Merge tag 'vfs-6.11.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Support passing NULL along AT_EMPTY_PATH for statx().

     NULL paths with any flag value other than AT_EMPTY_PATH go the
     usual route and end up with -EFAULT to retain compatibility (Rust
     is abusing calls of the sort to detect availability of statx)

     This avoids path lookup code, lockref management, memory allocation
     and in case of NULL path userspace memory access (which can be
     quite expensive with SMAP on x86_64)

   - Don't block i_writecount during exec. Remove the
     deny_write_access() mechanism for executables

   - Relax open_by_handle_at() permissions in specific cases where we
     can prove that the caller had sufficient privileges to open a file

   - Switch timespec64 fields in struct inode to discrete integers
     freeing up 4 bytes

  Fixes:

   - Fix false positive circular locking warning in hfsplus

   - Initialize hfs_inode_info after hfs_alloc_inode() in hfs

   - Avoid accidental overflows in vfs_fallocate()

   - Don't interrupt fallocate with EINTR in tmpfs to avoid constantly
     restarting shmem_fallocate()

   - Add missing quote in comment in fs/readdir

  Cleanups:

   - Don't assign and test in an if statement in mqueue. Move the
     assignment out of the if statement

   - Reflow the logic in may_create_in_sticky()

   - Remove the usage of the deprecated ida_simple_xx() API from procfs

   - Reject FSCONFIG_CMD_CREATE_EXCL requets that depend on the new
     mount api early

   - Rename variables in copy_tree() to make it easier to understand

   - Replace WARN(down_read_trylock, ...) abuse with proper asserts in
     various places in the VFS

   - Get rid of user_path_at_empty() and drop the empty argument from
     getname_flags()

   - Check for error while copying and no path in one branch in
     getname_flags()

   - Avoid redundant smp_mb() for THP handling in do_dentry_open()

   - Rename parent_ino to d_parent_ino and make it use RCU

   - Remove unused header include in fs/readdir

   - Export in_group_capable() helper and switch f2fs and fuse over to
     it instead of open-coding the logic in both places"

* tag 'vfs-6.11.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (27 commits)
  ipc: mqueue: remove assignment from IS_ERR argument
  vfs: rename parent_ino to d_parent_ino and make it use RCU
  vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)
  stat: use vfs_empty_path() helper
  fs: new helper vfs_empty_path()
  fs: reflow may_create_in_sticky()
  vfs: remove redundant smp_mb for thp handling in do_dentry_open
  fuse: Use in_group_or_capable() helper
  f2fs: Use in_group_or_capable() helper
  fs: Export in_group_or_capable()
  vfs: reorder checks in may_create_in_sticky
  hfs: fix to initialize fields of hfs_inode_info after hfs_alloc_inode()
  proc: Remove usage of the deprecated ida_simple_xx() API
  hfsplus: fix to avoid false alarm of circular locking
  Improve readability of copy_tree
  vfs: shave a branch in getname_flags
  vfs: retire user_path_at_empty and drop empty arg from getname_flags
  vfs: stop using user_path_at_empty in do_readlinkat
  tmpfs: don't interrupt fallocate with EINTR
  fs: don't block i_writecount during exec
  ...

28 files changed, 462 insertions, 254 deletions

diff --git a/fs/attr.c b/fs/attr.c
index 960a310581eb..825007d5cda4 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -17,8 +17,6 @@
 #include <linux/filelock.h>
 #include <linux/security.h>
 
-#include "internal.h"
-
 /**
  * setattr_should_drop_sgid - determine whether the setgid bit needs to be
  *                            removed
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index a43897b03ce9..6fdec541f8bf 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1216,7 +1216,6 @@ out_free_interp:
 		}
 		reloc_func_desc = interp_load_addr;
 
-		allow_write_access(interpreter);
 		fput(interpreter);
 
 		kfree(interp_elf_ex);
@@ -1308,7 +1307,6 @@ out_free_dentry:
 	kfree(interp_elf_ex);
 	kfree(interp_elf_phdata);
 out_free_file:
-	allow_write_access(interpreter);
 	if (interpreter)
 		fput(interpreter);
 out_free_ph:
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index b799701454a9..28a3439f163a 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -394,7 +394,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
 			goto error;
 		}
 
-		allow_write_access(interpreter);
 		fput(interpreter);
 		interpreter = NULL;
 	}
@@ -466,10 +465,8 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
 	retval = 0;
 
 error:
-	if (interpreter) {
-		allow_write_access(interpreter);
+	if (interpreter)
 		fput(interpreter);
-	}
 	kfree(interpreter_name);
 	kfree(exec_params.phdrs);
 	kfree(exec_params.loadmap);
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 68fa225f89e5..21ce5ec1ea76 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -247,13 +247,10 @@ static int load_misc_binary(struct linux_binprm *bprm)
 	if (retval < 0)
 		goto ret;
 
-	if (fmt->flags & MISC_FMT_OPEN_FILE) {
+	if (fmt->flags & MISC_FMT_OPEN_FILE)
 		interp_file = file_clone_open(fmt->interp_file);
-		if (!IS_ERR(interp_file))
-			deny_write_access(interp_file);
-	} else {
+	else
 		interp_file = open_exec(fmt->interpreter);
-	}
 	retval = PTR_ERR(interp_file);
 	if (IS_ERR(interp_file))
 		goto ret;
diff --git a/fs/dcache.c b/fs/dcache.c
index 5f9ffe5c9917..8bdc278a0205 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1555,7 +1555,7 @@ void shrink_dcache_for_umount(struct super_block *sb)
 {
 	struct dentry *dentry;
 
-	WARN(down_read_trylock(&sb->s_umount), "s_umount should've been locked");
+	rwsem_assert_held_write(&sb->s_umount);
 
 	dentry = sb->s_root;
 	sb->s_root = NULL;
@@ -3106,6 +3106,34 @@ void d_tmpfile(struct file *file, struct inode *inode)
 }
 EXPORT_SYMBOL(d_tmpfile);
 
+/*
+ * Obtain inode number of the parent dentry.
+ */
+ino_t d_parent_ino(struct dentry *dentry)
+{
+	struct dentry *parent;
+	struct inode *iparent;
+	unsigned seq;
+	ino_t ret;
+
+	scoped_guard(rcu) {
+		seq = raw_seqcount_begin(&dentry->d_seq);
+		parent = READ_ONCE(dentry->d_parent);
+		iparent = d_inode_rcu(parent);
+		if (likely(iparent)) {
+			ret = iparent->i_ino;
+			if (!read_seqcount_retry(&dentry->d_seq, seq))
+				return ret;
+		}
+	}
+
+	spin_lock(&dentry->d_lock);
+	ret = dentry->d_parent->d_inode->i_ino;
+	spin_unlock(&dentry->d_lock);
+	return ret;
+}
+EXPORT_SYMBOL(d_parent_ino);
+
 static __initdata unsigned long dhash_entries;
 static int __init set_dhash_entries(char *str)
 {
diff --git a/fs/exec.c b/fs/exec.c
index 40073142288f..4dee205452e2 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -952,10 +952,6 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
 			 path_noexec(&file->f_path)))
 		goto exit;
 
