fuse: disable FOPEN_PARALLEL_DIRECT_WRITES with FUSE_DIRECT_IO_ALLOW_MMAP

The new fuse init flag FUSE_DIRECT_IO_ALLOW_MMAP breaks assumptions made by
FOPEN_PARALLEL_DIRECT_WRITES and causes test generic/095 to hit
BUG_ON(fi->writectr < 0) assertions in fuse_set_nowrite():

generic/095 5s ...
  kernel BUG at fs/fuse/dir.c:1756!
...
  ? fuse_set_nowrite+0x3d/0xdd
  ? do_raw_spin_unlock+0x88/0x8f
  ? _raw_spin_unlock+0x2d/0x43
  ? fuse_range_is_writeback+0x71/0x84
  fuse_sync_writes+0xf/0x19
  fuse_direct_io+0x167/0x5bd
  fuse_direct_write_iter+0xf0/0x146

Auto disable FOPEN_PARALLEL_DIRECT_WRITES when server negotiated
FUSE_DIRECT_IO_ALLOW_MMAP.

Fixes: e78662e818f9 ("fuse: add a new fuse init flag to relax restrictions in no cache mode")
Cc: <stable@vger.kernel.org> # v6.6
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 89e870d1a5262edf48c0b61b63333459ba2d913b..a660f1f21540abbb3dd60e876ca81a587af3336e 100644 (file)
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1574,6 +1574,7 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
        ssize_t res;
        bool exclusive_lock =
                !(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) ||
+               get_fuse_conn(inode)->direct_io_allow_mmap ||
                iocb->ki_flags & IOCB_APPEND ||
                fuse_direct_write_extending_i_size(iocb, from);
 
@@ -1581,6 +1582,7 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
         * Take exclusive lock if
         * - Parallel direct writes are disabled - a user space decision
         * - Parallel direct writes are enabled and i_size is being extended.
+        * - Shared mmap on direct_io file is supported (FUSE_DIRECT_IO_ALLOW_MMAP).
         *   This might not be needed at all, but needs further investigation.
         */
        if (exclusive_lock)