct fd_data {
+	fmode_t mode;
+	unsigned fd;
+};
+
+static struct dentry *proc_fd_instantiate(struct dentry *dentry,
+	struct task_struct *task, const void *ptr)
 {
-	unsigned fd = (unsigned long)ptr;
+	const struct fd_data *data = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
 
 	ei = PROC_I(inode);
-	ei->fd = fd;
+	ei->fd = data->fd;
 
 	inode->i_op = &proc_pid_link_inode_operations;
 	inode->i_size = 64;
 
 	ei->op.proc_get_link = proc_fd_link;
+	tid_fd_update_inode(task, inode, data->mode);
 
 	d_set_d_op(dentry, &tid_fd_dentry_operations);
-	d_add(dentry, inode);
-
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
-		return 0;
- out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 static struct dentry *proc_lookupfd_common(struct inode *dir,
@@ -201,19 +208,21 @@ static struct dentry *proc_lookupfd_common(struct inode *dir,
 					   instantiate_t instantiate)
 {
 	struct task_struct *task = get_proc_task(dir);
-	int result = -ENOENT;
-	unsigned fd = name_to_int(&dentry->d_name);
+	struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
+	struct dentry *result = ERR_PTR(-ENOENT);
 
 	if (!task)
 		goto out_no_task;
-	if (fd == ~0U)
+	if (data.fd == ~0U)
+		goto out;
+	if (!tid_fd_mode(task, data.fd, &data.mode))
 		goto out;
 
-	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
+	result = instantiate(dentry, task, &data);
 out:
 	put_task_struct(task);
 out_no_task:
-	return ERR_PTR(result);
+	return result;
 }
 
 static int proc_readfd_common(struct file *file, struct dir_context *ctx,
@@ -236,17 +245,22 @@ static int proc_readfd_common(struct file *file, struct dir_context *ctx,
 	for (fd = ctx->pos - 2;
 	     fd < files_fdtable(files)->max_fds;
 	     fd++, ctx->pos++) {
+		struct file *f;
+		struct fd_data data;
 		char name[10 + 1];
 		int len;
 
-		if (!fcheck_files(files, fd))
+		f = fcheck_files(files, fd);
+		if (!f)
 			continue;
+		data.mode = f->f_mode;
 		rcu_read_unlock();
+		data.fd = fd;
 
 		len = snprintf(name, sizeof(name), "%u", fd);
 		if (!proc_fill_cache(file, ctx,
 				     name, len, instantiate, p,
-				     (void *)(unsigned long)fd))
+				     &data))
 			goto out_fd_loop;
 		cond_resched();
 		rcu_read_lock();
@@ -304,31 +318,25 @@ const struct inode_operations proc_fd_inode_operations = {
 	.setattr	= proc_setattr,
 };
 
-static int
-proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
-			struct task_struct *task, const void *ptr)
+static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry,
+	struct task_struct *task, const void *ptr)
 {
-	unsigned fd = (unsigned long)ptr;
+	const struct fd_data *data = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUSR);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
 
 	ei = PROC_I(inode);
-	ei->fd = fd;
+	ei->fd = data->fd;
 
 	inode->i_fop = &proc_fdinfo_file_operations;
+	tid_fd_update_inode(task, inode, 0);
 
 	d_set_d_op(dentry, &tid_fd_dentry_operations);
-	d_add(dentry, inode);
-
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
-		return 0;
- out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 static struct dentry *
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 02bb191..7b4d971 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -257,8 +257,7 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
 		if (!inode)
 			return ERR_PTR(-ENOMEM);
 		d_set_d_op(dentry, &proc_misc_dentry_ops);
-		d_add(dentry, inode);
-		return NULL;
+		return d_splice_alias(inode, dentry);
 	}
 	read_unlock(&proc_subdir_lock);
 	return ERR_PTR(-ENOENT);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index a318ae5..43c70c9 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -152,14 +152,14 @@ extern const struct dentry_operations pid_dentry_operations;
 extern int pid_getattr(const struct path *, struct kstat *, u32, unsigned int);
 extern int proc_setattr(struct dentry *, struct iattr *);
 extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
-extern int pid_revalidate(struct dentry *, unsigned int);
+extern void pid_update_inode(struct task_struct *, struct inode *);
 extern int pid_delete_dentry(const struct dentry *);
 extern int proc_pid_readdir(struct file *, struct dir_context *);
 extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int);
 extern loff_t mem_lseek(struct file *, loff_t, int);
 