-	err = deny_write_access(file);
-	if (err)
-		goto exit;
-
 out:
 	return file;
 
@@ -971,8 +967,7 @@ exit:
  *
  * Returns ERR_PTR on failure or allocated struct file on success.
  *
- * As this is a wrapper for the internal do_open_execat(), callers
- * must call allow_write_access() before fput() on release. Also see
+ * As this is a wrapper for the internal do_open_execat(). Also see
  * do_close_execat().
  */
 struct file *open_exec(const char *name)
@@ -1524,10 +1519,8 @@ static int prepare_bprm_creds(struct linux_binprm *bprm)
 /* Matches do_open_execat() */
 static void do_close_execat(struct file *file)
 {
-	if (!file)
-		return;
-	allow_write_access(file);
-	fput(file);
+	if (file)
+		fput(file);
 }
 
 static void free_bprm(struct linux_binprm *bprm)
@@ -1846,7 +1839,6 @@ static int exec_binprm(struct linux_binprm *bprm)
 		bprm->file = bprm->interpreter;
 		bprm->interpreter = NULL;
 
-		allow_write_access(exec);
 		if (unlikely(bprm->have_execfd)) {
 			if (bprm->executable) {
 				fput(exec);
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 07ea3d62b298..4f2dd4ab4486 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -427,7 +427,7 @@ EXPORT_SYMBOL_GPL(exportfs_encode_fh);
 
 struct dentry *
 exportfs_decode_fh_raw(struct vfsmount *mnt, struct fid *fid, int fh_len,
-		       int fileid_type,
+		       int fileid_type, unsigned int flags,
 		       int (*acceptable)(void *, struct dentry *),
 		       void *context)
 {
@@ -445,6 +445,11 @@ exportfs_decode_fh_raw(struct vfsmount *mnt, struct fid *fid, int fh_len,
 	if (IS_ERR_OR_NULL(result))
 		return result;
 
+	if ((flags & EXPORT_FH_DIR_ONLY) && !d_is_dir(result)) {
+		err = -ENOTDIR;
+		goto err_result;
+	}
+
 	/*
 	 * If no acceptance criteria was specified by caller, a disconnected
 	 * dentry is also accepatable. Callers may use this mode to query if
@@ -581,7 +586,7 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
 {
 	struct dentry *ret;
 
-	ret = exportfs_decode_fh_raw(mnt, fid, fh_len, fileid_type,
+	ret = exportfs_decode_fh_raw(mnt, fid, fh_len, fileid_type, 0,
 				     acceptable, context);
 	if (IS_ERR_OR_NULL(ret)) {
 		if (ret == ERR_PTR(-ENOMEM))
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index ec2aeccb69a3..8bffdeccdbc3 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -219,8 +219,7 @@ static int f2fs_acl_update_mode(struct mnt_idmap *idmap,
 		return error;
 	if (error == 0)
 		*acl = NULL;
-	if (!vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)) &&
-	    !capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
+	if (!in_group_or_capable(idmap, inode, i_gid_into_vfsgid(idmap, inode)))
 		mode &= ~S_ISGID;
 	*mode_p = mode;
 	return 0;
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 5c0b281a70f3..c1ad9b278c47 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -185,7 +185,7 @@ static int get_parent_ino(struct inode *inode, nid_t *pino)
 	if (!dentry)
 		return 0;
 
-	*pino = parent_ino(dentry);
+	*pino = d_parent_ino(dentry);
 	dput(dentry);
 	return 1;
 }
@@ -923,10 +923,8 @@ static void __setattr_copy(struct mnt_idmap *idmap,
 		inode_set_ctime_to_ts(inode, attr->ia_ctime);
 	if (ia_valid & ATTR_MODE) {
 		umode_t mode = attr->ia_mode;
-		vfsgid_t vfsgid = i_gid_into_vfsgid(idmap, inode);
 
-		if (!vfsgid_in_group_p(vfsgid) &&
-		    !capable_wrt_inode_uidgid(idmap, inode, CAP_FSETID))
+		if (!in_group_or_capable(idmap, inode, i_gid_into_vfsgid(idmap, inode)))
 			mode &= ~S_ISGID;
 		set_acl_inode(inode, mode);
 	}
diff --git a/fs/fhandle.c b/fs/fhandle.c
index 8a7f86c2139a..6e8cea16790e 100644
--- a/fs/fhandle.c
+++ b/fs/fhandle.c
@@ -115,88 +115,188 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name,
 	return err;
 }
 
-static struct vfsmount *get_vfsmount_from_fd(int fd)
+static int get_path_from_fd(int fd, struct path *root)
 {
-	struct vfsmount *mnt;
-
 	if (fd == AT_FDCWD) {
 		struct fs_struct *fs = current->fs;
 		spin_lock(&fs->lock);
-		mnt = mntget(fs->pwd.mnt);
+		*root = fs->pwd;
+		path_get(root);
 		spin_unlock(&fs->lock);
 	} else {
 		struct fd f = fdget(fd);
 		if (!f.file)
-			return ERR_PTR(-EBADF);
-		mnt = mntget(f.file->f_path.mnt);
+			return -EBADF;
+		*root = f.file->f_path;
+		path_get(root);
 		fdput(f);
 	}
-	return mnt;
+
+	return 0;
 }
 
+enum handle_to_path_flags {
+	HANDLE_CHECK_PERMS   = (1 << 0),
+	HANDLE_CHECK_SUBTREE = (1 << 1),
+};
+
+struct handle_to_path_ctx {
+	struct path root;
+	enum handle_to_path_flags flags;
+	unsigned int fh_flags;
+};
+
 static int vfs_dentry_acceptable(void *context, struct dentry *dentry)
 {
-	return 1;
+	struct handle_to_path_ctx *ctx = context;
+	struct user_namespace *user_ns = current_user_ns();
+	struct dentry *d, *root = ctx->root.dentry;
+	struct mnt_idmap *idmap = mnt_idmap(ctx->root.mnt);
+	int retval = 0;
+
+	if (!root)
+		return 1;
+
+	/* Old permission model with global CAP_DAC_READ_SEARCH. */
+	if (!ctx->flags)
+		return 1;
+
+	/*
+	 * It's racy as we're not taking rename_lock but we're able to ignore
+	 * permissions and we just need an approximation whether we were able
+	 * to follow a path to the file.
+	 *
+	 * It's also potentially expensive on some filesystems especially if
+	 * there is a deep path.
+	 */
+	d = dget(dentry);
+	while (d != root && !IS_ROOT(d)) {
+		struct dentry *parent = dget_parent(d);
+
+		/*
+		 * We know that we have the ability to override DAC permissions
+		 * as we've verified this earlier via CAP_DAC_READ_SEARCH. But
+		 * we also need to make sure that there aren't any unmapped
+		 * inodes in the path that would prevent us from reaching the
+		 * file.
+		 */
+		if (!privileged_wrt_inode_uidgid(user_ns, idmap,
+						 d_inode(parent))) {
+			dput(d);
+			dput(parent);
+			return retval;
+		}
+
+		dput(d);
+		d = parent;
+	}
+
+	if (!(ctx->flags & HANDLE_CHECK_SUBTREE) || d == root)
+		retval = 1;
+	WARN_ON_ONCE(d != root && d != root->d_sb->s_root);
+	dput(d);
+	return retval;
 }
 
