1 files changed, 250 insertions, 225 deletions

diff --git a/fs/namei.c b/fs/namei.c
index c0d551fc43a0..11f3a18d9d2d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1603,32 +1603,42 @@ static struct dentry *lookup_slow(const struct qstr *name,
 				  struct dentry *dir,
 				  unsigned int flags)
 {
-	struct dentry *dentry;
-	inode_lock(dir->d_inode);
-	dentry = d_lookup(dir, name);
-	if (unlikely(dentry)) {
+	struct dentry *dentry = ERR_PTR(-ENOENT), *old;
+	struct inode *inode = dir->d_inode;
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+	inode_lock_shared(inode);
+	/* Don't go there if it's already dead */
+	if (unlikely(IS_DEADDIR(inode)))
+		goto out;
+again:
+	dentry = d_alloc_parallel(dir, name, &wq);
+	if (IS_ERR(dentry))
+		goto out;
+	if (unlikely(!d_in_lookup(dentry))) {
 		if ((dentry->d_flags & DCACHE_OP_REVALIDATE) &&
 		    !(flags & LOOKUP_NO_REVAL)) {
 			int error = d_revalidate(dentry, flags);
 			if (unlikely(error <= 0)) {
-				if (!error)
+				if (!error) {
 					d_invalidate(dentry);
+					dput(dentry);
+					goto again;
+				}
 				dput(dentry);
 				dentry = ERR_PTR(error);
 			}
 		}
-		if (dentry) {
-			inode_unlock(dir->d_inode);
-			return dentry;
+	} else {
+		old = inode->i_op->lookup(inode, dentry, flags);
+		d_lookup_done(dentry);
+		if (unlikely(old)) {
+			dput(dentry);
+			dentry = old;
 		}
 	}
-	dentry = d_alloc(dir, name);
-	if (unlikely(!dentry)) {
-		inode_unlock(dir->d_inode);
-		return ERR_PTR(-ENOMEM);
-	}
-	dentry = lookup_real(dir->d_inode, dentry, flags);
-	inode_unlock(dir->d_inode);
+out:
+	inode_unlock_shared(inode);
 	return dentry;
 }
 
@@ -1740,15 +1750,17 @@ static int walk_component(struct nameidata *nd, int flags)
 					  nd->flags);
 		if (IS_ERR(path.dentry))
 			return PTR_ERR(path.dentry);
-		if (unlikely(d_is_negative(path.dentry))) {
-			dput(path.dentry);
-			return -ENOENT;
-		}
+
 		path.mnt = nd->path.mnt;
 		err = follow_managed(&path, nd);
 		if (unlikely(err < 0))
 			return err;
 
+		if (unlikely(d_is_negative(path.dentry))) {
+			path_to_nameidata(&path, nd);
+			return -ENOENT;
+		}
+
 		seq = 0;	/* we are already out of RCU mode */
 		inode = d_backing_inode(path.dentry);
 	}
@@ -1792,30 +1804,49 @@ static inline unsigned int fold_hash(unsigned long hash)
 	return hash_64(hash, 32);
 }
 
+/*
+ * This is George Marsaglia's XORSHIFT generator.
+ * It implements a maximum-period LFSR in only a few
+ * instructions.  It also has the property (required
+ * by hash_name()) that mix_hash(0) = 0.
+ */
+static inline unsigned long mix_hash(unsigned long hash)
+{
+	hash ^= hash << 13;
+	hash ^= hash >> 7;
+	hash ^= hash << 17;
+	return hash;
+}
+
 #else	/* 32-bit case */
 
 #define fold_hash(x) (x)
 
+static inline unsigned long mix_hash(unsigned long hash)
+{
+	hash ^= hash << 13;
+	hash ^= hash >> 17;
+	hash ^= hash << 5;
+	return hash;
+}
+
 #endif
 
 unsigned int full_name_hash(const unsigned char *name, unsigned int len)
 {
-	unsigned long a, mask;
-	unsigned long hash = 0;
+	unsigned long a, hash = 0;
 
 	for (;;) {
 		a = load_unaligned_zeropad(name);
 		if (len < sizeof(unsigned long))
 			break;
-		hash += a;
-		hash *= 9;
+		hash = mix_hash(hash + a);
 		name += sizeof(unsigned long);
 		len -= sizeof(unsigned long);
 		if (!len)
 			goto done;
 	}
-	mask = bytemask_from_count(len);
-	hash += mask & a;
+	hash += a & bytemask_from_count(len);
 done:
 	return fold_hash(hash);
 }
@@ -1833,7 +1864,7 @@ static inline u64 hash_name(const char *name)
 	hash = a = 0;
 	len = -sizeof(unsigned long);
 	do {
-		hash = (hash + a) * 9;
+		hash = mix_hash(hash + a);
 		len += sizeof(unsigned long);
 		a = load_unaligned_zeropad(name+len);
 		b = a ^ REPEAT_BYTE('/');
@@ -2265,6 +2296,33 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
 EXPORT_SYMBOL(vfs_path_lookup);
 
