Btrfs: fix dentry->d_parent abuses V2

Btrfs: fix dentry->d_parent abuses V2

[Josef Bacik]

Christoph pointed out that my original d_parent cleanup patch was big and hard
to review since it really did 3 seperate things. The cleanup is broke up like
this

1) For places we have to use dentry->d_parent, use dget_parent/dput
2) For places where we already have the parent inode anyway, use that instead
3) A small safety fix for btrfs_log_dentry_safe

These patches make up the original patch that I posted, and have been tested
with xfstests, and have been in my tree for 2 weeks with all of the other work
I've been doing and have survived fine.  Thanks,

Josef

[PATCH 1/3] Btrfs: use dget_parent where we can

[Josef Bacik]

There are lots of places where we do dentry->d_parent->d_inode without holding
the dentry->d_lock.  This could cause problems with rename.  So instead we need
to use dget_parent() and hold the reference to the parent as long as we are
going to use it's inode and then dput it at the end.

Signed-off-by: Josef Bacik <josef@redhat.com>
Cc: raven@themaw.net
---
 fs/btrfs/inode.c       |    9 ++++++---
 fs/btrfs/ioctl.c       |   20 ++++++++++++++++----
 fs/btrfs/transaction.c |    5 ++++-
 fs/btrfs/tree-log.c    |   21 +++++++++++++++++----
 4 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 558cac2..5cce618 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4810,10 +4810,12 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	if (err) {
 		drop_inode = 1;
 	} else {
+		struct dentry *parent = dget_parent(dentry);
 		btrfs_update_inode_block_group(trans, dir);
 		err = btrfs_update_inode(trans, root, inode);
 		BUG_ON(err);
-		btrfs_log_new_name(trans, inode, NULL, dentry->d_parent);
+		btrfs_log_new_name(trans, inode, NULL, parent);
+		dput(parent);
 	}
 
 	nr = trans->blocks_used;
@@ -6607,9 +6609,10 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	BUG_ON(ret);
 
 	if (old_inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
-		btrfs_log_new_name(trans, old_inode, old_dir,
-				   new_dentry->d_parent);
+		struct dentry *parent = dget_parent(new_dentry);
+		btrfs_log_new_name(trans, old_inode, old_dir, parent);
 		btrfs_end_log_trans(root);
+		dput(parent);
 	}
 out_fail:
 	btrfs_end_transaction_throttle(trans, root);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 463d91b..5dba458 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -233,7 +233,8 @@ static noinline int create_subvol(struct btrfs_root *root,
 	struct btrfs_inode_item *inode_item;
 	struct extent_buffer *leaf;
 	struct btrfs_root *new_root;
-	struct inode *dir = dentry->d_parent->d_inode;
+	struct dentry *parent = dget_parent(dentry);
+	struct inode *dir;
 	int ret;
 	int err;
 	u64 objectid;
@@ -242,8 +243,13 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	ret = btrfs_find_free_objectid(NULL, root->fs_info->tree_root,
 				       0, &objectid);
-	if (ret)
+	if (ret) {
+		dput(parent);
 		return ret;
+	}
+
+	dir = parent->d_inode;
+
 	/*
 	 * 1 - inode item
 	 * 2 - refs
@@ -251,8 +257,10 @@ static noinline int create_subvol(struct btrfs_root *root,
 	 * 2 - dir items
 	 */
 	trans = btrfs_start_transaction(root, 6);
-	if (IS_ERR(trans))
+	if (IS_ERR(trans)) {
+		dput(parent);
 		return PTR_ERR(trans);
+	}
 
 	leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
 				      0, objectid, NULL, 0, 0, 0);
@@ -339,6 +347,7 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
 fail:
+	dput(parent);
 	if (async_transid) {
 		*async_transid = trans->transid;
 		err = btrfs_commit_transaction_async(trans, root, 1);
@@ -354,6 +363,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 			   char *name, int namelen, u64 *async_transid)
 {
 	struct inode *inode;
+	struct dentry *parent;
 	struct btrfs_pending_snapshot *pending_snapshot;
 	struct btrfs_trans_handle *trans;
 	int ret;
@@ -396,7 +406,9 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 
 	btrfs_orphan_cleanup(pending_snapshot->snap);
 
