net: do not disable sg for packets requiring no checksum

[ Upstream commit c0d680e577ff171e7b37dbdb1b1bf5451e851f04 ]

A change in a series of VLAN-related changes appears to have
inadvertently disabled the use of the scatter gather feature of
network cards for transmission of non-IP ethernet protocols like ATA
over Ethernet (AoE).  Below is a reference to the commit that
introduces a "harmonize_features" function that turns off scatter
gather when the NIC does not support hardware checksumming for the
ethernet protocol of an sk buff.

  commit f01a5236bd4b140198fbcc550f085e8361fd73fa
  Author: Jesse Gross <jesse@nicira.com>
  Date:   Sun Jan 9 06:23:31 2011 +0000

      net offloading: Generalize netif_get_vlan_features().

The can_checksum_protocol function is not equipped to consider a
protocol that does not require checksumming.  Calling it for a
protocol that requires no checksum is inappropriate.

The patch below has harmonize_features call can_checksum_protocol when
the protocol needs a checksum, so that the network layer is not forced
to perform unnecessary skb linearization on the transmission of AoE
packets.  Unnecessary linearization results in decreased performance
and increased memory pressure, as reported here:

  http://www.spinics.net/lists/linux-mm/msg15184.html

The problem has probably not been widely experienced yet, because
only recently has the kernel.org-distributed aoe driver acquired the
ability to use payloads of over a page in size, with the patchset
recently included in the mm tree:

  https://lkml.org/lkml/2012/8/28/140

The coraid.com-distributed aoe driver already could use payloads of
greater than a page in size, but its users generally do not use the
newest kernels.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
aoe: assert AoE packets marked as requiring no checksum

[ Upstream commit 8babe8cc6570ed896b7b596337eb8fe730c3ff45 ]

In order for the network layer to see that AoE requires
no checksumming in a generic way, the packets must be
marked as requiring no checksum, so we make this requirement
explicit with the assertion.

Signed-off-by: Ed Cashin <ecashin@coraid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drm/savage: re-add busmaster enable, regression fix

commit df86b5765a48d5f557489577652bd6df145b0e1b upstream.

466e69b8b03b8c1987367912782bc12988ad8794 dropped busmaster enable from the
global drm code and moved it to the individual drivers, but missed the savage
driver. So, this re-adds busmaster enable to the savage driver, fixing the
regression.

Signed-off-by: Florian Zumbiehl <florz@florz.de>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: Adapt to new FC_PORTSPEED semantics

commit d22019778cd9ea04c1dadf7bf453920d5288f8d9 upstream.

Commit a9277e7783651d4e0a849f7988340b1c1cf748a4
"[SCSI] scsi_transport_fc: Getting FC Port Speed in sync with FC-GS"
changed the semantics of FC_PORTSPEED defines to
FDMI port attributes of FC-HBA/SM-HBA
which is different from the previous bit reversed
Report Port Speed Capabilities (RPSC) ELS of FC-GS/FC-LS.

Zfcp showed "10 Gbit" instead of "4 Gbit" for supported_speeds.
It now uses explicit bit conversion as the other LLDs already
do, in order to be independent of the kernel bit semantics.
See also http://marc.info/?l=linux-scsi&m=134452926830730&w=2

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: Make trace record tags unique

commit 0100998dbfe6dfcd90a6e912ca7ed6f255d48f25 upstream.

Duplicate fssrh_2 from a54ca0f62f953898b05549391ac2a8a4dad6482b
"[SCSI] zfcp: Redesign of the debug tracing for HBA records."
complicates distinction of generic status read response from
local link up.
Duplicate fsscth1 from 2c55b750a884b86dea8b4cc5f15e1484cc47a25c
"[SCSI] zfcp: Redesign of the debug tracing for SAN records."
complicates distinction of good common transport response from
invalid port handle.

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: Bounds checking for deferred error trace

commit 01e60527f0a49b3d7df603010bd6079bb4b6cf07 upstream.

The pl vector has scount elements, i.e. pl[scount-1] is the last valid
element. For maximum sized requests, payload->counter == scount after
the last loop iteration. Therefore, do bounds checking first (with
boolean shortcut) to not access the invalid element pl[scount].

Do not trust the maximum sbale->scount value from the HBA
but ensure we won't access the pl vector out of our allocated bounds.
While at it, clean up scoping and prevent unnecessary memset.

Minor fix for 86a9668a8d29ea711613e1cb37efa68e7c4db564
"[SCSI] zfcp: support for hardware data router"

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: Do not wakeup while suspended

commit cb45214960bc989af8b911ebd77da541c797717d upstream.

If the mapping of FCP device bus ID and corresponding subchannel
is modified while the Linux image is suspended, the resume of FCP
devices can fail. During resume, zfcp gets callbacks from cio regarding
the modified subchannels but they can be arbitrarily mixed with the
restore/resume callback. Since the cio callbacks would trigger
adapter recovery, zfcp could wakeup before the resume callback.
Therefore, ignore the cio callbacks regarding subchannels while
being suspended. We can safely do so, since zfcp does not deal itself
with subchannels. For problem determination purposes, we still trace the
ignored callback events.

