[PATCH 2/2] btrfs: use __free to automatically free btrfs_path on exit

[Leo Martins <loemra.dev@gmail.com>]

Introduces the __free attribute to xattr.c. Marks the path variable in
the btrfs_getxattr(), btrfs_setxattr(), and btrfs_listxattr() functions
with the __free(btrfs_free_path) attribute. When a variable is marked
with the __free attribute, the kernel will automatically call the
specified function (in this case, btrfs_free_path()) on the variable
when it goes out of scope. This ensures that the memory allocated for
the variable is properly released, preventing potential memory leaks. By
using the __free attribute, we can simplify the code and reduce the risk
of memory-related bugs.

Test Plan:
Built and booted the kernel with patch applied
Ran btrfs/fstests to make sure that no regressions were introduced

Signed-off-by: Leo Martins <loemra.dev@gmail.com>
---
 fs/btrfs/xattr.c | 28 ++++++++--------------------
 1 file changed, 8 insertions(+), 20 deletions(-)

diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 738c7bb8ea7c..a8d5db02202b 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -29,9 +29,8 @@ int btrfs_getxattr(const struct inode *inode, const char *name,
 {
 	struct btrfs_dir_item *di;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	struct btrfs_path *path;
+	struct btrfs_path *path __free(btrfs_free_path) = NULL;
 	struct extent_buffer *leaf;
-	int ret = 0;
 	unsigned long data_ptr;
 
 	path = btrfs_alloc_path();
@@ -42,24 +41,20 @@ int btrfs_getxattr(const struct inode *inode, const char *name,
 	di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)),
 			name, strlen(name), 0);
 	if (!di) {
-		ret = -ENODATA;
-		goto out;
+		return -ENODATA;
 	} else if (IS_ERR(di)) {
-		ret = PTR_ERR(di);
-		goto out;
+		return PTR_ERR(di);
 	}
 
 	leaf = path->nodes[0];
 	/* if size is 0, that means we want the size of the attr */
 	if (!size) {
-		ret = btrfs_dir_data_len(leaf, di);
-		goto out;
+		return btrfs_dir_data_len(leaf, di);
 	}
 
 	/* now get the data out of our dir_item */
 	if (btrfs_dir_data_len(leaf, di) > size) {
-		ret = -ERANGE;
-		goto out;
+		return -ERANGE;
 	}
 
 	/*
@@ -73,11 +68,7 @@ int btrfs_getxattr(const struct inode *inode, const char *name,
 				   btrfs_dir_name_len(leaf, di));
 	read_extent_buffer(leaf, buffer, data_ptr,
 			   btrfs_dir_data_len(leaf, di));
-	ret = btrfs_dir_data_len(leaf, di);
-
-out:
-	btrfs_free_path(path);
-	return ret;
+	return btrfs_dir_data_len(leaf, di);
 }
 
 int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
@@ -86,7 +77,7 @@ int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
 	struct btrfs_dir_item *di = NULL;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_fs_info *fs_info = root->fs_info;
-	struct btrfs_path *path;
+	struct btrfs_path *path __free(btrfs_free_path) = NULL;
 	size_t name_len = strlen(name);
 	int ret = 0;
 
@@ -214,7 +205,6 @@ int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode,
 		 */
 	}
 out:
-	btrfs_free_path(path);
 	if (!ret) {
 		set_bit(BTRFS_INODE_COPY_EVERYTHING,
 			&BTRFS_I(inode)->runtime_flags);
@@ -280,7 +270,7 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 	struct btrfs_key key;
 	struct inode *inode = d_inode(dentry);
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	struct btrfs_path *path;
+	struct btrfs_path *path __free(btrfs_free_path) = NULL;
 	int iter_ret = 0;
 	int ret = 0;
 	size_t total_size = 0, size_left = size;
@@ -356,8 +346,6 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 	else
 		ret = total_size;
 
-	btrfs_free_path(path);
-
 	return ret;
 }
 
-- 
2.43.5