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-rw-r--r--fs/fuse/file.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 1ee2fc92bc3e..4002889fbcc1 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -506,6 +506,98 @@ static void fuse_release_user_pages(struct fuse_req *req, int write)
}
}
+/**
+ * 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
+ * == bytes_transferred or rw == WRITE, the caller sets 'pos' to -1.
+ *
+ * An example:
+ * User requested DIO read of 64K. It was splitted into two 32K fuse requests,
+ * both submitted asynchronously. The first of them was ACKed by userspace as
+ * fully completed (req->out.args[0].size == 32K) resulting in pos == -1. The
+ * second request was ACKed as short, e.g. only 1K was read, resulting in
+ * pos == 33K.
+ *
+ * Thus, when all fuse requests are completed, the minimal non-negative 'pos'
+ * will be equal to the length of the longest contiguous fragment of
+ * transferred data starting from the beginning of IO request.
+ */
+static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
+{
+ int left;
+
+ spin_lock(&io->lock);
+ if (err)
+ io->err = io->err ? : err;
+ else if (pos >= 0 && (io->bytes < 0 || pos < io->bytes))
+ io->bytes = pos;
+
+ left = --io->reqs;
+ spin_unlock(&io->lock);
+
+ if (!left) {
+ long res;
+
+ 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 (!is_sync_kiocb(io->iocb)) {
+ struct path *path = &io->iocb->ki_filp->f_path;
+ struct inode *inode = path->dentry->d_inode;
+ 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);
+ }
+ }
+
+ aio_complete(io->iocb, res, 0);
+ kfree(io);
+ }
+}
+
+static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_req *req)
+{
+ struct fuse_io_priv *io = req->io;
+ ssize_t pos = -1;
+
+ fuse_release_user_pages(req, !io->write);
+
+ if (io->write) {
+ if (req->misc.write.in.size != req->misc.write.out.size)
+ pos = req->misc.write.in.offset - io->offset +
+ req->misc.write.out.size;
+ } else {
+ if (req->misc.read.in.size != req->out.args[0].size)
+ pos = req->misc.read.in.offset - io->offset +
+ req->out.args[0].size;
+ }
+
+ fuse_aio_complete(io, req->out.h.error, pos);
+}
+
+static size_t fuse_async_req_send(struct fuse_conn *fc, struct fuse_req *req,
+ size_t num_bytes, struct fuse_io_priv *io)
+{
+ spin_lock(&io->lock);
+ io->size += num_bytes;
+ io->reqs++;
+ spin_unlock(&io->lock);
+
+ req->io = io;
+ req->end = fuse_aio_complete_req;
+
+ fuse_request_send_background(fc, req);
+
+ return num_bytes;
+}
+
static size_t fuse_send_read(struct fuse_req *req, struct file *file,
loff_t pos, size_t count, fl_owner_t owner)
{