-	inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
+	parent = dget_parent(dentry);
+	inode = btrfs_lookup_dentry(parent->d_inode, dentry);
+	dput(parent);
 	if (IS_ERR(inode)) {
 		ret = PTR_ERR(inode);
 		goto fail;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 1fffbc0..f50e931 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -902,6 +902,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root = pending->root;
 	struct btrfs_root *parent_root;
 	struct inode *parent_inode;
+	struct dentry *parent;
 	struct dentry *dentry;
 	struct extent_buffer *tmp;
 	struct extent_buffer *old;
@@ -941,7 +942,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	trans->block_rsv = &pending->block_rsv;
 
 	dentry = pending->dentry;
-	parent_inode = dentry->d_parent->d_inode;
+	parent = dget_parent(dentry);
+	parent_inode = parent->d_inode;
 	parent_root = BTRFS_I(parent_inode)->root;
 	record_root_in_trans(trans, parent_root);
 
@@ -989,6 +991,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 				 parent_inode->i_ino, index,
 				 dentry->d_name.name, dentry->d_name.len);
 	BUG_ON(ret);
+	dput(parent);
 
 	key.offset = (u64)-1;
 	pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a29f193..77df14b 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2869,6 +2869,7 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 {
 	int ret = 0;
 	struct btrfs_root *root;
+	struct dentry *old_parent = NULL;
 
 	/*
 	 * for regular files, if its inode is already on disk, we don't
@@ -2910,10 +2911,13 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
 		inode = parent->d_inode;
 
 	}
+	dput(old_parent);
 out:
 	return ret;
 }
@@ -2945,6 +2949,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 {
 	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
 	struct super_block *sb;
+	struct dentry *old_parent = NULL;
 	int ret = 0;
 	u64 last_committed = root->fs_info->last_trans_committed;
 
@@ -3016,10 +3021,13 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget(parent);
+		dput(old_parent);
+		old_parent = parent;
 	}
 	ret = 0;
 end_trans:
+	dput(old_parent);
 	if (ret < 0) {
 		BUG_ON(ret != -ENOSPC);
 		root->fs_info->last_trans_log_full_commit = trans->transid;
@@ -3039,8 +3047,13 @@ end_no_trans:
 int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root, struct dentry *dentry)
 {
-	return btrfs_log_inode_parent(trans, root, dentry->d_inode,
-				      dentry->d_parent, 0);
+	struct dentry *parent = dget_parent(dentry);
+	int ret;
+
+	ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, 0);
+	dput(parent);
+
+	return ret;
 }
 
 /*
-- 
1.6.6.1

[PATCH 2/3] Btrfs: hold i_mutex when calling btrfs_log_dentry_safe

[Josef Bacik]

Since we walk up the path logging all of the parts of the inode's path, we need
to hold i_mutex to make sure that the inode is not renamed while we're logging
everything.  btrfs_log_dentry_safe does dget_parent and all of that jazz, but we
may get unexpected results if the rename changes the inode's location while
we're higher up the path logging those dentries, so do this for safety reasons.
Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/btrfs/file.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index e354c33..c1faded 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1047,8 +1047,14 @@ out:
 
 		if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
 			trans = btrfs_start_transaction(root, 0);
+			if (IS_ERR(trans)) {
+				num_written = PTR_ERR(trans);
+				goto done;
+			}
+			mutex_lock(&inode->i_mutex);
 			ret = btrfs_log_dentry_safe(trans, root,
 						    file->f_dentry);
+			mutex_unlock(&inode->i_mutex);
 			if (ret == 0) {
 				ret = btrfs_sync_log(trans, root);
 				if (ret == 0)
@@ -1067,6 +1073,7 @@ out:
 			     (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
 		}
 	}
+done:
 	current->backing_dev_info = NULL;
 	return num_written ? num_written : err;
 }
-- 
1.6.6.1

