Re: [Ext2-devel] [PATCH] JBD: fix against journal overflow

[Alex Tomas <alex@clusterfs.com>]

>>>>> Stephen C Tweedie (SCT) writes:
 SCT> I don't see how that "limit" is relevant here.  wbuf is nothing but the
 SCT> size of the IO batches we pass to ll_rw_block() during that commit
 SCT> phase.  j_free affects the total size of space the *entire* commit has
 SCT> to run into, and (as akpm has commented with a big marker beside it)
 SCT> start_this_handle() reserves a *lot* of headroom for the extra space
 SCT> that may be needed for transaction metadata.



		/* If there's no more to do, or if the descriptor is full,
		   let the IO rip! */

		if (bufs == ARRAY_SIZE(wbuf) ||
		    commit_transaction->t_buffers == NULL ||
		    space_left < sizeof(journal_block_tag_t) + 16) {

                        ....

			/* Force a new descriptor to be generated next
                           time round the loop. */
			descriptor = NULL;
			bufs = 0;

------------------------^^^^^^^^^^^^^^^^^^^


 SCT> Have you really seen this patch make a difference in testing?

of course