-static int do_handle_to_path(int mountdirfd, struct file_handle *handle,
-			     struct path *path)
+static int do_handle_to_path(struct file_handle *handle, struct path *path,
+			     struct handle_to_path_ctx *ctx)
 {
-	int retval = 0;
 	int handle_dwords;
+	struct vfsmount *mnt = ctx->root.mnt;
 
-	path->mnt = get_vfsmount_from_fd(mountdirfd);
-	if (IS_ERR(path->mnt)) {
-		retval = PTR_ERR(path->mnt);
-		goto out_err;
-	}
 	/* change the handle size to multiple of sizeof(u32) */
 	handle_dwords = handle->handle_bytes >> 2;
-	path->dentry = exportfs_decode_fh(path->mnt,
+	path->dentry = exportfs_decode_fh_raw(mnt,
 					  (struct fid *)handle->f_handle,
 					  handle_dwords, handle->handle_type,
-					  vfs_dentry_acceptable, NULL);
-	if (IS_ERR(path->dentry)) {
-		retval = PTR_ERR(path->dentry);
-		goto out_mnt;
+					  ctx->fh_flags,
+					  vfs_dentry_acceptable, ctx);
+	if (IS_ERR_OR_NULL(path->dentry)) {
+		if (path->dentry == ERR_PTR(-ENOMEM))
+			return -ENOMEM;
+		return -ESTALE;
 	}
+	path->mnt = mntget(mnt);
 	return 0;
-out_mnt:
-	mntput(path->mnt);
-out_err:
-	return retval;
+}
+
+/*
+ * Allow relaxed permissions of file handles if the caller has the
+ * ability to mount the filesystem or create a bind-mount of the
+ * provided @mountdirfd.
+ *
+ * In both cases the caller may be able to get an unobstructed way to
+ * the encoded file handle. If the caller is only able to create a
+ * bind-mount we need to verify that there are no locked mounts on top
+ * of it that could prevent us from getting to the encoded file.
+ *
+ * In principle, locked mounts can prevent the caller from mounting the
+ * filesystem but that only applies to procfs and sysfs neither of which
+ * support decoding file handles.
+ */
+static inline bool may_decode_fh(struct handle_to_path_ctx *ctx,
+				 unsigned int o_flags)
+{
+	struct path *root = &ctx->root;
+
+	/*
+	 * Restrict to O_DIRECTORY to provide a deterministic API that avoids a
+	 * confusing api in the face of disconnected non-dir dentries.
+	 *
+	 * There's only one dentry for each directory inode (VFS rule)...
+	 */
+	if (!(o_flags & O_DIRECTORY))
+		return false;
+
+	if (ns_capable(root->mnt->mnt_sb->s_user_ns, CAP_SYS_ADMIN))
+		ctx->flags = HANDLE_CHECK_PERMS;
+	else if (is_mounted(root->mnt) &&
+		 ns_capable(real_mount(root->mnt)->mnt_ns->user_ns,
+			    CAP_SYS_ADMIN) &&
+		 !has_locked_children(real_mount(root->mnt), root->dentry))
+		ctx->flags = HANDLE_CHECK_PERMS | HANDLE_CHECK_SUBTREE;
+	else
+		return false;
+
+	/* Are we able to override DAC permissions? */
+	if (!ns_capable(current_user_ns(), CAP_DAC_READ_SEARCH))
+		return false;
+
+	ctx->fh_flags = EXPORT_FH_DIR_ONLY;
+	return true;
 }
 
 static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
-		   struct path *path)
+		   struct path *path, unsigned int o_flags)
 {
 	int retval = 0;
 	struct file_handle f_handle;
 	struct file_handle *handle = NULL;
+	struct handle_to_path_ctx ctx = {};
 
-	/*
-	 * With handle we don't look at the execute bit on the
-	 * directory. Ideally we would like CAP_DAC_SEARCH.
-	 * But we don't have that
-	 */
-	if (!capable(CAP_DAC_READ_SEARCH)) {
-		retval = -EPERM;
+	retval = get_path_from_fd(mountdirfd, &ctx.root);
+	if (retval)
 		goto out_err;
+
+	if (!capable(CAP_DAC_READ_SEARCH) && !may_decode_fh(&ctx, o_flags)) {
+		retval = -EPERM;
+		goto out_path;
 	}
+
 	if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) {
 		retval = -EFAULT;
-		goto out_err;
+		goto out_path;
 	}
 	if ((f_handle.handle_bytes > MAX_HANDLE_SZ) ||
 	    (f_handle.handle_bytes == 0)) {
 		retval = -EINVAL;
-		goto out_err;
+		goto out_path;
 	}
 	handle = kmalloc(struct_size(handle, f_handle, f_handle.handle_bytes),
 			 GFP_KERNEL);
 	if (!handle) {
 		retval = -ENOMEM;
-		goto out_err;
+		goto out_path;
 	}
 	/* copy the full handle */
 	*handle = f_handle;
@@ -207,10 +307,12 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh,
 		goto out_handle;
 	}
 
-	retval = do_handle_to_path(mountdirfd, handle, path);
+	retval = do_handle_to_path(handle, path, &ctx);
 
 out_handle:
 	kfree(handle);
+out_path:
+	path_put(&ctx.root);
 out_err:
 	return retval;
 }
@@ -223,7 +325,7 @@ static long do_handle_open(int mountdirfd, struct file_handle __user *ufh,
 	struct file *file;
 	int fd;
 
-	retval = handle_to_path(mountdirfd, ufh, &path);
+	retval = handle_to_path(mountdirfd, ufh, &path, open_flag);
 	if (retval)
 		return retval;
 
diff --git a/fs/fsopen.c b/fs/fsopen.c
index 6593ae518115..ed2dd000622e 100644
--- a/fs/fsopen.c
+++ b/fs/fsopen.c
@@ -220,10 +220,6 @@ static int vfs_cmd_create(struct fs_context *fc, bool exclusive)
 	if (!mount_capable(fc))
 		return -EPERM;
 
