Merge tag 'for-5.12-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "This is the first batch of fixes that usually arrive during the merge
  window code freeze. Regressions and stable material.

  Regressions:

   - fix deadlock in log sync in zoned mode

   - fix bugs in subpage mode still wrongly assuming sectorsize == page
     size

  Fixes:

   - fix missing kunmap of the Q stripe in RAID6

   - block group fixes:
      - fix race between extent freeing/allocation when using bitmaps
      - avoid double put of block group when emptying cluster

   - swapfile fixes:
      - fix swapfile writes vs running scrub
      - fix swapfile activation vs snapshot creation

   - fix stale data exposure after cloning a hole with NO_HOLES enabled

   - remove tree-checker check that does not work in case information
     from other leaves is necessary"

* tag 'for-5.12-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: zoned: fix deadlock on log sync
  btrfs: avoid double put of block group when emptying cluster
  btrfs: fix stale data exposure after cloning a hole with NO_HOLES enabled
  btrfs: tree-checker: do not error out if extent ref hash doesn't match
  btrfs: fix race between swap file activation and snapshot creation
  btrfs: fix race between writes to swap files and scrub
  btrfs: avoid checking for RO block group twice during nocow writeback
  btrfs: fix race between extent freeing/allocation when using bitmaps
  btrfs: make check_compressed_csum() to be subpage compatible
  btrfs: make btrfs_submit_compressed_read() subpage compatible
  btrfs: fix raid6 qstripe kmap

1 files changed, 38 insertions, 6 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2e1c282c202d..3ca6a8b70b0b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1674,9 +1674,6 @@ next_slot:
 			 */
 			btrfs_release_path(path);
 
-			/* If extent is RO, we must COW it */
-			if (btrfs_extent_readonly(fs_info, disk_bytenr))
-				goto out_check;
 			ret = btrfs_cross_ref_exist(root, ino,
 						    found_key.offset -
 						    extent_offset, disk_bytenr, false);
@@ -1723,6 +1720,7 @@ next_slot:
 				WARN_ON_ONCE(freespace_inode);
 				goto out_check;
 			}
+			/* If the extent's block group is RO, we must COW */
 			if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr))
 				goto out_check;
 			nocow = true;
@@ -10200,6 +10198,7 @@ static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr,
 	sp->ptr = ptr;
 	sp->inode = inode;
 	sp->is_block_group = is_block_group;
+	sp->bg_extent_count = 1;
 
 	spin_lock(&fs_info->swapfile_pins_lock);
 	p = &fs_info->swapfile_pins.rb_node;
@@ -10213,6 +10212,8 @@ static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr,
 			   (sp->ptr == entry->ptr && sp->inode > entry->inode)) {
 			p = &(*p)->rb_right;
 		} else {
+			if (is_block_group)
+				entry->bg_extent_count++;
 			spin_unlock(&fs_info->swapfile_pins_lock);
 			kfree(sp);
 			return 1;
@@ -10238,8 +10239,11 @@ static void btrfs_free_swapfile_pins(struct inode *inode)
 		sp = rb_entry(node, struct btrfs_swapfile_pin, node);
 		if (sp->inode == inode) {
 			rb_erase(&sp->node, &fs_info->swapfile_pins);
-			if (sp->is_block_group)
+			if (sp->is_block_group) {
+				btrfs_dec_block_group_swap_extents(sp->ptr,
+							   sp->bg_extent_count);
 				btrfs_put_block_group(sp->ptr);
+			}
 			kfree(sp);
 		}
 		node = next;
@@ -10300,7 +10304,8 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 			       sector_t *span)
 {
 	struct inode *inode = file_inode(file);
-	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
+	struct btrfs_root *root = BTRFS_I(inode)->root;
+	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct extent_state *cached_state = NULL;
 	struct extent_map *em = NULL;
@@ -10351,13 +10356,27 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 	   "cannot activate swapfile while exclusive operation is running");
 		return -EBUSY;
 	}
+
+	/*
+	 * Prevent snapshot creation while we are activating the swap file.
+	 * We do not want to race with snapshot creation. If snapshot creation
+	 * already started before we bumped nr_swapfiles from 0 to 1 and
+	 * completes before the first write into the swap file after it is
+	 * activated, than that write would fallback to COW.
+	 */
+	if (!btrfs_drew_try_write_lock(&root->snapshot_lock)) {
+		btrfs_exclop_finish(fs_info);
+		btrfs_warn(fs_info,
+	   "cannot activate swapfile because snapshot creation is in progress");
+		return -EINVAL;
+	}
 	/*
 	 * Snapshots can create extents which require COW even if NODATACOW is
 	 * set. We use this counter to prevent snapshots. We must increment it
 	 * before walking the extents because we don't want a concurrent
 	 * snapshot to run after we've already checked the extents.
 	 */
-	atomic_inc(&BTRFS_I(inode)->root->nr_swapfiles);
+	atomic_inc(&root->nr_swapfiles);
 
 	isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);
 
@@ -10454,6 +10473,17 @@ static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 			goto out;
 		}
 
+		if (!btrfs_inc_block_group_swap_extents(bg)) {
+			btrfs_warn(fs_info,
+			   "block group for swapfile at %llu is read-only%s",
+			   bg->start,
+			   atomic_read(&fs_info->scrubs_running) ?
+				       " (scrub running)" : "");
+			btrfs_put_block_group(bg);
+			ret = -EINVAL;
+			goto out;
+		}
+
 		ret = btrfs_add_swapfile_pin(inode, bg, true);
 		if (ret) {
 			btrfs_put_block_group(bg);
@@ -10492,6 +10522,8 @@ out:
 	if (ret)
 		btrfs_swap_deactivate(file);
 
+	btrfs_drew_write_unlock(&root->snapshot_lock);
+
 	btrfs_exclop_finish(fs_info);
 
 	if (ret)