1. 17 Jan, 2011 2 commits
  2. 16 Jan, 2011 37 commits
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/scsi-post-merge-2.6 · 8a335bc6
      Linus Torvalds authored
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/scsi-post-merge-2.6:
        ocfs2: Make OCFS2_FS depend on CONFIGFS_FS
        dlm: Make DLM depend on CONFIGFS_FS
        net: Make NETCONSOLE_DYNAMIC depend on CONFIGFS_FS
        configfs: change depends -> select SYSFS
        [SCSI] sd,sr: kill compat SDEV_MEDIA_CHANGE event
        [SCSI] sd: implement sd_check_events()
      8a335bc6
    • James Bottomley's avatar
      parisc: fix compile breakage caused by inlining maybe_mkwrite · 11537421
      James Bottomley authored
      On PARISC, we have an include of linux/mm.h inside our asm/pgtable.h, so
      this patch
      
        commit 14fd403f
        Author: Andrea Arcangeli <aarcange@redhat.com>
        Date:   Thu Jan 13 15:46:37 2011 -0800
      
            thp: export maybe_mkwrite
      
      causes us an unsatisfiable use of pte_mkwrite in linux/mm.h.
      
      The fix is to avoid including linux/mm.h in our pgtable.h, which
      unbreaks the build.
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      11537421
    • Andrea Arcangeli's avatar
      fix non-x86 build failure in pmdp_get_and_clear · b3697c02
      Andrea Arcangeli authored
      pmdp_get_and_clear/pmdp_clear_flush/pmdp_splitting_flush were trapped as
      BUG() and they were defined only to diminish the risk of build issues on
      not-x86 archs and to be consistent with the generic pte methods previously
      defined in include/asm-generic/pgtable.h.
      
      But they are causing more trouble than they were supposed to solve, so
      it's simpler not to define them when THP is off.
      
      This is also correcting the export of pmdp_splitting_flush which is
      currently unused (x86 isn't using the generic implementation in
      mm/pgtable-generic.c and no other arch needs that [yet]).
      Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
      Sam Ravnborg <sam@ravnborg.org>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b3697c02
    • Al Viro's avatar
      VFS: Fix UP compile error in fs/namespace.c · 7e3d0eb0
      Al Viro authored
      mnt_longterm is there only on SMP
      Reported-and-tested-by: default avatarJoachim Eastwood <manabian@gmail.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      7e3d0eb0
    • Nicholas Bellinger's avatar
      ocfs2: Make OCFS2_FS depend on CONFIGFS_FS · 7b1fff7e
      Nicholas Bellinger authored
      This patch fixes the following kconfig error after changing
      CONFIGFS_FS -> select SYSFS:
      
      fs/sysfs/Kconfig:1:error: recursive dependency detected!
      fs/sysfs/Kconfig:1:	symbol SYSFS is selected by CONFIGFS_FS
      fs/configfs/Kconfig:1:	symbol CONFIGFS_FS is selected by OCFS2_FS
      fs/ocfs2/Kconfig:1:	symbol OCFS2_FS depends on SYSFS
      Signed-off-by: default avatarNicholas A. Bellinger <nab@linux-iscsi.org>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: James Bottomley <James.Bottomley@suse.de>
      7b1fff7e
    • Nicholas Bellinger's avatar
      dlm: Make DLM depend on CONFIGFS_FS · 86c747d2
      Nicholas Bellinger authored
      This patch fixes the following kconfig error after changing
      CONFIGFS_FS -> select SYSFS:
      
      fs/sysfs/Kconfig:1:error: recursive dependency detected!
      fs/sysfs/Kconfig:1:	symbol SYSFS is selected by CONFIGFS_FS
      fs/configfs/Kconfig:1:	symbol CONFIGFS_FS is selected by DLM
      fs/dlm/Kconfig:1:	symbol DLM depends on SYSFS
      Signed-off-by: default avatarNicholas A. Bellinger <nab@linux-iscsi.org>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: James Bottomley <James.Bottomley@suse.de>
      86c747d2
    • Nicholas Bellinger's avatar
      net: Make NETCONSOLE_DYNAMIC depend on CONFIGFS_FS · d9f9ab51
      Nicholas Bellinger authored
      This patch fixes the following kconfig error after changing
      CONFIGFS_FS -> select SYSFS:
      
