fuse: fix wrong ff->iomode state changes from parallel dio write

There is a confusion with fuse_file_uncached_io_{start,end} interface.
These helpers do two things when called from passthrough open()/release():
1. Take/drop negative refcount of fi->iocachectr (inode uncached io mode)
2. State change ff->iomode IOM_NONE <-> IOM_UNCACHED (file uncached open)

The calls from parallel dio write path need to take a reference on
fi->iocachectr, but they should not be changing ff->iomode state, because
in this case, the fi->iocachectr reference does not stick around until file
release().

Factor out helpers fuse_inode_uncached_io_{start,end}, to be used from
parallel dio write path and rename fuse_file_*cached_io_{start,end} helpers
to fuse_file_*cached_io_{open,release} to clarify the difference.

Fixes: 205c1d802683 ("fuse: allow parallel dio writes with FUSE_DIRECT_IO_ALLOW_MMAP")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 3a5d88878335..99e44ea7d875 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -175,6 +175,7 @@ static void fuse_evict_inode(struct inode *inode)
 		}
 	}
 	if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
+		WARN_ON(fi->iocachectr != 0);
 		WARN_ON(!list_empty(&fi->write_files));
 		WARN_ON(!list_empty(&fi->queued_writes));
 	}