Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 926ed31..4a48a8c 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -11,17 +11,11 @@
 #include "xfs_trans_resv.h"
 #include "xfs_bit.h"
 #include "xfs_mount.h"
-#include "xfs_defer.h"
 #include "xfs_inode.h"
 #include "xfs_bmap.h"
-#include "xfs_bmap_util.h"
 #include "xfs_bmap_btree.h"
-#include "xfs_alloc.h"
-#include "xfs_error.h"
 #include "xfs_trans.h"
 #include "xfs_trans_space.h"
-#include "xfs_trace.h"
-#include "xfs_buf.h"
 #include "xfs_icache.h"
 #include "xfs_rtalloc.h"
 
@@ -64,8 +58,12 @@
 	int		log;		/* loop counter, log2 of ext. size */
 	xfs_suminfo_t	sum;		/* summary data */
 
+	/* There are no extents at levels < m_rsum_cache[bbno]. */
+	if (mp->m_rsum_cache && low < mp->m_rsum_cache[bbno])
+		low = mp->m_rsum_cache[bbno];
+
 	/*
-	 * Loop over logs of extent sizes.  Order is irrelevant.
+	 * Loop over logs of extent sizes.
 	 */
 	for (log = low; log <= high; log++) {
 		/*
@@ -80,13 +78,17 @@
 		 */
 		if (sum) {
 			*stat = 1;
-			return 0;
+			goto out;
 		}
 	}
 	/*
 	 * Found nothing, return failure.
 	 */
 	*stat = 0;
+out:
+	/* There were no extents at levels < log. */
+	if (mp->m_rsum_cache && log > mp->m_rsum_cache[bbno])
+		mp->m_rsum_cache[bbno] = log;
 	return 0;
 }
 
@@ -853,6 +855,21 @@
 	return error;
 }
 
+static void
+xfs_alloc_rsum_cache(
+	xfs_mount_t	*mp,		/* file system mount structure */
+	xfs_extlen_t	rbmblocks)	/* number of rt bitmap blocks */
+{
+	/*
+	 * The rsum cache is initialized to all zeroes, which is trivially a
+	 * lower bound on the minimum level with any free extents. We can
+	 * continue without the cache if it couldn't be allocated.
+	 */
+	mp->m_rsum_cache = kmem_zalloc_large(rbmblocks, 0);
+	if (!mp->m_rsum_cache)
+		xfs_warn(mp, "could not allocate realtime summary cache");
+}
+
 /*
  * Visible (exported) functions.
  */
@@ -881,6 +898,7 @@
 	xfs_extlen_t	rsumblocks;	/* current number of rt summary blks */
 	xfs_sb_t	*sbp;		/* old superblock */
 	xfs_fsblock_t	sumbno;		/* summary block number */
+	uint8_t		*rsum_cache;	/* old summary cache */
 
 	sbp = &mp->m_sb;
 	/*
@@ -937,10 +955,15 @@
 	error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks, mp->m_rsumip);
 	if (error)
 		return error;
+
+	rsum_cache = mp->m_rsum_cache;
+	if (nrbmblocks != sbp->sb_rbmblocks)
+		xfs_alloc_rsum_cache(mp, nrbmblocks);
+
 	/*
 	 * Allocate a new (fake) mount/sb.
 	 */
-	nmp = kmem_alloc(sizeof(*nmp), KM_SLEEP);
+	nmp = kmem_alloc(sizeof(*nmp), 0);
 	/*
 	 * Loop over the bitmap blocks.
 	 * We will do everything one bitmap block at a time.
@@ -1062,6 +1085,20 @@
 	 */
 	kmem_free(nmp);
 
+	/*
+	 * If we had to allocate a new rsum_cache, we either need to free the
+	 * old one (if we succeeded) or free the new one and restore the old one
+	 * (if there was an error).
+	 */
+	if (rsum_cache != mp->m_rsum_cache) {
+		if (error) {
+			kmem_free(mp->m_rsum_cache);
+			mp->m_rsum_cache = rsum_cache;
+		} else {
+			kmem_free(rsum_cache);
+		}
+	}
+
 	return error;
 }
 
@@ -1187,8 +1224,8 @@
 }
 
 /*
- * Get the bitmap and summary inodes into the mount structure
- * at mount time.
+ * Get the bitmap and summary inodes and the summary cache into the mount
+ * structure at mount time.
  */
 int					/* error */
 xfs_rtmount_inodes(
@@ -1198,19 +1235,18 @@
 	xfs_sb_t	*sbp;
 
 	sbp = &mp->m_sb;
-	if (sbp->sb_rbmino == NULLFSINO)
-		return 0;
 	error = xfs_iget(mp, NULL, sbp->sb_rbmino, 0, 0, &mp->m_rbmip);
 	if (error)
 		return error;
 	ASSERT(mp->m_rbmip != NULL);
-	ASSERT(sbp->sb_rsumino != NULLFSINO);
+
 	error = xfs_iget(mp, NULL, sbp->sb_rsumino, 0, 0, &mp->m_rsumip);
 	if (error) {
 		xfs_irele(mp->m_rbmip);
 		return error;
 	}
 	ASSERT(mp->m_rsumip != NULL);
+	xfs_alloc_rsum_cache(mp, sbp->sb_rbmblocks);
 	return 0;
 }
 
@@ -1218,6 +1254,7 @@
 xfs_rtunmount_inodes(
 	struct xfs_mount	*mp)
 {
+	kmem_free(mp->m_rsum_cache);
 	if (mp->m_rbmip)
 		xfs_irele(mp->m_rbmip);
 	if (mp->m_rsumip)