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authorJosef Bacik <jbacik@fb.com>2016-05-27 13:24:13 -0400
committerDavid Sterba <dsterba@suse.com>2016-07-07 18:45:53 +0200
commit8ca17f0f59529df9e2132ca594ff00c52a9bc556 (patch)
tree52539f2d8ab37e71a6115cc1dab18ed2aeaa101c /fs/btrfs/relocation.c
parentac2fabac4211431b607b326c2233e73b81e86af2 (diff)
Btrfs: use FLUSH_LIMIT for relocation in reserve_metadata_bytes
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@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/relocation.c')
-rw-r--r--fs/btrfs/relocation.c37
1 files changed, 20 insertions, 17 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 23e16de52e23..fc067b07e31f 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -2604,25 +2604,28 @@ 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 earlier 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;