Merge tag 'for-5.20-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs updates from David Sterba:
 "This brings some long awaited changes, the send protocol bump,
  otherwise lots of small improvements and fixes. The main core part is
  reworking bio handling, cleaning up the submission and endio and
  improving error handling.

  There are some changes outside of btrfs adding helpers or updating
  API, listed at the end of the changelog.

  Features:

   - sysfs:
      - export chunk size, in debug mode add tunable for setting its size
      - show zoned among features (was only in debug mode)
      - show commit stats (number, last/max/total duration)

   - send protocol updated to 2
      - new commands:
         - ability write larger data chunks than 64K
         - send raw compressed extents (uses the encoded data ioctls),
           ie. no decompression on send side, no compression needed on
           receive side if supported
         - send 'otime' (inode creation time) among other timestamps
         - send file attributes (a.k.a file flags and xflags)
      - this is first version bump, backward compatibility on send and
        receive side is provided
      - there are still some known and wanted commands that will be
        implemented in the near future, another version bump will be
        needed, however we want to minimize that to avoid causing
        usability issues

   - print checksum type and implementation at mount time

   - don't print some messages at mount (mentioned as people asked about
     it), we want to print messages namely for new features so let's
     make some space for that
      - big metadata - this has been supported for a long time and is
        not a feature that's worth mentioning
      - skinny metadata - same reason, set by default by mkfs

  Performance improvements:

   - reduced amount of reserved metadata for delayed items
      - when inserted items can be batched into one leaf
      - when deleting batched directory index items
      - when deleting delayed items used for deletion
      - overall improved count of files/sec, decreased subvolume lock
        contention

   - metadata item access bounds checker micro-optimized, with a few
     percent of improved runtime for metadata-heavy operations

   - increase direct io limit for read to 256 sectors, improved
     throughput by 3x on sample workload

  Notable fixes:

   - raid56
      - reduce parity writes, skip sectors of stripe when there are no
        data updates
      - restore reading from on-disk data instead of using stripe cache,
        this reduces chances to damage correct data due to RMW cycle

   - refuse to replay log with unknown incompat read-only feature bit
     set

   - zoned
      - fix page locking when COW fails in the middle of allocation
      - improved tracking of active zones, ZNS drives may limit the
        number and there are ENOSPC errors due to that limit and not
        actual lack of space
      - adjust maximum extent size for zone append so it does not cause
        late ENOSPC due to underreservation

   - mirror reading error messages show the mirror number

   - don't fallback to buffered IO for NOWAIT direct IO writes, we don't
     have the NOWAIT semantics for buffered io yet

   - send, fix sending link commands for existing file paths when there
     are deleted and created hardlinks for same files

   - repair all mirrors for profiles with more than 1 copy (raid1c34)

   - fix repair of compressed extents, unify where error detection and
     repair happen

  Core changes:

   - bio completion cleanups
      - don't double defer compression bios
      - simplify endio workqueues
      - add more data to btrfs_bio to avoid allocation for read requests
      - rework bio error handling so it's same what block layer does,
        the submission works and errors are consumed in endio
      - when asynchronous bio offload fails fall back to synchronous
        checksum calculation to avoid errors under writeback or memory
        pressure

   - new trace points
      - raid56 events
      - ordered extent operations

   - super block log_root_transid deprecated (never used)

   - mixed_backref and big_metadata sysfs feature files removed, they've
     been default for sufficiently long time, there are no known users
     and mixed_backref could be confused with mixed_groups

  Non-btrfs changes, API updates:

   - minor highmem API update to cover const arguments

   - switch all kmap/kmap_atomic to kmap_local

   - remove redundant flush_dcache_page()

   - address_space_operations::writepage callback removed

   - add bdev_max_segments() helper"

* tag 'for-5.20-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (163 commits)
  btrfs: don't call btrfs_page_set_checked in finish_compressed_bio_read
  btrfs: fix repair of compressed extents
  btrfs: remove the start argument to check_data_csum and export
  btrfs: pass a btrfs_bio to btrfs_repair_one_sector
  btrfs: simplify the pending I/O counting in struct compressed_bio
  btrfs: repair all known bad mirrors
  btrfs: merge btrfs_dev_stat_print_on_error with its only caller
  btrfs: join running log transaction when logging new name
  btrfs: simplify error handling in btrfs_lookup_dentry
  btrfs: send: always use the rbtree based inode ref management infrastructure
  btrfs: send: fix sending link commands for existing file paths
  btrfs: send: introduce recorded_ref_alloc and recorded_ref_free
  btrfs: zoned: wait until zone is finished when allocation didn't progress
  btrfs: zoned: write out partially allocated region
  btrfs: zoned: activate necessary block group
  btrfs: zoned: activate metadata block group on flush_space
  btrfs: zoned: disable metadata overcommit for zoned
  btrfs: zoned: introduce space_info->active_total_bytes
  btrfs: zoned: finish least available block group on data bg allocation
  btrfs: let can_allocate_chunk return error
  ...