-	/* require the new mount api */
-	if (exclusive && fc->ops == &legacy_fs_context_ops)
-		return -EOPNOTSUPP;
-
 	fc->phase = FS_CONTEXT_CREATING;
 	fc->exclusive = exclusive;
 
@@ -411,6 +407,7 @@ SYSCALL_DEFINE5(fsconfig,
 		case FSCONFIG_SET_PATH:
 		case FSCONFIG_SET_PATH_EMPTY:
 		case FSCONFIG_SET_FD:
+		case FSCONFIG_CMD_CREATE_EXCL:
 			ret = -EOPNOTSUPP;
 			goto out_f;
 		}
@@ -451,7 +448,7 @@ SYSCALL_DEFINE5(fsconfig,
 		fallthrough;
 	case FSCONFIG_SET_PATH:
 		param.type = fs_value_is_filename;
-		param.name = getname_flags(_value, lookup_flags, NULL);
+		param.name = getname_flags(_value, lookup_flags);
 		if (IS_ERR(param.name)) {
 			ret = PTR_ERR(param.name);
 			goto out_key;
diff --git a/fs/fuse/acl.c b/fs/fuse/acl.c
index 3d192b80a561..04cfd8fee992 100644
--- a/fs/fuse/acl.c
+++ b/fs/fuse/acl.c
@@ -146,8 +146,8 @@ int fuse_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * be stripped.
 		 */
 		if (fc->posix_acl &&
-		    !vfsgid_in_group_p(i_gid_into_vfsgid(&nop_mnt_idmap, inode)) &&
-		    !capable_wrt_inode_uidgid(&nop_mnt_idmap, inode, CAP_FSETID))
+		    !in_group_or_capable(&nop_mnt_idmap, inode,
+					 i_gid_into_vfsgid(&nop_mnt_idmap, inode)))
 			extra_flags |= FUSE_SETXATTR_ACL_KILL_SGID;
 
 		ret = fuse_setxattr(inode, name, value, size, 0, extra_flags);
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 8c34798a0715..744e10b46904 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -200,6 +200,7 @@ struct inode *hfs_new_inode(struct inode *dir, const struct qstr *name, umode_t
 	HFS_I(inode)->flags = 0;
 	HFS_I(inode)->rsrc_inode = NULL;
 	HFS_I(inode)->fs_blocks = 0;
+	HFS_I(inode)->tz_secondswest = sys_tz.tz_minuteswest * 60;
 	if (S_ISDIR(mode)) {
 		inode->i_size = 2;
 		HFS_SB(sb)->folder_count++;
@@ -275,6 +276,8 @@ void hfs_inode_read_fork(struct inode *inode, struct hfs_extent *ext,
 	for (count = 0, i = 0; i < 3; i++)
 		count += be16_to_cpu(ext[i].count);
 	HFS_I(inode)->first_blocks = count;
+	HFS_I(inode)->cached_start = 0;
+	HFS_I(inode)->cached_blocks = 0;
 
 	inode->i_size = HFS_I(inode)->phys_size = log_size;
 	HFS_I(inode)->fs_blocks = (log_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c
index ca2ba8c9f82e..901e83d65d20 100644
--- a/fs/hfsplus/bfind.c
+++ b/fs/hfsplus/bfind.c
@@ -25,19 +25,8 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
 	fd->key = ptr + tree->max_key_len + 2;
 	hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
 		tree->cnid, __builtin_return_address(0));
-	switch (tree->cnid) {
-	case HFSPLUS_CAT_CNID:
-		mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
-		break;
-	case HFSPLUS_EXT_CNID:
-		mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
-		break;
-	case HFSPLUS_ATTR_CNID:
-		mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
-		break;
-	default:
-		BUG();
-	}
+	mutex_lock_nested(&tree->tree_lock,
+			hfsplus_btree_lock_class(tree));
 	return 0;
 }
 
diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index 3c572e44f2ad..9c51867dddc5 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -430,7 +430,8 @@ int hfsplus_free_fork(struct super_block *sb, u32 cnid,
 		hfsplus_free_extents(sb, ext_entry, total_blocks - start,
 				     total_blocks);
 		total_blocks = start;
-		mutex_lock(&fd.tree->tree_lock);
+		mutex_lock_nested(&fd.tree->tree_lock,
+			hfsplus_btree_lock_class(fd.tree));
 	} while (total_blocks > blocks);
 	hfs_find_exit(&fd);
 
@@ -592,7 +593,8 @@ void hfsplus_file_truncate(struct inode *inode)
 					     alloc_cnt, alloc_cnt - blk_cnt);
 			hfsplus_dump_extent(hip->first_extents);
 			hip->first_blocks = blk_cnt;
-			mutex_lock(&fd.tree->tree_lock);
+			mutex_lock_nested(&fd.tree->tree_lock,
+				hfsplus_btree_lock_class(fd.tree));
 			break;
 		}
 		res = __hfsplus_ext_cache_extent(&fd, inode, alloc_cnt);
@@ -606,7 +608,8 @@ void hfsplus_file_truncate(struct inode *inode)
 		hfsplus_free_extents(sb, hip->cached_extents,
 				     alloc_cnt - start, alloc_cnt - blk_cnt);
 		hfsplus_dump_extent(hip->cached_extents);
-		mutex_lock(&fd.tree->tree_lock);
+		mutex_lock_nested(&fd.tree->tree_lock,
+				hfsplus_btree_lock_class(fd.tree));
 		if (blk_cnt > start) {
 			hip->extent_state |= HFSPLUS_EXT_DIRTY;
 			break;
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 012a3d003fbe..9e78f181c24f 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -553,6 +553,27 @@ static inline __be32 __hfsp_ut2mt(time64_t ut)
 	return cpu_to_be32(lower_32_bits(ut) + HFSPLUS_UTC_OFFSET);
 }
 
+static inline enum hfsplus_btree_mutex_classes
+hfsplus_btree_lock_class(struct hfs_btree *tree)
+{
+	enum hfsplus_btree_mutex_classes class;
+
+	switch (tree->cnid) {
+	case HFSPLUS_CAT_CNID:
+		class = CATALOG_BTREE_MUTEX;
+		break;
+	case HFSPLUS_EXT_CNID:
+		class = EXTENTS_BTREE_MUTEX;
+		break;
+	case HFSPLUS_ATTR_CNID:
+		class = ATTR_BTREE_MUTEX;
+		break;
+	default:
+		BUG();
+	}
+	return class;
+}
+
 /* compatibility */
 #define hfsp_mt2ut(t)		(struct timespec64){ .tv_sec = __hfsp_mt2ut(t) }
 #define hfsp_ut2mt(t)		__hfsp_ut2mt((t).tv_sec)
diff --git a/fs/hfsplus/ioctl.c b/fs/hfsplus/ioctl.c
index 5661a2e24d03..40d04dba13ac 100644
--- a/fs/hfsplus/ioctl.c
+++ b/fs/hfsplus/ioctl.c
@@ -40,7 +40,7 @@ static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
 