The following kernel messages could be seen on resume:

kernel: <WWPN>: parent <FCP device bus ID> should not be sleeping

As part of adapter reopen recovery, zfcp performs auto port scanning
which can erroneously try to register new remote ports with
scsi_transport_fc and the device core code complains about the parent
(adapter) still sleeping.

kernel: zfcp.3dff9c: <FCP device bus ID>:\
 Setting up the QDIO connection to the FCP adapter failed
<last kernel message repeated 3 more times>
kernel: zfcp.574d43: <FCP device bus ID>:\
 ERP cannot recover an error on the FCP device

In such cases, the adapter gave up recovery and remained blocked along
with its child objects: remote ports and LUNs/scsi devices. Even the
adapter shutdown as part of giving up recovery failed because the ccw
device state remained disconnected. Later, the corresponding remote
ports ran into dev_loss_tmo. As a result, the LUNs were erroneously
not available again after resume.

Even a manually triggered adapter recovery (e.g. sysfs attribute
failed, or device offline/online via sysfs) could not recover the
adapter due to the remaining disconnected state of the corresponding
ccw device.

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: remove invalid reference to list iterator variable

commit ca579c9f136af4274ccfd1bcaee7f38a29a0e2e9 upstream.

If list_for_each_entry, etc complete a traversal of the list, the iterator
variable ends up pointing to an address at an offset from the list head,
and not a meaningful structure.  Thus this value should not be used after
the end of the iterator.  Replace port->adapter->scsi_host by
adapter->scsi_host.

This problem was found using Coccinelle (http://coccinelle.lip6.fr/).

Oversight in upsteam commit of v2.6.37
a1ca48319a9aa1c5b57ce142f538e76050bb8972
"[SCSI] zfcp: Move ACL/CFDC code to zfcp_cfdc.c"
which merged the content of zfcp_erp_port_access_changed().

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: restore refcount check on port_remove

commit d99b601b63386f3395dc26a699ae703a273d9982 upstream.

Upstream commit f3450c7b917201bb49d67032e9f60d5125675d6a
"[SCSI] zfcp: Replace local reference counting with common kref"
accidentally dropped a reference count check before tearing down
zfcp_ports that are potentially in use by zfcp_units.
Even remote ports in use can be removed causing
unreachable garbage objects zfcp_ports with zfcp_units.
Thus units won't come back even after a manual port_rescan.
The kref of zfcp_port->dev.kobj is already used by the driver core.
We cannot re-use it to track the number of zfcp_units.
Re-introduce our own counter for units per port
and check on port_remove.

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SCSI: zfcp: only access zfcp_scsi_dev for valid scsi_device

commit d436de8ce25f53a8a880a931886821f632247943 upstream.

__scsi_remove_device (e.g. due to dev_loss_tmo) calls
zfcp_scsi_slave_destroy which in turn sends a close LUN FSF request to
the adapter. After 30 seconds without response,
zfcp_erp_timeout_handler kicks the ERP thread failing the close LUN
ERP action. zfcp_erp_wait in zfcp_erp_lun_shutdown_wait and thus
zfcp_scsi_slave_destroy returns and then scsi_device is no longer
valid. Sometime later the response to the close LUN FSF request may
finally come in. However, commit
b62a8d9b45b971a67a0f8413338c230e3117dff5
"[SCSI] zfcp: Use SCSI device data zfcp_scsi_dev instead of zfcp_unit"
introduced a number of attempts to unconditionally access struct
zfcp_scsi_dev through struct scsi_device causing a use-after-free.
This leads to an Oops due to kernel page fault in one of:
zfcp_fsf_abort_fcp_command_handler, zfcp_fsf_open_lun_handler,
zfcp_fsf_close_lun_handler, zfcp_fsf_req_trace,
zfcp_fsf_fcp_handler_common.
Move dereferencing of zfcp private data zfcp_scsi_dev allocated in
scsi_device via scsi_transport_reserve_device after the check for
potentially aborted FSF request and thus no longer valid scsi_device.
Only then assign sdev_to_zfcp(sdev) to the local auto variable struct
zfcp_scsi_dev *zfcp_sdev.

Signed-off-by: Martin Peschke <mpeschke@linux.vnet.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
PCI: Check P2P bridge for invalid secondary/subordinate range

commit 1965f66e7db08d1ebccd24a59043eba826cc1ce8 upstream.

For bridges with "secondary > subordinate", i.e., invalid bus number
apertures, we don't enumerate anything behind the bridge unless the
user specified "pci=assign-busses".

This patch makes us automatically try to reassign the downstream bus
numbers in this case (just for that bridge, not for all bridges as
"pci=assign-busses" does).