[PATCH 3/3] Btrfs: make btrfs_add_nondir take parent inode as an argument

[Josef Bacik]

Everybody who calls btrfs_add_nondir just passes in the dentry of the new file
and then dereference dentry->d_parent->d_inode, but everybody who calls
btrfs_add_nondir() are already passed the parent's inode.  So instead of
dereferencing dentry->d_parent, just make btrfs_add_nondir take the dir inode as
an argument and pass that along so we don't have to worry about d_parent.
Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/btrfs/inode.c |   38 ++++++++++++++++----------------------
 1 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5cce618..2579207 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4622,12 +4622,12 @@ int btrfs_add_link(struct btrfs_trans_handle *trans,
 }
 
 static int btrfs_add_nondir(struct btrfs_trans_handle *trans,
-			    struct dentry *dentry, struct inode *inode,
-			    int backref, u64 index)
+			    struct inode *dir, struct dentry *dentry,
+			    struct inode *inode, int backref, u64 index)
 {
-	int err = btrfs_add_link(trans, dentry->d_parent->d_inode,
-				 inode, dentry->d_name.name,
-				 dentry->d_name.len, backref, index);
+	int err = btrfs_add_link(trans, dir, inode,
+				 dentry->d_name.name, dentry->d_name.len,
+				 backref, index);
 	if (!err) {
 		d_instantiate(dentry, inode);
 		return 0;
@@ -4668,8 +4668,7 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
 	btrfs_set_trans_block_group(trans, dir);
 
 	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
-				dentry->d_name.len,
-				dentry->d_parent->d_inode->i_ino, objectid,
+				dentry->d_name.len, dir->i_ino, objectid,
 				BTRFS_I(dir)->block_group, mode, &index);
 	err = PTR_ERR(inode);
 	if (IS_ERR(inode))
@@ -4682,7 +4681,7 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
 	}
 
 	btrfs_set_trans_block_group(trans, inode);
-	err = btrfs_add_nondir(trans, dentry, inode, 0, index);
+	err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
 	if (err)
 		drop_inode = 1;
 	else {
@@ -4730,10 +4729,8 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 	btrfs_set_trans_block_group(trans, dir);
 
 	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
-				dentry->d_name.len,
-				dentry->d_parent->d_inode->i_ino,
-				objectid, BTRFS_I(dir)->block_group, mode,
-				&index);
+				dentry->d_name.len, dir->i_ino, objectid,
+				BTRFS_I(dir)->block_group, mode, &index);
 	err = PTR_ERR(inode);
 	if (IS_ERR(inode))
 		goto out_unlock;
@@ -4745,7 +4742,7 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 	}
 
 	btrfs_set_trans_block_group(trans, inode);
-	err = btrfs_add_nondir(trans, dentry, inode, 0, index);
+	err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
 	if (err)
 		drop_inode = 1;
 	else {
@@ -4805,7 +4802,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	btrfs_set_trans_block_group(trans, dir);
 	ihold(inode);
 
-	err = btrfs_add_nondir(trans, dentry, inode, 1, index);
+	err = btrfs_add_nondir(trans, dir, dentry, inode, 1, index);
 
 	if (err) {
 		drop_inode = 1;
@@ -4855,8 +4852,7 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 	btrfs_set_trans_block_group(trans, dir);
 
 	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
-				dentry->d_name.len,
-				dentry->d_parent->d_inode->i_ino, objectid,
+				dentry->d_name.len, dir->i_ino, objectid,
 				BTRFS_I(dir)->block_group, S_IFDIR | mode,
 				&index);
 	if (IS_ERR(inode)) {
@@ -4879,9 +4875,8 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 	if (err)
 		goto out_fail;
 