      fs/sysfs/Kconfig:1:error: recursive dependency detected!
      fs/sysfs/Kconfig:1:	symbol SYSFS is selected by CONFIGFS_FS
      fs/configfs/Kconfig:1:	symbol CONFIGFS_FS is selected by NETCONSOLE_DYNAMIC
      drivers/net/Kconfig:3390:	symbol NETCONSOLE_DYNAMIC depends on SYSFS
      Signed-off-by: default avatarNicholas A. Bellinger <nab@linux-iscsi.org>
      Cc: Joel Becker <jlbec@evilplan.org>
      Cc: Randy Dunlap <randy.dunlap@oracle.com>
      Cc: Stephen Rothwell <sfr@canb.auug.org.au>
      Cc: James Bottomley <James.Bottomley@suse.de>
      d9f9ab51
    • Nicholas Bellinger's avatar
      configfs: change depends -> select SYSFS · e2051172
      Nicholas Bellinger authored
      This patch changes configfs to select SYSFS to fix the following:
      
      warning: (TARGET_CORE && GFS2_FS) selects CONFIGFS_FS which has unmet direct dependencies (SYSFS)
      Reported-by: default avatarRandy Dunlap <randy.dunlap@oracle.com>
      Signed-off-by: default avatarNicholas A. Bellinger <nab@linux-iscsi.org>
      Acked-by: default avatarJoel Becker <jlbec@evilplan.org>
      e2051172
    • Nicholas Bellinger's avatar
    • Stefan Schmidt's avatar
      fs/btrfs: Fix build of ctree · f8b18087
      Stefan Schmidt authored
      Fix the build failure in some configurations:
      
           CC [M]  fs/btrfs/ctree.o
        In file included from fs/btrfs/ctree.c:21:0:
        fs/btrfs/ctree.h:1003:17: error: field 'super_kobj' has incomplete type
        fs/btrfs/ctree.h:1074:17: error: field 'root_kobj' has incomplete type
        make[2]: *** [fs/btrfs/ctree.o] Error 1
        make[1]: *** [fs/btrfs] Error 2
        make: *** [fs] Error 2
      
      caused by commit 57cc7215 ("headers: kobject.h redux")
      
      We need to include kobject.h here.
      Reported-by: default avatarJeff Garzik <jeff@garzik.org>
      Fix-suggested-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      Signed-off-by: default avatarStefan Schmidt <stefan@datenfreihafen.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f8b18087
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-linus · 5520ebd3
      Linus Torvalds authored
      * git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-linus:
        Squashfs: simplify CONFIG_SQUASHFS_LZO handling
        Squashfs: move squashfs_i() definition from squashfs.h
        Squashfs: get rid of default n in Kconfig
        Squashfs: add missing check in zlib_wrapper
        Squashfs: remove unnecessary variable in zlib_wrapper
        Squashfs: Add XZ compression configuration option
        Squashfs: add XZ compression support
      5520ebd3
    • Rafael J. Wysocki's avatar
      ACPI: Fix boot problem related to APEI with acpi_disabled set · d3072e6a
      Rafael J. Wysocki authored
      Commit 415e12b2 ("PCI/ACPI: Request _OSC control once for each root
      bridge (v3)") put the acpi_hest_init() call in acpi_pci_root_init() into
      a wrong place, presumably because the author confused acpi_pci_disabled
      with acpi_disabled.  Bring the code ordering in acpi_pci_root_init()
      back to sanity.
      
      Additionally, make sure that hest_disable is set when acpi_disabled is
      set, which is going to prevent acpi_hest_parse(), that still may be
      executed for acpi_disabled=1 through aer_acpi_firmware_first(), from
      crashing because of uninitialized hest_tab.
      Reported-and-tested-by: default avatarAndres Salomon <dilinger@queued.net>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d3072e6a
    • Rafael J. Wysocki's avatar
      PCI / ACPI: Fix build of the AER driver for CONFIG_ACPI unset · fc8fe1e9
      Rafael J. Wysocki authored
      After commit 415e12b2 ("PCI/ACPI: Request _OSC control once for each
      root bridge (v3)") include/linux/pci-acpi.h is included by
      drivers/pci/pcie/aer/aerdrv.c and if CONFIG_ACPI is unset, the bogus and
      unnecessary alternative definition of acpi_find_root_bridge_handle()
      causes a build error to occur.
      
      Remove the offending piece of garbage.
      Reported-and-tested-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      fc8fe1e9
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 · f8206b92
      Linus Torvalds authored
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (23 commits)
        sanitize vfsmount refcounting changes
        fix old umount_tree() breakage
        autofs4: Merge the remaining dentry ops tables
        Unexport do_add_mount() and add in follow_automount(), not ->d_automount()
        Allow d_manage() to be used in RCU-walk mode
        Remove a further kludge from __do_follow_link()
        autofs4: Bump version
        autofs4: Add v4 pseudo direct mount support
        autofs4: Fix wait validation
        autofs4: Clean up autofs4_free_ino()
        autofs4: Clean up dentry operations
        autofs4: Clean up inode operations
        autofs4: Remove unused code
        autofs4: Add d_manage() dentry operation
        autofs4: Add d_automount() dentry operation
        Remove the automount through follow_link() kludge code from pathwalk
        CIFS: Use d_automount() rather than abusing follow_link()
        NFS: Use d_automount() rather than abusing follow_link()
        AFS: Use d_automount() rather than abusing follow_link()
        Add an AT_NO_AUTOMOUNT flag to suppress terminal automount
        ...
      f8206b92
    • Al Viro's avatar
      sanitize vfsmount refcounting changes · f03c6599
      Al Viro authored
      Instead of splitting refcount between (per-cpu) mnt_count
      and (SMP-only) mnt_longrefs, make all references contribute
      to mnt_count again and keep track of how many are longterm
      ones.
      
