Merge branch 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull nowait read support from Al Viro:
"Support IOCB_NOWAIT for buffered reads and block devices"

* 'work.read_write' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
block_dev: support RFW_NOWAIT on block device nodes
fs: support RWF_NOWAIT for buffered reads
fs: support IOCB_NOWAIT in generic_file_buffered_read
fs: pass iocb to do_generic_file_read

fs/aio.c

···
 		goto out_put_req;
 	}
 
-	if ((req->common.ki_flags & IOCB_NOWAIT) &&
-			!(req->common.ki_flags & IOCB_DIRECT)) {
-		ret = -EOPNOTSUPP;
-		goto out_put_req;
-	}
-
 	ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
 	if (unlikely(ret)) {
 		pr_debug("EFAULT: aio_key\n");

fs/block_dev.c

···
 	 */
 	filp->f_flags |= O_LARGEFILE;
 
+	filp->f_mode |= FMODE_NOWAIT;
+
 	if (filp->f_flags & O_NDELAY)
 		filp->f_mode |= FMODE_NDELAY;
 	if (filp->f_flags & O_EXCL)
···
 
 	if (iocb->ki_pos >= size)
 		return -ENOSPC;
+
+	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
+		return -EOPNOTSUPP;
 
 	iov_iter_truncate(from, size - iocb->ki_pos);
 

fs/btrfs/file.c

···
 	loff_t oldsize;
 	int clean_page = 0;
 
+	if (!(iocb->ki_flags & IOCB_DIRECT) &&
+	    (iocb->ki_flags & IOCB_NOWAIT))
+		return -EOPNOTSUPP;
+
 	if (!inode_trylock(inode)) {
 		if (iocb->ki_flags & IOCB_NOWAIT)
 			return -EAGAIN;
···
 
 static int btrfs_file_open(struct inode *inode, struct file *filp)
 {
-	filp->f_mode |= FMODE_AIO_NOWAIT;
+	filp->f_mode |= FMODE_NOWAIT;
 	return generic_file_open(inode, filp);
 }
 

fs/ext4/file.c

···
 	if (IS_DAX(inode))
 		return ext4_dax_write_iter(iocb, from);
 #endif
+	if (!o_direct && (iocb->ki_flags & IOCB_NOWAIT))
+		return -EOPNOTSUPP;
 
 	if (!inode_trylock(inode)) {
 		if (iocb->ki_flags & IOCB_NOWAIT)
···
 			return ret;
 	}
 
-	/* Set the flags to support nowait AIO */
-	filp->f_mode |= FMODE_AIO_NOWAIT;
-
+	filp->f_mode |= FMODE_NOWAIT;
 	return dquot_file_open(inode, filp);
 }
 

fs/xfs/xfs_file.c

···
 
 	trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
 
-	xfs_ilock(ip, XFS_IOLOCK_SHARED);
+	if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
+		if (iocb->ki_flags & IOCB_NOWAIT)
+			return -EAGAIN;
+		xfs_ilock(ip, XFS_IOLOCK_SHARED);
+	}
 	ret = generic_file_read_iter(iocb, to);
 	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
···
 	int			enospc = 0;
 	int			iolock;
 
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		return -EOPNOTSUPP;
+
 write_retry:
 	iolock = XFS_IOLOCK_EXCL;
 	xfs_ilock(ip, iolock);
···
 		return -EFBIG;
 	if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
 		return -EIO;
-	file->f_mode |= FMODE_AIO_NOWAIT;
+	file->f_mode |= FMODE_NOWAIT;
 	return 0;
 }
 

include/linux/fs.h

···
 /* File was opened by fanotify and shouldn't generate fanotify events */
 #define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
 
-/* File is capable of returning -EAGAIN if AIO will block */
-#define FMODE_AIO_NOWAIT	((__force fmode_t)0x8000000)
+/* File is capable of returning -EAGAIN if I/O will block */
+#define FMODE_NOWAIT	((__force fmode_t)0x8000000)
 
 /*
  * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
···
 		return -EOPNOTSUPP;
 
 	if (flags & RWF_NOWAIT) {
-		if (!(ki->ki_filp->f_mode & FMODE_AIO_NOWAIT))
+		if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
 			return -EOPNOTSUPP;
 		ki->ki_flags |= IOCB_NOWAIT;
 	}

mm/filemap.c

···
 }
 
 /**
- * do_generic_file_read - generic file read routine
- * @filp:	the file to read
- * @ppos:	current file position
+ * generic_file_buffered_read - generic file read routine
+ * @iocb:	the iocb to read
  * @iter:	data destination
  * @written:	already copied
  *
···
  * This is really ugly. But the goto's actually try to clarify some
  * of the logic when it comes to error handling etc.
  */
-static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
+static ssize_t generic_file_buffered_read(struct kiocb *iocb,
 		struct iov_iter *iter, ssize_t written)
 {
+	struct file *filp = iocb->ki_filp;
 	struct address_space *mapping = filp->f_mapping;
 	struct inode *inode = mapping->host;
 	struct file_ra_state *ra = &filp->f_ra;
+	loff_t *ppos = &iocb->ki_pos;
 	pgoff_t index;
 	pgoff_t last_index;
 	pgoff_t prev_index;
···
 
 		page = find_get_page(mapping, index);
 		if (!page) {
+			if (iocb->ki_flags & IOCB_NOWAIT)
+				goto would_block;
 			page_cache_sync_readahead(mapping,
 					ra, filp,
 					index, last_index - index);
···
 					index, last_index - index);
 		}
 		if (!PageUptodate(page)) {
+			if (iocb->ki_flags & IOCB_NOWAIT) {
+				put_page(page);
+				goto would_block;
+			}
+
 			/*
 			 * See comment in do_read_cache_page on why
 			 * wait_on_page_locked is used to avoid unnecessarily
···
 		goto readpage;
 	}
 
+would_block:
+	error = -EAGAIN;
 out:
 	ra->prev_pos = prev_index;
 	ra->prev_pos <<= PAGE_SHIFT;
···
 ssize_t
 generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 {
-	struct file *file = iocb->ki_filp;
-	ssize_t retval = 0;
 	size_t count = iov_iter_count(iter);
+	ssize_t retval = 0;
 
 	if (!count)
 		goto out; /* skip atime */
 
 	if (iocb->ki_flags & IOCB_DIRECT) {
+		struct file *file = iocb->ki_filp;
 		struct address_space *mapping = file->f_mapping;
 		struct inode *inode = mapping->host;
 		loff_t size;
···
 			goto out;
 	}
 
-	retval = do_generic_file_read(file, &iocb->ki_pos, iter, retval);
+	retval = generic_file_buffered_read(iocb, iter, retval);
 out:
 	return retval;
 }