Btrfs: do transaction space reservation before joining the transaction

We have to do weird things when handling enospc in the transaction joining code.
Because we've already joined the transaction we cannot commit the transaction
within the reservation code since it will deadlock, so we have to return EAGAIN
and then make sure we don't retry too many times.  Instead of doing this, just
do the reservation the normal way before we join the transaction, that way we
can do whatever we want to try and reclaim space, and then if it fails we know
for sure we are out of space and we can return ENOSPC.  Thanks,

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

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 60e13ef23a5e500d371b44e06092afd7de047dd4..28e170bcdcb57163d18fb52a3f0beb6527b53fa8 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2223,9 +2223,6 @@ void btrfs_set_inode_space_info(struct btrfs_root *root, struct inode *ionde);
 void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
 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);
 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root);
 int btrfs_orphan_reserve_metadata(struct btrfs_trans_handle *trans,

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 71cd456fdb60360d44edd113ab7c593bdacfa658..0ed5fe03a06a5bdbb76edb5a99fced0087a40fe8 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3874,26 +3874,6 @@ int btrfs_truncate_reserve_metadata(struct btrfs_trans_handle *trans,
        return 0;
 }
 
-int btrfs_trans_reserve_metadata(struct btrfs_trans_handle *trans,
-                                struct btrfs_root *root,
-                                int num_items)
-{
-       u64 num_bytes;
-       int ret;
-
-       if (num_items == 0 || root->fs_info->chunk_root == root)
-               return 0;
-
-       num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
-       ret = btrfs_block_rsv_add(trans, root, &root->fs_info->trans_block_rsv,
-                                 num_bytes);
-       if (!ret) {
-               trans->bytes_reserved += num_bytes;
-               trans->block_rsv = &root->fs_info->trans_block_rsv;
-       }
-       return ret;
-}
-
 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
                                  struct btrfs_root *root)
 {

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 51dcec86757f071654bc3866123e65157ef0286b..654755b189519f0b5f183642e813da2fffa92c57 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -260,7 +260,7 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 {
        struct btrfs_trans_handle *h;
        struct btrfs_transaction *cur_trans;
-       int retries = 0;
+       u64 num_bytes = 0;
        int ret;
 
        if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
@@ -274,6 +274,19 @@ static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
                h->block_rsv = NULL;
                goto got_it;
        }
+
+       /*
+        * Do the reservation before we join the transaction so we can do all
+        * the appropriate flushing if need be.
+        */
+       if (num_items > 0 && root != root->fs_info->chunk_root) {
+               num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
+               ret = btrfs_block_rsv_add(NULL, root,
+                                         &root->fs_info->trans_block_rsv,
+                                         num_bytes);
+               if (ret)
+                       return ERR_PTR(ret);
+       }
 again:
        h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
        if (!h)
@@ -310,24 +323,9 @@ again:
                goto again;
        }
 
-       if (num_items > 0) {
-               ret = btrfs_trans_reserve_metadata(h, root, num_items);
-               if (ret == -EAGAIN && !retries) {
-                       retries++;
-                       btrfs_commit_transaction(h, root);
-                       goto again;
-               } else if (ret == -EAGAIN) {
-                       /*
-                        * We have already retried and got EAGAIN, so really we
-                        * don't have space, so set ret to -ENOSPC.
-                        */
-                       ret = -ENOSPC;
-               }
-
-               if (ret < 0) {
-                       btrfs_end_transaction(h, root);
-                       return ERR_PTR(ret);
-               }
+       if (num_bytes) {
+               h->block_rsv = &root->fs_info->trans_block_rsv;
+               h->bytes_reserved = num_bytes;
        }
 
 got_it: