On Wed, Sep 28, 2016 at 06:42:14PM -0700, Bart Van Assche wrote:

On 09/28/16 17:39, Darrick J. Wong wrote:

quoted

+	if (end > isize) {
+		if (mode & FALLOC_FL_KEEP_SIZE) {
+			len = isize - start;
+			end = start + len - 1;
+		} else
+			return -EINVAL;
+	}

If FALLOC_FL_KEEP_SIZE has been set and end == isize the above code won't
reduce end to isize - 1. Shouldn't "end > isize" be changed into "end >=
isize" ?

Oops.  Will fix and send out a v2.

quoted

+	switch (mode) {
+	case FALLOC_FL_ZERO_RANGE:
+	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
+		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
+					    GFP_KERNEL, false);
+		if (error)
+			return error;
+		break;
+	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
+		/* Only punch if the device can do zeroing discard. */
+		if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data)
+			return -EOPNOTSUPP;
+		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
+					     GFP_KERNEL, 0);
+		if (error)
+			return error;
+		break;
+	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
+		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
+					     GFP_KERNEL, 0);
+		if (error)
+			return error;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}

Have you considered to move "if (error) return error" out of the switch
statement?

Sure, I could do that.

quoted

+	/*
+	 * Invalidate again; if someone wandered in and dirtied a page,
+	 * the caller will be given -EBUSY;
+	 */
+	return invalidate_inode_pages2_range(mapping,
+					     start >> PAGE_SHIFT,
+					     end >> PAGE_SHIFT);

A comment might be appropriate here that since end is inclusive and since
the third argument of invalidate_inode_pages2_range() is inclusive that
rounding down will yield the correct result.

/methot the documentation of invalidate_inode_pages2_range was clear
enough on that point, but I could throw that into the comment too.

--D

Bart.