 /**
+ * lookup_hash - lookup single pathname component on already hashed name
+ * @name:	name and hash to lookup
+ * @base:	base directory to lookup from
+ *
+ * The name must have been verified and hashed (see lookup_one_len()).  Using
+ * this after just full_name_hash() is unsafe.
+ *
+ * This function also doesn't check for search permission on base directory.
+ *
+ * Use lookup_one_len_unlocked() instead, unless you really know what you are
+ * doing.
+ *
+ * Do not hold i_mutex; this helper takes i_mutex if necessary.
+ */
+struct dentry *lookup_hash(const struct qstr *name, struct dentry *base)
+{
+	struct dentry *ret;
+
+	ret = lookup_dcache(name, base, 0);
+	if (!ret)
+		ret = lookup_slow(name, base, 0);
+
+	return ret;
+}
+EXPORT_SYMBOL(lookup_hash);
+
+/**
  * lookup_one_len - filesystem helper to lookup single pathname component
  * @name:	pathname component to lookup
  * @base:	base directory to lookup from
@@ -2335,7 +2393,6 @@ struct dentry *lookup_one_len_unlocked(const char *name,
 	struct qstr this;
 	unsigned int c;
 	int err;
-	struct dentry *ret;
 
 	this.name = name;
 	this.len = len;
@@ -2367,10 +2424,7 @@ struct dentry *lookup_one_len_unlocked(const char *name,
 	if (err)
 		return ERR_PTR(err);
 
-	ret = lookup_dcache(&this, base, 0);
-	if (!ret)
-		ret = lookup_slow(&this, base, 0);
-	return ret;
+	return lookup_hash(&this, base);
 }
 EXPORT_SYMBOL(lookup_one_len_unlocked);
 
@@ -2812,155 +2866,56 @@ static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode)
 static int atomic_open(struct nameidata *nd, struct dentry *dentry,
 			struct path *path, struct file *file,
 			const struct open_flags *op,
-			bool got_write, bool need_lookup,
+			int open_flag, umode_t mode,
 			int *opened)
 {
+	struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
 	struct inode *dir =  nd->path.dentry->d_inode;
-	unsigned open_flag = open_to_namei_flags(op->open_flag);
-	umode_t mode;
 	int error;
-	int acc_mode;
-	int create_error = 0;
-	struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
-	bool excl;
-
-	BUG_ON(dentry->d_inode);
-
-	/* Don't create child dentry for a dead directory. */
-	if (unlikely(IS_DEADDIR(dir))) {
-		error = -ENOENT;
-		goto out;
-	}
-
-	mode = op->mode;
-	if ((open_flag & O_CREAT) && !IS_POSIXACL(dir))
-		mode &= ~current_umask();
 
-	excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT);
-	if (excl)
+	if (!(~open_flag & (O_EXCL | O_CREAT)))	/* both O_EXCL and O_CREAT */
 		open_flag &= ~O_TRUNC;
 
-	/*
-	 * Checking write permission is tricky, bacuse we don't know if we are
-	 * going to actually need it: O_CREAT opens should work as long as the
-	 * file exists.  But checking existence breaks atomicity.  The trick is
-	 * to check access and if not granted clear O_CREAT from the flags.
-	 *
-	 * Another problem is returing the "right" error value (e.g. for an
-	 * O_EXCL open we want to return EEXIST not EROFS).
-	 */
-	if (((open_flag & (O_CREAT | O_TRUNC)) ||
-	    (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) {
-		if (!(open_flag & O_CREAT)) {
-			/*
-			 * No O_CREATE -> atomicity not a requirement -> fall
-			 * back to lookup + open
-			 */
-			goto no_open;
-		} else if (open_flag & (O_EXCL | O_TRUNC)) {
-			/* Fall back and fail with the right error */
-			create_error = -EROFS;
-			goto no_open;
-		} else {
-			/* No side effects, safe to clear O_CREAT */
-			create_error = -EROFS;
-			open_flag &= ~O_CREAT;
-		}
-	}
-
-	if (open_flag & O_CREAT) {
-		error = may_o_create(&nd->path, dentry, mode);
-		if (error) {
-			create_error = error;
-			if (open_flag & O_EXCL)
-				goto no_open;
-			open_flag &= ~O_CREAT;
-		}
-	}
-
 	if (nd->flags & LOOKUP_DIRECTORY)
 		open_flag |= O_DIRECTORY;
 
