fuse: enable asynchronous processing direct IO
In case of synchronous DIO request (i.e. read(2) or write(2) for a file
opened with O_DIRECT), the patch submits fuse requests asynchronously, but
waits for their completions before return from fuse_direct_IO().
In case of asynchronous DIO request (i.e. libaio io_submit() or a file opened
with O_DIRECT), the patch submits fuse requests asynchronously and return
-EIOCBQUEUED immediately.
The only special case is async DIO extending file. Here the patch falls back
to old behaviour because we can't return -EIOCBQUEUED and update i_size later,
without i_mutex hold. And we have no method to wait on real async I/O
requests.
The patch also clean __fuse_direct_write() up: it's better to update i_size
in its callers. Thanks Brian for suggestion.
Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e207dcd..ba1d503 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1366,11 +1366,8 @@
ssize_t res;
res = generic_write_checks(file, ppos, &count, 0);
- if (!res) {
+ if (!res)
res = fuse_direct_io(io, iov, nr_segs, count, ppos, 1);
- if (!io->async && res > 0)
- fuse_write_update_size(inode, *ppos);
- }
fuse_invalidate_attr(inode);
@@ -1391,6 +1388,8 @@
/* Don't allow parallel writes to the same file */
mutex_lock(&inode->i_mutex);
res = __fuse_direct_write(&io, &iov, 1, ppos);
+ if (res > 0)
+ fuse_write_update_size(inode, *ppos);
mutex_unlock(&inode->i_mutex);
return res;
@@ -2360,23 +2359,61 @@
ssize_t ret = 0;
struct file *file = NULL;
loff_t pos = 0;
+ struct inode *inode;
+ loff_t i_size;
+ size_t count = iov_length(iov, nr_segs);
struct fuse_io_priv *io;
file = iocb->ki_filp;
pos = offset;
+ inode = file->f_mapping->host;
+ i_size = i_size_read(inode);
- io = kzalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
+ io = kmalloc(sizeof(struct fuse_io_priv), GFP_KERNEL);
if (!io)
return -ENOMEM;
-
+ spin_lock_init(&io->lock);
+ io->reqs = 1;
+ io->bytes = -1;
+ io->size = 0;
+ io->offset = offset;
+ io->write = (rw == WRITE);
+ io->err = 0;
io->file = file;
+ /*
+ * By default, we want to optimize all I/Os with async request
+ * submission to the client filesystem.
+ */
+ io->async = 1;
+ io->iocb = iocb;
+
+ /*
+ * We cannot asynchronously extend the size of a file. We have no method
+ * to wait on real async I/O requests, so we must submit this request
+ * synchronously.
+ */
+ if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE)
+ io->async = false;
if (rw == WRITE)
ret = __fuse_direct_write(io, iov, nr_segs, &pos);
else
ret = __fuse_direct_read(io, iov, nr_segs, &pos);
- kfree(io);
+ if (io->async) {
+ fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
+
+ /* we have a non-extending, async request, so return */
+ if (ret > 0 && !is_sync_kiocb(iocb))
+ return -EIOCBQUEUED;
+
+ ret = wait_on_sync_kiocb(iocb);
+ } else {
+ kfree(io);
+ }
+
+ if (rw == WRITE && ret > 0)
+ fuse_write_update_size(inode, pos);
return ret;
}