[PATCH v8 resend 0/2] avoid xfs transaction reservation recursion

[Yafang Shao <laoar.shao@gmail.com>]

This patchset avoids transaction reservation recursion by reintroducing
the discarded PF_FSTRANS in a new way, suggested by Dave. In this new
implementation, four new helpers are introduced, which are
xfs_trans_context_{set, clear, update, active},
suggested by Dave. And re-using the task->journal_info to indicates
whehter the task is in fstrans or not, suggested by Willy

Patch #1 is picked from Willy's patchset "Overhaul memalloc_no*"[1]

[1]
https://lore.kernel.org/linux-mm/20200625113122.7540-1-willy@infradead.org/

v8:
- check xfs_trans_context_active() in xfs_vm_writepage(s), per Dave.

v7:
- check fstrans recursion for XFS only, by introducing a new member in
  struct writeback_control.

v6:
- add Michal's ack and comment in patch #1.

v5:
- pick one of Willy's patch
- introduce four new helpers, per Dave

v4:
- retitle from "xfs: introduce task->in_fstrans for transaction reservation
  recursion protection"
- reuse current->journal_info, per Willy


Matthew Wilcox (Oracle) (1):
  mm: Add become_kswapd and restore_kswapd

Yafang Shao (1):
  xfs: avoid transaction reservation recursion

 fs/iomap/buffered-io.c    |  7 -------
 fs/xfs/libxfs/xfs_btree.c | 14 ++++++++------
 fs/xfs/xfs_aops.c         | 23 +++++++++++++++++++++--
 fs/xfs/xfs_linux.h        |  4 ----
 fs/xfs/xfs_trans.c        | 19 +++++++++----------
 fs/xfs/xfs_trans.h        | 30 ++++++++++++++++++++++++++++++
 include/linux/sched/mm.h  | 23 +++++++++++++++++++++++
 mm/vmscan.c               | 16 +---------------
 8 files changed, 92 insertions(+), 44 deletions(-)

-- 
1.8.3.1