 	file->f_path.dentry = DENTRY_NOT_SET;
 	file->f_path.mnt = nd->path.mnt;
-	error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode,
-				      opened);
-	if (error < 0) {
-		if (create_error && error == -ENOENT)
-			error = create_error;
-		goto out;
-	}
-
-	if (error) {	/* returned 1, that is */
+	error = dir->i_op->atomic_open(dir, dentry, file,
+				       open_to_namei_flags(open_flag),
+				       mode, opened);
+	d_lookup_done(dentry);
+	if (!error) {
+		/*
+		 * We didn't have the inode before the open, so check open
+		 * permission here.
+		 */
+		int acc_mode = op->acc_mode;
+		if (*opened & FILE_CREATED) {
+			WARN_ON(!(open_flag & O_CREAT));
+			fsnotify_create(dir, dentry);
+			acc_mode = 0;
+		}
+		error = may_open(&file->f_path, acc_mode, open_flag);
+		if (WARN_ON(error > 0))
+			error = -EINVAL;
+	} else if (error > 0) {
 		if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
 			error = -EIO;
-			goto out;
-		}
-		if (file->f_path.dentry) {
-			dput(dentry);
-			dentry = file->f_path.dentry;
-		}
-		if (*opened & FILE_CREATED)
-			fsnotify_create(dir, dentry);
-		if (!dentry->d_inode) {
-			WARN_ON(*opened & FILE_CREATED);
-			if (create_error) {
-				error = create_error;
-				goto out;
-			}
 		} else {
-			if (excl && !(*opened & FILE_CREATED)) {
-				error = -EEXIST;
-				goto out;
+			if (file->f_path.dentry) {
+				dput(dentry);
+				dentry = file->f_path.dentry;
 			}
+			if (*opened & FILE_CREATED)
+				fsnotify_create(dir, dentry);
+			path->dentry = dentry;
+			path->mnt = nd->path.mnt;
+			return 1;
 		}
-		goto looked_up;
-	}
-
-	/*
-	 * We didn't have the inode before the open, so check open permission
-	 * here.
-	 */
-	acc_mode = op->acc_mode;
-	if (*opened & FILE_CREATED) {
-		WARN_ON(!(open_flag & O_CREAT));
-		fsnotify_create(dir, dentry);
-		acc_mode = 0;
 	}
-	error = may_open(&file->f_path, acc_mode, open_flag);
-	if (error)
-		fput(file);
-
-out:
 	dput(dentry);
 	return error;
-
-no_open:
-	if (need_lookup) {
-		dentry = lookup_real(dir, dentry, nd->flags);
-		if (IS_ERR(dentry))
-			return PTR_ERR(dentry);
-
-		if (create_error) {
-			int open_flag = op->open_flag;
-
-			error = create_error;
-			if ((open_flag & O_EXCL)) {
-				if (!dentry->d_inode)
-					goto out;
-			} else if (!dentry->d_inode) {
-				goto out;
-			} else if ((open_flag & O_TRUNC) &&
-				   d_is_reg(dentry)) {
-				goto out;
-			}
-			/* will fail later, go on to get the right error */
-		}
-	}
-looked_up:
-	path->dentry = dentry;
-	path->mnt = nd->path.mnt;
-	return 1;
 }
 
 /*
@@ -2988,62 +2943,118 @@ static int lookup_open(struct nameidata *nd, struct path *path,
 {
 	struct dentry *dir = nd->path.dentry;
 	struct inode *dir_inode = dir->d_inode;
+	int open_flag = op->open_flag;
 	struct dentry *dentry;
-	int error;
-	bool need_lookup = false;
+	int error, create_error = 0;
+	umode_t mode = op->mode;
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+	if (unlikely(IS_DEADDIR(dir_inode)))
+		return -ENOENT;
 
