Fixes for 5.7:

- Fix a partially uninitialized variable.
 - Teach the background gc threads to apply for fsfreeze protection.
 - Fix some scaling problems when multiple threads try to flush the
   filesystem when we're about to hit ENOSPC.
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Merge tag 'xfs-5.7-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs fixes from Darrick Wong:
 "The three commits here fix some livelocks and other clashes with
  fsfreeze, a potential corruption problem, and a minor race between
  processes freeing and allocating space when the filesystem is near
  ENOSPC.

  Summary:

   - Fix a partially uninitialized variable.

   - Teach the background gc threads to apply for fsfreeze protection.

   - Fix some scaling problems when multiple threads try to flush the
     filesystem when we're about to hit ENOSPC"

* tag 'xfs-5.7-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: move inode flush to the sync workqueue
  xfs: fix partially uninitialized structure in xfs_reflink_remap_extent
  xfs: acquire superblock freeze protection on eofblocks scans

fs/xfs/xfs_icache.c

@@ -911,7 +911,12 @@ xfs_eofblocks_worker(
 {
 	struct xfs_mount *mp = container_of(to_delayed_work(work),
 				struct xfs_mount, m_eofblocks_work);
+
+	if (!sb_start_write_trylock(mp->m_super))
+		return;
 	xfs_icache_free_eofblocks(mp, NULL);
+	sb_end_write(mp->m_super);
+
 	xfs_queue_eofblocks(mp);
 }
 
@@ -938,7 +943,12 @@ xfs_cowblocks_worker(
 {
 	struct xfs_mount *mp = container_of(to_delayed_work(work),
 				struct xfs_mount, m_cowblocks_work);
+
+	if (!sb_start_write_trylock(mp->m_super))
+		return;
 	xfs_icache_free_cowblocks(mp, NULL);
+	sb_end_write(mp->m_super);
+
 	xfs_queue_cowblocks(mp);
 }
 

fs/xfs/xfs_ioctl.c

@@ -2363,7 +2363,10 @@ xfs_file_ioctl(
 		if (error)
 			return error;
 
-		return xfs_icache_free_eofblocks(mp, &keofb);
+		sb_start_write(mp->m_super);
+		error = xfs_icache_free_eofblocks(mp, &keofb);
+		sb_end_write(mp->m_super);
+		return error;
 	}
 
 	default:

fs/xfs/xfs_mount.h

@@ -167,8 +167,12 @@ typedef struct xfs_mount {
 	struct xfs_kobj		m_error_meta_kobj;
 	struct xfs_error_cfg	m_error_cfg[XFS_ERR_CLASS_MAX][XFS_ERR_ERRNO_MAX];
 	struct xstats		m_stats;	/* per-fs stats */
-	struct ratelimit_state	m_flush_inodes_ratelimit;
 
+	/*
+	 * Workqueue item so that we can coalesce multiple inode flush attempts
+	 * into a single flush.
+	 */
+	struct work_struct	m_flush_inodes_work;
 	struct workqueue_struct *m_buf_workqueue;
 	struct workqueue_struct	*m_unwritten_workqueue;
 	struct workqueue_struct	*m_cil_workqueue;

fs/xfs/xfs_reflink.c

@@ -1051,6 +1051,7 @@ xfs_reflink_remap_extent(
 		uirec.br_startblock = irec->br_startblock + rlen;
 		uirec.br_startoff = irec->br_startoff + rlen;
 		uirec.br_blockcount = unmap_len - rlen;
+		uirec.br_state = irec->br_state;
 		unmap_len = rlen;
 
 		/* If this isn't a real mapping, we're done. */

fs/xfs/xfs_super.c

@@ -516,6 +516,20 @@ xfs_destroy_mount_workqueues(
 	destroy_workqueue(mp->m_buf_workqueue);
 }
 
+static void
+xfs_flush_inodes_worker(
+	struct work_struct	*work)
+{
+	struct xfs_mount	*mp = container_of(work, struct xfs_mount,
+						   m_flush_inodes_work);
+	struct super_block	*sb = mp->m_super;
+
+	if (down_read_trylock(&sb->s_umount)) {
+		sync_inodes_sb(sb);
+		up_read(&sb->s_umount);
+	}
+}
+
 /*
  * Flush all dirty data to disk. Must not be called while holding an XFS_ILOCK
  * or a page lock. We use sync_inodes_sb() here to ensure we block while waiting
@@ -526,15 +540,15 @@ void
 xfs_flush_inodes(
 	struct xfs_mount	*mp)
 {
-	struct super_block	*sb = mp->m_super;
-
-	if (!__ratelimit(&mp->m_flush_inodes_ratelimit))
+	/*
+	 * If flush_work() returns true then that means we waited for a flush
+	 * which was already in progress.  Don't bother running another scan.
+	 */
+	if (flush_work(&mp->m_flush_inodes_work))
 		return;
 
-	if (down_read_trylock(&sb->s_umount)) {
-		sync_inodes_sb(sb);
-		up_read(&sb->s_umount);
-	}
+	queue_work(mp->m_sync_workqueue, &mp->m_flush_inodes_work);
+	flush_work(&mp->m_flush_inodes_work);
 }
 
 /* Catch misguided souls that try to use this interface on XFS */
@@ -1369,17 +1383,6 @@ xfs_fc_fill_super(
 	if (error)
 		goto out_free_names;
 
-	/*
-	 * Cap the number of invocations of xfs_flush_inodes to 16 for every
-	 * quarter of a second.  The magic numbers here were determined by
-	 * observation neither to cause stalls in writeback when there are a
-	 * lot of IO threads and the fs is near ENOSPC, nor cause any fstest
-	 * regressions.  YMMV.
-	 */
-	ratelimit_state_init(&mp->m_flush_inodes_ratelimit, HZ / 4, 16);
-	ratelimit_set_flags(&mp->m_flush_inodes_ratelimit,
-			RATELIMIT_MSG_ON_RELEASE);
-
 	error = xfs_init_mount_workqueues(mp);
 	if (error)
 		goto out_close_devices;
@@ -1752,6 +1755,7 @@ static int xfs_init_fs_context(
 	spin_lock_init(&mp->m_perag_lock);
 	mutex_init(&mp->m_growlock);
 	atomic_set(&mp->m_active_trans, 0);
+	INIT_WORK(&mp->m_flush_inodes_work, xfs_flush_inodes_worker);
 	INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
 	INIT_DELAYED_WORK(&mp->m_eofblocks_work, xfs_eofblocks_worker);
 	INIT_DELAYED_WORK(&mp->m_cowblocks_work, xfs_cowblocks_worker);