 /* Lookups */
-typedef int instantiate_t(struct inode *, struct dentry *,
+typedef struct dentry *instantiate_t(struct dentry *,
 				     struct task_struct *, const void *);
 extern bool proc_fill_cache(struct file *, struct dir_context *, const char *, int,
 			   instantiate_t, struct task_struct *, const void *);
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 59b17e5..dd2b35f 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -87,28 +87,24 @@ static const struct inode_operations proc_ns_link_inode_operations = {
 	.setattr	= proc_setattr,
 };
 
-static int proc_ns_instantiate(struct inode *dir,
-	struct dentry *dentry, struct task_struct *task, const void *ptr)
+static struct dentry *proc_ns_instantiate(struct dentry *dentry,
+	struct task_struct *task, const void *ptr)
 {
 	const struct proc_ns_operations *ns_ops = ptr;
 	struct inode *inode;
 	struct proc_inode *ei;
 
-	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO);
+	inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRWXUGO);
 	if (!inode)
-		goto out;
+		return ERR_PTR(-ENOENT);
 
 	ei = PROC_I(inode);
 	inode->i_op = &proc_ns_link_inode_operations;
 	ei->ns_ops = ns_ops;
+	pid_update_inode(task, inode);
 
 	d_set_d_op(dentry, &pid_dentry_operations);
-	d_add(dentry, inode);
-	/* Close the race of the process dying before we return the dentry */
-	if (pid_revalidate(dentry, 0))
-		return 0;
-out:
-	return -ENOENT;
+	return d_splice_alias(inode, dentry);
 }
 
 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
@@ -147,12 +143,10 @@ const struct file_operations proc_ns_dir_operations = {
 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 				struct dentry *dentry, unsigned int flags)
 {
-	int error;
 	struct task_struct *task = get_proc_task(dir);
 	const struct proc_ns_operations **entry, **last;
 	unsigned int len = dentry->d_name.len;
-
-	error = -ENOENT;
+	struct dentry *res = ERR_PTR(-ENOENT);
 
 	if (!task)
 		goto out_no_task;
@@ -167,11 +161,11 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 	if (entry == last)
 		goto out;
 
-	error = proc_ns_instantiate(dir, dentry, task, *entry);
+	res = proc_ns_instantiate(dentry, task, *entry);
 out:
 	put_task_struct(task);
 out_no_task:
-	return ERR_PTR(error);
+	return res;
 }
 
 const struct inode_operations proc_ns_dir_inode_operations = {
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 8989936..4d765e5 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -554,9 +554,8 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry,
 	if (!inode)
 		goto out;
 
-	err = NULL;
 	d_set_d_op(dentry, &proc_sys_dentry_operations);
-	d_add(dentry, inode);
+	err = d_splice_alias(inode, dentry);
 
 out:
 	if (h)
@@ -684,6 +683,7 @@ static bool proc_sys_fill_cache(struct file *file,
 		if (IS_ERR(child))
 			return false;
 		if (d_in_lookup(child)) {
+			struct dentry *res;
 			inode = proc_sys_make_inode(dir->d_sb, head, table);
 			if (!inode) {
 				d_lookup_done(child);
@@ -691,7 +691,16 @@ static bool proc_sys_fill_cache(struct file *file,
 				return false;
 			}
 			d_set_d_op(child, &proc_sys_dentry_operations);
-			d_add(child, inode);
+			res = d_splice_alias(inode, child);
+			d_lookup_done(child);
+			if (unlikely(res)) {
+				if (IS_ERR(res)) {
+					dput(child);
+					return false;
+				}
+				dput(child);
+				child = res;
+			}
 		}
 	}
 	inode = d_inode(child);