1. 23 Jul, 2013 3 commits
    • Lv Zheng's avatar
      ACPI: Add facility to remove all _OSI strings · 741d8128
      Lv Zheng authored
      This patch changes the "acpi_osi=" boot parameter implementation so
      that:
      1. "acpi_osi=!" can be used to disable all _OSI OS vendor strings by
         default.  It is meaningless to specify "acpi_osi=!" multiple
         times as it can only affect the default state of the target _OSI
         strings.
      2. "acpi_osi=!*" can be used to remove all _OSI OS vendor strings
         and all _OSI feature group strings.  It is useful to specify
         "acpi_osi=!*" multiple times through kernel command line to
         override the current state of the target _OSI strings.
      Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
      Reviewed-by: default avatarZhang Rui <rui.zhang@intel.com>
      Acked-by: default avatarLen Brown <len.brown@intel.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      741d8128
    • Lv Zheng's avatar
      ACPI: Add facility to disable all _OSI OS vendor strings · 5dc17986
      Lv Zheng authored
      This patch introduces "acpi_osi=!" command line to force Linux replying
      "UNSUPPORTED" to all of the _OSI strings.  This patch is based on an
      ACPICA enhancement - the new API acpi_update_interfaces().
      
      The _OSI object provides the platform with the ability to query OSPM
      to determine the set of ACPI related interfaces, behaviors, or
      features that the operating system supports.  The argument passed to
      the _OSI is a string like the followings:
      1. Feature Group String, examples include
         Module Device
         Processor Device
         3.0 _SCP Extensions
         Processor Aggregator Device
         ...
      2. OS Vendor String, examples include
         Linux
         FreeBSD
         Windows
         ...
      
      There are AML codes provided in the ACPI namespace written in the
      following style to determine OSPM interfaces / features:
          Method(OSCK)
          {
              if (CondRefOf(_OSI, Local0))
              {
                  if (\_OSI("Windows"))
                  {
                      Return (One)
                  }
                  if (\_OSI("Windows 2006"))
                  {
                      Return (Ones)
                  }
                  Return (Zero)
              }
              Return (Zero)
          }
      
      There is a debugging facility implemented in Linux.  Users can pass
      "acpi_osi=" boot parameters to the kernel to tune the _OSI evaluation
      result so that certain AML codes can be executed.  Current
      implementation includes:
      1. 'acpi_osi=' - this makes CondRefOf(_OSI, Local0) TRUE
      2. 'acpi_osi="Windows"' - this makes \_OSI("Windows") TRUE
      3. 'acpi_osi="!Windows"' - this makes \_OSI("Windows") FALSE
      The function to implement this feature is also used as a quirk mechanism
      in the Linux ACPI subystem.
      
      When _OSI is evaluatated by the AML codes, ACPICA replies "SUPPORTED"
      to all Windows operating system vendor strings.  This is because
      Windows operating systems return "SUPPORTED" if the argument to the
      _OSI method specifies an earlier version of Windows.  Please refer to
      the following MSDN document:
      
      How to Identify the Windows Version in ACPI by Using _OSI
      http://msdn.microsoft.com/en-us/library/hardware/gg463275.aspx
      
      This adds difficulties when developers want to feed specific Windows
      operating system vendor string to the BIOS codes for debugging
      purpose, multiple acpi_osi="!xxx" have to be specified in the command
      line to force Linux replying "UNSUPPORTED" to the Windows OS vendor
      strings listed in the AML codes.
      Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
      Reviewed-by: default avatarZhang Rui <rui.zhang@intel.com>
      Acked-by: default avatarLen Brown <len.brown@intel.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      5dc17986
    • Lv Zheng's avatar
      ACPICA: Add acpi_update_interfaces() public interface · 2cf9f5bc
      Lv Zheng authored
      Add new API to allow OSPM to disable/enable specific types of _OSI
      interface strings.
      