1 files changed, 88 insertions, 180 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1b23d806a647..4c3166f3c725 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -51,7 +51,6 @@
 				 BTRFS_SUPER_FLAG_METADUMP |\
 				 BTRFS_SUPER_FLAG_METADUMP_V2)
 
-static void end_workqueue_fn(struct btrfs_work *work);
 static void btrfs_destroy_ordered_extents(struct btrfs_root *root);
 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 				      struct btrfs_fs_info *fs_info);
@@ -64,40 +63,6 @@ static int btrfs_destroy_pinned_extent(struct btrfs_fs_info *fs_info,
 static int btrfs_cleanup_transaction(struct btrfs_fs_info *fs_info);
 static void btrfs_error_commit_super(struct btrfs_fs_info *fs_info);
 
-/*
- * btrfs_end_io_wq structs are used to do processing in task context when an IO
- * is complete.  This is used during reads to verify checksums, and it is used
- * by writes to insert metadata for new file extents after IO is complete.
- */
-struct btrfs_end_io_wq {
-	struct bio *bio;
-	bio_end_io_t *end_io;
-	void *private;
-	struct btrfs_fs_info *info;
-	blk_status_t status;
-	enum btrfs_wq_endio_type metadata;
-	struct btrfs_work work;
-};
-
-static struct kmem_cache *btrfs_end_io_wq_cache;
-
-int __init btrfs_end_io_wq_init(void)
-{
-	btrfs_end_io_wq_cache = kmem_cache_create("btrfs_end_io_wq",
-					sizeof(struct btrfs_end_io_wq),
-					0,
-					SLAB_MEM_SPREAD,
-					NULL);
-	if (!btrfs_end_io_wq_cache)
-		return -ENOMEM;
-	return 0;
-}
-
-void __cold btrfs_end_io_wq_exit(void)
-{
-	kmem_cache_destroy(btrfs_end_io_wq_cache);
-}
-
 static void btrfs_free_csum_hash(struct btrfs_fs_info *fs_info)
 {
 	if (fs_info->csum_shash)
@@ -256,8 +221,8 @@ static int verify_parent_transid(struct extent_io_tree *io_tree,
 		goto out;
 	}
 	btrfs_err_rl(eb->fs_info,
-		"parent transid verify failed on %llu wanted %llu found %llu",
-			eb->start,
+"parent transid verify failed on logical %llu mirror %u wanted %llu found %llu",
+			eb->start, eb->read_mirror,
 			parent_transid, btrfs_header_generation(eb));
 	ret = 1;
 	clear_extent_buffer_uptodate(eb);
@@ -587,21 +552,23 @@ static int validate_extent_buffer(struct extent_buffer *eb)
 
 	found_start = btrfs_header_bytenr(eb);
 	if (found_start != eb->start) {
-		btrfs_err_rl(fs_info, "bad tree block start, want %llu have %llu",
-			     eb->start, found_start);
+		btrfs_err_rl(fs_info,
+			"bad tree block start, mirror %u want %llu have %llu",
+			     eb->read_mirror, eb->start, found_start);
 		ret = -EIO;
 		goto out;
 	}
 	if (check_tree_block_fsid(eb)) {
-		btrfs_err_rl(fs_info, "bad fsid on block %llu",
-			     eb->start);
+		btrfs_err_rl(fs_info, "bad fsid on logical %llu mirror %u",
+			     eb->start, eb->read_mirror);
 		ret = -EIO;
 		goto out;
 	}
 	found_level = btrfs_header_level(eb);
 	if (found_level >= BTRFS_MAX_LEVEL) {
-		btrfs_err(fs_info, "bad tree block level %d on %llu",
-			  (int)btrfs_header_level(eb), eb->start);
+		btrfs_err(fs_info,
+			"bad tree block level, mirror %u level %d on logical %llu",
+			eb->read_mirror, btrfs_header_level(eb), eb->start);
 		ret = -EIO;
 		goto out;
 	}
@@ -612,8 +579,8 @@ static int validate_extent_buffer(struct extent_buffer *eb)
 
