RE: [RFCv2 2/3] block: add helper for setting and clearing S_DAX on inode
From: Elliott, Robert (Persistent Memory) <hidden>
Date: 2016-05-14 05:06:59
Also in:
linux-fsdevel, linux-nvme
-----Original Message----- From: linux-block-owner@vger.kernel.org [mailto:linux-block- owner@vger.kernel.org] On Behalf Of Jon Derrick Sent: Friday, May 13, 2016 7:03 PM
...
Subject: [RFCv2 2/3] block: add helper for setting and clearing S_DAX on inode inode->i_flags locking rules suggest using the i_mutex lock. This patch adds a helper to do the locking and setting of S_DAX on the block device inode.
...
+static void bd_set_dax(struct block_device *bdev, bool enabled)
+{
+ struct inode *inode = bdev->bd_inode;
+
+ inode_lock(inode);
+ if (enabled)
+ inode->i_flags = S_DAX;
+ else
+ inode->i_flags &= ~S_DAX;
+ inode_unlock(inode);
+}This is not symmetric - setting wipes out any other bits, but clearing only clears the S_DAX bit. That seems confusing for a helper function. Using |= would be symmetric, but wouldn't replace what __blkdev_get does (if what it does is appropriate).
quoted hunk ↗ jump to hunk
@@ -1206,9 +1218,9 @@ static int __blkdev_get(struct block_device *bdev,fmode_t mode, int for_part) bdev->bd_queue = disk->queue; bdev->bd_contains = bdev; if (IS_ENABLED(CONFIG_BLK_DEV_DAX) && disk->fops-quoted
direct_access)- bdev->bd_inode->i_flags = S_DAX; + bd_set_dax(bdev, 1); else - bdev->bd_inode->i_flags &= ~S_DAX; + bd_set_dax(bdev, 0);