 	/* Directory containing the bootable system */
 	vh->finder_info[0] = bvh->finder_info[0] =
-		cpu_to_be32(parent_ino(dentry));
+		cpu_to_be32(d_parent_ino(dentry));
 
 	/*
 	 * Bootloader. Just using the inode here breaks in the case of
@@ -51,7 +51,7 @@ static int hfsplus_ioctl_bless(struct file *file, int __user *user_flags)
 
 	/* Per spec, the OS X system folder - same as finder_info[0] here */
 	vh->finder_info[5] = bvh->finder_info[5] =
-		cpu_to_be32(parent_ino(dentry));
+		cpu_to_be32(d_parent_ino(dentry));
 
 	mutex_unlock(&sbi->vh_mutex);
 	return 0;
diff --git a/fs/inode.c b/fs/inode.c
index 3a41f83a4ba5..e0815acc5abb 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2538,6 +2538,7 @@ bool in_group_or_capable(struct mnt_idmap *idmap,
 		return true;
 	return false;
 }
+EXPORT_SYMBOL(in_group_or_capable);
 
 /**
  * mode_strip_sgid - handle the sgid bit for non-directories
diff --git a/fs/internal.h b/fs/internal.h
index ab2225136f60..f26454c60a98 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -247,6 +247,8 @@ extern const struct dentry_operations ns_dentry_operations;
 int getname_statx_lookup_flags(int flags);
 int do_statx(int dfd, struct filename *filename, unsigned int flags,
 	     unsigned int mask, struct statx __user *buffer);
+int do_statx_fd(int fd, unsigned int flags, unsigned int mask,
+		struct statx __user *buffer);
 
 /*
  * fs/splice.c:
@@ -321,3 +323,15 @@ struct stashed_operations {
 int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data,
 		      struct path *path);
 void stashed_dentry_prune(struct dentry *dentry);
+/**
+ * path_mounted - check whether path is mounted
+ * @path: path to check
+ *
+ * Determine whether @path refers to the root of a mount.
+ *
+ * Return: true if @path is the root of a mount, false if not.
+ */
+static inline bool path_mounted(const struct path *path)
+{
+	return path->mnt->mnt_root == path->dentry;
+}
diff --git a/fs/mount.h b/fs/mount.h
index 4a42fc68f4cc..4adce73211ae 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -152,3 +152,4 @@ static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)
 }
 
 extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);
+bool has_locked_children(struct mount *mnt, struct dentry *dentry);
diff --git a/fs/namei.c b/fs/namei.c
index 87f96a9078f4..3a4c40e12f78 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -126,7 +126,7 @@
 #define EMBEDDED_NAME_MAX	(PATH_MAX - offsetof(struct filename, iname))
 
 struct filename *
-getname_flags(const char __user *filename, int flags, int *empty)
+getname_flags(const char __user *filename, int flags)
 {
 	struct filename *result;
 	char *kname;
@@ -148,9 +148,20 @@ getname_flags(const char __user *filename, int flags, int *empty)
 	result->name = kname;
 
 	len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
-	if (unlikely(len < 0)) {
-		__putname(result);
-		return ERR_PTR(len);
+	/*
+	 * Handle both empty path and copy failure in one go.
+	 */
+	if (unlikely(len <= 0)) {
+		if (unlikely(len < 0)) {
+			__putname(result);
+			return ERR_PTR(len);
+		}
+
+		/* The empty path is special. */
+		if (!(flags & LOOKUP_EMPTY)) {
+			__putname(result);
+			return ERR_PTR(-ENOENT);
+		}
 	}
 
 	/*
@@ -180,6 +191,12 @@ getname_flags(const char __user *filename, int flags, int *empty)
 			kfree(result);
 			return ERR_PTR(len);
 		}
+		/* The empty path is special. */
+		if (unlikely(!len) && !(flags & LOOKUP_EMPTY)) {
+			__putname(kname);
+			kfree(result);
+			return ERR_PTR(-ENOENT);
+		}
 		if (unlikely(len == PATH_MAX)) {
 			__putname(kname);
 			kfree(result);
@@ -188,16 +205,6 @@ getname_flags(const char __user *filename, int flags, int *empty)
 	}
 
 	atomic_set(&result->refcnt, 1);
-	/* The empty path is special. */
-	if (unlikely(!len)) {
-		if (empty)
-			*empty = 1;
-		if (!(flags & LOOKUP_EMPTY)) {
-			putname(result);
-			return ERR_PTR(-ENOENT);
-		}
-	}
-
 	result->uptr = filename;
 	result->aname = NULL;
 	audit_getname(result);
@@ -209,13 +216,13 @@ getname_uflags(const char __user *filename, int uflags)
 {
 	int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
 
-	return getname_flags(filename, flags, NULL);
+	return getname_flags(filename, flags);
 }
 
 struct filename *
 getname(const char __user * filename)
 {
-	return getname_flags(filename, 0, NULL);
+	return getname_flags(filename, 0);
 }
 
 struct filename *
@@ -1233,29 +1240,48 @@ int may_linkat(struct mnt_idmap *idmap, const struct path *link)
  *
  * Returns 0 if the open is allowed, -ve on error.
  */
-static int may_create_in_sticky(struct mnt_idmap *idmap,
-				struct nameidata *nd, struct inode *const inode)
+static int may_create_in_sticky(struct mnt_idmap *idmap, struct nameidata *nd,
+				struct inode *const inode)
 {
 	umode_t dir_mode = nd->dir_mode;
-	vfsuid_t dir_vfsuid = nd->dir_vfsuid;
+	vfsuid_t dir_vfsuid = nd->dir_vfsuid, i_vfsuid;
+
+	if (likely(!(dir_mode & S_ISVTX)))
+		return 0;
+
+	if (S_ISREG(inode->i_mode) && !sysctl_protected_regular)
+		return 0;
 
-	if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) ||
-	    (!sysctl_protected_regular && S_ISREG(inode->i_mode)) ||
-	    likely(!(dir_mode & S_ISVTX)) ||
-	    vfsuid_eq(i_uid_into_vfsuid(idmap, inode), dir_vfsuid) ||
-	    vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode), current_fsuid()))
+	if (S_ISFIFO(inode->i_mode) && !sysctl_protected_fifos)
 		return 0;
 
