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From:   Christoph Hellwig <hch@lst.de>
To:     Al Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>
Cc:     Namjae Jeon <linkinjeon@kernel.org>,
        Sungjong Seo <sj1557.seo@samsung.com>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        "Darrick J. Wong" <djwong@kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        ntfs3@lists.linux.dev, linux-xfs@vger.kernel.org
Subject: [PATCH 07/13] xfs: close the external block devices in xfs_mount_free
Date:   Tue,  8 Aug 2023 09:15:54 -0700
Message-Id: <20230808161600.1099516-8-hch@lst.de>
In-Reply-To: <20230808161600.1099516-1-hch@lst.de>
References: <20230808161600.1099516-1-hch@lst.de>
MIME-Version: 1.0
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Precedence: bulk

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 needs to be
kept in ->put_super as the main block device is closed in
kill_block_super already.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_buf.c   |  1 -
 fs/xfs/xfs_super.c | 27 +++++++++++++++++++--------
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index c57e6e03dfa80c..3b903f6bce98d8 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -1945,7 +1945,6 @@ xfs_free_buftarg(
 	percpu_counter_destroy(&btp->bt_io_count);
 	list_lru_destroy(&btp->bt_lru);
 
-	blkdev_issue_flush(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 37b1b763a0bef0..67343364ac66e9 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -396,14 +396,14 @@ xfs_blkdev_get(
 }
 
 STATIC void
-xfs_close_devices(
+xfs_flush_disk_caches(
 	struct xfs_mount	*mp)
 {
 	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
-		xfs_free_buftarg(mp->m_logdev_targp);
+		blkdev_issue_flush(mp->m_logdev_targp->bt_bdev);
 	if (mp->m_rtdev_targp)
-		xfs_free_buftarg(mp->m_rtdev_targp);
-	xfs_free_buftarg(mp->m_ddev_targp);
+		blkdev_issue_flush(mp->m_rtdev_targp->bt_bdev);
+	blkdev_issue_flush(mp->m_ddev_targp->bt_bdev);
 }
 
 /*
@@ -741,6 +741,17 @@ 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 +1137,7 @@ xfs_fs_put_super(
 	xfs_inodegc_free_percpu(mp);
 	xfs_destroy_percpu_counters(mp);
 	xfs_destroy_mount_workqueues(mp);
-	xfs_close_devices(mp);
+	xfs_flush_disk_caches(mp);
 }
 
 static long
@@ -1499,7 +1510,7 @@ xfs_fs_fill_super(
 
 	error = xfs_init_mount_workqueues(mp);
 	if (error)
-		goto out_close_devices;
+		goto out_flush_caches;
 
 	error = xfs_init_percpu_counters(mp);
 	if (error)
@@ -1713,8 +1724,8 @@ 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_flush_caches:
+	xfs_flush_disk_caches(mp);
 	return error;
 
  out_unmount:
-- 
2.39.2