 	if (memcmp(result, header_csum, csum_size) != 0) {
 		btrfs_warn_rl(fs_info,
-	"checksum verify failed on %llu wanted " CSUM_FMT " found " CSUM_FMT " level %d",
-			      eb->start,
+"checksum verify failed on logical %llu mirror %u wanted " CSUM_FMT " found " CSUM_FMT " level %d",
+			      eb->start, eb->read_mirror,
 			      CSUM_FMT_VALUE(csum_size, header_csum),
 			      CSUM_FMT_VALUE(csum_size, result),
 			      btrfs_header_level(eb));
@@ -638,8 +605,8 @@ static int validate_extent_buffer(struct extent_buffer *eb)
 		set_extent_buffer_uptodate(eb);
 	else
 		btrfs_err(fs_info,
-			  "block=%llu read time tree block corruption detected",
-			  eb->start);
+		"read time tree block corruption detected on logical %llu mirror %u",
+			  eb->start, eb->read_mirror);
 out:
 	return ret;
 }
@@ -740,58 +707,6 @@ err:
 	return ret;
 }
 
-static void end_workqueue_bio(struct bio *bio)
-{
-	struct btrfs_end_io_wq *end_io_wq = bio->bi_private;
-	struct btrfs_fs_info *fs_info;
-	struct btrfs_workqueue *wq;
-
-	fs_info = end_io_wq->info;
-	end_io_wq->status = bio->bi_status;
-
-	if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
-		if (end_io_wq->metadata == BTRFS_WQ_ENDIO_METADATA)
-			wq = fs_info->endio_meta_write_workers;
-		else if (end_io_wq->metadata == BTRFS_WQ_ENDIO_FREE_SPACE)
-			wq = fs_info->endio_freespace_worker;
-		else if (end_io_wq->metadata == BTRFS_WQ_ENDIO_RAID56)
-			wq = fs_info->endio_raid56_workers;
-		else
-			wq = fs_info->endio_write_workers;
-	} else {
-		if (end_io_wq->metadata == BTRFS_WQ_ENDIO_RAID56)
-			wq = fs_info->endio_raid56_workers;
-		else if (end_io_wq->metadata)
-			wq = fs_info->endio_meta_workers;
-		else
-			wq = fs_info->endio_workers;
-	}
-
-	btrfs_init_work(&end_io_wq->work, end_workqueue_fn, NULL, NULL);
-	btrfs_queue_work(wq, &end_io_wq->work);
-}
-
-blk_status_t btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
-			enum btrfs_wq_endio_type metadata)
-{
-	struct btrfs_end_io_wq *end_io_wq;
-
-	end_io_wq = kmem_cache_alloc(btrfs_end_io_wq_cache, GFP_NOFS);
-	if (!end_io_wq)
-		return BLK_STS_RESOURCE;
-
-	end_io_wq->private = bio->bi_private;
-	end_io_wq->end_io = bio->bi_end_io;
-	end_io_wq->info = info;
-	end_io_wq->status = 0;
-	end_io_wq->bio = bio;
-	end_io_wq->metadata = metadata;
-
-	bio->bi_private = end_io_wq;
-	bio->bi_end_io = end_workqueue_bio;
-	return 0;
-}
-
 static void run_one_async_start(struct btrfs_work *work)
 {
 	struct async_submit_bio *async;
@@ -816,7 +731,6 @@ static void run_one_async_done(struct btrfs_work *work)
 {
 	struct async_submit_bio *async;
 	struct inode *inode;
-	blk_status_t ret;
 
 	async = container_of(work, struct  async_submit_bio, work);
 	inode = async->inode;
@@ -834,11 +748,7 @@ static void run_one_async_done(struct btrfs_work *work)
 	 * This changes nothing when cgroups aren't in use.
 	 */
 	async->bio->bi_opf |= REQ_CGROUP_PUNT;
-	ret = btrfs_map_bio(btrfs_sb(inode->i_sb), async->bio, async->mirror_num);
-	if (ret) {
-		async->bio->bi_status = ret;
-		bio_endio(async->bio);
-	}
+	btrfs_submit_bio(btrfs_sb(inode->i_sb), async->bio, async->mirror_num);
 }
 
 static void run_one_async_free(struct btrfs_work *work)
@@ -849,16 +759,23 @@ static void run_one_async_free(struct btrfs_work *work)
 	kfree(async);
 }
 