      ACPICA does not have the knowledge about whether an _OSI interface
      string is an OS vendor string or a feature group string and there
      isn't any API interface to allow OSPM to install a new interface
      string as a feature group string.
      This patch simply adds all feature group strings defined by ACPI
      specification into the acpi_default_supported_interfaces with
      ACPI_OSI_FEATURE flag set to fix this gap.  This patch also adds
      codes to keep their default states as ACPI_OSI_INVALID before the
      initialization and after the termination.
      Signed-off-by: default avatarLv Zheng <lv.zheng@intel.com>
      Reviewed-by: default avatarZhang Rui <rui.zhang@intel.com>
      Signed-off-by: default avatarBob Moore <robert.moore@intel.com>
      Acked-by: default avatarLen Brown <len.brown@intel.com>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      
      Conflicts:
      	include/acpi/actypes.h (with commit 242b2287)
      2cf9f5bc
  2. 22 Jul, 2013 6 commits
  3. 21 Jul, 2013 5 commits
    • Linus Torvalds's avatar
      Linux 3.11-rc2 · 3b2f64d0
      Linus Torvalds authored
      3b2f64d0
    • Linus Torvalds's avatar
      Merge tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · ea45ea70
      Linus Torvalds authored
      Pull ACPI video support fixes from Rafael Wysocki:
       "I'm sending a separate pull request for this as it may be somewhat
        controversial.  The breakage addressed here is not really new and the
        fixes may not satisfy all users of the affected systems, but we've had
        so much back and forth dance in this area over the last several weeks
        that I think it's time to actually make some progress.
      
        The source of the problem is that about a year ago we started to tell
        BIOSes that we're compatible with Windows 8, which we really need to
        do, because some systems shipping with Windows 8 are tested with it
        and nothing else, so if we tell their BIOSes that we aren't compatible
        with Windows 8, we expose our users to untested BIOS/AML code paths.
      
        However, as it turns out, some Windows 8-specific AML code paths are
        not tested either, because Windows 8 actually doesn't use the ACPI
        methods containing them, so if we declare Windows 8 compatibility and
        attempt to use those ACPI methods, things break.  That occurs mostly
        in the backlight support area where in particular the _BCM and _BQC
        methods are plain unusable on some systems if the OS declares Windows
        8 compatibility.
      
        [ The additional twist is that they actually become usable if the OS
          says it is not compatible with Windows 8, but that may cause
          problems to show up elsewhere ]
      
        Investigation carried out by Matthew Garrett indicates that what
        Windows 8 does about backlight is to leave backlight control up to
        individual graphics drivers.  At least there's evidence that it does
        that if the Intel graphics driver is used, so we've decided to follow
        Windows 8 in that respect and allow i915 to control backlight (Daniel
        likes that part).
      
        The first commit from Aaron Lu makes ACPICA export the variable from
        which we can infer whether or not the BIOS believes that we are
        compatible with Windows 8.
      
        The second commit from Matthew Garrett prepares the ACPI video driver
        by making it initialize the ACPI backlight even if it is not going to
        be used afterward (that is needed for backlight control to work on
        Thinkpads).
      
        The third commit implements the actual workaround making i915 take
        over backlight control if the firmware thinks it's dealing with
        Windows 8 and is based on the work of multiple developers, including
        Matthew Garrett, Chun-Yi Lee, Seth Forshee, and Aaron Lu.
      
        The final commit from Aaron Lu makes us follow Windows 8 by informing
        the firmware through the _DOS method that it should not carry out
        automatic brightness changes, so that brightness can be controlled by
        GUI.
      
        Hopefully, this approach will allow us to avoid using blacklists of
        systems that should not declare Windows 8 compatibility just to avoid
        backlight control problems in the future.
      
         - Change from Aaron Lu makes ACPICA export a variable which can be
           used by driver code to determine whether or not the BIOS believes
           that we are compatible with Windows 8.
      
         - Change from Matthew Garrett makes the ACPI video driver initialize
           the ACPI backlight even if it is not going to be used afterward
           (that is needed for backlight control to work on Thinkpads).
      
         - Fix from Rafael J Wysocki implements Windows 8 backlight support
           workaround making i915 take over bakclight control if the firmware
           thinks it's dealing with Windows 8.  Based on the work of multiple
           developers including Matthew Garrett, Chun-Yi Lee, Seth Forshee,
           and Aaron Lu.
      
