linux-ext4 - [PATCH 06/13] xfs: close the external block devices in xfs_mount

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Date:   Wed,  9 Aug 2023 15:05:38 -0700
From:   Christoph Hellwig <hch@....de>
To:     Al Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>
Cc:     Namjae Jeon <linkinjeon@...nel.org>,
        Sungjong Seo <sj1557.seo@...sung.com>,
        "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Konstantin Komarov <almaz.alexandrovich@...agon-software.com>,
        "Darrick J. Wong" <djwong@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        ntfs3@...ts.linux.dev, linux-xfs@...r.kernel.org
Subject: [PATCH 06/13] xfs: close the external block devices in xfs_mount_free

blkdev_put must not be called under sb->s_umount to avoid a lock order
reversal with disk->open_mutex.  Move closing the buftargs into ->kill_sb
to archive that.  Note that the flushing of the disk caches and
block device mapping invalidated needs to stay in ->put_super as the main
block device is closed in kill_block_super already.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/xfs/xfs_buf.c   |  2 --
 fs/xfs/xfs_super.c | 36 ++++++++++++++++++++++++++----------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e33eb17648dfed..3b903f6bce98d8 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1945,8 +1945,6 @@ xfs_free_buftarg(
 	percpu_counter_destroy(&btp->bt_io_count);
 	list_lru_destroy(&btp->bt_lru);
 
-	blkdev_issue_flush(btp->bt_bdev);
-	invalidate_bdev(btp->bt_bdev);
 	fs_put_dax(btp->bt_daxdev, btp->bt_mount);
 	/* the main block device is closed by kill_block_super */
 	if (bdev != btp->bt_mount->m_super->s_bdev)
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 368c05a2dea5b9..4ae3b01ed038c7 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -396,14 +396,19 @@ xfs_blkdev_get(
 }
 
 STATIC void
-xfs_close_devices(
+xfs_shutdown_devices(
 	struct xfs_mount	*mp)
 {
-	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
-		xfs_free_buftarg(mp->m_logdev_targp);
-	if (mp->m_rtdev_targp)
-		xfs_free_buftarg(mp->m_rtdev_targp);
-	xfs_free_buftarg(mp->m_ddev_targp);
+	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp) {
+		blkdev_issue_flush(mp->m_logdev_targp->bt_bdev);
+		invalidate_bdev(mp->m_logdev_targp->bt_bdev);
+	}
+	if (mp->m_rtdev_targp) {
+		blkdev_issue_flush(mp->m_rtdev_targp->bt_bdev);
+		invalidate_bdev(mp->m_rtdev_targp->bt_bdev);
+	}
+	blkdev_issue_flush(mp->m_ddev_targp->bt_bdev);
+	invalidate_bdev(mp->m_ddev_targp->bt_bdev);
 }
 
 /*
@@ -741,6 +746,17 @@ static void
 xfs_mount_free(
 	struct xfs_mount	*mp)
 {
+	/*
+	 * Free the buftargs here because blkdev_put needs to be called outside
+	 * of sb->s_umount, which is held around the call to ->put_super.
+	 */
+	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
+		xfs_free_buftarg(mp->m_logdev_targp);
+	if (mp->m_rtdev_targp)
+		xfs_free_buftarg(mp->m_rtdev_targp);
+	if (mp->m_ddev_targp)
+		xfs_free_buftarg(mp->m_ddev_targp);
+
 	kfree(mp->m_rtname);
 	kfree(mp->m_logname);
 	kmem_free(mp);
@@ -1126,7 +1142,7 @@ xfs_fs_put_super(
 	xfs_inodegc_free_percpu(mp);
 	xfs_destroy_percpu_counters(mp);
 	xfs_destroy_mount_workqueues(mp);
-	xfs_close_devices(mp);
+	xfs_shutdown_devices(mp);
 }
 
 static long
@@ -1499,7 +1515,7 @@ xfs_fs_fill_super(
 
 	error = xfs_init_mount_workqueues(mp);
 	if (error)
-		goto out_close_devices;
+		goto out_shutdown_devices;
 
 	error = xfs_init_percpu_counters(mp);
 	if (error)
@@ -1713,8 +1729,8 @@ xfs_fs_fill_super(
 	xfs_destroy_percpu_counters(mp);
  out_destroy_workqueues:
 	xfs_destroy_mount_workqueues(mp);
- out_close_devices:
-	xfs_close_devices(mp);
+ out_shutdown_devices:
+	xfs_shutdown_devices(mp);
 	return error;
 
  out_unmount:
-- 
2.39.2