Merge tag 'v4.13-rc1' into fixes

The fixes branch is based off a random pre-rc1 commit, because we had
some fixes that needed to go in before rc1 was released.

However we now need to fix some code that went in after that point, but
before rc1, so merge rc1 to get that code into fixes so we can fix it!

1 files changed, 263 insertions, 82 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 809048913889..c492ba75c659 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -12,6 +12,10 @@
 #include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/xattr.h>
+#include <linux/exportfs.h>
+#include <linux/uuid.h>
+#include <linux/namei.h>
+#include <linux/ratelimit.h>
 #include "overlayfs.h"
 #include "ovl_entry.h"
 
@@ -47,6 +51,19 @@ struct super_block *ovl_same_sb(struct super_block *sb)
 	return ofs->same_sb;
 }
 
+bool ovl_can_decode_fh(struct super_block *sb)
+{
+	return (sb->s_export_op && sb->s_export_op->fh_to_dentry &&
+		!uuid_is_null(&sb->s_uuid));
+}
+
+struct dentry *ovl_indexdir(struct super_block *sb)
+{
+	struct ovl_fs *ofs = sb->s_fs_info;
+
+	return ofs->indexdir;
+}
+
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
 	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
@@ -78,7 +95,7 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 	struct ovl_entry *oe = dentry->d_fsdata;
 	enum ovl_path_type type = 0;
 
-	if (oe->__upperdentry) {
+	if (ovl_dentry_upper(dentry)) {
 		type = __OVL_PATH_UPPER;
 
 		/*
@@ -99,10 +116,9 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 void ovl_path_upper(struct dentry *dentry, struct path *path)
 {
 	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-	struct ovl_entry *oe = dentry->d_fsdata;
 
 	path->mnt = ofs->upper_mnt;
-	path->dentry = ovl_upperdentry_dereference(oe);
+	path->dentry = ovl_dentry_upper(dentry);
 }
 
 void ovl_path_lower(struct dentry *dentry, struct path *path)
@@ -126,47 +142,47 @@ enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
 
 struct dentry *ovl_dentry_upper(struct dentry *dentry)
 {
+	return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
+}
+
+struct dentry *ovl_dentry_lower(struct dentry *dentry)
+{
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	return ovl_upperdentry_dereference(oe);
+	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
 }
 
-static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
+struct dentry *ovl_dentry_real(struct dentry *dentry)
 {
-	return oe->numlower ? oe->lowerstack[0].dentry : NULL;
+	return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
 }
 
-struct dentry *ovl_dentry_lower(struct dentry *dentry)
+struct inode *ovl_inode_upper(struct inode *inode)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct dentry *upperdentry = ovl_upperdentry_dereference(OVL_I(inode));
 
-	return __ovl_dentry_lower(oe);
+	return upperdentry ? d_inode(upperdentry) : NULL;
 }
 
-struct dentry *ovl_dentry_real(struct dentry *dentry)
+struct inode *ovl_inode_lower(struct inode *inode)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
-	struct dentry *realdentry;
-
-	realdentry = ovl_upperdentry_dereference(oe);
-	if (!realdentry)
-		realdentry = __ovl_dentry_lower(oe);
+	return OVL_I(inode)->lower;
+}
 
-	return realdentry;
+struct inode *ovl_inode_real(struct inode *inode)
+{
+	return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
 }
 
+
 struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
-
-	return oe->cache;
+	return OVL_I(d_inode(dentry))->cache;
 }
 
 void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
-
-	oe->cache = cache;
+	OVL_I(d_inode(dentry))->cache = cache;
 }
 
 bool ovl_dentry_is_opaque(struct dentry *dentry)
@@ -175,23 +191,35 @@ bool ovl_dentry_is_opaque(struct dentry *dentry)
 	return oe->opaque;
 }
 
-bool ovl_dentry_is_impure(struct dentry *dentry)
+bool ovl_dentry_is_whiteout(struct dentry *dentry)
+{
+	return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
+}
+
+void ovl_dentry_set_opaque(struct dentry *dentry)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	return oe->impure;
+	oe->opaque = true;
 }
 
-bool ovl_dentry_is_whiteout(struct dentry *dentry)
+/*
+ * For hard links it's possible for ovl_dentry_upper() to return positive, while
+ * there's no actual upper alias for the inode.  Copy up code needs to know
+ * about the existence of the upper alias, so it can't use ovl_dentry_upper().
+ */
+bool ovl_dentry_has_upper_alias(struct dentry *dentry)
 {
-	return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
+	struct ovl_entry *oe = dentry->d_fsdata;
+
+	return oe->has_upper;
 }
 
-void ovl_dentry_set_opaque(struct dentry *dentry)
+void ovl_dentry_set_upper_alias(struct dentry *dentry)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	oe->opaque = true;
+	oe->has_upper = true;
 }
 
 bool ovl_redirect_dir(struct super_block *sb)
@@ -203,63 +231,59 @@ bool ovl_redirect_dir(struct super_block *sb)
 
 const char *ovl_dentry_get_redirect(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
-
-	return oe->redirect;
+	return OVL_I(d_inode(dentry))->redirect;
 }
 
 void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_inode *oi = OVL_I(d_inode(dentry));
 
