linux-ext4 - [PATCH 06/29] dax: move the partition alignment check into fs_dax_get_by

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Date:   Tue,  9 Nov 2021 09:32:46 +0100
From:   Christoph Hellwig <hch@....de>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Mike Snitzer <snitzer@...hat.com>, Ira Weiny <ira.weiny@...el.com>,
        dm-devel@...hat.com, linux-xfs@...r.kernel.org,
        nvdimm@...ts.linux.dev, linux-s390@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-erofs@...ts.ozlabs.org,
        linux-ext4@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH 06/29] dax: move the partition alignment check into fs_dax_get_by_bdev

fs_dax_get_by_bdev is the primary interface to find a dax device for a
block device, so move the partition alignment check there instead of
wiring it up through ->dax_supported.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/dax/super.c | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 04fc680542e8d..482fe775324a4 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -93,6 +93,12 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 	if (!blk_queue_dax(bdev->bd_disk->queue))
 		return NULL;
 
+	if ((get_start_sect(bdev) * SECTOR_SIZE) % PAGE_SIZE ||
+	    (bdev_nr_sectors(bdev) * SECTOR_SIZE) % PAGE_SIZE) {
+		pr_info("%pg: error: unaligned partition for dax\n", bdev);
+		return NULL;
+	}
+
 	id = dax_read_lock();
 	dax_dev = xa_load(&dax_hosts, (unsigned long)bdev->bd_disk);
 	if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode))
@@ -107,10 +113,6 @@ bool generic_fsdax_supported(struct dax_device *dax_dev,
 		struct block_device *bdev, int blocksize, sector_t start,
 		sector_t sectors)
 {
-	pgoff_t pgoff, pgoff_end;
-	sector_t last_page;
-	int err;
-
 	if (blocksize != PAGE_SIZE) {
 		pr_info("%pg: error: unsupported blocksize for dax\n", bdev);
 		return false;
@@ -121,19 +123,6 @@ bool generic_fsdax_supported(struct dax_device *dax_dev,
 		return false;
 	}
 
-	err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
-	if (err) {
-		pr_info("%pg: error: unaligned partition for dax\n", bdev);
-		return false;
-	}
-
-	last_page = PFN_DOWN((start + sectors - 1) * 512) * PAGE_SIZE / 512;
-	err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
-	if (err) {
-		pr_info("%pg: error: unaligned partition for dax\n", bdev);
-		return false;
-	}
-
 	return true;
 }
 EXPORT_SYMBOL_GPL(generic_fsdax_supported);
-- 
2.30.2