Re: [PATCH] 2.4.14-pre7 Missing disk req queue unplugs

[Anton Altaparmakov]

This patch is not needed after all. Implementing the sync_page method in 
the address_space operations using fs/buffer.c::block_sync_page() 
completely fixed the hangs I was seing with NTFS TNG.

Best regards,

Anton

At 15:30 03/11/2001, Anton Altaparmakov wrote:
>Linus,
>
>Please apply below patch for your next -pre kernel.
>
>This patch adds two disk request queue unplugs in mm/filemap.c which are
>present in -ac kernels but not in -pre kernels.
>
>Without this patch NTFS TNG will hang when it tries to read anything using
>the page cache. Same for BeFS as reported by Will Dyson. The hangs would
>"unhang" as soon as something else caused disk io to happen (e.g. doing
>md5sum on an ext2 partition on a file that hasn't been accessed before
>so it isn't in the page cache yet).
>
>With this patch NTFS TNG no longer hangs. I haven't tried BeFS but I am
>confident it will be fixed by this patch, too.
>
>Thanks go to Andrew Morton for locating the problem causing the hangs.
>
>Best regards,
>
>         Anton
>--
>Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
>Linux NTFS maintainer / WWW: http://linux-ntfs.sf.net/
>ICQ: 8561279 / WWW: http://www-stu.christs.cam.ac.uk/~aia21/
>
>--- linux-2.4.14-pre7-unplug.diff ---
>
>diff -u -urN linux-2.4.14-pre7-vanilla/mm/filemap.c 
>linux-2.4.14-pre7-aia1/mm/filemap.c
>--- linux-2.4.14-pre7-vanilla/mm/filemap.c      Sat Nov  3 12:17:55 2001
>+++ linux-2.4.14-pre7-aia1/mm/filemap.c Sat Nov  3 15:18:22 2001
>@@ -769,6 +769,7 @@
>                 if (!PageLocked(page))
>                         break;
>                 sync_page(page);
>+               run_task_queue(&tq_disk);
>                 schedule();
>         } while (PageLocked(page));
>         tsk->state = TASK_RUNNING;
>@@ -800,7 +801,9 @@
>                 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
>                 if (PageLocked(page)) {
>                         sync_page(page);
>+                       run_task_queue(&tq_disk);
>                         schedule();
>+                       continue;
>                 }
>                 if (!TryLockPage(page))
>                         break;