Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

Pull fuse update from Miklos Szeredi:
 "This contains direct I/O fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: return patrial success from fuse_direct_io()
  fuse: Add reference counting for fuse_io_priv
  fuse: do not use iocb after it may have been freed

3 files changed, 46 insertions, 23 deletions

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index 8e3ee1936c7e..c5b6b7165489 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -90,7 +90,7 @@ static struct list_head *cuse_conntbl_head(dev_t devt)
 
 static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to)
 {
-	struct fuse_io_priv io = { .async = 0, .file = kiocb->ki_filp };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
 	loff_t pos = 0;
 
 	return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);
@@ -98,7 +98,7 @@ static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to)
 
 static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from)
 {
-	struct fuse_io_priv io = { .async = 0, .file = kiocb->ki_filp };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb->ki_filp);
 	loff_t pos = 0;
 	/*
 	 * No locking or generic_write_checks(), the server is
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index b03d253ece15..9dde38f12c07 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -528,6 +528,11 @@ static void fuse_release_user_pages(struct fuse_req *req, int write)
 	}
 }
 
+static void fuse_io_release(struct kref *kref)
+{
+	kfree(container_of(kref, struct fuse_io_priv, refcnt));
+}
+
 static ssize_t fuse_get_res_by_io(struct fuse_io_priv *io)
 {
 	if (io->err)
@@ -585,8 +590,9 @@ static void fuse_aio_complete(struct fuse_io_priv *io, int err, ssize_t pos)
 		}
 
 		io->iocb->ki_complete(io->iocb, res, 0);
-		kfree(io);
 	}
+
+	kref_put(&io->refcnt, fuse_io_release);
 }
 
 static void fuse_aio_complete_req(struct fuse_conn *fc, struct fuse_req *req)
@@ -613,6 +619,7 @@ 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);
+	kref_get(&io->refcnt);
 	io->size += num_bytes;
 	io->reqs++;
 	spin_unlock(&io->lock);
@@ -691,7 +698,7 @@ static void fuse_short_read(struct fuse_req *req, struct inode *inode,
 
 static int fuse_do_readpage(struct file *file, struct page *page)
 {
-	struct fuse_io_priv io = { .async = 0, .file = file };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
 	struct inode *inode = page->mapping->host;
 	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_req *req;
@@ -984,7 +991,7 @@ static size_t fuse_send_write_pages(struct fuse_req *req, struct file *file,
 	size_t res;
 	unsigned offset;
 	unsigned i;
-	struct fuse_io_priv io = { .async = 0, .file = file };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
 
 	for (i = 0; i < req->num_pages; i++)
 		fuse_wait_on_page_writeback(inode, req->pages[i]->index);
@@ -1240,6 +1247,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
 			       size_t *nbytesp, int write)
 {
 	size_t nbytes = 0;  /* # bytes already packed in req */
+	ssize_t ret = 0;
 
 	/* Special case for kernel I/O: can copy directly into the buffer */
 	if (ii->type & ITER_KVEC) {
@@ -1259,13 +1267,12 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
 	while (nbytes < *nbytesp && req->num_pages < req->max_pages) {
 		unsigned npages;
 		size_t start;
-		ssize_t ret = iov_iter_get_pages(ii,
-					&req->pages[req->num_pages],
+		ret = iov_iter_get_pages(ii, &req->pages[req->num_pages],
 					*nbytesp - nbytes,
 					req->max_pages - req->num_pages,
 					&start);
 		if (ret < 0)
-			return ret;
+			break;
 
 		iov_iter_advance(ii, ret);
 		nbytes += ret;
@@ -1288,7 +1295,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii,
 
 	*nbytesp = nbytes;
 
-	return 0;
+	return ret;
 }
 
 static inline int fuse_iter_npages(const struct iov_iter *ii_p)
@@ -1312,6 +1319,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 	pgoff_t idx_to = (pos + count - 1) >> PAGE_CACHE_SHIFT;
 	ssize_t res = 0;
 	struct fuse_req *req;
+	int err = 0;
 
 	if (io->async)
 		req = fuse_get_req_for_background(fc, fuse_iter_npages(iter));
@@ -1332,11 +1340,9 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 		size_t nres;
 		fl_owner_t owner = current->files;
 		size_t nbytes = min(count, nmax);
-		int err = fuse_get_user_pages(req, iter, &nbytes, write);
-		if (err) {
-			res = err;
+		err = fuse_get_user_pages(req, iter, &nbytes, write);
+		if (err && !nbytes)
 			break;
-		}
 
