btrfs: zoned: support dev-replace in zoned filesystems

This is 4/4 patch to implement device-replace on zoned filesystems.

Even after the copying is done, the write pointers of the source device
and the destination device may not be synchronized. For example, when
the last allocated extent is freed before device-replace process, the
extent is not copied, leaving a hole there.

Synchronize the write pointers by writing zeroes to the destination
device.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 92904902d160..e0c3ec01e324 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1628,6 +1628,9 @@ static int fill_writer_pointer_gap(struct scrub_ctx *sctx, u64 physical)
 	if (!btrfs_is_zoned(sctx->fs_info))
 		return 0;
 
+	if (!btrfs_dev_is_sequential(sctx->wr_tgtdev, physical))
+		return 0;
+
 	if (sctx->write_pointer < physical) {
 		length = physical - sctx->write_pointer;
 
@@ -3069,6 +3072,32 @@ static void sync_replace_for_zoned(struct scrub_ctx *sctx)
 	wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
 }
 
+static int sync_write_pointer_for_zoned(struct scrub_ctx *sctx, u64 logical,
+					u64 physical, u64 physical_end)
+{
+	struct btrfs_fs_info *fs_info = sctx->fs_info;
+	int ret = 0;
+
+	if (!btrfs_is_zoned(fs_info))
+		return 0;
+
+	wait_event(sctx->list_wait, atomic_read(&sctx->bios_in_flight) == 0);
+
+	mutex_lock(&sctx->wr_lock);
+	if (sctx->write_pointer < physical_end) {
+		ret = btrfs_sync_zone_write_pointer(sctx->wr_tgtdev, logical,
+						    physical,
+						    sctx->write_pointer);
+		if (ret)
+			btrfs_err(fs_info,
+				  "zoned: failed to recover write pointer");
+	}
+	mutex_unlock(&sctx->wr_lock);
+	btrfs_dev_clear_zone_empty(sctx->wr_tgtdev, physical);
+
+	return ret;
+}
+
 static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
 					   struct map_lookup *map,
 					   struct btrfs_device *scrub_dev,
@@ -3475,6 +3504,17 @@ out:
 	blk_finish_plug(&plug);
 	btrfs_free_path(path);
 	btrfs_free_path(ppath);
+
+	if (sctx->is_dev_replace && ret >= 0) {
+		int ret2;
+
+		ret2 = sync_write_pointer_for_zoned(sctx, base + offset,
+						    map->stripes[num].physical,
+						    physical_end);
+		if (ret2)
+			ret = ret2;
+	}
+
 	return ret < 0 ? ret : 0;
 }