fuse: handle synchronous iocbs internally

Based on a patch from Maxim Patlasov <MPatlasov@parallels.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 32 insertions, 20 deletions

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index c01ec3bdcfd8..f81d83eb9758 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -528,6 +528,17 @@ static void fuse_release_user_pages(struct fuse_req *req, int write)
         }
 }
 
+static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
+{
+        if (io->err)
+                return io->err;
+
+        if (io->bytes >= 0 && io->write)
+                return -EIO;
+
+        return io->bytes < 0 ? io->size : io->bytes;
+}
+
 /**
  * In case of short read, the caller sets 'pos' to the position of
  * actual end of fuse request in IO request. Otherwise, if bytes_requested
@@ -546,6 +557,7 @@ static void fuse_release_user_pages(struct fuse_req *req, int write)
  */
 static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 {
+        bool is_sync = is_sync_kiocb(io->iocb);
         int left;
 
         spin_lock(&io->lock);
@@ -555,27 +567,21 @@ static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
                 io->bytes = pos;
 
         left = --io->reqs;
+        if (!left && is_sync)
+                complete(io->done);
         spin_unlock(&io->lock);
 
-        if (!left) {
-                long res;
+        if (!left && !is_sync) {
+                ssize_t res = fuse_get_res_by_io(io);
 
-                if (io->err)
-                        res = io->err;
-                else if (io->bytes >= 0 && io->write)
-                        res = -EIO;
-                else {
-                        res = io->bytes < 0 ? io->size : io->bytes;
+                if (res >= 0) {
+                        struct inode *inode = file_inode(io->iocb->ki_filp);
+                        struct fuse_conn *fc = get_fuse_conn(inode);
+                        struct fuse_inode *fi = get_fuse_inode(inode);
 
-                        if (!is_sync_kiocb(io->iocb)) {
-                                struct inode *inode = file_inode(io->iocb->ki_filp);
-                                struct fuse_conn *fc = get_fuse_conn(inode);
-                                struct fuse_inode *fi = get_fuse_inode(inode);
-
-                                spin_lock(&fc->lock);
-                                fi->attr_version = ++fc->attr_version;
-                                spin_unlock(&fc->lock);
-                        }
+                        spin_lock(&fc->lock);
+                        fi->attr_version = ++fc->attr_version;
+                        spin_unlock(&fc->lock);
                 }
 
                 aio_complete(io->iocb, res, 0);
@@ -2801,6 +2807,7 @@ static ssize_t
 fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
                         loff_t offset)
 {
+        DECLARE_COMPLETION_ONSTACK(wait);
         ssize_t ret = 0;
         struct file *file = iocb->ki_filp;
         struct fuse_file *ff = file->private_data;
@@ -2852,6 +2859,9 @@ fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
         if (!is_sync_kiocb(iocb) && (offset + count > i_size) && rw == WRITE)
                 io->async = false;
 
+        if (io->async && is_sync_kiocb(iocb))
+                io->done = &wait;
+
         if (rw == WRITE)
                 ret = __fuse_direct_write(io, iter, &pos);
         else
@@ -2864,11 +2874,12 @@ fuse_direct_IO(int rw, struct kiocb *iocb, struct iov_iter *iter,
                 if (!is_sync_kiocb(iocb))
                         return -EIOCBQUEUED;
 
-                ret = wait_on_sync_kiocb(iocb);
-        } else {
-                kfree(io);
+                wait_for_completion(&wait);
+                ret = fuse_get_res_by_io(io);
         }
 
+        kfree(io);
+
         if (rw == WRITE) {
                 if (ret > 0)
                         fuse_write_update_size(inode, pos);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 1cdfb07c1376..7354dc142a50 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -263,6 +263,7 @@ struct fuse_io_priv {
         int err;
         struct kiocb *iocb;
         struct file *file;
+        struct completion *done;
 };
 
 /**