-blk_status_t btrfs_wq_submit_bio(struct inode *inode, struct bio *bio,
-				 int mirror_num, u64 dio_file_offset,
-				 extent_submit_bio_start_t *submit_bio_start)
+/*
+ * Submit bio to an async queue.
+ *
+ * Retrun:
+ * - true if the work has been succesfuly submitted
+ * - false in case of error
+ */
+bool btrfs_wq_submit_bio(struct inode *inode, struct bio *bio, int mirror_num,
+			 u64 dio_file_offset,
+			 extent_submit_bio_start_t *submit_bio_start)
 {
 	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
 	struct async_submit_bio *async;
 
 	async = kmalloc(sizeof(*async), GFP_NOFS);
 	if (!async)
-		return BLK_STS_RESOURCE;
+		return false;
 
 	async->inode = inode;
 	async->bio = bio;
@@ -876,7 +793,7 @@ blk_status_t btrfs_wq_submit_bio(struct inode *inode, struct bio *bio,
 		btrfs_queue_work(fs_info->hipri_workers, &async->work);
 	else
 		btrfs_queue_work(fs_info->workers, &async->work);
-	return 0;
+	return true;
 }
 
 static blk_status_t btree_csum_one_bio(struct bio *bio)
@@ -902,7 +819,7 @@ static blk_status_t btree_submit_bio_start(struct inode *inode, struct bio *bio,
 {
 	/*
 	 * when we're called for a write, we're already in the async
-	 * submission context.  Just jump into btrfs_map_bio
+	 * submission context.  Just jump into btrfs_submit_bio.
 	 */
 	return btree_csum_one_bio(bio);
 }
@@ -924,32 +841,29 @@ void btrfs_submit_metadata_bio(struct inode *inode, struct bio *bio, int mirror_
 	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 	blk_status_t ret;
 
+	bio->bi_opf |= REQ_META;
+
 	if (btrfs_op(bio) != BTRFS_MAP_WRITE) {
-		/*
-		 * called for a read, do the setup so that checksum validation
-		 * can happen in the async kernel threads
-		 */
-		ret = btrfs_bio_wq_end_io(fs_info, bio,
-					  BTRFS_WQ_ENDIO_METADATA);
-		if (!ret)
-			ret = btrfs_map_bio(fs_info, bio, mirror_num);
-	} else if (!should_async_write(fs_info, BTRFS_I(inode))) {
-		ret = btree_csum_one_bio(bio);
-		if (!ret)
-			ret = btrfs_map_bio(fs_info, bio, mirror_num);
-	} else {
-		/*
-		 * kthread helpers are used to submit writes so that
-		 * checksumming can happen in parallel across all CPUs
-		 */
-		ret = btrfs_wq_submit_bio(inode, bio, mirror_num, 0,
-					  btree_submit_bio_start);
+		btrfs_submit_bio(fs_info, bio, mirror_num);
+		return;
 	}
 
+	/*
+	 * Kthread helpers are used to submit writes so that checksumming can
+	 * happen in parallel across all CPUs.
+	 */
+	if (should_async_write(fs_info, BTRFS_I(inode)) &&
+	    btrfs_wq_submit_bio(inode, bio, mirror_num, 0, btree_submit_bio_start))
+		return;
+
+	ret = btree_csum_one_bio(bio);
 	if (ret) {
 		bio->bi_status = ret;
 		bio_endio(bio);
+		return;
 	}
+
+	btrfs_submit_bio(fs_info, bio, mirror_num);
 }
 
 #ifdef CONFIG_MIGRATION
@@ -1870,7 +1784,7 @@ again:
 fail:
 	/*
 	 * If our caller provided us an anonymous device, then it's his
-	 * responsability to free it in case we fail. So we have to set our
+	 * responsibility to free it in case we fail. So we have to set our
 	 * root's anon_dev to 0 to avoid a double free, once by btrfs_put_root()
 	 * and once again by our caller.
 	 */
@@ -1953,25 +1867,6 @@ struct btrfs_root *btrfs_get_fs_root_commit_root(struct btrfs_fs_info *fs_info,
 	return root;
 }
 
-/*
- * called by the kthread helper functions to finally call the bio end_io
- * functions.  This is where read checksum verification actually happens
- */
-static void end_workqueue_fn(struct btrfs_work *work)
-{
-	struct bio *bio;
-	struct btrfs_end_io_wq *end_io_wq;
-
-	end_io_wq = container_of(work, struct btrfs_end_io_wq, work);
-	bio = end_io_wq->bio;
-
-	bio->bi_status = end_io_wq->status;
-	bio->bi_private = end_io_wq->private;
-	bio->bi_end_io = end_io_wq->end_io;
-	bio_endio(bio);
-	kmem_cache_free(btrfs_end_io_wq_cache, end_io_wq);
-}
-
 static int cleaner_kthread(void *arg)
 {
 	struct btrfs_fs_info *fs_info = arg;
@@ -2278,10 +2173,14 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 	btrfs_destroy_workqueue(fs_info->delalloc_workers);
 	btrfs_destroy_workqueue(fs_info->hipri_workers);
 	btrfs_destroy_workqueue(fs_info->workers);
-	btrfs_destroy_workqueue(fs_info->endio_workers);
-	btrfs_destroy_workqueue(fs_info->endio_raid56_workers);
+	if (fs_info->endio_workers)
+		destroy_workqueue(fs_info->endio_workers);
+	if (fs_info->endio_raid56_workers)
+		destroy_workqueue(fs_info->endio_raid56_workers);
 	if (fs_info->rmw_workers)
 		destroy_workqueue(fs_info->rmw_workers);
+	if (fs_info->compressed_write_workers)
+		destroy_workqueue(fs_info->compressed_write_workers);
 	btrfs_destroy_workqueue(fs_info->endio_write_workers);
 	btrfs_destroy_workqueue(fs_info->endio_freespace_worker);
 	btrfs_destroy_workqueue(fs_info->delayed_workers);
@@ -2295,8 +2194,8 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info *fs_info)
 	 * the queues used for metadata I/O, since tasks from those other work
 	 * queues can do metadata I/O operations.
 	 */
-	btrfs_destroy_workqueue(fs_info->endio_meta_workers);
-	btrfs_destroy_workqueue(fs_info->endio_meta_write_workers);
+	if (fs_info->endio_meta_workers)
+		destroy_workqueue(fs_info->endio_meta_workers);
 }
 
 static void free_root_extent_buffers(struct btrfs_root *root)
@@ -2426,7 +2325,9 @@ static void btrfs_init_btree_inode(struct btrfs_fs_info *fs_info)
 	extent_map_tree_init(&BTRFS_I(inode)->extent_tree);
 
 	BTRFS_I(inode)->root = btrfs_grab_root(fs_info->tree_root);
-	memset(&BTRFS_I(inode)->location, 0, sizeof(struct btrfs_key));
+	BTRFS_I(inode)->location.objectid = BTRFS_BTREE_INODE_OBJECTID;
+	BTRFS_I(inode)->location.type = 0;
+	BTRFS_I(inode)->location.offset = 0;
 	set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
 	btrfs_insert_inode_hash(inode);
 }
@@ -2475,25 +2376,18 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info)
 	fs_info->fixup_workers =
 		btrfs_alloc_workqueue(fs_info, "fixup", flags, 1, 0);
 
