fuse: introduce inode io modes

The fuse inode io mode is determined by the mode of its open files/mmaps
and parallel dio opens and expressed in the value of fi->iocachectr:

 > 0 - caching io: files open in caching mode or mmap on direct_io file
 < 0 - parallel dio: direct io mode with parallel dio writes enabled
== 0 - direct io: no files open in caching mode and no files mmaped

Note that iocachectr value of 0 might become positive or negative,
while non-parallel dio is getting processed.

direct_io mmap uses page cache, so first mmap will mark the file as
ff->io_opened and increment fi->iocachectr to enter the caching io mode.

If the server opens the file in caching mode while it is already open
for parallel dio or vice versa the open fails.

This allows executing parallel dio when inode is not in caching mode
and no mmaps have been performed on the inode in question.

Signed-off-by: Bernd Schubert <bschubert@ddn.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 27f50b4bd7f3..9af356fbc578 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -113,6 +113,9 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
 		struct fuse_release_args *ra = ff->release_args;
 		struct fuse_args *args = (ra ? &ra->args : NULL);
 
+		if (ra && ra->inode)
+			fuse_file_io_release(ff, ra->inode);
+
 		if (!args) {
 			/* Do nothing when server does not implement 'open' */
 		} else if (sync) {
@@ -204,6 +207,11 @@ int fuse_finish_open(struct inode *inode, struct file *file)
 {
 	struct fuse_file *ff = file->private_data;
 	struct fuse_conn *fc = get_fuse_conn(inode);
+	int err;
+
+	err = fuse_file_io_open(file, inode);
+	if (err)
+		return err;
 
 	if (ff->open_flags & FOPEN_STREAM)
 		stream_open(inode, file);
@@ -2509,6 +2517,7 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct fuse_file *ff = file->private_data;
 	struct fuse_conn *fc = ff->fm->fc;
+	int rc;
 
 	/* DAX mmap is superior to direct_io mmap */
 	if (FUSE_IS_DAX(file_inode(file)))
@@ -2528,6 +2537,11 @@ static int fuse_file_mmap(struct file *file, struct vm_area_struct *vma)
 			/* MAP_PRIVATE */
 			return generic_file_mmap(file, vma);
 		}
+
+		/* First mmap of direct_io file enters caching inode io mode. */
+		rc = fuse_file_cached_io_start(file_inode(file), ff);
+		if (rc)
+			return rc;
 	}
 
 	if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
@@ -3296,6 +3310,7 @@ void fuse_init_file_inode(struct inode *inode, unsigned int flags)
 	INIT_LIST_HEAD(&fi->write_files);
 	INIT_LIST_HEAD(&fi->queued_writes);
 	fi->writectr = 0;
+	fi->iocachectr = 0;
 	init_waitqueue_head(&fi->page_waitq);
 	fi->writepages = RB_ROOT;