[v2,0/3] btrfs path auto free

Message

Leo Martins Aug. 27, 2024, 7:08 p.m. UTC

The DEFINE_FREE macro defines a wrapper function for a given memory
cleanup function which takes a pointer as an argument and calls the
cleanup function with the value of the pointer. The __free macro adds
a scoped-based cleanup to a variable, using the __cleanup attribute
to specify the cleanup function that should be called when the variable
goes out of scope.

Using this cleanup code pattern ensures that memory is properly freed
when it's no longer needed, preventing memory leaks and reducing the
risk of crashes or other issues caused by incorrect memory management.
Even if the code is already memory safe, using this pattern reduces
the risk of introducing memory-related bugs in the future

In this series of patches I've added a DEFINE_FREE for btrfs_free_path
and created a macro BTRFS_PATH_AUTO_FREE to clearly identify path
declarations that will be automatically freed.

I've included some simple examples of where this pattern can be used.
The trivial examples are ones where there is one exit path and the only
cleanup performed is a call to btrfs_free_path.

There appear to be around 130 instances that would be a pretty simple to
convert to this pattern. Is it worth going back and updating
all trivial instances or would it be better to leave them and use the pattern
in new code? Another option is to have all path declarations declared
with BTRFS_PATH_AUTO_FREE and not remove any btrfs_free_path instances.
In theory this would not change the functionality as it is fine to call
btrfs_free_path on an already freed path.

Leo Martins (3):
  btrfs: DEFINE_FREE for btrfs_free_path
  btrfs: BTRFS_PATH_AUTO_FREE in zoned.c
  btrfs: BTRFS_PATH_AUTO_FREE in orphan.c

 fs/btrfs/ctree.c  |  2 +-
 fs/btrfs/ctree.h  |  4 ++++
 fs/btrfs/orphan.c | 19 ++++++-------------
 fs/btrfs/zoned.c  | 34 +++++++++++-----------------------
 4 files changed, 22 insertions(+), 37 deletions(-)