-	/*
-	 * endios are largely parallel and should have a very
-	 * low idle thresh
-	 */
 	fs_info->endio_workers =
-		btrfs_alloc_workqueue(fs_info, "endio", flags, max_active, 4);
+		alloc_workqueue("btrfs-endio", flags, max_active);
 	fs_info->endio_meta_workers =
-		btrfs_alloc_workqueue(fs_info, "endio-meta", flags,
-				      max_active, 4);
-	fs_info->endio_meta_write_workers =
-		btrfs_alloc_workqueue(fs_info, "endio-meta-write", flags,
-				      max_active, 2);
+		alloc_workqueue("btrfs-endio-meta", flags, max_active);
 	fs_info->endio_raid56_workers =
-		btrfs_alloc_workqueue(fs_info, "endio-raid56", flags,
-				      max_active, 4);
+		alloc_workqueue("btrfs-endio-raid56", flags, max_active);
 	fs_info->rmw_workers = alloc_workqueue("btrfs-rmw", flags, max_active);
 	fs_info->endio_write_workers =
 		btrfs_alloc_workqueue(fs_info, "endio-write", flags,
 				      max_active, 2);
+	fs_info->compressed_write_workers =
+		alloc_workqueue("btrfs-compressed-write", flags, max_active);
 	fs_info->endio_freespace_worker =
 		btrfs_alloc_workqueue(fs_info, "freespace-write", flags,
 				      max_active, 0);
@@ -2508,7 +2402,7 @@ static int btrfs_init_workqueues(struct btrfs_fs_info *fs_info)
 	if (!(fs_info->workers && fs_info->hipri_workers &&
 	      fs_info->delalloc_workers && fs_info->flush_workers &&
 	      fs_info->endio_workers && fs_info->endio_meta_workers &&
-	      fs_info->endio_meta_write_workers &&
+	      fs_info->compressed_write_workers &&
 	      fs_info->endio_write_workers && fs_info->endio_raid56_workers &&
 	      fs_info->endio_freespace_worker && fs_info->rmw_workers &&
 	      fs_info->caching_workers && fs_info->fixup_workers &&
@@ -2535,6 +2429,9 @@ static int btrfs_init_csum_hash(struct btrfs_fs_info *fs_info, u16 csum_type)
 
 	fs_info->csum_shash = csum_shash;
 
+	btrfs_info(fs_info, "using %s (%s) checksum algorithm",
+			btrfs_super_csum_name(csum_type),
+			crypto_shash_driver_name(csum_shash));
 	return 0;
 }
 
@@ -3253,6 +3150,7 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
 	init_waitqueue_head(&fs_info->transaction_blocked_wait);
 	init_waitqueue_head(&fs_info->async_submit_wait);
 	init_waitqueue_head(&fs_info->delayed_iputs_wait);
+	init_waitqueue_head(&fs_info->zone_finish_wait);
 
 	/* Usable values until the real ones are cached from the superblock */
 	fs_info->nodesize = 4096;
@@ -3260,6 +3158,8 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info)
 	fs_info->sectorsize_bits = ilog2(4096);
 	fs_info->stripesize = 4096;
 
+	fs_info->max_extent_size = BTRFS_MAX_EXTENT_SIZE;
+
 	spin_lock_init(&fs_info->swapfile_pins_lock);
 	fs_info->swapfile_pins = RB_ROOT;
 
@@ -3591,16 +3491,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	 */
 	fs_info->compress_type = BTRFS_COMPRESS_ZLIB;
 
-	/*
-	 * Flag our filesystem as having big metadata blocks if they are bigger
-	 * than the page size.
-	 */
-	if (btrfs_super_nodesize(disk_super) > PAGE_SIZE) {
-		if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
-			btrfs_info(fs_info,
-				"flagging fs with big metadata feature");
-		features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
-	}
 
 	/* Set up fs_info before parsing mount options */
 	nodesize = btrfs_super_nodesize(disk_super);
@@ -3638,8 +3528,12 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	else if (fs_info->compress_type == BTRFS_COMPRESS_ZSTD)
 		features |= BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD;
 
-	if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
-		btrfs_info(fs_info, "has skinny extents");
+	/*
+	 * Flag our filesystem as having big metadata blocks if they are bigger
+	 * than the page size.
+	 */
+	if (btrfs_super_nodesize(disk_super) > PAGE_SIZE)
+		features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
 
 	/*
 	 * mixed block groups end up with duplicate but slightly offset
@@ -3668,6 +3562,20 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 		err = -EINVAL;
 		goto fail_alloc;
 	}
+	/*
+	 * We have unsupported RO compat features, although RO mounted, we
+	 * should not cause any metadata write, including log replay.
+	 * Or we could screw up whatever the new feature requires.
+	 */
+	if (unlikely(features && btrfs_super_log_root(disk_super) &&
+		     !btrfs_test_opt(fs_info, NOLOGREPLAY))) {
+		btrfs_err(fs_info,
+"cannot replay dirty log with unsupported compat_ro features (0x%llx), try rescue=nologreplay",
+			  features);
+		err = -EINVAL;
+		goto fail_alloc;
+	}
+
 
 	if (sectorsize < PAGE_SIZE) {
 		struct btrfs_subpage_info *subpage_info;