We used to allow you to set FLUSH_ALL and then just wouldn't do things like
commit transactions or wait on ordered extents if we noticed you were in a
transaction. However now that all the flushing for FLUSH_ALL is asynchronous
we've lost the ability to tell, and we could end up deadlocking. So instead use
FLUSH_LIMIT in reserve_metadata_bytes in relocation and then return -EAGAIN if
we error out to preserve the previous behavior. I've also added an ASSERT() to
catch anybody else who tries to do this. Thanks,
Signed-off-by: Josef Bacik <jbacik@xxxxxx>
---
fs/btrfs/extent-tree.c | 2 ++
fs/btrfs/relocation.c | 37 ++++++++++++++++++++-----------------
2 files changed, 22 insertions(+), 17 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 528b9a8..651a811 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5070,6 +5070,8 @@ static int __reserve_metadata_bytes(struct btrfs_root *root,
int ret = 0;
ASSERT(orig_bytes);
+ ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL);
+
spin_lock(&space_info->lock);
ret = -ENOSPC;
used = space_info->bytes_used + space_info->bytes_reserved +
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 959cb4e..ca145fc 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2603,25 +2603,28 @@ static int reserve_metadata_space(struct btrfs_trans_handle *trans,
trans->block_rsv = rc->block_rsv;
rc->reserved_bytes += num_bytes;
+
+ /*
+ * We are under a transaction here so we can only do limited flushing.
+ * If we get an enospc just kick back -EAGAIN so we know to drop the
+ * transaction and try to refill when we can flush all the things.
+ */
ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
- BTRFS_RESERVE_FLUSH_ALL);
+ BTRFS_RESERVE_FLUSH_LIMIT);
if (ret) {
- if (ret == -EAGAIN) {
- tmp = rc->extent_root->nodesize *
- RELOCATION_RESERVED_NODES;
- while (tmp <= rc->reserved_bytes)
- tmp <<= 1;
- /*
- * only one thread can access block_rsv at this point,
- * so we don't need hold lock to protect block_rsv.
- * we expand more reservation size here to allow enough
- * space for relocation and we will return eailer in
- * enospc case.
- */
- rc->block_rsv->size = tmp + rc->extent_root->nodesize *
- RELOCATION_RESERVED_NODES;
- }
- return ret;
+ tmp = rc->extent_root->nodesize * RELOCATION_RESERVED_NODES;
+ while (tmp <= rc->reserved_bytes)
+ tmp <<= 1;
+ /*
+ * only one thread can access block_rsv at this point,
+ * so we don't need hold lock to protect block_rsv.
+ * we expand more reservation size here to allow enough
+ * space for relocation and we will return eailer in
+ * enospc case.
+ */
+ rc->block_rsv->size = tmp + rc->extent_root->nodesize *
+ RELOCATION_RESERVED_NODES;
+ return -EAGAIN;
}
return 0;
--
1.8.3.1
--
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