ext4: Fix lack of credits BUG() when deleting a badly fragmented inode

The extents codepath for ext4_truncate() requests journal transaction
credits in very small chunks, requesting only what is needed.  This
means there may not be enough credits left on the transaction handle
after ext4_truncate() returns and then when ext4_delete_inode() tries
finish up its work, it may not have enough transaction credits,
causing a BUG() oops in the jbd2 core.

Also, reserve an extra 2 blocks when starting an ext4_delete_inode()
since we need to update the inode bitmap, as well as update the
orphaned inode linked list.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 29 insertions, 1 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 37f834bc7cd6..2697eaf0368f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -191,6 +191,7 @@ static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
 void ext4_delete_inode (struct inode * inode)
 {
         handle_t *handle;
+        int err;
 
         if (ext4_should_order_data(inode))
                 ext4_begin_ordered_truncate(inode, 0);
@@ -199,8 +200,9 @@ void ext4_delete_inode (struct inode * inode)
         if (is_bad_inode(inode))
                 goto no_delete;
 
-        handle = start_transaction(inode);
+        handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
         if (IS_ERR(handle)) {
+                ext4_std_error(inode->i_sb, PTR_ERR(handle));
                 /*
                  * If we're going to skip the normal cleanup, we still need to
                  * make sure that the in-core orphan linked list is properly
@@ -213,8 +215,34 @@ void ext4_delete_inode (struct inode * inode)
         if (IS_SYNC(inode))
                 handle->h_sync = 1;
         inode->i_size = 0;
+        err = ext4_mark_inode_dirty(handle, inode);
+        if (err) {
+                ext4_warning(inode->i_sb, __func__,
+                             "couldn't mark inode dirty (err %d)", err);
+                goto stop_handle;
+        }
         if (inode->i_blocks)
                 ext4_truncate(inode);
+
+        /*
+         * ext4_ext_truncate() doesn't reserve any slop when it
+         * restarts journal transactions; therefore there may not be
+         * enough credits left in the handle to remove the inode from
+         * the orphan list and set the dtime field.
+         */
+        if (handle->h_buffer_credits < 3) {
+                err = ext4_journal_extend(handle, 3);
+                if (err > 0)
+                        err = ext4_journal_restart(handle, 3);
+                if (err != 0) {
+                        ext4_warning(inode->i_sb, __func__,
+                                     "couldn't extend journal (err %d)", err);
+                stop_handle:
+                        ext4_journal_stop(handle);
+                        goto no_delete;
+                }
+        }
+
         /*
          * Kill off the orphan record which ext4_truncate created.
          * AKPM: I think this can be inside the above `if'.