         - Fix from Aaron Lu makes the kernel follow Windows 8 by informing
           the firmware through the _DOS method that it should not carry out
           automatic brightness changes, so that brightness can be controlled
           by GUI"
      
      * tag 'acpi-video-3.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
        ACPI / video: no automatic brightness changes by win8-compatible firmware
        ACPI / video / i915: No ACPI backlight if firmware expects Windows 8
        ACPI / video: Always call acpi_video_init_brightness() on init
        ACPICA: expose OSI version
      ea45ea70
    • Linus Torvalds's avatar
      Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 · 90db76e8
      Linus Torvalds authored
      Pull ext[34] tmpfile bugfix from Ted Ts'o:
       "Fix regression caused by commit af51a2ac which added ->tmpfile()
        support (along with a similar fix for ext3)"
      
      * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
        ext3: fix a BUG when opening a file with O_TMPFILE flag
        ext4: fix a BUG when opening a file with O_TMPFILE flag
      90db76e8
    • Zheng Liu's avatar
      ext3: fix a BUG when opening a file with O_TMPFILE flag · dda5690d
      Zheng Liu authored
      When we try to open a file with O_TMPFILE flag, we will trigger a bug.
      The root cause is that in ext4_orphan_add() we check ->i_nlink == 0 and
      this check always fails because we set ->i_nlink = 1 in
      inode_init_always().  We can use the following program to trigger it:
      
      int main(int argc, char *argv[])
      {
      	int fd;
      
      	fd = open(argv[1], O_TMPFILE, 0666);
      	if (fd < 0) {
      		perror("open ");
      		return -1;
      	}
      	close(fd);
      	return 0;
      }
      
      The oops message looks like this:
      
      kernel: kernel BUG at fs/ext3/namei.c:1992!
      kernel: invalid opcode: 0000 [#1] SMP
      kernel: Modules linked in: ext4 jbd2 crc16 cpufreq_ondemand ipv6 dm_mirror dm_region_hash dm_log dm_mod parport_pc parport serio_raw sg dcdbas pcspkr i2c_i801 ehci_pci ehci_hcd button acpi_cpufreq mperf e1000e ptp pps_core ttm drm_kms_helper drm hwmon i2c_algo_bit i2c_core ext3 jbd sd_mod ahci libahci libata scsi_mod uhci_hcd
      kernel: CPU: 0 PID: 2882 Comm: tst_tmpfile Not tainted 3.11.0-rc1+ #4
      kernel: Hardware name: Dell Inc. OptiPlex 780 /0V4W66, BIOS A05 08/11/2010
      kernel: task: ffff880112d30050 ti: ffff8801124d4000 task.ti: ffff8801124d4000
      kernel: RIP: 0010:[<ffffffffa00db5ae>] [<ffffffffa00db5ae>] ext3_orphan_add+0x6a/0x1eb [ext3]
      kernel: RSP: 0018:ffff8801124d5cc8  EFLAGS: 00010202
      kernel: RAX: 0000000000000000 RBX: ffff880111510128 RCX: ffff8801114683a0
      kernel: RDX: 0000000000000000 RSI: ffff880111510128 RDI: ffff88010fcf65a8
      kernel: RBP: ffff8801124d5d18 R08: 0080000000000000 R09: ffffffffa00d3b7f
      kernel: R10: ffff8801114683a0 R11: ffff8801032a2558 R12: 0000000000000000
      kernel: R13: ffff88010fcf6800 R14: ffff8801032a2558 R15: ffff8801115100d8
      kernel: FS:  00007f5d172b5700(0000) GS:ffff880117c00000(0000) knlGS:0000000000000000
      kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      kernel: CR2: 00007f5d16df15d0 CR3: 0000000110b1d000 CR4: 00000000000407f0
      kernel: Stack:
      kernel: 000000000000000c ffff8801048a7dc8 ffff8801114685a8 ffffffffa00b80d7
      kernel: ffff8801124d5e38 ffff8801032a2558 ffff88010ce24d68 0000000000000000
      kernel: ffff88011146b300 ffff8801124d5d44 ffff8801124d5d78 ffffffffa00db7e1
      kernel: Call Trace:
      kernel: [<ffffffffa00b80d7>] ? journal_start+0x8c/0xbd [jbd]
      kernel: [<ffffffffa00db7e1>] ext3_tmpfile+0xb2/0x13b [ext3]
      kernel: [<ffffffff821076f8>] path_openat+0x11f/0x5e7
      kernel: [<ffffffff821c86b4>] ? list_del+0x11/0x30
      kernel: [<ffffffff82065fa2>] ?  __dequeue_entity+0x33/0x38
      kernel: [<ffffffff82107cd5>] do_filp_open+0x3f/0x8d
      kernel: [<ffffffff82112532>] ? __alloc_fd+0x50/0x102
      kernel: [<ffffffff820f9296>] do_sys_open+0x13b/0x1cd
      kernel: [<ffffffff820f935c>] SyS_open+0x1e/0x20
      kernel: [<ffffffff82398c02>] system_call_fastpath+0x16/0x1b
      kernel: Code: 39 c7 0f 85 67 01 00 00 0f b7 03 25 00 f0 00 00 3d 00 40 00 00 74 18 3d 00 80 00 00 74 11 3d 00 a0 00 00 74 0a 83 7b 48 00 74 04 <0f> 0b eb fe 49 8b 85 50 03 00 00 4c 89 f6 48 c7 c7 c0 99 0e a0
      kernel: RIP  [<ffffffffa00db5ae>] ext3_orphan_add+0x6a/0x1eb [ext3]
      kernel: RSP <ffff8801124d5cc8>
      