-	err = btrfs_add_link(trans, dentry->d_parent->d_inode,
-				 inode, dentry->d_name.name,
-				 dentry->d_name.len, 0, index);
+	err = btrfs_add_link(trans, dir, inode, dentry->d_name.name,
+			     dentry->d_name.len, 0, index);
 	if (err)
 		goto out_fail;
 
@@ -6761,8 +6756,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 	btrfs_set_trans_block_group(trans, dir);
 
 	inode = btrfs_new_inode(trans, root, dir, dentry->d_name.name,
-				dentry->d_name.len,
-				dentry->d_parent->d_inode->i_ino, objectid,
+				dentry->d_name.len, dir->i_ino, objectid,
 				BTRFS_I(dir)->block_group, S_IFLNK|S_IRWXUGO,
 				&index);
 	err = PTR_ERR(inode);
@@ -6776,7 +6770,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 	}
 
 	btrfs_set_trans_block_group(trans, inode);
-	err = btrfs_add_nondir(trans, dentry, inode, 0, index);
+	err = btrfs_add_nondir(trans, dir, dentry, inode, 0, index);
 	if (err)
 		drop_inode = 1;
 	else {
-- 
1.6.6.1

[PATCH] Btrfs: use dget_parent where we can UPDATED

[Josef Bacik]

There are lots of places where we do dentry->d_parent->d_inode without holding
the dentry->d_lock.  This could cause problems with rename.  So instead we need
to use dget_parent() and hold the reference to the parent as long as we are
going to use it's inode and then dput it at the end.

Signed-off-by: Josef Bacik <josef@redhat.com>
Cc: raven@themaw.net
---
-screwed up and used dget() instead of dget_parent() in one place

 fs/btrfs/inode.c       |    9 ++++++---
 fs/btrfs/ioctl.c       |   20 ++++++++++++++++----
 fs/btrfs/transaction.c |    5 ++++-
 fs/btrfs/tree-log.c    |   21 +++++++++++++++++----
 4 files changed, 43 insertions(+), 12 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 558cac2..821ec73 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4810,10 +4810,12 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
 	if (err) {
 		drop_inode = 1;
 	} else {
+		struct dentry *parent = dget_parent(dentry);
 		btrfs_update_inode_block_group(trans, dir);
 		err = btrfs_update_inode(trans, root, inode);
 		BUG_ON(err);
-		btrfs_log_new_name(trans, inode, NULL, dentry->d_parent);
+		btrfs_log_new_name(trans, inode, NULL, parent);
+		dput(parent);
 	}
 
 	nr = trans->blocks_used;
@@ -6607,8 +6609,9 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	BUG_ON(ret);
 
 	if (old_inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
-		btrfs_log_new_name(trans, old_inode, old_dir,
-				   new_dentry->d_parent);
+		struct dentry *parent = dget_parent(new_dentry);
+		btrfs_log_new_name(trans, old_inode, old_dir, parent);
+		dput(parent);
 		btrfs_end_log_trans(root);
 	}
 out_fail:
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 463d91b..5dba458 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -233,7 +233,8 @@ static noinline int create_subvol(struct btrfs_root *root,
 	struct btrfs_inode_item *inode_item;
 	struct extent_buffer *leaf;
 	struct btrfs_root *new_root;
-	struct inode *dir = dentry->d_parent->d_inode;
+	struct dentry *parent = dget_parent(dentry);
+	struct inode *dir;
 	int ret;
 	int err;
 	u64 objectid;
@@ -242,8 +243,13 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	ret = btrfs_find_free_objectid(NULL, root->fs_info->tree_root,
 				       0, &objectid);
-	if (ret)
+	if (ret) {
+		dput(parent);
 		return ret;
+	}
+
+	dir = parent->d_inode;
+
 	/*
 	 * 1 - inode item
 	 * 2 - refs
@@ -251,8 +257,10 @@ static noinline int create_subvol(struct btrfs_root *root,
 	 * 2 - dir items
 	 */
 	trans = btrfs_start_transaction(root, 6);
-	if (IS_ERR(trans))
+	if (IS_ERR(trans)) {
+		dput(parent);
 		return PTR_ERR(trans);
+	}
 
 	leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
 				      0, objectid, NULL, 0, 0, 0);
@@ -339,6 +347,7 @@ static noinline int create_subvol(struct btrfs_root *root,
 
 	d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
 fail:
+	dput(parent);
 	if (async_transid) {
 		*async_transid = trans->transid;
 		err = btrfs_commit_transaction_async(trans, root, 1);
@@ -354,6 +363,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 			   char *name, int namelen, u64 *async_transid)
 {
 	struct inode *inode;
+	struct dentry *parent;
 	struct btrfs_pending_snapshot *pending_snapshot;
 	struct btrfs_trans_handle *trans;
 	int ret;
@@ -396,7 +406,9 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
 
 	btrfs_orphan_cleanup(pending_snapshot->snap);
 
-	inode = btrfs_lookup_dentry(dentry->d_parent->d_inode, dentry);
+	parent = dget_parent(dentry);
+	inode = btrfs_lookup_dentry(parent->d_inode, dentry);
+	dput(parent);
 	if (IS_ERR(inode)) {
 		ret = PTR_ERR(inode);
 		goto fail;
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 1fffbc0..f50e931 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -902,6 +902,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	struct btrfs_root *root = pending->root;
 	struct btrfs_root *parent_root;
 	struct inode *parent_inode;
+	struct dentry *parent;
 	struct dentry *dentry;
 	struct extent_buffer *tmp;
 	struct extent_buffer *old;
@@ -941,7 +942,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	trans->block_rsv = &pending->block_rsv;
 
 	dentry = pending->dentry;
-	parent_inode = dentry->d_parent->d_inode;
+	parent = dget_parent(dentry);
+	parent_inode = parent->d_inode;
 	parent_root = BTRFS_I(parent_inode)->root;
 	record_root_in_trans(trans, parent_root);
 
@@ -989,6 +991,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 				 parent_inode->i_ino, index,
 				 dentry->d_name.name, dentry->d_name.len);
 	BUG_ON(ret);
+	dput(parent);
 
 	key.offset = (u64)-1;
 	pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a29f193..054744a 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2869,6 +2869,7 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 {
 	int ret = 0;
 	struct btrfs_root *root;
+	struct dentry *old_parent = NULL;
 
 	/*
 	 * for regular files, if its inode is already on disk, we don't
@@ -2910,10 +2911,13 @@ static noinline int check_parent_dirs_for_sync(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
 		inode = parent->d_inode;
 
 	}
+	dput(old_parent);
 out:
 	return ret;
 }
@@ -2945,6 +2949,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 {
 	int inode_only = exists_only ? LOG_INODE_EXISTS : LOG_INODE_ALL;
 	struct super_block *sb;
+	struct dentry *old_parent = NULL;
 	int ret = 0;
 	u64 last_committed = root->fs_info->last_trans_committed;
 
@@ -3016,10 +3021,13 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 		if (IS_ROOT(parent))
 			break;
 
-		parent = parent->d_parent;
+		parent = dget_parent(parent);
+		dput(old_parent);
+		old_parent = parent;
 	}
 	ret = 0;
 end_trans:
+	dput(old_parent);
 	if (ret < 0) {
 		BUG_ON(ret != -ENOSPC);
 		root->fs_info->last_trans_log_full_commit = trans->transid;
@@ -3039,8 +3047,13 @@ end_no_trans:
 int btrfs_log_dentry_safe(struct btrfs_trans_handle *trans,
 			  struct btrfs_root *root, struct dentry *dentry)
 {
-	return btrfs_log_inode_parent(trans, root, dentry->d_inode,
-				      dentry->d_parent, 0);
+	struct dentry *parent = dget_parent(dentry);
+	int ret;
+
+	ret = btrfs_log_inode_parent(trans, root, dentry->d_inode, parent, 0);
+	dput(parent);
+
+	return ret;
 }
 
 /*
-- 
1.6.6.1