-	if (likely(dir_mode & 0002) ||
-	    (dir_mode & 0020 &&
-	     ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
-	      (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
-		const char *operation = S_ISFIFO(inode->i_mode) ?
-					"sticky_create_fifo" :
-					"sticky_create_regular";
-		audit_log_path_denied(AUDIT_ANOM_CREAT, operation);
+	i_vfsuid = i_uid_into_vfsuid(idmap, inode);
+
+	if (vfsuid_eq(i_vfsuid, dir_vfsuid))
+		return 0;
+
+	if (vfsuid_eq_kuid(i_vfsuid, current_fsuid()))
+		return 0;
+
+	if (likely(dir_mode & 0002)) {
+		audit_log_path_denied(AUDIT_ANOM_CREAT, "sticky_create");
 		return -EACCES;
 	}
+
+	if (dir_mode & 0020) {
+		if (sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) {
+			audit_log_path_denied(AUDIT_ANOM_CREAT,
+					      "sticky_create_fifo");
+			return -EACCES;
+		}
+
+		if (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode)) {
+			audit_log_path_denied(AUDIT_ANOM_CREAT,
+					      "sticky_create_regular");
+			return -EACCES;
+		}
+	}
+
 	return 0;
 }
 
@@ -2969,16 +2995,16 @@ int path_pts(struct path *path)
 }
 #endif
 
-int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
-		 struct path *path, int *empty)
+int user_path_at(int dfd, const char __user *name, unsigned flags,
+		 struct path *path)
 {
-	struct filename *filename = getname_flags(name, flags, empty);
+	struct filename *filename = getname_flags(name, flags);
 	int ret = filename_lookup(dfd, filename, flags, path, NULL);
 
 	putname(filename);
 	return ret;
 }
-EXPORT_SYMBOL(user_path_at_empty);
+EXPORT_SYMBOL(user_path_at);
 
 int __check_sticky(struct mnt_idmap *idmap, struct inode *dir,
 		   struct inode *inode)
diff --git a/fs/namespace.c b/fs/namespace.c
index 5a51315c6678..3aadd5361a18 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1846,19 +1846,6 @@ bool may_mount(void)
 	return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
 }
 
-/**
- * path_mounted - check whether path is mounted
- * @path: path to check
- *
- * Determine whether @path refers to the root of a mount.
- *
- * Return: true if @path is the root of a mount, false if not.
- */
-static inline bool path_mounted(const struct path *path)
-{
-	return path->mnt->mnt_root == path->dentry;
-}
-
 static void warn_mandlock(void)
 {
 	pr_warn_once("=======================================================\n"
@@ -1966,69 +1953,72 @@ static bool mnt_ns_loop(struct dentry *dentry)
 	return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
 }
 
-struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
+struct mount *copy_tree(struct mount *src_root, struct dentry *dentry,
 					int flag)
 {
-	struct mount *res, *p, *q, *r, *parent;
+	struct mount *res, *src_parent, *src_root_child, *src_mnt,
+		*dst_parent, *dst_mnt;
 
-	if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt))
+	if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(src_root))
 		return ERR_PTR(-EINVAL);
 
 	if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry))
 		return ERR_PTR(-EINVAL);
 
-	res = q = clone_mnt(mnt, dentry, flag);
-	if (IS_ERR(q))
-		return q;
+	res = dst_mnt = clone_mnt(src_root, dentry, flag);
+	if (IS_ERR(dst_mnt))
+		return dst_mnt;
 
-	q->mnt_mountpoint = mnt->mnt_mountpoint;
+	src_parent = src_root;
+	dst_mnt->mnt_mountpoint = src_root->mnt_mountpoint;
 
-	p = mnt;
-	list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
-		struct mount *s;
-		if (!is_subdir(r->mnt_mountpoint, dentry))
+	list_for_each_entry(src_root_child, &src_root->mnt_mounts, mnt_child) {
+		if (!is_subdir(src_root_child->mnt_mountpoint, dentry))
 			continue;
 
-		for (s = r; s; s = next_mnt(s, r)) {
+		for (src_mnt = src_root_child; src_mnt;
+		    src_mnt = next_mnt(src_mnt, src_root_child)) {
 			if (!(flag & CL_COPY_UNBINDABLE) &&
-			    IS_MNT_UNBINDABLE(s)) {
-				if (s->mnt.mnt_flags & MNT_LOCKED) {
+			    IS_MNT_UNBINDABLE(src_mnt)) {
+				if (src_mnt->mnt.mnt_flags & MNT_LOCKED) {
 					/* Both unbindable and locked. */
-					q = ERR_PTR(-EPERM);
+					dst_mnt = ERR_PTR(-EPERM);
 					goto out;
 				} else {
-					s = skip_mnt_tree(s);
+					src_mnt = skip_mnt_tree(src_mnt);
 					continue;
 				}
 			}
 			if (!(flag & CL_COPY_MNT_NS_FILE) &&
-			    is_mnt_ns_file(s->mnt.mnt_root)) {
-				s = skip_mnt_tree(s);
+			    is_mnt_ns_file(src_mnt->mnt.mnt_root)) {
+				src_mnt = skip_mnt_tree(src_mnt);
 				continue;
 			}
-			while (p != s->mnt_parent) {
-				p = p->mnt_parent;
-				q = q->mnt_parent;
+			while (src_parent != src_mnt->mnt_parent) {
+				src_parent = src_parent->mnt_parent;
+				dst_mnt = dst_mnt->mnt_parent;
 			}
-			p = s;
-			parent = q;
-			q = clone_mnt(p, p->mnt.mnt_root, flag);
-			if (IS_ERR(q))
+
+			src_parent = src_mnt;
+			dst_parent = dst_mnt;
+			dst_mnt = clone_mnt(src_mnt, src_mnt->mnt.mnt_root, flag);
+			if (IS_ERR(dst_mnt))
 				goto out;
 			lock_mount_hash();
-			list_add_tail(&q->mnt_list, &res->mnt_list);
-			attach_mnt(q, parent, p->mnt_mp, false);
+			list_add_tail(&dst_mnt->mnt_list, &res->mnt_list);
+			attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp, false);
 			unlock_mount_hash();
 		}
 	}
 	return res;
+
 out:
 	if (res) {
 		lock_mount_hash();
 		umount_tree(res, UMOUNT_SYNC);
 		unlock_mount_hash();
 	}
-	return q;
+	return dst_mnt;
 }
 
 /* Caller should check returned pointer for errors */
@@ -2078,7 +2068,7 @@ void drop_collected_mounts(struct vfsmount *mnt)
 	namespace_unlock();
 }
 
-static bool has_locked_children(struct mount *mnt, struct dentry *dentry)
+bool has_locked_children(struct mount *mnt, struct dentry *dentry)
 {
 	struct mount *child;
 