      Here we couldn't call clear_nlink() directly because in d_tmpfile() we
      will call inode_dec_link_count() to decrease ->i_nlink.  So this commit
      tries to call d_tmpfile() before ext4_orphan_add() to fix this problem.
      Signed-off-by: default avatarZheng Liu <wenqing.lz@taobao.com>
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      dda5690d
    • Zheng Liu's avatar
      ext4: fix a BUG when opening a file with O_TMPFILE flag · e94bd349
      Zheng Liu authored
      When we try to open a file with O_TMPFILE flag, we will trigger a bug.
      The root cause is that in ext4_orphan_add() we check ->i_nlink == 0 and
      this check always fails because we set ->i_nlink = 1 in
      inode_init_always().  We can use the following program to trigger it:
      
      int main(int argc, char *argv[])
      {
      	int fd;
      
      	fd = open(argv[1], O_TMPFILE, 0666);
      	if (fd < 0) {
      		perror("open ");
      		return -1;
      	}
      	close(fd);
      	return 0;
      }
      
      The oops message looks like this:
      
      kernel BUG at fs/ext4/namei.c:2572!
      invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
      Modules linked in: dlci bridge stp hidp cmtp kernelcapi l2tp_ppp l2tp_netlink l2tp_core sctp libcrc32c rfcomm tun fuse nfnetli
      nk can_raw ipt_ULOG can_bcm x25 scsi_transport_iscsi ipx p8023 p8022 appletalk phonet psnap vmw_vsock_vmci_transport af_key vmw_vmci rose vsock atm can netrom ax25 af_rxrpc ir
      da pppoe pppox ppp_generic slhc bluetooth nfc rfkill rds caif_socket caif crc_ccitt af_802154 llc2 llc snd_hda_codec_realtek snd_hda_intel snd_hda_codec serio_raw snd_pcm pcsp
      kr edac_core snd_page_alloc snd_timer snd soundcore r8169 mii sr_mod cdrom pata_atiixp radeon backlight drm_kms_helper ttm
      CPU: 1 PID: 1812571 Comm: trinity-child2 Not tainted 3.11.0-rc1+ #12
      Hardware name: Gigabyte Technology Co., Ltd. GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
      task: ffff88007dfe69a0 ti: ffff88010f7b6000 task.ti: ffff88010f7b6000
      RIP: 0010:[<ffffffff8125ce69>]  [<ffffffff8125ce69>] ext4_orphan_add+0x299/0x2b0
      RSP: 0018:ffff88010f7b7cf8  EFLAGS: 00010202
      RAX: 0000000000000000 RBX: ffff8800966d3020 RCX: 0000000000000000
      RDX: 0000000000000000 RSI: ffff88007dfe70b8 RDI: 0000000000000001
      RBP: ffff88010f7b7d40 R08: ffff880126a3c4e0 R09: ffff88010f7b7ca0
      R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801271fd668
      R13: ffff8800966d2f78 R14: ffff88011d7089f0 R15: ffff88007dfe69a0
      FS:  00007f70441a3740(0000) GS:ffff88012a800000(0000) knlGS:00000000f77c96c0
      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      CR2: 0000000002834000 CR3: 0000000107964000 CR4: 00000000000007e0
      DR0: 0000000000780000 DR1: 0000000000000000 DR2: 0000000000000000
      DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
      Stack:
       0000000000002000 00000020810b6dde 0000000000000000 ffff88011d46db00
       ffff8800966d3020 ffff88011d7089f0 ffff88009c7f4c10 ffff88010f7b7f2c
       ffff88007dfe69a0 ffff88010f7b7da8 ffffffff8125cfac ffff880100000004
      Call Trace:
       [<ffffffff8125cfac>] ext4_tmpfile+0x12c/0x180
       [<ffffffff811cba78>] path_openat+0x238/0x700
       [<ffffffff8100afc4>] ? native_sched_clock+0x24/0x80
       [<ffffffff811cc647>] do_filp_open+0x47/0xa0
       [<ffffffff811db73f>] ? __alloc_fd+0xaf/0x200
       [<ffffffff811ba2e4>] do_sys_open+0x124/0x210
       [<ffffffff81010725>] ? syscall_trace_enter+0x25/0x290
