1 files changed, 27 insertions, 9 deletions

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index a6eec9747c74..6b8338ec2464 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -204,6 +204,20 @@ static int add_transaction_credits(journal_t *journal, int blocks,
                  * attach this handle to a new transaction.
                  */
                 atomic_sub(total, &t->t_outstanding_credits);
+
+                /*
+                 * Is the number of reserved credits in the current transaction too
+                 * big to fit this handle? Wait until reserved credits are freed.
+                 */
+                if (atomic_read(&journal->j_reserved_credits) + total >
+                    journal->j_max_transaction_buffers) {
+                        read_unlock(&journal->j_state_lock);
+                        wait_event(journal->j_wait_reserved,
+                                   atomic_read(&journal->j_reserved_credits) + total <=
+                                   journal->j_max_transaction_buffers);
+                        return 1;
+                }
+
                 wait_transaction_locked(journal);
                 return 1;
         }
@@ -262,20 +276,24 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
         int             rsv_blocks = 0;
         unsigned long ts = jiffies;
 
+        if (handle->h_rsv_handle)
+                rsv_blocks = handle->h_rsv_handle->h_buffer_credits;
+
         /*
-         * 1/2 of transaction can be reserved so we can practically handle
-         * only 1/2 of maximum transaction size per operation
+         * Limit the number of reserved credits to 1/2 of maximum transaction
+         * size and limit the number of total credits to not exceed maximum
+         * transaction size per operation.
          */
-        if (WARN_ON(blocks > journal->j_max_transaction_buffers / 2)) {
-                printk(KERN_ERR "JBD2: %s wants too many credits (%d > %d)\n",
-                       current->comm, blocks,
-                       journal->j_max_transaction_buffers / 2);
+        if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
+            (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
+                printk(KERN_ERR "JBD2: %s wants too many credits "
+                       "credits:%d rsv_credits:%d max:%d\n",
+                       current->comm, blocks, rsv_blocks,
+                       journal->j_max_transaction_buffers);
+                WARN_ON(1);
                 return -ENOSPC;
         }
 
-        if (handle->h_rsv_handle)
-                rsv_blocks = handle->h_rsv_handle->h_buffer_credits;
-
 alloc_transaction:
         if (!journal->j_running_transaction) {
                 /*