bcachefs: bch2_trans_kmalloc no longer allocates memory with btree locks held

When allocating memory, gfp flags should generally be

 - GFP_NOWAIT|__GFP_NOWARN if btree locks are held
 - GFP_NOFS if in the IO path or otherwise holding resources needed for
   IO submission
 - GFP_KERNEL otherwise

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 1cc53b37f78e71506343b807f6baf5af55156cb6..9072819176dec14428727010707e2ab0d129f461 100644 (file)
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -2790,6 +2790,7 @@ void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
        unsigned new_top = trans->mem_top + size;
        size_t old_bytes = trans->mem_bytes;
        size_t new_bytes = roundup_pow_of_two(new_top);
+       int ret;
        void *new_mem;
        void *p;
 
@@ -2797,15 +2798,27 @@ void *__bch2_trans_kmalloc(struct btree_trans *trans, size_t size)
 
        WARN_ON_ONCE(new_bytes > BTREE_TRANS_MEM_MAX);
 
-       new_mem = krealloc(trans->mem, new_bytes, GFP_NOFS);
-       if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
-               new_mem = mempool_alloc(&trans->c->btree_trans_mem_pool, GFP_KERNEL);
-               new_bytes = BTREE_TRANS_MEM_MAX;
-               kfree(trans->mem);
-       }
+       new_mem = krealloc(trans->mem, new_bytes, GFP_NOWAIT|__GFP_NOWARN);
+       if (unlikely(!new_mem)) {
+               bch2_trans_unlock(trans);
+
+               new_mem = krealloc(trans->mem, new_bytes, GFP_KERNEL);
+               if (!new_mem && new_bytes <= BTREE_TRANS_MEM_MAX) {
+                       new_mem = mempool_alloc(&trans->c->btree_trans_mem_pool, GFP_KERNEL);
+                       new_bytes = BTREE_TRANS_MEM_MAX;
+                       kfree(trans->mem);
+               }
+
+               if (!new_mem)
+                       return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
+
+               trans->mem = new_mem;
+               trans->mem_bytes = new_bytes;
 
-       if (!new_mem)
-               return ERR_PTR(-BCH_ERR_ENOMEM_trans_kmalloc);
+               ret = bch2_trans_relock(trans);
+               if (ret)
+                       return ERR_PTR(ret);
+       }
 
        trans->mem = new_mem;
        trans->mem_bytes = new_bytes;