The PCI host bridge scan handler installs its own notify handler,
handle_hotplug_event_root(), by itself.  Nevertheless, the ACPI
hotplug framework also installs the common notify handler,
acpi_hotplug_notify_cb(), for PCI root bridges.  This causes
acpi_hotplug_notify_cb() to call _OST method with unsupported
error as hotplug.enabled is not set.

To address this issue, introduce hotplug.ignore flag, which
indicates that the scan handler installs its own notify handler by
itself.  The ACPI hotplug framework does not install the common
notify handler when this flag is set.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
[rjw: Changed the name of the new flag]
Cc: 3.9+ <stable@vger.kernel.org> # 3.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit bd950799 (PCI: acpiphp: Convert to dynamic debug) removed users
of acpiphp_debug variable and the variable itself but the declaration was
left in the header file. Drop this unused declaration.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Before commit 6931007c (ACPI / scan: Start matching drivers
after trying scan handlers) the match_driver flag for all devices
was set in acpi_add_single_object(), but now it is set by
acpi_bus_device_attach() which is not called for the "fixed"
devices added by acpi_bus_scan_fixed().  This means that
flags.match_driver is never set for those devices now, so make
acpi_bus_scan_fixed() set it before calling device_attach().

Fixes: 6931007c (ACPI / scan: Start matching drivers after trying scan handlers)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

If a PCI host bridge cannot be enumerated due to an error in
pci_acpi_scan_root(), its ACPI device object's driver_data field
has to be cleared by acpi_pci_root_add() before freeing the
object pointed to by that field, or some later acpi_pci_find_root()
checks that should fail may succeed and cause quite a bit of
confusion to ensue.

Fix acpi_pci_root_add() to clear device->driver_data before
returning an error code as appropriate.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

Since the PCI host bridge scan handler does not set hotplug.enabled,
the check of it in acpi_bus_device_eject() effectively prevents the
root bridge hot removal from working after commit a3b1b1ef
(ACPI / hotplug: Merge device hot-removal routines).  However, that
check is not necessary, because the other acpi_bus_device_eject()
users, acpi_hotplug_notify_cb and acpi_eject_store(), do the same
check by themselves before executing that function.

For this reason, remove the scan handler check from
acpi_bus_device_eject() to make PCI hot bridge hot removal work
again.

Fixes: a3b1b1ef (ACPI / hotplug: Merge device hot-removal routines)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

Since acpi_bus_get_device() returns a plain int and not acpi_status,
ACPI_FAILURE() should not be used for checking its return value.  Fix
that.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

There are two different interfaces for queuing up work items on the
ACPI hotplug workqueue, alloc_acpi_hp_work() used by PCI and PCI host
bridge hotplug code and acpi_os_hotplug_execute() used by the common
ACPI hotplug code and docking stations.  They both are somewhat
cumbersome to use and work slightly differently.

The users of alloc_acpi_hp_work() have to submit a work function that
will extract the necessary data items from a struct acpi_hp_work
object allocated by alloc_acpi_hp_work() and then will free that
object, while it would be more straightforward to simply use a work
function with one more argument and let the interface take care of
the execution details.

The users of acpi_os_hotplug_execute() also have to deal with the
fact that it takes only one argument in addition to the work function
pointer, although acpi_os_execute_deferred() actually takes care of
the allocation and freeing of memory, so it would have been able to
pass more arguments to the work function if it hadn't been
constrained by the connection with acpi_os_execute().

Moreover, while alloc_acpi_hp_work() makes GFP_KERNEL memory
allocations, which is correct, because hotplug work items are
always queued up from process context, acpi_os_hotplug_execute()
uses GFP_ATOMIC, as that is needed by acpi_os_execute().  Also,
acpi_os_execute_deferred() queued up by it waits for the ACPI event
workqueues to flush before executing the work function, whereas
alloc_acpi_hp_work() can't do anything similar.  That leads to
somewhat arbitrary differences in behavior between various ACPI
hotplug code paths and has to be straightened up.

For this reason, replace both alloc_acpi_hp_work() and
acpi_os_hotplug_execute() with a single interface,
acpi_hotplug_execute(), combining their behavior and being more
friendly to its users than any of the two.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

According to the ACPI spec (5.0, Section 6.3.5), the "Device
insertion in progress (pending)" (0x80) _OST status code is
reserved for the "Insertion Processing" (0x200) source event
which is "a result of an OSPM action".  Specifically, it is not
a notification, so that status code should not be used during
notification processing, which unfortunately is done by
acpi_scan_bus_device_check().

For this reason, drop the ACPI_OST_SC_INSERT_IN_PROGRESS _OST
status evaluation from there (it was a mistake to put it in there
in the first place).
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All applicable <stable@vger.kernel.org>

Since _handle_hotplug_event_root() is run from the ACPI hotplug
workqueue, it doesn't need to queue up a work item to eject a PCI
host bridge on the same workqueue.  Instead, it can just carry out
the eject by calling acpi_bus_device_eject() directly, so make that
happen.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no real reasn why acpi_bus_device_eject() and
acpi_bus_hot_remove_device() should work differently, so rework
acpi_bus_device_eject() so that it can be called internally by
both acpi_bus_hot_remove_device() and acpi_eject_store_work().
Accordingly, rework acpi_hotplug_notify_cb() to queue up the
execution of acpi_bus_hot_remove_device() through
acpi_os_hotplug_execute() on eject request notifications.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

Notice that handle_root_bridge_removal() is the only user of
acpi_bus_hot_remove_device(), so it doesn't have to be exported
any more and can be made internal to the ACPI core.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

Simplify handle_root_bridge_removal() and acpi_eject_store() by
getting rid of struct acpi_eject_event and passing device objects
directly to async routines executed via acpi_os_hotplug_execute().
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

It is required to do get_device() on the struct acpi_device in
question before passing it to acpi_bus_hot_remove_device() through
acpi_os_hotplug_execute(), because acpi_bus_hot_remove_device()
calls acpi_scan_hot_remove() that does put_device() on that
object.

The ACPI PCI root removal routine, handle_root_bridge_removal(),
doesn't do that, which may lead to premature freeing of the
device object or to executing put_device() on an object that
has been freed already.

Fix this problem by making handle_root_bridge_removal() use
get_device() as appropriate.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Cc: All applicable <stable@vger.kernel.org>

In theory, an ACPI device object may be the parent of another
device object whose hotplug is disabled by user space through its
scan handler.  In that case, the eject operation targeting the
parent should fail as though the parent's own hotplug was disabled,
but currently this is not the case, because acpi_scan_hot_remove()
doesn't check the disable/enable hotplug status of the children
of the top-most object passed to it.

To fix this, modify acpi_bus_offline_companions() to return an
error code if hotplug is disabled for the given device object.
[Also change the name of the function to acpi_bus_offline(),
because it is not only about companions any more, and change
the name of acpi_bus_online_companions() accordingly.]  Make
acpi_scan_hot_remove() propagate that error to its callers.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

ACPI scan handlers should always be attached to struct acpi_device
objects before any ACPI drivers, but there is a window during which
a driver may be attached to a struct acpi_device before checking if
there is a matching scan handler.  Namely, that will happen if an
ACPI driver module is loaded during acpi_bus_scan() right after
the first namespace walk is complete and before the given device
is processed by the second namespace walk.

To prevent that from happening, set the match_driver flags of
struct acpi_device objects right before running device_attach()
for them in acpi_bus_device_attach().
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

Since acpi_pci_slot_init() is now called from acpi_pci_init()
and pci-acpi.h contains its header, remove that header (and the
empty definition of that function for CONFIG_ACPI_PCI_SLOT unset)
from internal.h as it doesn't have to be there any more.  That also
avoids a build warning about duplicate function definitions for
CONFIG_ACPI_PCI_SLOT unset.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

We already have predefined marco for method name "_STA', so
using the marco instead of directly using the string.
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Use kobject_init_and_add() since we have nothing special to do between
kobject_init() and kobject_add().
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kobject_add() sets the parent pointer, so we don't need to do it
explicitly.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Set the kobject name via kobject_add() instead of using kobject_set_name(),
which is deprecated per Documentation/kobject.txt.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

cpu_hotplug_driver_lock() serializes CPU online/offline operations
when ARCH_CPU_PROBE_RELEASE is set.  This lock interface is no longer
necessary with the following reason:

 - lock_device_hotplug() now protects CPU online/offline operations,
   including the probe & release interfaces enabled by
   ARCH_CPU_PROBE_RELEASE.  The use of cpu_hotplug_driver_lock() is
   redundant.
 - cpu_hotplug_driver_lock() is only valid when ARCH_CPU_PROBE_RELEASE
   is defined, which is misleading and is only enabled on powerpc.

This patch removes the cpu_hotplug_driver_lock() interface.  As
a result, ARCH_CPU_PROBE_RELEASE only enables / disables the cpu
probe & release interface as intended.  There is no functional change
in this patch.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Commit d7c53c9e enabled ARCH_CPU_PROBE_RELEASE on x86 in order to
serialize CPU online/offline operations.  Although it is the config
option to enable CPU hotplug test interfaces, probe & release, it is
also the option to enable cpu_hotplug_driver_lock() as well.  Therefore,
this option had to be enabled on x86 with dummy arch_cpu_probe() and
arch_cpu_release().

Since then, lock_device_hotplug() was introduced to serialize CPU
online/offline & hotplug operations.  Therefore, this config option
is no longer required for the serialization.  This patch disables
this config option on x86 and revert the changes made by commit
d7c53c9e.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

lock_device_hotplug[_sysfs]() serializes CPU & Memory online/offline
and hotplug operations.  However, this lock is not held in the debug
interfaces below that initiate CPU online/offline operations.

 - _debug_hotplug_cpu(), cpu0 hotplug test interface enabled by
   CONFIG_DEBUG_HOTPLUG_CPU0.
 - cpu_probe_store() and cpu_release_store(), cpu hotplug test interface
   enabled by CONFIG_ARCH_CPU_PROBE_RELEASE.

This patch changes the above interfaces to hold lock_device_hotplug().
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

_debug_hotplug_cpu() is a debug interface that puts cpu0 offline during
boot-up when CONFIG_DEBUG_HOTPLUG_CPU0 is set.  After cpu0 is put offline
in this interface, however, /sys/devices/system/cpu/cpu0/online still
shows 1 (online).

This patch fixes _debug_hotplug_cpu() to update dev->offline when CPU
online/offline operation succeeded.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull staging fixes from Greg KH:
 "Here are a number of small staging tree and iio driver fixes.  Nothing
  major, just lots of little things"

* tag 'staging-3.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (34 commits)
  iio:buffer_cb: Add missing iio_buffer_init()
  iio: Prevent race between IIO chardev opening and IIO device free
  iio: fix: Keep a reference to the IIO device for open file descriptors
  iio: Stop sampling when the device is removed
  iio: Fix crash when scan_bytes is computed with active_scan_mask == NULL
  iio: Fix mcp4725 dev-to-indio_dev conversion in suspend/resume
  iio: Fix bma180 dev-to-indio_dev conversion in suspend/resume
  iio: Fix tmp006 dev-to-indio_dev conversion in suspend/resume
  iio: iio_device_add_event_sysfs() bugfix
  staging: iio: ade7854-spi: Fix return value
  staging:iio:hmc5843: Fix measurement conversion
  iio: isl29018: Fix uninitialized value
  staging:iio:dummy fix kfifo_buf kconfig dependency issue if kfifo modular and buffer enabled for built in dummy driver.
  iio: at91: fix adc_clk overflow
  staging: line6: add bounds check in snd_toneport_source_put()
  Staging: comedi: Fix dependencies for drivers misclassified as PCI
  staging: r8188eu: Adjust RX gain
  staging: r8188eu: Fix smatch warning in core/rtw_ieee80211.
  staging: r8188eu: Fix smatch error in core/rtw_mlme_ext.c
  staging: r8188eu: Fix Smatch off-by-one warning in hal/rtl8188e_hal_init.c
  ...

Pull USB fixes from Greg KH:
 "Here are a number of small USB fixes for 3.12-rc2.

  One is a revert of a EHCI change that isn't quite ready for 3.12.
  Others are minor things, gadget fixes, Kconfig fixes, and some quirks
  and documentation updates.

  All have been in linux-next for a bit"

* tag 'usb-3.12-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  USB: pl2303: distinguish between original and cloned HX chips
  USB: Faraday fotg210: fix email addresses
  USB: fix typo in usb serial simple driver Kconfig
  Revert "USB: EHCI: support running URB giveback in tasklet context"
  usb: s3c-hsotg: do not disconnect gadget when receiving ErlySusp intr
  usb: s3c-hsotg: fix unregistration function
  usb: gadget: f_mass_storage: reset endpoint driver data when disabled
  usb: host: fsl-mph-dr-of: Staticize local symbols
  usb: gadget: f_eem: Staticize eem_alloc
  usb: gadget: f_ecm: Staticize ecm_alloc
  usb: phy: omap-usb3: Fix return value
  usb: dwc3: gadget: avoid memory leak when failing to allocate all eps
  usb: dwc3: remove extcon dependency
  usb: gadget: add '__ref' for rndis_config_register() and cdc_config_register()
  usb: dwc3: pci: add support for BayTrail
  usb: gadget: cdc2: fix conversion to new interface of f_ecm
  usb: gadget: fix a bug and a WARN_ON in dummy-hcd
  usb: gadget: mv_u3d_core: fix violation of locking discipline in mv_u3d_ep_disable()

Pull drm fixes from Dave Airlie:
 - some small fixes for msm and exynos
 - a regression revert affecting nouveau users with old userspace
 - intel pageflip deadlock and gpu hang fixes, hsw modesetting hangs

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (22 commits)
  Revert "drm: mark context support as a legacy subsystem"
  drm/i915: Don't enable the cursor on a disable pipe
  drm/i915: do not update cursor in crtc mode set
  drm/exynos: fix return value check in lowlevel_buffer_allocate()
  drm/exynos: Fix address space warnings in exynos_drm_fbdev.c
  drm/exynos: Fix address space warning in exynos_drm_buf.c
  drm/exynos: Remove redundant OF dependency
  drm/msm: drop unnecessary set_need_resched()
  drm/i915: kill set_need_resched
  drm/msm: fix potential NULL pointer dereference
  drm/i915/dvo: set crtc timings again for panel fixed modes
  drm/i915/sdvo: Robustify the dtd<->drm_mode conversions
  drm/msm: workaround for missing irq
  drm/msm: return -EBUSY if bo still active
  drm/msm: fix return value check in ERR_PTR()
  drm/msm: fix cmdstream size check
  drm/msm: hangcheck harder
  drm/msm: handle read vs write fences
  drm/i915/sdvo: Fully translate sync flags in the dtd->mode conversion
  drm/i915: Use proper print format for debug prints
  ...

Pull block IO fixes from Jens Axboe:
 "After merge window, no new stuff this time only a collection of neatly
  confined and simple fixes"

* 'for-3.12/core' of git://git.kernel.dk/linux-block:
  cfq: explicitly use 64bit divide operation for 64bit arguments
  block: Add nr_bios to block_rq_remap tracepoint
  If the queue is dying then we only call the rq->end_io callout. This leaves bios setup on the request, because the caller assumes when the blk_execute_rq_nowait/blk_execute_rq call has completed that the rq->bios have been cleaned up.
  bio-integrity: Fix use of bs->bio_integrity_pool after free
  blkcg: relocate root_blkg setting and clearing
  block: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...)
  block: trace all devices plug operation

Pull btrfs fixes from Chris Mason:
 "These are mostly bug fixes and a two small performance fixes.  The
  most important of the bunch are Josef's fix for a snapshotting
  regression and Mark's update to fix compile problems on arm"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (25 commits)
  Btrfs: create the uuid tree on remount rw
  btrfs: change extent-same to copy entire argument struct
  Btrfs: dir_inode_operations should use btrfs_update_time also
  btrfs: Add btrfs: prefix to kernel log output
  btrfs: refuse to remount read-write after abort
  Btrfs: btrfs_ioctl_default_subvol: Revert back to toplevel subvolume when arg is 0
  Btrfs: don't leak transaction in btrfs_sync_file()
  Btrfs: add the missing mutex unlock in write_all_supers()
  Btrfs: iput inode on allocation failure
  Btrfs: remove space_info->reservation_progress
  Btrfs: kill delay_iput arg to the wait_ordered functions
  Btrfs: fix worst case calculator for space usage
  Revert "Btrfs: rework the overcommit logic to be based on the total size"
  Btrfs: improve replacing nocow extents
  Btrfs: drop dir i_size when adding new names on replay
  Btrfs: replay dir_index items before other items
  Btrfs: check roots last log commit when checking if an inode has been logged
  Btrfs: actually log directory we are fsync()'ing
  Btrfs: actually limit the size of delalloc range
  Btrfs: allocate the free space by the existed max extent size when ENOSPC
  ...

'samples' is 64bit operant, but do_div() second parameter is 32.
do_div silently truncates high 32 bits and calculated result
is invalid.

In case if low 32bit of 'samples' are zeros then do_div() produces
kernel crash.
Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Merge tag 'iio-fixes-for-3.12a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus

Jonathan writes:

First round of IIO fixes for 3.12

A series of wrong 'struct dev' assumptions in suspend/resume callbacks
following on from this issue being identified in a new driver review.
One to watch out for in future.

