for-5.4-rc6-tag

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Merge tag 'for-5.4-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "A few regressions and fixes for stable.

  Regressions:

   - fix a race leading to metadata space leak after task received a
     signal

   - un-deprecate 2 ioctls, marked as deprecated by mistake

  Fixes:

   - fix limit check for number of devices during chunk allocation

   - fix a race due to double evaluation of i_size_read inside max()
     macro, can cause a crash

   - remove wrong device id check in tree-checker"

* tag 'for-5.4-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: un-deprecate ioctls START_SYNC and WAIT_SYNC
  btrfs: save i_size to avoid double evaluation of i_size_read in compress_file_range
  Btrfs: fix race leading to metadata space leak after task received signal
  btrfs: tree-checker: Fix wrong check on max devid
  btrfs: Consider system chunk array size for new SYSTEM chunks

fs/btrfs/inode.c

@@ -474,6 +474,7 @@ static noinline int compress_file_range(struct async_chunk *async_chunk)
 	u64 start = async_chunk->start;
 	u64 end = async_chunk->end;
 	u64 actual_end;
+	u64 i_size;
 	int ret = 0;
 	struct page **pages = NULL;
 	unsigned long nr_pages;
@@ -488,7 +489,19 @@ static noinline int compress_file_range(struct async_chunk *async_chunk)
 	inode_should_defrag(BTRFS_I(inode), start, end, end - start + 1,
 			SZ_16K);
 
-	actual_end = min_t(u64, i_size_read(inode), end + 1);
+	/*
+	 * We need to save i_size before now because it could change in between
+	 * us evaluating the size and assigning it.  This is because we lock and
+	 * unlock the page in truncate and fallocate, and then modify the i_size
+	 * later on.
+	 *
+	 * The barriers are to emulate READ_ONCE, remove that once i_size_read
+	 * does that for us.
+	 */
+	barrier();
+	i_size = i_size_read(inode);
+	barrier();
+	actual_end = min_t(u64, i_size, end + 1);
 again:
 	will_compress = 0;
 	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;

fs/btrfs/ioctl.c

@@ -4195,9 +4195,6 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
 	u64 transid;
 	int ret;
 
-	btrfs_warn(root->fs_info,
-	"START_SYNC ioctl is deprecated and will be removed in kernel 5.7");
-
 	trans = btrfs_attach_transaction_barrier(root);
 	if (IS_ERR(trans)) {
 		if (PTR_ERR(trans) != -ENOENT)
@@ -4225,9 +4222,6 @@ static noinline long btrfs_ioctl_wait_sync(struct btrfs_fs_info *fs_info,
 {
 	u64 transid;
 
-	btrfs_warn(fs_info,
-		"WAIT_SYNC ioctl is deprecated and will be removed in kernel 5.7");
-
 	if (argp) {
 		if (copy_from_user(&transid, argp, sizeof(transid)))
 			return -EFAULT;

fs/btrfs/space-info.c

@@ -893,6 +893,15 @@ static void wait_reserve_ticket(struct btrfs_fs_info *fs_info,
 	while (ticket->bytes > 0 && ticket->error == 0) {
 		ret = prepare_to_wait_event(&ticket->wait, &wait, TASK_KILLABLE);
 		if (ret) {
+			/*
+			 * Delete us from the list. After we unlock the space
+			 * info, we don't want the async reclaim job to reserve
+			 * space for this ticket. If that would happen, then the
+			 * ticket's task would not known that space was reserved
+			 * despite getting an error, resulting in a space leak
+			 * (bytes_may_use counter of our space_info).
+			 */
+			list_del_init(&ticket->list);
 			ticket->error = -EINTR;
 			break;
 		}
@@ -945,12 +954,24 @@ static int handle_reserve_ticket(struct btrfs_fs_info *fs_info,
 	spin_lock(&space_info->lock);
 	ret = ticket->error;
 	if (ticket->bytes || ticket->error) {
+		/*
+		 * Need to delete here for priority tickets. For regular tickets
+		 * either the async reclaim job deletes the ticket from the list
+		 * or we delete it ourselves at wait_reserve_ticket().
+		 */
 		list_del_init(&ticket->list);
 		if (!ret)
 			ret = -ENOSPC;
 	}
 	spin_unlock(&space_info->lock);
 	ASSERT(list_empty(&ticket->list));
+	/*
+	 * Check that we can't have an error set if the reservation succeeded,
+	 * as that would confuse tasks and lead them to error out without
+	 * releasing reserved space (if an error happens the expectation is that
+	 * space wasn't reserved at all).
+	 */
+	ASSERT(!(ticket->bytes == 0 && ticket->error));
 	return ret;
 }
 

fs/btrfs/tree-checker.c

@@ -686,9 +686,7 @@ static void dev_item_err(const struct extent_buffer *eb, int slot,
 static int check_dev_item(struct extent_buffer *leaf,
 			  struct btrfs_key *key, int slot)
 {
-	struct btrfs_fs_info *fs_info = leaf->fs_info;
 	struct btrfs_dev_item *ditem;
-	u64 max_devid = max(BTRFS_MAX_DEVS(fs_info), BTRFS_MAX_DEVS_SYS_CHUNK);
 
 	if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) {
 		dev_item_err(leaf, slot,
@@ -696,12 +694,6 @@ static int check_dev_item(struct extent_buffer *leaf,
 			     key->objectid, BTRFS_DEV_ITEMS_OBJECTID);
 		return -EUCLEAN;
 	}
-	if (key->offset > max_devid) {
-		dev_item_err(leaf, slot,
-			     "invalid devid: has=%llu expect=[0, %llu]",
-			     key->offset, max_devid);
-		return -EUCLEAN;
-	}
 	ditem = btrfs_item_ptr(leaf, slot, struct btrfs_dev_item);
 	if (btrfs_device_id(leaf, ditem) != key->offset) {
 		dev_item_err(leaf, slot,

fs/btrfs/volumes.c

@@ -4967,6 +4967,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	} else if (type & BTRFS_BLOCK_GROUP_SYSTEM) {
 		max_stripe_size = SZ_32M;
 		max_chunk_size = 2 * max_stripe_size;
+		devs_max = min_t(int, devs_max, BTRFS_MAX_DEVS_SYS_CHUNK);
 	} else {
 		btrfs_err(info, "invalid chunk type 0x%llx requested",
 		       type);