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 0b75305fb5f5..dd4e11a703aa 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -247,7 +247,7 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 		dentry = dget(exp->ex_path.dentry);
 	else {
 		dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid,
-						data_left, fileid_type,
+						data_left, fileid_type, 0,
 						nfsd_acceptable, exp);
 		if (IS_ERR_OR_NULL(dentry)) {
 			trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp,
diff --git a/fs/open.c b/fs/open.c
index 278b3edcda44..22adbef7ecc2 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -247,6 +247,7 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 {
 	struct inode *inode = file_inode(file);
 	long ret;
+	loff_t sum;
 
 	if (offset < 0 || len <= 0)
 		return -EINVAL;
@@ -319,8 +320,11 @@ int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
 		return -ENODEV;
 
-	/* Check for wrap through zero too */
-	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
+	/* Check for wraparound */
+	if (check_add_overflow(offset, len, &sum))
+		return -EFBIG;
+
+	if (sum > inode->i_sb->s_maxbytes)
 		return -EFBIG;
 
 	if (!file->f_op->fallocate)
@@ -982,12 +986,11 @@ static int do_dentry_open(struct file *f,
 	 */
 	if (f->f_mode & FMODE_WRITE) {
 		/*
-		 * Paired with smp_mb() in collapse_file() to ensure nr_thps
-		 * is up to date and the update to i_writecount by
-		 * get_write_access() is visible. Ensures subsequent insertion
-		 * of THPs into the page cache will fail.
+		 * Depends on full fence from get_write_access() to synchronize
+		 * against collapse_file() regarding i_writecount and nr_thps
+		 * updates. Ensures subsequent insertion of THPs into the page
+		 * cache will fail.
 		 */
-		smp_mb();
 		if (filemap_nr_thps(inode->i_mapping)) {
 			struct address_space *mapping = inode->i_mapping;
 
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 775ce0bcf08c..c02f1e63f82d 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -202,8 +202,8 @@ int proc_alloc_inum(unsigned int *inum)
 {
 	int i;
 
-	i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
-			   GFP_KERNEL);
+	i = ida_alloc_max(&proc_inum_ida, UINT_MAX - PROC_DYNAMIC_FIRST,
+			  GFP_KERNEL);
 	if (i < 0)
 		return i;
 
@@ -213,7 +213,7 @@ int proc_alloc_inum(unsigned int *inum)
 
 void proc_free_inum(unsigned int inum)
 {
-	ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
+	ida_free(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
 }
 
 static int proc_misc_d_revalidate(struct dentry *dentry, unsigned int flags)
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 627eb2f72ef3..a2b256dac36e 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2246,9 +2246,7 @@ int dquot_disable(struct super_block *sb, int type, unsigned int flags)
 	int cnt;
 	struct quota_info *dqopt = sb_dqopt(sb);
 
-	/* s_umount should be held in exclusive mode */
-	if (WARN_ON_ONCE(down_read_trylock(&sb->s_umount)))
-		up_read(&sb->s_umount);
+	rwsem_assert_held_write(&sb->s_umount);
 
 	/* Cannot turn off usage accounting without turning off limits, or
 	 * suspend quotas and simultaneously turn quotas off. */
@@ -2510,9 +2508,7 @@ int dquot_resume(struct super_block *sb, int type)
 	int ret = 0, cnt;
 	unsigned int flags;
 
-	/* s_umount should be held in exclusive mode */
-	if (WARN_ON_ONCE(down_read_trylock(&sb->s_umount)))
-		up_read(&sb->s_umount);
+	rwsem_assert_held_write(&sb->s_umount);
 
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		if (type != -1 && cnt != type)
diff --git a/fs/readdir.c b/fs/readdir.c
index 278bc0254732..d6c82421902a 100644
--- a/fs/readdir.c
+++ b/fs/readdir.c
@@ -22,8 +22,6 @@
 #include <linux/compat.h>
 #include <linux/uaccess.h>
 
-#include <asm/unaligned.h>
-
 /*
  * Some filesystems were never converted to '->iterate_shared()'
  * and their directory iterators want the inode lock held for
@@ -72,7 +70,7 @@ int wrap_directory_iterator(struct file *file,
 EXPORT_SYMBOL(wrap_directory_iterator);
 
 /*
- * Note the "unsafe_put_user() semantics: we goto a
+ * Note the "unsafe_put_user()" semantics: we goto a
  * label for errors.
  */
 #define unsafe_copy_dirent_name(_dst, _src, _len, label) do {	\
diff --git a/fs/stat.c b/fs/stat.c
index 70bd3e888cfa..6f65b3456cad 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -214,6 +214,43 @@ int getname_statx_lookup_flags(int flags)
 	return lookup_flags;
 }
 
+static int vfs_statx_path(struct path *path, int flags, struct kstat *stat,
+			  u32 request_mask)
+{
+	int error = vfs_getattr(path, stat, request_mask, flags);
+
+	if (request_mask & STATX_MNT_ID_UNIQUE) {
+		stat->mnt_id = real_mount(path->mnt)->mnt_id_unique;
+		stat->result_mask |= STATX_MNT_ID_UNIQUE;
+	} else {
+		stat->mnt_id = real_mount(path->mnt)->mnt_id;
+		stat->result_mask |= STATX_MNT_ID;
+	}
+
+	if (path_mounted(path))
+		stat->attributes |= STATX_ATTR_MOUNT_ROOT;
+	stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;
+
+	/* Handle STATX_DIOALIGN for block devices. */
+	if (request_mask & STATX_DIOALIGN) {
+		struct inode *inode = d_backing_inode(path->dentry);
+
+		if (S_ISBLK(inode->i_mode))
+			bdev_statx_dioalign(inode, stat);
+	}
+
+	return error;
+}
+
+static int vfs_statx_fd(int fd, int flags, struct kstat *stat,
+			  u32 request_mask)
+{
+	CLASS(fd_raw, f)(fd);
+	if (!f.file)
+		return -EBADF;
+	return vfs_statx_path(&f.file->f_path, flags, stat, request_mask);
+}
+
 /**
  * vfs_statx - Get basic and extra attributes by filename
  * @dfd: A file descriptor representing the base dir for a relative filename
@@ -243,36 +280,13 @@ static int vfs_statx(int dfd, struct filename *filename, int flags,
 retry:
 	error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
 	if (error)
-		goto out;
-
-	error = vfs_getattr(&path, stat, request_mask, flags);
-
-	if (request_mask & STATX_MNT_ID_UNIQUE) {
-		stat->mnt_id = real_mount(path.mnt)->mnt_id_unique;
-		stat->result_mask |= STATX_MNT_ID_UNIQUE;
-	} else {
-		stat->mnt_id = real_mount(path.mnt)->mnt_id;
-		stat->result_mask |= STATX_MNT_ID;
-	}
-
-	if (path.mnt->mnt_root == path.dentry)
-		stat->attributes |= STATX_ATTR_MOUNT_ROOT;
-	stat->attributes_mask |= STATX_ATTR_MOUNT_ROOT;
-
-	/* Handle STATX_DIOALIGN for block devices. */
-	if (request_mask & STATX_DIOALIGN) {
-		struct inode *inode = d_backing_inode(path.dentry);
-
-		if (S_ISBLK(inode->i_mode))
-			bdev_statx_dioalign(inode, stat);
-	}
-
+		return error;
+	error = vfs_statx_path(&path, flags, stat, request_mask);
 	path_put(&path);
 	if (retry_estale(error, lookup_flags)) {
 		lookup_flags |= LOOKUP_REVAL;
 		goto retry;
 	}
-out:
 	return error;
 }
 
