btrfs: zoned: introduce space_info->active_total_bytes

The active_total_bytes, like the total_bytes, accounts for the total bytes
of active block groups in the space_info.

With an introduction of active_total_bytes, we can check if the reserved
bytes can be written to the block groups without activating a new block
group. The check is necessary for metadata allocation on zoned
filesystem. We cannot finish a block group, which may require waiting
for the current transaction, from the metadata allocation context.
Instead, we need to ensure the ongoing allocation (reserved bytes) fits
in active block groups.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 32 insertions, 9 deletions

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 62d25112310d..826193c31dff 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -295,7 +295,7 @@ out:
 void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
 			     u64 total_bytes, u64 bytes_used,
 			     u64 bytes_readonly, u64 bytes_zone_unusable,
-			     struct btrfs_space_info **space_info)
+			     bool active, struct btrfs_space_info **space_info)
 {
 	struct btrfs_space_info *found;
 	int factor;
@@ -306,6 +306,8 @@ void btrfs_update_space_info(struct btrfs_fs_info *info, u64 flags,
 	ASSERT(found);
 	spin_lock(&found->lock);
 	found->total_bytes += total_bytes;
+	if (active)
+		found->active_total_bytes += total_bytes;
 	found->disk_total += total_bytes * factor;
 	found->bytes_used += bytes_used;
 	found->disk_used += bytes_used * factor;
@@ -369,6 +371,22 @@ static u64 calc_available_free_space(struct btrfs_fs_info *fs_info,
 	return avail;
 }
 
+static inline u64 writable_total_bytes(struct btrfs_fs_info *fs_info,
+				       struct btrfs_space_info *space_info)
+{
+	/*
+	 * On regular filesystem, all total_bytes are always writable. On zoned
+	 * filesystem, there may be a limitation imposed by max_active_zones.
+	 * For metadata allocation, we cannot finish an existing active block
+	 * group to avoid a deadlock. Thus, we need to consider only the active
+	 * groups to be writable for metadata space.
+	 */
+	if (!btrfs_is_zoned(fs_info) || (space_info->flags & BTRFS_BLOCK_GROUP_DATA))
+		return space_info->total_bytes;
+
+	return space_info->active_total_bytes;
+}
+
 int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 			 struct btrfs_space_info *space_info, u64 bytes,
 			 enum btrfs_reserve_flush_enum flush)
@@ -383,7 +401,7 @@ int btrfs_can_overcommit(struct btrfs_fs_info *fs_info,
 	used = btrfs_space_info_used(space_info, true);
 	avail = calc_available_free_space(fs_info, space_info, flush);
 
-	if (used + bytes < space_info->total_bytes + avail)
+	if (used + bytes < writable_total_bytes(fs_info, space_info) + avail)
 		return 1;
 	return 0;
 }
@@ -419,7 +437,7 @@ again:
 		ticket = list_first_entry(head, struct reserve_ticket, list);
 
 		/* Check and see if our ticket can be satisfied now. */
-		if ((used + ticket->bytes <= space_info->total_bytes) ||
+		if ((used + ticket->bytes <= writable_total_bytes(fs_info, space_info)) ||
 		    btrfs_can_overcommit(fs_info, space_info, ticket->bytes,
 					 flush)) {
 			btrfs_space_info_update_bytes_may_use(fs_info,
@@ -750,6 +768,7 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 {
 	u64 used;
 	u64 avail;
+	u64 total;
 	u64 to_reclaim = space_info->reclaim_size;
 
 	lockdep_assert_held(&space_info->lock);
@@ -764,8 +783,9 @@ btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,
 	 * space.  If that's the case add in our overage so we make sure to put
 	 * appropriate pressure on the flushing state machine.
 	 */
-	if (space_info->total_bytes + avail < used)
-		to_reclaim += used - (space_info->total_bytes + avail);
+	total = writable_total_bytes(fs_info, space_info);
+	if (total + avail < used)
+		to_reclaim += used - (total + avail);
 
 	return to_reclaim;
 }
@@ -775,9 +795,12 @@ static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 {
 	u64 global_rsv_size = fs_info->global_block_rsv.reserved;
 	u64 ordered, delalloc;
-	u64 thresh = div_factor_fine(space_info->total_bytes, 90);
+	u64 total = writable_total_bytes(fs_info, space_info);
+	u64 thresh;
 	u64 used;
 
+	thresh = div_factor_fine(total, 90);
+
 	lockdep_assert_held(&space_info->lock);
 
 	/* If we're just plain full then async reclaim just slows us down. */
@@ -839,8 +862,8 @@ static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 					   BTRFS_RESERVE_FLUSH_ALL);
 	used = space_info->bytes_used + space_info->bytes_reserved +
 	       space_info->bytes_readonly + global_rsv_size;
-	if (used < space_info->total_bytes)
-		thresh += space_info->total_bytes - used;
+	if (used < total)
+		thresh += total - used;
 	thresh >>= space_info->clamp;
 
 	used = space_info->bytes_pinned;
@@ -1557,7 +1580,7 @@ static int __reserve_bytes(struct btrfs_fs_info *fs_info,
 	 * can_overcommit() to ensure we can overcommit to continue.
 	 */
 	if (!pending_tickets &&
-	    ((used + orig_bytes <= space_info->total_bytes) ||
+	    ((used + orig_bytes <= writable_total_bytes(fs_info, space_info)) ||
 	     btrfs_can_overcommit(fs_info, space_info, orig_bytes, flush))) {
 		btrfs_space_info_update_bytes_may_use(fs_info, space_info,
 						      orig_bytes);