Merge tag 'for-6.12-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:

 - fix dangling pointer to rb-tree of defragmented inodes after cleanup

 - a followup fix to handle concurrent lseek on the same fd that could
   leak memory under some conditions

 - fix wrong root id reported in tree checker when verifying dref

* tag 'for-6.12-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix use-after-free on rbtree that tracks inodes for auto defrag
  btrfs: tree-checker: fix the wrong output of data backref objectid
  btrfs: fix race setting file private on concurrent lseek using same fd

5 files changed, 37 insertions, 4 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 9a4b7c119318..e152fde888fc 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -152,6 +152,7 @@ struct btrfs_inode {
 	 * logged_trans), to access/update delalloc_bytes, new_delalloc_bytes,
 	 * defrag_bytes, disk_i_size, outstanding_extents, csum_bytes and to
 	 * update the VFS' inode number of bytes used.
+	 * Also protects setting struct file::private_data.
 	 */
 	spinlock_t lock;
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1a44fb9845e3..317a3712270f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -463,6 +463,8 @@ struct btrfs_file_private {
 	void *filldir_buf;
 	u64 last_index;
 	struct extent_state *llseek_cached_state;
+	/* Task that allocated this structure. */
+	struct task_struct *owner_task;
 };
 
 static inline u32 BTRFS_LEAF_DATA_SIZE(const struct btrfs_fs_info *info)
diff --git a/fs/btrfs/defrag.c b/fs/btrfs/defrag.c
index acf1f39e45d0..b95ef44c326b 100644
--- a/fs/btrfs/defrag.c
+++ b/fs/btrfs/defrag.c
@@ -213,6 +213,8 @@ void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
 					     &fs_info->defrag_inodes, rb_node)
 		kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
 
+	fs_info->defrag_inodes = RB_ROOT;
+
 	spin_unlock(&fs_info->defrag_inodes_lock);
 }
 
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index c5e36f58eb07..4fb521d91b06 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3485,7 +3485,7 @@ static bool find_desired_extent_in_hole(struct btrfs_inode *inode, int whence,
 static loff_t find_desired_extent(struct file *file, loff_t offset, int whence)
 {
 	struct btrfs_inode *inode = BTRFS_I(file->f_mapping->host);
-	struct btrfs_file_private *private = file->private_data;
+	struct btrfs_file_private *private;
 	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct extent_state *cached_state = NULL;
 	struct extent_state **delalloc_cached_state;
@@ -3513,7 +3513,19 @@ static loff_t find_desired_extent(struct file *file, loff_t offset, int whence)
 	    inode_get_bytes(&inode->vfs_inode) == i_size)
 		return i_size;
 
-	if (!private) {
+	spin_lock(&inode->lock);
+	private = file->private_data;
+	spin_unlock(&inode->lock);
+
+	if (private && private->owner_task != current) {
+		/*
+		 * Not allocated by us, don't use it as its cached state is used
+		 * by the task that allocated it and we don't want neither to
+		 * mess with it nor get incorrect results because it reflects an
+		 * invalid state for the current task.
+		 */
+		private = NULL;
+	} else if (!private) {
 		private = kzalloc(sizeof(*private), GFP_KERNEL);
 		/*
 		 * No worries if memory allocation failed.
@@ -3521,7 +3533,23 @@ static loff_t find_desired_extent(struct file *file, loff_t offset, int whence)
 		 * lseek SEEK_HOLE/DATA calls to a file when there's delalloc,
 		 * so everything will still be correct.
 		 */
-		file->private_data = private;
+		if (private) {
+			bool free = false;
+
+			private->owner_task = current;
+
+			spin_lock(&inode->lock);
+			if (file->private_data)
+				free = true;
+			else
+				file->private_data = private;
+			spin_unlock(&inode->lock);
+
+			if (free) {
+				kfree(private);
+				private = NULL;
+			}
+		}
 	}
 
 	if (private)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 634d69964fe4..7b50263723bc 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -1517,7 +1517,7 @@ static int check_extent_item(struct extent_buffer *leaf,
 				     dref_objectid > BTRFS_LAST_FREE_OBJECTID)) {
 				extent_err(leaf, slot,
 					   "invalid data ref objectid value %llu",
-					   dref_root);
+					   dref_objectid);
 				return -EUCLEAN;
 			}
 			if (unlikely(!IS_ALIGNED(dref_offset,