 	*opened &= ~FILE_CREATED;
-	dentry = lookup_dcache(&nd->last, dir, nd->flags);
-	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
+	dentry = d_lookup(dir, &nd->last);
+	for (;;) {
+		if (!dentry) {
+			dentry = d_alloc_parallel(dir, &nd->last, &wq);
+			if (IS_ERR(dentry))
+				return PTR_ERR(dentry);
+		}
+		if (d_in_lookup(dentry))
+			break;
 
-	if (!dentry) {
-		dentry = d_alloc(dir, &nd->last);
-		if (unlikely(!dentry))
-			return -ENOMEM;
-		need_lookup = true;
-	} else if (dentry->d_inode) {
+		if (!(dentry->d_flags & DCACHE_OP_REVALIDATE))
+			break;
+
+		error = d_revalidate(dentry, nd->flags);
+		if (likely(error > 0))
+			break;
+		if (error)
+			goto out_dput;
+		d_invalidate(dentry);
+		dput(dentry);
+		dentry = NULL;
+	}
+	if (dentry->d_inode) {
 		/* Cached positive dentry: will open in f_op->open */
 		goto out_no_open;
 	}
 
-	if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) {
-		return atomic_open(nd, dentry, path, file, op, got_write,
-				   need_lookup, opened);
+	/*
+	 * Checking write permission is tricky, bacuse we don't know if we are
+	 * going to actually need it: O_CREAT opens should work as long as the
+	 * file exists.  But checking existence breaks atomicity.  The trick is
+	 * to check access and if not granted clear O_CREAT from the flags.
+	 *
+	 * Another problem is returing the "right" error value (e.g. for an
+	 * O_EXCL open we want to return EEXIST not EROFS).
+	 */
+	if (open_flag & O_CREAT) {
+		if (!IS_POSIXACL(dir->d_inode))
+			mode &= ~current_umask();
+		if (unlikely(!got_write)) {
+			create_error = -EROFS;
+			open_flag &= ~O_CREAT;
+			if (open_flag & (O_EXCL | O_TRUNC))
+				goto no_open;
+			/* No side effects, safe to clear O_CREAT */
+		} else {
+			create_error = may_o_create(&nd->path, dentry, mode);
+			if (create_error) {
+				open_flag &= ~O_CREAT;
+				if (open_flag & O_EXCL)
+					goto no_open;
+			}
+		}
+	} else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
+		   unlikely(!got_write)) {
+		/*
+		 * No O_CREATE -> atomicity not a requirement -> fall
+		 * back to lookup + open
+		 */
+		goto no_open;
 	}
 
-	if (need_lookup) {
-		BUG_ON(dentry->d_inode);
+	if (dir_inode->i_op->atomic_open) {
+		error = atomic_open(nd, dentry, path, file, op, open_flag,
+				    mode, opened);
+		if (unlikely(error == -ENOENT) && create_error)
+			error = create_error;
+		return error;
+	}
 
-		dentry = lookup_real(dir_inode, dentry, nd->flags);
-		if (IS_ERR(dentry))
-			return PTR_ERR(dentry);
+no_open:
+	if (d_in_lookup(dentry)) {
+		struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
+							     nd->flags);
+		d_lookup_done(dentry);
+		if (unlikely(res)) {
+			if (IS_ERR(res)) {
+				error = PTR_ERR(res);
+				goto out_dput;
+			}
+			dput(dentry);
+			dentry = res;
+		}
 	}
 
 	/* Negative dentry, just create the file */
-	if (!dentry->d_inode && (op->open_flag & O_CREAT)) {
-		umode_t mode = op->mode;
-		if (!IS_POSIXACL(dir->d_inode))
-			mode &= ~current_umask();
-		/*
-		 * This write is needed to ensure that a
-		 * rw->ro transition does not occur between
-		 * the time when the file is created and when
-		 * a permanent write count is taken through
-		 * the 'struct file' in finish_open().
-		 */
-		if (!got_write) {
-			error = -EROFS;
-			goto out_dput;
-		}
+	if (!dentry->d_inode && (open_flag & O_CREAT)) {
 		*opened |= FILE_CREATED;
-		error = security_path_mknod(&nd->path, dentry, mode, 0);
-		if (error)
+		audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+		if (!dir_inode->i_op->create) {
+			error = -EACCES;
 			goto out_dput;
-		error = vfs_create(dir->d_inode, dentry, mode,
-				   nd->flags & LOOKUP_EXCL);
+		}
+		error = dir_inode->i_op->create(dir_inode, dentry, mode,
+						open_flag & O_EXCL);
 		if (error)
 			goto out_dput;
+		fsnotify_create(dir_inode, dentry);
+	}
+	if (unlikely(create_error) && !dentry->d_inode) {
+		error = create_error;
+		goto out_dput;
 	}
 out_no_open:
 	path->dentry = dentry;
@@ -3115,7 +3126,7 @@ static int do_last(struct nameidata *nd,
 	}
 
