William Lee Irwin III <wli@xxxxxxxxxxxxxx> wrote: >> An answer should be devised for this. My numerous SCSI CD-ROM devices >> (I have 5 across several different machines of several different arches) >> are rather unlikely to be happy with /* FIXME: XXX ... as an answer. [...] >> Mutatis mutandis for my SCSI tape drive. On Thu, Jun 23, 2005 at 09:50:11PM -0700, Andrew Morton wrote: > This scsi code is already rather wrong. There isn't much point in just > setting PG_dirty and leaving the page marked as clean in the radix tree. > As it is we'll lose data if the user reads it into a MAP_SHARED memory > buffer. > set_page_dirty_lock() should be used here. That can sleep. > The above two functions are called under write_lock_irqsave() (at least) > and might be called from irq context (dunno). So we cannot use > set_page_dirty_lock() and we don't have a ref on the page's inode. We > could use set_page_dirty() and be racy against page reclaim. > But to get all this correct (and it's very incorrect now) we'd need to punt > the page dirtying up to process context, along the lines of > bio_check_pages_dirty(). > Or, if st_unmap_user_pages() and sgl_unmap_user_pages() are not called from > irq context then we should arrange for them to be called without locks held > and use set_page_dirty_lock(). This all sounds very reasonable. I was originally more concerned about the new FIXME getting introduced but this sounds like a good way to resolve the preexisting FIXME's surrounding all this. -- wli - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
