[PATCH 0/3] Btrfs: stop abusing current->journal_info for direct I/O

[Omar Sandoval <osandov@osandov.com>]

From: Omar Sandoval <osandov@fb.com>

Hi, everyone,

Btrfs currently abuses current->journal_info in btrfs_direct_IO() in
order to pass around some state to get_block() and submit_io(). This
hack is ugly and unnecessary because the data we pass around is only
used in one call frame. Robbie Ko also pointed out [1] that it could
potentially cause a crash if we happen to end up in start_transaction()
(e.g., from memory reclaim calling into btrfs_evict_inode(), which can
start a transaction). I'm not convinced that Robbie's case can happen in
practice since we are using GFP_NOFS for allocations during direct I/O,
but either way it's fragile and nasty.

This series stops using current->journal_info and instead adds some
extra arguments to the generic direct I/O code so that we can pass
things around like sane people.

Based on Linus' master.

Thanks!

1: https://patchwork.kernel.org/patch/10389077/

Omar Sandoval (3):
  fs: add initial bh_result->b_private value to __blockdev_direct_IO()
  fs: add private argument to dio_submit_t
  Btrfs: stop abusing current->journal_info in btrfs_direct_IO()

 fs/btrfs/inode.c   | 39 ++++++++++-----------------------------
 fs/direct-io.c     | 12 +++++++-----
 fs/ext4/inode.c    |  6 +++---
 fs/gfs2/aops.c     |  2 +-
 fs/ocfs2/aops.c    |  5 ++---
 include/linux/fs.h | 10 +++++-----
 6 files changed, 28 insertions(+), 46 deletions(-)

-- 
2.17.0