       [<ffffffff811ba3ee>] SyS_open+0x1e/0x20
       [<ffffffff816ca8d4>] tracesys+0xdd/0xe2
       [<ffffffff81001001>] ? start_thread_common.constprop.6+0x1/0xa0
      Code: 04 00 00 00 89 04 24 31 c0 e8 c4 77 04 00 e9 43 fe ff ff 66 25 00 d0 66 3d 00 80 0f 84 0e fe ff ff 83 7b 48 00 0f 84 04 fe ff ff <0f> 0b 49 8b 8c 24 50 07 00 00 e9 88 fe ff ff 0f 1f 84 00 00 00
      
      Here we couldn't call clear_nlink() directly because in d_tmpfile() we
      will call inode_dec_link_count() to decrease ->i_nlink.  So this commit
      tries to call d_tmpfile() before ext4_orphan_add() to fix this problem.
      Reported-by: default avatarDave Jones <davej@redhat.com>
      Signed-off-by: default avatarZheng Liu <wenqing.lz@taobao.com>
      Tested-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
      Tested-by: default avatarDave Jones <davej@redhat.com>
      Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
      Acked-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      e94bd349
  4. 20 Jul, 2013 7 commits
    • Linus Torvalds's avatar
      Merge tag 'staging-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging · f6a0d9d5
      Linus Torvalds authored
      Pull staging tree fixes from Greg KH:
       "Here are a few iio driver fixes for 3.11-rc2.  They are still spread
        across drivers/iio and drivers/staging/iio so they are coming in
        through this tree.
      
        I've also removed the drivers/staging/csr/ driver as the developers
        who originally sent it to me have moved on to other companies, and CSR
        still will not send us the specs for the device, making the driver
        pretty much obsolete and impossible to fix up.  Deleting it now
        prevents people from sending in lots of tiny codingsyle fixes that
        will never go anywhere.
      
        It also helps to offset the large lustre filesystem merge that
        happened in 3.11-rc1 in the overall 3.11.0 diffstat.  :)"
      
      * tag 'staging-3.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
        staging: csr: remove driver
        iio: lps331ap: Fix wrong in_pressure_scale output value
        iio staging: fix lis3l02dq, read error handling
        staging:iio:ad7291: add missing .driver_module to struct iio_info
        iio: ti_am335x_adc: add missing .driver_module to struct iio_info
        iio: mxs-lradc: Remove useless check in read_raw
        iio: mxs-lradc: Fix misuse of iio->trig
        iio: inkern: fix iio_convert_raw_to_processed_unlocked
        iio: Fix iio_channel_has_info
        iio:trigger: device_unregister->device_del to avoid double free
        iio: dac: ad7303: fix error return code in ad7303_probe()
      f6a0d9d5
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · 36231d25
      Linus Torvalds authored
      Pull vfs fixes from Al Viro:
       "The sget() one is a long-standing bug and will need to go into -stable
        (in fact, it had been originally caught in RHEL6), the other two are
        3.11-only"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        vfs: constify dentry parameter in d_count()
        livelock avoidance in sget()
        allow O_TMPFILE to work with O_WRONLY
      36231d25
    • Linus Torvalds's avatar
      Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 · 19bf1c2c
      Linus Torvalds authored
      Pull ext4 bugfixes from Ted Ts'o:
       "Fixes for 3.11-rc2, sent at 5pm, in the professoinal style.  :-)"
      
      I'm not sure I like this new level of "professionalism".
      9-5, people, 9-5.
      
      * tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
        ext4: call ext4_es_lru_add() after handling cache miss
        ext4: yield during large unlinks
        ext4: make the extent_status code more robust against ENOMEM failures
        ext4: simplify calculation of blocks to free on error
        ext4: fix error handling in ext4_ext_truncate()
      19bf1c2c
    • Linus Torvalds's avatar
      Merge tag 'nfs-for-3.11-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs · 3be542d4
      Linus Torvalds authored
      Pull NFS client bugfixes from Trond Myklebust:
       - Fix a regression against NFSv4 FreeBSD servers when creating a new
         file
       - Fix another regression in rpc_client_register()
      
      * tag 'nfs-for-3.11-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
        NFSv4: Fix a regression against the FreeBSD server
        SUNRPC: Fix another issue with rpc_client_register()
      3be542d4
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next · 90290c4e
      Linus Torvalds authored
      Pull btrfs fixes from Josef Bacik:
       "I'm playing the role of Chris Mason this week while he's on vacation.
        There are a few critical fixes for btrfs here, all regressions and
        have been tested well"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-next:
        Btrfs: fix wrong write offset when replacing a device
        Btrfs: re-add root to dead root list if we stop dropping it
        Btrfs: fix lock leak when resuming snapshot deletion
        Btrfs: update drop progress before stopping snapshot dropping
      90290c4e
    • Peng Tao's avatar
      vfs: constify dentry parameter in d_count() · 24924a20
      Peng Tao authored
      so that it can be used in places like d_compare/d_hash
      without causing a compiler warning.
      Signed-off-by: default avatarPeng Tao <tao.peng@emc.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      24924a20
    • Al Viro's avatar
      livelock avoidance in sget() · acfec9a5
      Al Viro authored
      Eric Sandeen has found a nasty livelock in sget() - take a mount(2) about
      to fail.  The superblock is on ->fs_supers, ->s_umount is held exclusive,
      ->s_active is 1.  Along comes two more processes, trying to mount the same
      thing; sget() in each is picking that superblock, bumping ->s_count and
      trying to grab ->s_umount.  ->s_active is 3 now.  Original mount(2)
      finally gets to deactivate_locked_super() on failure; ->s_active is 2,
      superblock is still ->fs_supers because shutdown will *not* happen until
      ->s_active hits 0.  ->s_umount is dropped and now we have two processes
      chasing each other:
      s_active = 2, A acquired ->s_umount, B blocked
      A sees that the damn thing is stillborn, does deactivate_locked_super()
      s_active = 1, A drops ->s_umount, B gets it
      A restarts the search and finds the same superblock.  And bumps it ->s_active.
      s_active = 2, B holds ->s_umount, A blocked on trying to get it
      ... and we are in the earlier situation with A and B switched places.
      
      The root cause, of course, is that ->s_active should not grow until we'd
      got MS_BORN.  Then failing ->mount() will have deactivate_locked_super()
      shut the damn thing down.  Fortunately, it's easy to do - the key point
      is that grab_super() is called only for superblocks currently on ->fs_supers,
      so it can bump ->s_count and grab ->s_umount first, then check MS_BORN and
      bump ->s_active; we must never increment ->s_count for superblocks past
      ->kill_sb(), but grab_super() is never called for those.
      
      The bug is pretty old; we would've caught it by now, if not for accidental
      exclusion between sget() for block filesystems; the things like cgroup or
      e.g. mtd-based filesystems don't have anything of that sort, so they get
      bitten.  The right way to deal with that is obviously to fix sget()...
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      acfec9a5
  5. 19 Jul, 2013 19 commits