A number of driver specific fixes
1) at91 - fix a overflow in clock rate computation
2) dummy - Kconfig dependency issue
3) isl29018 - uninitialized value
4) hmc5843 - measurement conversion bug introduced by recent cleanup.
5) ade7854-spi - wrong return value.

Some IIO core fixes
1) Wrong value picked up for event code creation for a modified channel
2) A null dereference on failure to initialize a buffer after no buffer has
   been in use, when using the available_scan_masks approach.
3) Sampling not stopped when a device is removed. Effects forced removal
   such as hot unplugging.
4) Prevent device going away if a chrdev is still open in userspace.
5) Prevent race on chardev opening and device being freed.
6) Add a missing iio_buffer_init in the call back buffer.

These last few are the first part of a set from Lars-Peter Clausen who
has been taking a closer look at our removal paths and buffer handling
than anyone has for quite some time.

Pull NFS client bugfix from Trond Myklebust:
 "Fix a regression due to incorrect sharing of gss auth caches"

* tag 'nfs-for-3.12-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  RPCSEC_GSS: fix crash on destroying gss auth

Adding the number of bios in a remapped request to 'block_rq_remap'
tracepoint.

Request remapper clones bios in a request to track the completion
status of each bio. So the number of bios can be useful information
for investigation.

Related discussions:
  http://www.redhat.com/archives/dm-devel/2013-August/msg00084.html
  http://www.redhat.com/archives/dm-devel/2013-September/msg00024.htmlSigned-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Users have been complaining of the uuid tree stuff warning that there is no uuid
root when trying to do snapshot operations.  This is because if you mount -o ro
we will not create the uuid tree.  But then if you mount -o rw,remount we will
still not create it and then any subsequent snapshot/subvol operations you try
to do will fail gloriously.  Fix this by creating the uuid_root on remount rw if
it was not already there.  Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

btrfs_ioctl_file_extent_same() uses __put_user_unaligned() to copy some data
back to it's argument struct. Unfortunately, not all architectures provide
__put_user_unaligned(), so compiles break on them if btrfs is selected.

Instead, just copy the whole struct in / out at the start and end of
operations, respectively.
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Commit 2bc55652 (Btrfs: don't update atime on
RO subvolumes) ensures that the access time of an inode is not updated when
the inode lives in a read-only subvolume.
However, if a directory on a read-only subvolume is accessed, the atime is
updated. This results in a write operation to a read-only subvolume. I
believe that access times should never be updated on read-only subvolumes.

To reproduce:

 # mkfs.btrfs -f /dev/dm-3
 (...)
 # mount /dev/dm-3 /mnt
 # btrfs subvol create /mnt/sub
 	Create subvolume '/mnt/sub'
 # mkdir /mnt/sub/dir
 # echo "abc" > /mnt/sub/dir/file
 # btrfs subvol snapshot -r /mnt/sub /mnt/rosnap
 	Create a readonly snapshot of '/mnt/sub' in '/mnt/rosnap'
 # stat /mnt/rosnap/dir
 	File: `/mnt/rosnap/dir'
 	Size: 8         Blocks: 0          IO Block: 4096   directory
 Device: 16h/22d    Inode: 257         Links: 1
 Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
 	Access: 2013-09-11 07:21:49.389157126 -0400
 	Modify: 2013-09-11 07:22:02.330156079 -0400
 	Change: 2013-09-11 07:22:02.330156079 -0400
 # ls /mnt/rosnap/dir
 	file
 # stat /mnt/rosnap/dir
 	File: `/mnt/rosnap/dir'
 	Size: 8         Blocks: 0          IO Block: 4096   directory
 Device: 16h/22d    Inode: 257         Links: 1
 Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
 	Access: 2013-09-11 07:22:56.797151670 -0400
 	Modify: 2013-09-11 07:22:02.330156079 -0400
 	Change: 2013-09-11 07:22:02.330156079 -0400
Reported-by: Koen De Wit <koen.de.wit@oracle.com>
Signed-off-by: Guangyu Sun <guangyu.sun@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

The kernel log entries for device label %s and device fsid %pU
are missing the btrfs: prefix. Add those here.
Signed-off-by: Frank Holton <fholton@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

It's still possible to flip the filesystem into RW mode after it's
remounted RO due to an abort. There are lots of places that check for
the superblock error bit and will not write data, but we should not let
the filesystem appear read-write.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

This patch makes it possible to set BTRFS_FS_TREE_OBJECTID as the default
subvolume by passing a subvolume id of 0.
Signed-off-by: chandan <chandan@linux.vnet.ibm.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>