 retry_lookup:
-	if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
+	if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
 		error = mnt_want_write(nd->path.mnt);
 		if (!error)
 			got_write = true;
@@ -3125,9 +3136,15 @@ retry_lookup:
 		 * dropping this one anyway.
 		 */
 	}
-	inode_lock(dir->d_inode);
+	if (open_flag & O_CREAT)
+		inode_lock(dir->d_inode);
+	else
+		inode_lock_shared(dir->d_inode);
 	error = lookup_open(nd, &path, file, op, got_write, opened);
-	inode_unlock(dir->d_inode);
+	if (open_flag & O_CREAT)
+		inode_unlock(dir->d_inode);
+	else
+		inode_unlock_shared(dir->d_inode);
 
 	if (error <= 0) {
 		if (error)
@@ -3207,10 +3224,6 @@ finish_open:
 		return error;
 	}
 	audit_inode(nd->name, nd->path.dentry, 0);
-	if (unlikely(d_is_symlink(nd->path.dentry)) && !(open_flag & O_PATH)) {
-		error = -ELOOP;
-		goto out;
-	}
 	error = -EISDIR;
 	if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
 		goto out;
@@ -3227,11 +3240,9 @@ finish_open:
 		got_write = true;
 	}
 finish_open_created:
-	if (likely(!(open_flag & O_PATH))) {
-		error = may_open(&nd->path, acc_mode, open_flag);
-		if (error)
-			goto out;
-	}
+	error = may_open(&nd->path, acc_mode, open_flag);
+	if (error)
+		goto out;
 	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
 	error = vfs_open(&nd->path, file, current_cred());
 	if (!error) {
@@ -3243,18 +3254,13 @@ finish_open_created:
 	}
 opened:
 	error = open_check_o_direct(file);
-	if (error)
-		goto exit_fput;
-	error = ima_file_check(file, op->acc_mode, *opened);
-	if (error)
-		goto exit_fput;
-
-	if (will_truncate) {
+	if (!error)
+		error = ima_file_check(file, op->acc_mode, *opened);
+	if (!error && will_truncate)
 		error = handle_truncate(file);
-		if (error)
-			goto exit_fput;
-	}
 out:
+	if (unlikely(error) && (*opened & FILE_OPENED))
+		fput(file);
 	if (unlikely(error > 0)) {
 		WARN_ON(1);
 		error = -EINVAL;
@@ -3264,10 +3270,6 @@ out:
 	path_put(&save_parent);
 	return error;
 
-exit_fput:
-	fput(file);
-	goto out;
-
 stale_open:
 	/* If no saved parent or already retried then can't retry */
 	if (!save_parent.dentry || retried)
@@ -3345,6 +3347,18 @@ out:
 	return error;
 }
 
+static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
+{
+	struct path path;
+	int error = path_lookupat(nd, flags, &path);
+	if (!error) {
+		audit_inode(nd->name, path.dentry, 0);
+		error = vfs_open(&path, file, current_cred());
+		path_put(&path);
+	}
+	return error;
+}
+
 static struct file *path_openat(struct nameidata *nd,
 			const struct open_flags *op, unsigned flags)
 {
@@ -3364,6 +3378,13 @@ static struct file *path_openat(struct nameidata *nd,
 		goto out2;
 	}
 
+	if (unlikely(file->f_flags & O_PATH)) {
+		error = do_o_path(nd, flags, file);
+		if (!error)
+			opened |= FILE_OPENED;
+		goto out2;
+	}
+
 	s = path_init(nd, flags);
 	if (IS_ERR(s)) {
 		put_filp(file);
@@ -4211,7 +4232,11 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	bool new_is_dir = false;
 	unsigned max_links = new_dir->i_sb->s_max_links;
 
-	if (source == target)
+	/*
+	 * Check source == target.
+	 * On overlayfs need to look at underlying inodes.
+	 */
+	if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0))
 		return 0;
 
 	error = may_delete(old_dir, old_dentry, is_dir);