@@ -289,18 +303,10 @@ int vfs_fstatat(int dfd, const char __user *filename,
 	 * If AT_EMPTY_PATH is set, we expect the common case to be that
 	 * empty path, and avoid doing all the extra pathname work.
 	 */
-	if (dfd >= 0 && flags == AT_EMPTY_PATH) {
-		char c;
-
-		ret = get_user(c, filename);
-		if (unlikely(ret))
-			return ret;
-
-		if (likely(!c))
-			return vfs_fstat(dfd, stat);
-	}
+	if (flags == AT_EMPTY_PATH && vfs_empty_path(dfd, filename))
+		return vfs_fstat(dfd, stat);
 
-	name = getname_flags(filename, getname_statx_lookup_flags(statx_flags), NULL);
+	name = getname_flags(filename, getname_statx_lookup_flags(statx_flags));
 	ret = vfs_statx(dfd, name, statx_flags, stat, STATX_BASIC_STATS);
 	putname(name);
 
@@ -488,34 +494,39 @@ static int do_readlinkat(int dfd, const char __user *pathname,
 			 char __user *buf, int bufsiz)
 {
 	struct path path;
+	struct filename *name;
 	int error;
-	int empty = 0;
 	unsigned int lookup_flags = LOOKUP_EMPTY;
 
 	if (bufsiz <= 0)
 		return -EINVAL;
 
 retry:
-	error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
-	if (!error) {
-		struct inode *inode = d_backing_inode(path.dentry);
-
-		error = empty ? -ENOENT : -EINVAL;
-		/*
-		 * AFS mountpoints allow readlink(2) but are not symlinks
-		 */
-		if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
-			error = security_inode_readlink(path.dentry);
-			if (!error) {
-				touch_atime(&path);
-				error = vfs_readlink(path.dentry, buf, bufsiz);
-			}
-		}
-		path_put(&path);
-		if (retry_estale(error, lookup_flags)) {
-			lookup_flags |= LOOKUP_REVAL;
-			goto retry;
+	name = getname_flags(pathname, lookup_flags);
+	error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
+	if (unlikely(error)) {
+		putname(name);
+		return error;
+	}
+
+	/*
+	 * AFS mountpoints allow readlink(2) but are not symlinks
+	 */
+	if (d_is_symlink(path.dentry) ||
+	    d_backing_inode(path.dentry)->i_op->readlink) {
+		error = security_inode_readlink(path.dentry);
+		if (!error) {
+			touch_atime(&path);
+			error = vfs_readlink(path.dentry, buf, bufsiz);
 		}
+	} else {
+		error = (name->name[0] == '\0') ? -ENOENT : -EINVAL;
+	}
+	path_put(&path);
+	putname(name);
+	if (retry_estale(error, lookup_flags)) {
+		lookup_flags |= LOOKUP_REVAL;
+		goto retry;
 	}
 	return error;
 }
@@ -674,7 +685,8 @@ int do_statx(int dfd, struct filename *filename, unsigned int flags,
 	if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
 		return -EINVAL;
 
-	/* STATX_CHANGE_COOKIE is kernel-only for now. Ignore requests
+	/*
+	 * STATX_CHANGE_COOKIE is kernel-only for now. Ignore requests
 	 * from userland.
 	 */
 	mask &= ~STATX_CHANGE_COOKIE;
@@ -686,16 +698,41 @@ int do_statx(int dfd, struct filename *filename, unsigned int flags,
 	return cp_statx(&stat, buffer);
 }
 
+int do_statx_fd(int fd, unsigned int flags, unsigned int mask,
+	     struct statx __user *buffer)
+{
+	struct kstat stat;
+	int error;
+
+	if (mask & STATX__RESERVED)
+		return -EINVAL;
+	if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
+		return -EINVAL;
+
+	/*
+	 * STATX_CHANGE_COOKIE is kernel-only for now. Ignore requests
+	 * from userland.
+	 */
+	mask &= ~STATX_CHANGE_COOKIE;
+
+	error = vfs_statx_fd(fd, flags, &stat, mask);
+	if (error)
+		return error;
+
+	return cp_statx(&stat, buffer);
+}
+
 /**
  * sys_statx - System call to get enhanced stats
  * @dfd: Base directory to pathwalk from *or* fd to stat.
- * @filename: File to stat or "" with AT_EMPTY_PATH
+ * @filename: File to stat or either NULL or "" with AT_EMPTY_PATH
  * @flags: AT_* flags to control pathwalk.
  * @mask: Parts of statx struct actually required.
  * @buffer: Result buffer.
  *
  * Note that fstat() can be emulated by setting dfd to the fd of interest,
- * supplying "" as the filename and setting AT_EMPTY_PATH in the flags.
+ * supplying "" (or preferably NULL) as the filename and setting AT_EMPTY_PATH
+ * in the flags.
  */
 SYSCALL_DEFINE5(statx,
 		int, dfd, const char __user *, filename, unsigned, flags,
@@ -703,9 +740,24 @@ SYSCALL_DEFINE5(statx,
 		struct statx __user *, buffer)
 {
 	int ret;
+	unsigned lflags;
 	struct filename *name;
 
-	name = getname_flags(filename, getname_statx_lookup_flags(flags), NULL);
+	/*
+	 * Short-circuit handling of NULL and "" paths.
+	 *
+	 * For a NULL path we require and accept only the AT_EMPTY_PATH flag
+	 * (possibly |'d with AT_STATX flags).
+	 *
+	 * However, glibc on 32-bit architectures implements fstatat as statx
+	 * with the "" pathname and AT_NO_AUTOMOUNT | AT_EMPTY_PATH flags.
+	 * Supporting this results in the uglification below.
+	 */
+	lflags = flags & ~(AT_NO_AUTOMOUNT | AT_STATX_SYNC_TYPE);
+	if (lflags == AT_EMPTY_PATH && vfs_empty_path(dfd, filename))
+		return do_statx_fd(dfd, flags & ~AT_NO_AUTOMOUNT, mask, buffer);
+
+	name = getname_flags(filename, getname_statx_lookup_flags(flags));
 	ret = do_statx(dfd, name, flags, mask, buffer);
 	putname(name);