Fix mmap + page fault deadlocks

This set fixes a process hang issue in btrfs and gf2 filesystems. When we do a direct IO read or write when the buffer given by the user is memory-mapped to the file range we are going to do IO, we end up ending in a deadlock. This is triggered by the test case generic/647 from fstests.

This fix depends on the iov_iter and iomap changes introduced in the commit c03098d4b9ad ("Merge tag 'gfs2-v5.15-rc5-mmap-fault' of
git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2") and they are part of this set for stable-5.15.y.

Please note that patch 3/17 in this patchset changes the prototype and renames an exported symbol as below. All its references are updated as well.

-EXPORT_SYMBOL(iov_iter_fault_in_readable);
+EXPORT_SYMBOL(fault_in_iov_iter_readable);

Andreas Gruenbacher (15):
powerpc/kvm: Fix kvm_use_magic_page
gup: Turn fault_in_pages_{readable,writeable} into

    fault_in_{readable,writeable}

iov_iter: Turn iov_iter_fault_in_readable into
fault_in_iov_iter_readable
iov_iter: Introduce fault_in_iov_iter_writeable
gfs2: Add wrapper for iomap_file_buffered_write
gfs2: Clean up function may_grant
gfs2: Move the inode glock locking to gfs2_file_buffered_write
gfs2: Eliminate ip->i_gh
gfs2: Fix mmap + page fault deadlocks for buffered I/O
iomap: Fix iomap_dio_rw return value for user copies
iomap: Support partial direct I/O on user copy failures
iomap: Add done_before argument to iomap_dio_rw
gup: Introduce FOLL_NOFAULT flag to disable page faults
iov_iter: Introduce nofault flag to disable page faults
gfs2: Fix mmap + page fault deadlocks for direct I/O

Bob Peterson (1):
gfs2: Introduce flag for glock holder auto-demotion

Filipe Manana (1):
btrfs: fix deadlock due to page faults during direct IO reads and
writes

 arch/powerpc/kernel/kvm.c           |   3 +-
 arch/powerpc/kernel/signal_32.c     |   4 +-
 arch/powerpc/kernel/signal_64.c     |   2 +-
 arch/x86/kernel/fpu/signal.c        |   7 +-
 drivers/gpu/drm/armada/armada_gem.c |   7 +-
 fs/btrfs/file.c                     | 142 ++++++++++--
 fs/btrfs/ioctl.c                    |   5 +-
 fs/erofs/data.c                     |   2 +-
 fs/ext4/file.c                      |   5 +-
 fs/f2fs/file.c                      |   2 +-
 fs/fuse/file.c                      |   2 +-
 fs/gfs2/bmap.c                      |  60 +----
 fs/gfs2/file.c                      | 252 +++++++++++++++++++--
 fs/gfs2/glock.c                     | 330 +++++++++++++++++++++-------
 fs/gfs2/glock.h                     |  20 ++
 fs/gfs2/incore.h                    |   4 +-
 fs/iomap/buffered-io.c              |   2 +-
 fs/iomap/direct-io.c                |  29 ++-
 fs/ntfs/file.c                      |   2 +-
 fs/ntfs3/file.c                     |   2 +-
 fs/xfs/xfs_file.c                   |   6 +-
 fs/zonefs/super.c                   |   4 +-
 include/linux/iomap.h               |  11 +-
 include/linux/mm.h                  |   3 +-
 include/linux/pagemap.h             |  58 +----
 include/linux/uio.h                 |   4 +-
 lib/iov_iter.c                      |  98 +++++++--
 mm/filemap.c                        |   4 +-
 mm/gup.c                            | 139 +++++++++++-
 29 files changed, 911 insertions(+), 298 deletions(-)

2.33.1