Patch Name:  PHKL_8953

Patch Description: s700 10.20 VXFS stopped processing I/O, processes hang

Creation Date: 96/10/17

Post Date:  96/11/20

Hardware Platforms - OS Releases:
        s700: 10.20

Products: N/A

Filesets:
        OS-Core.CORE-KRN

Automatic Reboot?: Yes

Status: General Superseded

Critical:
        Yes
        PHKL_8953: HANG
        PHKL_8331: CORRUPTION

Path Name:  /hp-ux_patches/s700/10.X/PHKL_8953

Symptoms:
        PHKL_8953:
        The K400 4-way suddenly stopped to work. The user heavily
        accessed vxfs snapshot filesystem and have done sync's in
        parallel. We TOC'ed the system.

        PHKL_8331:
        Data loss with UFS files using fragments.

Defect Description:
        PHKL_8953:
        The problem is caused by a defect in getnewbuf procedure in
        vfs_bio.c file. When Vxfs calls getnewbuf() to acquire a
        buffer, it passes BX_NONBLOCK in bxflags to avoid potential
        deadlock. However, the getnewbuf() proceeds to call
        bwrite() to flush the buffer without checking the bxflags
        when it finds a B_DELWRI buffer. This causes Vxfs with
        snapshot to hang.

        The fix for this defect is to make fix for getnewbuf() in
        file vfs_bio.c. When getnewbuf() ends up grabbing a DELWRI
        buffer with BX_NONBLOCK, it will release the buffer and
        return NULL instead of flushing and returning the buffer.

        PHKL_8331:
        There was a code path where dirty buffers could possibly
        be dropped (not flushed) when extending UFS files using
        fragments.

SR:
        1653166496 4701327338 4701333419

Patch Files:
        /usr/conf/lib/libhp-ux.a(vfs_bio.o)
        /usr/conf/lib/libufs.a(ufs_alloc.o)

what(1) Output:
        /usr/conf/lib/libhp-ux.a(vfs_bio.o):
                vfs_bio.c  $Date: 96/10/20 14:15:32 $ $Revision: 1.2
                        6.98.15 $ PATCH_10.20 (PHKL_8953)
        /usr/conf/lib/libufs.a(ufs_alloc.o):
                ufs_alloc.c  $Date: 96/08/20 14:18:16 $ $Revision: 1
                        .38.98.7 $ PATCH_10.20 (PHKL_8331)

cksum(1) Output:
        1465121610 28360 /usr/conf/lib/libhp-ux.a(vfs_bio.o)
        3255850541 17616 /usr/conf/lib/libufs.a(ufs_alloc.o)

Patch Conflicts: None

Patch Dependencies:  None

Hardware Dependencies:  None

Other Dependencies:  None

Supersedes:
        PHKL_8331

Equivalent Patches:
        PHKL_8954:
        s800: 10.20

Patch Package Size:  100 Kbytes

Installation Instructions:
        Please review all instructions and the Hewlett-Packard
        SupportLine User Guide or your Hewlett-Packard support terms
        and conditions for precautions, scope of license,
        restrictions, and, limitation of liability and warranties,
        before installing this patch.
        ------------------------------------------------------------
        1. Back up your system before installing a patch.

        2. Login as root.

        3. Copy the patch to the /tmp directory.

        4. Move to the /tmp directory and unshar the patch:

                cd /tmp
                sh PHKL_8953

        5a. For a standalone system, run swinstall to install the
            patch:

                swinstall -x autoreboot=true -x match_target=true \
                        -s /tmp/PHKL_8953.depot

        5b. For a homogeneous NFS Diskless cluster run swcluster on the
            server to install the patch on the server and the clients:

                swcluster -i -b

            This will invoke swcluster in the interactive mode and
            force all clients to be shut down.

            WARNING: All cluster clients must be shut down prior to the
                     patch installation.  Installing the patch while the
                     clients are booted is unsupported and can lead to
                     serious problems.

            The swcluster command will invoke an swinstall session in which
            you must specify:

                alternate root path  -  default is /export/shared_root/OS_700
                source depot path    -  /tmp/PHKL_8953.depot

            To complete the installation, select the patch by choosing
            "Actions -> Match What Target Has" and then "Actions -> Install"
            from the Menubar.

        5c. For a heterogeneous NFS Diskless cluster:

                - run swinstall on the server as in step 5a to install
                  the patch on the cluster server.

                - run swcluster on the server as in step 5b to install
                  the patch on the cluster clients.

        By default swinstall will archive the original software in
        /var/adm/sw/patch/PHKL_8953.  If you do not wish to retain a
        copy of the original software, you can create an empty file
        named /var/adm/sw/patch/PATCH_NOSAVE.

        Warning: If this file exists when a patch is installed, the
                 patch cannot be deinstalled.  Please be careful
                 when using this feature.

        It is recommended that you move the PHKL_8953.text file to
        /var/adm/sw/patch for future reference.

        To put this patch on a magnetic tape and install from the
        tape drive, use the command:

                dd if=/tmp/PHKL_8953.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions:  None