Btrfs: rework how we reserve metadata bytes

With multi-threaded writes we were getting ENOSPC early because somebody would
come in, start flushing delalloc because they couldn't make their reservation,
and in the meantime other threads would come in and use the space that was
getting freed up, so when the original thread went to check to see if they had
space they didn't and they'd return ENOSPC.  So instead if we have some free
space but not enough for our reservation, take the reservation and then start
doing the flushing.  The only time we don't take reservations is when we've
already overcommitted our space, that way we don't have people who come late to
the party way overcommitting ourselves.  This also moves all of the retrying and
flushing code into reserve_metdata_bytes so it's all uniform.  This keeps my
fs_mark test from returning -ENOSPC as soon as it starts and actually lets me
fill up the disk.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f32404db2c5d..47bc66e34da7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2082,7 +2082,7 @@ int btrfs_check_data_free_space(struct inode *inode, u64 bytes);
 void btrfs_free_reserved_data_space(struct inode *inode, u64 bytes);
 int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
-                                int num_items, int *retries);
+                                int num_items);
 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root);
 int btrfs_orphan_reserve_metadata(struct btrfs_trans_handle *trans,
@@ -2103,7 +2103,7 @@ void btrfs_add_durable_block_rsv(struct btrfs_fs_info *fs_info,
 int btrfs_block_rsv_add(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root,
                         struct btrfs_block_rsv *block_rsv,
-                        u64 num_bytes, int *retries);
+                        u64 num_bytes);
 int btrfs_block_rsv_check(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root,
                           struct btrfs_block_rsv *block_rsv,