 		if (write)
 			nres = fuse_send_write(req, io, pos, nbytes, owner);
@@ -1346,11 +1352,11 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 		if (!io->async)
 			fuse_release_user_pages(req, !write);
 		if (req->out.h.error) {
-			if (!res)
-				res = req->out.h.error;
+			err = req->out.h.error;
 			break;
 		} else if (nres > nbytes) {
-			res = -EIO;
+			res = 0;
+			err = -EIO;
 			break;
 		}
 		count -= nres;
@@ -1374,7 +1380,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
 	if (res > 0)
 		*ppos = pos;
 
-	return res;
+	return res > 0 ? res : err;
 }
 EXPORT_SYMBOL_GPL(fuse_direct_io);
 
@@ -1398,7 +1404,7 @@ static ssize_t __fuse_direct_read(struct fuse_io_priv *io,
 
 static ssize_t fuse_direct_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-	struct fuse_io_priv io = { .async = 0, .file = iocb->ki_filp };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(iocb->ki_filp);
 	return __fuse_direct_read(&io, to, &iocb->ki_pos);
 }
 
@@ -1406,7 +1412,7 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file_inode(file);
-	struct fuse_io_priv io = { .async = 0, .file = file };
+	struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(file);
 	ssize_t res;
 
 	if (is_bad_inode(inode))
@@ -2843,6 +2849,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 	loff_t i_size;
 	size_t count = iov_iter_count(iter);
 	struct fuse_io_priv *io;
+	bool is_sync = is_sync_kiocb(iocb);
 
 	pos = offset;
 	inode = file->f_mapping->host;
@@ -2863,6 +2870,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 	if (!io)
 		return -ENOMEM;
 	spin_lock_init(&io->lock);
+	kref_init(&io->refcnt);
 	io->reqs = 1;
 	io->bytes = -1;
 	io->size = 0;
@@ -2882,12 +2890,18 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 	 * to wait on real async I/O requests, so we must submit this request
 	 * synchronously.
 	 */
-	if (!is_sync_kiocb(iocb) && (offset + count > i_size) &&
+	if (!is_sync && (offset + count > i_size) &&
 	    iov_iter_rw(iter) == WRITE)
 		io->async = false;
 
-	if (io->async && is_sync_kiocb(iocb))
+	if (io->async && is_sync) {
+		/*
+		 * Additional reference to keep io around after
+		 * calling fuse_aio_complete()
+		 */
+		kref_get(&io->refcnt);
 		io->done = &wait;
+	}
 
 	if (iov_iter_rw(iter) == WRITE) {
 		ret = fuse_direct_io(io, iter, &pos, FUSE_DIO_WRITE);
@@ -2900,14 +2914,14 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
 		fuse_aio_complete(io, ret < 0 ? ret : 0, -1);
 
 		/* we have a non-extending, async request, so return */
-		if (!is_sync_kiocb(iocb))
+		if (!is_sync)
 			return -EIOCBQUEUED;
 
 		wait_for_completion(&wait);
 		ret = fuse_get_res_by_io(io);
 	}
 
-	kfree(io);
+	kref_put(&io->refcnt, fuse_io_release);
 
 	if (iov_iter_rw(iter) == WRITE) {
 		if (ret > 0)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index ce394b5fe6b4..eddbe02c4028 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -22,6 +22,7 @@
 #include <linux/rbtree.h>
 #include <linux/poll.h>
 #include <linux/workqueue.h>
+#include <linux/kref.h>
 
 /** Max number of pages that can be used in a single read request */
 #define FUSE_MAX_PAGES_PER_REQ 32
@@ -243,6 +244,7 @@ struct fuse_args {
 
 /** The request IO state (for asynchronous processing) */
 struct fuse_io_priv {
+	struct kref refcnt;
 	int async;
 	spinlock_t lock;
 	unsigned reqs;
@@ -256,6 +258,13 @@ struct fuse_io_priv {
 	struct completion *done;
 };
 
+#define FUSE_IO_PRIV_SYNC(f) \
+{					\
+	.refcnt = { ATOMIC_INIT(1) },	\
+	.async = 0,			\
+	.file = f,			\
+}
+
 /**
  * Request flags
  *