xfs: only call xfs_setsize_buftarg once per buffer target

It's silly to call xfs_setsize_buftarg from xfs_alloc_buftarg with the
block device LBA size because we don't need to ask the block layer to
validate a geometry number that it provided us.  Instead, set the
preliminary bt_meta_sector* fields to the LBA size in preparation for
reading the primary super.

However, we still want to flush and invalidate the pagecache for all
three block devices before we start reading metadata from those devices,
so call sync_blockdev() per bdev in xfs_alloc_buftarg().

This will enable a subsequent patch to validate hw atomic write geometry
against the filesystem geometry.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>
[jpg: call sync_blockdev() from xfs_alloc_buftarg()]
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Author: Darrick J. Wong

fs/xfs/xfs_buf.c

@@ -1733,11 +1733,7 @@ xfs_setsize_buftarg(
 		return -EINVAL;
 	}
 
-	/*
-	 * Flush the block device pagecache so our bios see anything dirtied
-	 * before mount.
-	 */
-	return sync_blockdev(btp->bt_bdev);
+	return 0;
 }
 
 int
@@ -1786,6 +1782,8 @@ xfs_alloc_buftarg(
 {
 	struct xfs_buftarg	*btp;
 	const struct dax_holder_operations *ops = NULL;
+	int			error;
+
 
 #if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
 	ops = &xfs_dax_holder_operations;
@@ -1806,21 +1804,31 @@ xfs_alloc_buftarg(
 						btp->bt_bdev);
 	}
 
+	/*
+	 * Flush and invalidate all devices' pagecaches before reading any
+	 * metadata because XFS doesn't use the bdev pagecache.
+	 */
+	error = sync_blockdev(btp->bt_bdev);
+	if (error)
+		goto error_free;
+
 	/*
 	 * When allocating the buftargs we have not yet read the super block and
 	 * thus don't know the file system sector size yet.
 	 */
-	if (xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev)))
-		goto error_free;
-	if (xfs_init_buftarg(btp, bdev_logical_block_size(btp->bt_bdev),
-			mp->m_super->s_id))
+	btp->bt_meta_sectorsize = bdev_logical_block_size(btp->bt_bdev);
+	btp->bt_meta_sectormask = btp->bt_meta_sectorsize - 1;
+
+	error = xfs_init_buftarg(btp, btp->bt_meta_sectorsize,
+				mp->m_super->s_id);
+	if (error)
 		goto error_free;
 
 	return btp;
 
 error_free:
 	kfree(btp);
-	return NULL;
+	return ERR_PTR(error);
 }
 
 static inline void

fs/xfs/xfs_super.c

@@ -482,21 +482,29 @@ xfs_open_devices(
 	/*
 	 * Setup xfs_mount buffer target pointers
 	 */
-	error = -ENOMEM;
 	mp->m_ddev_targp = xfs_alloc_buftarg(mp, sb->s_bdev_file);
-	if (!mp->m_ddev_targp)
+	if (IS_ERR(mp->m_ddev_targp)) {
+		error = PTR_ERR(mp->m_ddev_targp);
+		mp->m_ddev_targp = NULL;
 		goto out_close_rtdev;
+	}
 
 	if (rtdev_file) {
 		mp->m_rtdev_targp = xfs_alloc_buftarg(mp, rtdev_file);
-		if (!mp->m_rtdev_targp)
+		if (IS_ERR(mp->m_rtdev_targp)) {
+			error = PTR_ERR(mp->m_rtdev_targp);
+			mp->m_rtdev_targp = NULL;
 			goto out_free_ddev_targ;
+		}
 	}
 
 	if (logdev_file && file_bdev(logdev_file) != ddev) {
 		mp->m_logdev_targp = xfs_alloc_buftarg(mp, logdev_file);
-		if (!mp->m_logdev_targp)
+		if (IS_ERR(mp->m_logdev_targp)) {
+			error = PTR_ERR(mp->m_logdev_targp);
+			mp->m_logdev_targp = NULL;
 			goto out_free_rtdev_targ;
+		}
 	} else {
 		mp->m_logdev_targp = mp->m_ddev_targp;
 		/* Handle won't be used, drop it */