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>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 37f834bc7cd6df84a4d5c1e4b42c2f8bd425f337..2697eaf0368f2cf76d64b936b407f5c4a97840e4 100644 (file)
--- 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'.