[PATCH 5.19 043/207] btrfs: zoned: wait for extent buffer IOs before finishing a zone

Greg Kroah-Hartman
2022-09-26T11:35:21Z

From: Naohiro Aota <naohiro.aota@wdc.com>

commit 2dd7e7bc02829eded71be2342a93dc035f5223f9 upstream.

Before sending REQ_OP_ZONE_FINISH to a zone, we need to ensure that
ongoing IOs already finished. Or, we will see a "Zone Is Full" error for
the IOs, as the ZONE_FINISH command makes the zone full.

We ensure that with btrfs_wait_block_group_reservations() and
btrfs_wait_ordered_roots() for a data block group. And, for a metadata
block group, the comparison of alloc_offset vs meta_write_pointer mostly
ensures IOs for the allocated region already sent. However, there still
can be a little time frame where the IOs are sent but not yet completed.

Introduce wait_eb_writebacks() to ensure such IOs are completed for a
metadata block group. It walks the buffer_radix to find extent buffers in
the block group and calls wait_on_extent_buffer_writeback() on them.

Fixes: afba2bc036b0 ("btrfs: zoned: implement active zone tracking")
CC: stable@vger.kernel.org # 5.19+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/zoned.c | 40 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 62e7007a7e46..73c6929f7be6 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1918,10 +1918,44 @@ out_unlock:
return ret;
}

+static void wait_eb_writebacks(struct btrfs_block_group *block_group)
+{
+ struct btrfs_fs_info *fs_info = block_group->fs_info;
+ const u64 end = block_group->start + block_group->length;
+ struct radix_tree_iter iter;
+ struct extent_buffer *eb;
+ void __rcu **slot;
+
+ rcu_read_lock();
+ radix_tree_for_each_slot(slot, &fs_info->buffer_radix, &iter,
+ block_group->start >> fs_info->sectorsize_bits) {
+ eb = radix_tree_deref_slot(slot);
+ if (!eb)
+ continue;
+ if (radix_tree_deref_retry(eb)) {
+ slot = radix_tree_iter_retry(&iter);
+ continue;
+ }
+
+ if (eb->start < block_group->start)
+ continue;
+ if (eb->start >= end)
+ break;
+
+ slot = radix_tree_iter_resume(slot, &iter);
+ rcu_read_unlock();
+ wait_on_extent_buffer_writeback(eb);
+ rcu_read_lock();
+ }
+ rcu_read_unlock();
+}
+
static int do_zone_finish(struct btrfs_block_group *block_group, bool fully_written)
{
struct btrfs_fs_info *fs_info = block_group->fs_info;
struct map_lookup *map;
+ const bool is_metadata = (block_group->flags &
+ (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM));
int ret = 0;
int i;

@@ -1932,8 +1966,7 @@ static int do_zone_finish(struct btrfs_block_group *block_group, bool fully_writ
}

/* Check if we have unwritten allocated space */
- if ((block_group->flags &
- (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM)) &&
+ if (is_metadata &&
block_group->start + block_group->alloc_offset > block_group->meta_write_pointer) {
spin_unlock(&block_group->lock);
return -EAGAIN;
@@ -1958,6 +1991,9 @@ static int do_zone_finish(struct btrfs_block_group *block_group, bool fully_writ
/* No need to wait for NOCOW writers. Zoned mode does not allow that */
btrfs_wait_ordered_roots(fs_info, U64_MAX, block_group->start,
block_group->length);
+ /* Wait for extent buffers to be written. */
+ if (is_metadata)
+ wait_eb_writebacks(block_group);

spin_lock(&block_group->lock);

--
2.37.3