We don't discover all the devices on the Intel DP43BF motherboard
without this change (or "pci=assign-busses") because its BIOS configures
a bridge as:

    pci 0000:00:1e.0: PCI bridge to [bus 20-08] (subtractive decode)

[bhelgaas: changelog, change message to dev_info]
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=18412
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=625754
Reported-by: Brian C. Huffman <bhuffman@graze.net>
Reported-by: VL <vl.homutov@gmail.com>
Tested-by: VL <vl.homutov@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
ext4: ignore last group w/o enough space when resizing instead of BUG'ing

commit 03c1c29053f678234dbd51bf3d65f3b7529021de upstream.

If the last group does not have enough space for group tables, ignore
it instead of calling BUG_ON().

Reported-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: don't copy non-existent gdt blocks when resizing

commit 6df935ad2fced9033ab52078825fcaf6365f34b7 upstream.

The resize code was copying blocks at the beginning of each block
group in order to copy the superblock and block group descriptor table
(gdt) blocks.  This was, unfortunately, being done even for block
groups that did not have super blocks or gdt blocks.  This is a
complete waste of perfectly good I/O bandwidth, to skip writing those
blocks for sparse bg's.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: avoid duplicate writes of the backup bg descriptor blocks

commit 2ebd1704ded88a8ae29b5f3998b13959c715c4be upstream.

The resize code was needlessly writing the backup block group
descriptor blocks multiple times (once per block group) during an
online resize.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: fix potential deadlock in ext4_nonda_switch()

commit 00d4e7362ed01987183e9528295de3213031309c upstream.

In ext4_nonda_switch(), if the file system is getting full we used to
call writeback_inodes_sb_if_idle().  The problem is that we can be
holding i_mutex already, and this causes a potential deadlock when
writeback_inodes_sb_if_idle() when it tries to take s_umount.  (See
lockdep output below).

As it turns out we don't need need to hold s_umount; the fact that we
are in the middle of the write(2) system call will keep the superblock
pinned.  Unfortunately writeback_inodes_sb() checks to make sure
s_umount is taken, and the VFS uses a different mechanism for making
sure the file system doesn't get unmounted out from under us.  The
simplest way of dealing with this is to just simply grab s_umount
using a trylock, and skip kicking the writeback flusher thread in the
very unlikely case that we can't take a read lock on s_umount without
blocking.

Also, we now check the cirteria for kicking the writeback thread
before we decide to whether to fall back to non-delayed writeback, so
if there are any outstanding delayed allocation writes, we try to get
them resolved as soon as possible.

   [ INFO: possible circular locking dependency detected ]
   3.6.0-rc1-00042-gce894ca #367 Not tainted
   -------------------------------------------------------
   dd/8298 is trying to acquire lock:
    (&type->s_umount_key#18){++++..}, at: [<c02277d4>] writeback_inodes_sb_if_idle+0x28/0x46

   but task is already holding lock:
    (&sb->s_type->i_mutex_key#8){+.+...}, at: [<c01ddcce>] generic_file_aio_write+0x5f/0xd3

   which lock already depends on the new lock.

   2 locks held by dd/8298:
    #0:  (sb_writers#2){.+.+.+}, at: [<c01ddcc5>] generic_file_aio_write+0x56/0xd3
    #1:  (&sb->s_type->i_mutex_key#8){+.+...}, at: [<c01ddcce>] generic_file_aio_write+0x5f/0xd3

   stack backtrace:
   Pid: 8298, comm: dd Not tainted 3.6.0-rc1-00042-gce894ca #367
   Call Trace:
    [<c015b79c>] ? console_unlock+0x345/0x372
    [<c06d62a1>] print_circular_bug+0x190/0x19d
    [<c019906c>] __lock_acquire+0x86d/0xb6c
    [<c01999db>] ? mark_held_locks+0x5c/0x7b
    [<c0199724>] lock_acquire+0x66/0xb9
    [<c02277d4>] ? writeback_inodes_sb_if_idle+0x28/0x46
    [<c06db935>] down_read+0x28/0x58
    [<c02277d4>] ? writeback_inodes_sb_if_idle+0x28/0x46
    [<c02277d4>] writeback_inodes_sb_if_idle+0x28/0x46
    [<c026f3b2>] ext4_nonda_switch+0xe1/0xf4
    [<c0271ece>] ext4_da_write_begin+0x27/0x193
    [<c01dcdb0>] generic_file_buffered_write+0xc8/0x1bb
    [<c01ddc47>] __generic_file_aio_write+0x1dd/0x205
    [<c01ddce7>] generic_file_aio_write+0x78/0xd3
    [<c026d336>] ext4_file_write+0x480/0x4a6
    [<c0198c1d>] ? __lock_acquire+0x41e/0xb6c
    [<c0180944>] ? sched_clock_cpu+0x11a/0x13e
    [<c01967e9>] ? trace_hardirqs_off+0xb/0xd
    [<c018099f>] ? local_clock+0x37/0x4e
    [<c0209f2c>] do_sync_write+0x67/0x9d
    [<c0209ec5>] ? wait_on_retry_sync_kiocb+0x44/0x44
    [<c020a7b9>] vfs_write+0x7b/0xe6
    [<c020a9a6>] sys_write+0x3b/0x64
    [<c06dd4bd>] syscall_call+0x7/0xb

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>