-	kfree(oe->redirect);
-	oe->redirect = redirect;
+	kfree(oi->redirect);
+	oi->redirect = redirect;
 }
 
-void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
+void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
+		    struct dentry *lowerdentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	if (upperdentry)
+		OVL_I(inode)->__upperdentry = upperdentry;
+	if (lowerdentry)
+		OVL_I(inode)->lower = d_inode(lowerdentry);
 
-	WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
-	WARN_ON(oe->__upperdentry);
-	/*
-	 * Make sure upperdentry is consistent before making it visible to
-	 * ovl_upperdentry_dereference().
-	 */
-	smp_wmb();
-	oe->__upperdentry = upperdentry;
+	ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);
 }
 
-void ovl_inode_init(struct inode *inode, struct inode *realinode, bool is_upper)
+void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
 {
-	WRITE_ONCE(inode->i_private, (unsigned long) realinode |
-		   (is_upper ? OVL_ISUPPER_MASK : 0));
-}
+	struct inode *upperinode = d_inode(upperdentry);
 
-void ovl_inode_update(struct inode *inode, struct inode *upperinode)
-{
-	WARN_ON(!upperinode);
-	WARN_ON(!inode_unhashed(inode));
-	WRITE_ONCE(inode->i_private,
-		   (unsigned long) upperinode | OVL_ISUPPER_MASK);
-	if (!S_ISDIR(upperinode->i_mode))
+	WARN_ON(OVL_I(inode)->__upperdentry);
+
+	/*
+	 * Make sure upperdentry is consistent before making it visible
+	 */
+	smp_wmb();
+	OVL_I(inode)->__upperdentry = upperdentry;
+	if (!S_ISDIR(upperinode->i_mode) && inode_unhashed(inode)) {
+		inode->i_private = upperinode;
 		__insert_inode_hash(inode, (unsigned long) upperinode);
+	}
 }
 
 void ovl_dentry_version_inc(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct inode *inode = d_inode(dentry);
 
-	WARN_ON(!inode_is_locked(dentry->d_inode));
-	oe->version++;
+	WARN_ON(!inode_is_locked(inode));
+	OVL_I(inode)->version++;
 }
 
 u64 ovl_dentry_version_get(struct dentry *dentry)
 {
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct inode *inode = d_inode(dentry);
 
-	WARN_ON(!inode_is_locked(dentry->d_inode));
-	return oe->version;
+	WARN_ON(!inode_is_locked(inode));
+	return OVL_I(inode)->version;
 }
 
 bool ovl_is_whiteout(struct dentry *dentry)
@@ -276,32 +300,21 @@ struct file *ovl_path_open(struct path *path, int flags)
 
 int ovl_copy_up_start(struct dentry *dentry)
 {
-	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-	struct ovl_entry *oe = dentry->d_fsdata;
+	struct ovl_inode *oi = OVL_I(d_inode(dentry));
 	int err;
 
-	spin_lock(&ofs->copyup_wq.lock);
-	err = wait_event_interruptible_locked(ofs->copyup_wq, !oe->copying);
-	if (!err) {
-		if (oe->__upperdentry)
-			err = 1; /* Already copied up */
-		else
-			oe->copying = true;
+	err = mutex_lock_interruptible(&oi->lock);
+	if (!err && ovl_dentry_has_upper_alias(dentry)) {
+		err = 1; /* Already copied up */
+		mutex_unlock(&oi->lock);
 	}
-	spin_unlock(&ofs->copyup_wq.lock);
 
 	return err;
 }
 
 void ovl_copy_up_end(struct dentry *dentry)
 {
-	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
-	struct ovl_entry *oe = dentry->d_fsdata;
-
-	spin_lock(&ofs->copyup_wq.lock);
-	oe->copying = false;
-	wake_up_locked(&ofs->copyup_wq);
-	spin_unlock(&ofs->copyup_wq.lock);
+	mutex_unlock(&OVL_I(d_inode(dentry))->lock);
 }
 
 bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
@@ -343,9 +356,8 @@ int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
 int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
 {
 	int err;
-	struct ovl_entry *oe = dentry->d_fsdata;
 
-	if (oe->impure)
+	if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
 		return 0;
 
 	/*
@@ -355,7 +367,176 @@ int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
 	err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
 				 "y", 1, 0);
 	if (!err)
-		oe->impure = true;
+		ovl_set_flag(OVL_IMPURE, d_inode(dentry));
 
 	return err;
 }
+
+void ovl_set_flag(unsigned long flag, struct inode *inode)
+{
+	set_bit(flag, &OVL_I(inode)->flags);
+}
+
+bool ovl_test_flag(unsigned long flag, struct inode *inode)
+{
+	return test_bit(flag, &OVL_I(inode)->flags);
+}
+
+/**
+ * Caller must hold a reference to inode to prevent it from being freed while
+ * it is marked inuse.
+ */
+bool ovl_inuse_trylock(struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	bool locked = false;
+
+	spin_lock(&inode->i_lock);
+	if (!(inode->i_state & I_OVL_INUSE)) {
+		inode->i_state |= I_OVL_INUSE;
+		locked = true;
+	}
+	spin_unlock(&inode->i_lock);
+
+	return locked;
+}
+
+void ovl_inuse_unlock(struct dentry *dentry)
+{
+	if (dentry) {
+		struct inode *inode = d_inode(dentry);
+
+		spin_lock(&inode->i_lock);
+		WARN_ON(!(inode->i_state & I_OVL_INUSE));
+		inode->i_state &= ~I_OVL_INUSE;
+		spin_unlock(&inode->i_lock);
+	}
+}
+
+/* Called must hold OVL_I(inode)->oi_lock */
+static void ovl_cleanup_index(struct dentry *dentry)
+{
+	struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
+	struct dentry *lowerdentry = ovl_dentry_lower(dentry);
+	struct dentry *upperdentry = ovl_dentry_upper(dentry);
+	struct dentry *index = NULL;
+	struct inode *inode;
+	struct qstr name;
+	int err;
+
+	err = ovl_get_index_name(lowerdentry, &name);
+	if (err)
+		goto fail;
+
+	inode = d_inode(upperdentry);
+	if (inode->i_nlink != 1) {
+		pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
+				    upperdentry, inode->i_ino, inode->i_nlink);
+		/*
+		 * We either have a bug with persistent union nlink or a lower
+		 * hardlink was added while overlay is mounted. Adding a lower
+		 * hardlink and then unlinking all overlay hardlinks would drop
+		 * overlay nlink to zero before all upper inodes are unlinked.
+		 * As a safety measure, when that situation is detected, set
+		 * the overlay nlink to the index inode nlink minus one for the
+		 * index entry itself.
+		 */
+		set_nlink(d_inode(dentry), inode->i_nlink - 1);
+		ovl_set_nlink_upper(dentry);
+		goto out;
+	}
+
+	inode_lock_nested(dir, I_MUTEX_PARENT);
+	/* TODO: whiteout instead of cleanup to block future open by handle */
+	index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
+	err = PTR_ERR(index);
+	if (!IS_ERR(index))
+		err = ovl_cleanup(dir, index);
+	inode_unlock(dir);
+	if (err)
+		goto fail;
+
+out:
+	dput(index);
+	return;
+
+fail:
+	pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err);
+	goto out;
+}
+
+/*
+ * Operations that change overlay inode and upper inode nlink need to be
+ * synchronized with copy up for persistent nlink accounting.
+ */
+int ovl_nlink_start(struct dentry *dentry, bool *locked)
+{
+	struct ovl_inode *oi = OVL_I(d_inode(dentry));
+	const struct cred *old_cred;
+	int err;
+
+	if (!d_inode(dentry) || d_is_dir(dentry))
+		return 0;
+
+	/*
+	 * With inodes index is enabled, we store the union overlay nlink
+	 * in an xattr on the index inode. When whiting out lower hardlinks
+	 * we need to decrement the overlay persistent nlink, but before the
+	 * first copy up, we have no upper index inode to store the xattr.
+	 *
+	 * As a workaround, before whiteout/rename over of a lower hardlink,
+	 * copy up to create the upper index. Creating the upper index will
+	 * initialize the overlay nlink, so it could be dropped if unlink
+	 * or rename succeeds.
+	 *
+	 * TODO: implement metadata only index copy up when called with
+	 *       ovl_copy_up_flags(dentry, O_PATH).
+	 */
+	if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) &&
+	    d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) {
+		err = ovl_copy_up(dentry);
+		if (err)
+			return err;
+	}
+
+	err = mutex_lock_interruptible(&oi->lock);
+	if (err)
+		return err;
+
+	if (!ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+		goto out;
+
+	old_cred = ovl_override_creds(dentry->d_sb);
+	/*
+	 * The overlay inode nlink should be incremented/decremented IFF the
+	 * upper operation succeeds, along with nlink change of upper inode.
+	 * Therefore, before link/unlink/rename, we store the union nlink
+	 * value relative to the upper inode nlink in an upper inode xattr.
+	 */
+	err = ovl_set_nlink_upper(dentry);
+	revert_creds(old_cred);
+
+out:
+	if (err)
+		mutex_unlock(&oi->lock);
+	else
+		*locked = true;
+
+	return err;
+}
+
+void ovl_nlink_end(struct dentry *dentry, bool locked)
+{
+	if (locked) {
+		if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
+		    d_inode(dentry)->i_nlink == 0) {
+			const struct cred *old_cred;
+
+			old_cred = ovl_override_creds(dentry->d_sb);
+			ovl_cleanup_index(dentry);
+			revert_creds(old_cred);
+		}
+
+		mutex_unlock(&OVL_I(d_inode(dentry))->lock);
+	}
+}