      Accounting rules for longterm count:
      	* 1 for each fs_struct.root.mnt
      	* 1 for each fs_struct.pwd.mnt
      	* 1 for having non-NULL ->mnt_ns
      	* decrement to 0 happens only under vfsmount lock exclusive
      
      That allows nice common case for mntput() - since we can't drop the
      final reference until after mnt_longterm has reached 0 due to the rules
      above, mntput() can grab vfsmount lock shared and check mnt_longterm.
      If it turns out to be non-zero (which is the common case), we know
      that this is not the final mntput() and can just blindly decrement
      percpu mnt_count.  Otherwise we grab vfsmount lock exclusive and
      do usual decrement-and-check of percpu mnt_count.
      
      For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm();
      namespace.c uses the latter in places where we don't already hold
      vfsmount lock exclusive and opencodes a few remaining spots where
      we need to manipulate mnt_longterm.
      
      Note that we mostly revert the code outside of fs/namespace.c back
      to what we used to have; in particular, normal code doesn't need
      to care about two kinds of references, etc.  And we get to keep
      the optimization Nick's variant had bought us...
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      f03c6599
    • Al Viro's avatar
      fix old umount_tree() breakage · 7b8a53fd
      Al Viro authored
      Expiry-related code calls umount_tree() several times with
      the same list to collect vfsmounts to.  Which is fine, except
      that umount_tree() implicitly assumed that the list would
      be empty on each call - it moves the victims over there and
      then iterates through the list kicking them out.  It's *almost*
      idempotent, so everything nearly worked.  However, mnt->ghosts
      handling (and thus expirability checks) had been broken - that
      part was not idempotent...
      
      The fix is trivial - use local temporary list, splice it to
      the the collector list when we are through.
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      7b8a53fd
    • David Howells's avatar
      autofs4: Merge the remaining dentry ops tables · b650c858
      David Howells authored
      Merge the remaining autofs4 dentry ops tables.  It doesn't matter if
      d_automount and d_manage are present on something that's not mountable or
      holdable as these ops are only used if the appropriate flags are set in
      dentry->d_flags.
      
      [AV] switch to ->s_d_op, since now _everything_ on autofs4 is using the
      same dentry_operations.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      b650c858
    • David Howells's avatar
      Unexport do_add_mount() and add in follow_automount(), not ->d_automount() · ea5b778a
      David Howells authored
      Unexport do_add_mount() and make ->d_automount() return the vfsmount to be
      added rather than calling do_add_mount() itself.  follow_automount() will then
      do the addition.
      
      This slightly complicates things as ->d_automount() normally wants to add the
      new vfsmount to an expiration list and start an expiration timer.  The problem
      with that is that the vfsmount will be deleted if it has a refcount of 1 and
      the timer will not repeat if the expiration list is empty.
      
      To this end, we require the vfsmount to be returned from d_automount() with a
      refcount of (at least) 2.  One of these refs will be dropped unconditionally.
      In addition, follow_automount() must get a 3rd ref around the call to
      do_add_mount() lest it eat a ref and return an error, leaving the mount we
      have open to being expired as we would otherwise have only 1 ref on it.
      
      d_automount() should also add the the vfsmount to the expiration list (by
      calling mnt_set_expiry()) and start the expiration timer before returning, if
      this mechanism is to be used.  The vfsmount will be unlinked from the
      expiration list by follow_automount() if do_add_mount() fails.
      
      This patch also fixes the call to do_add_mount() for AFS to propagate the mount
      flags from the parent vfsmount.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      ea5b778a
    • David Howells's avatar
      Allow d_manage() to be used in RCU-walk mode · ab90911f
      David Howells authored
      Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well
      as when it is in Ref-walk mode.  This permits __follow_mount_rcu() to call
      d_manage() directly.  d_manage() needs a parameter to indicate that it is in
      RCU-walk mode as it isn't allowed to sleep if in that mode (but should return
      -ECHILD instead).
      
      autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon
      accesses it and otherwise request dropping back to ref-walk mode.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      ab90911f
    • David Howells's avatar
      Remove a further kludge from __do_follow_link() · 87556ef1
      David Howells authored
      Remove a further kludge from __do_follow_link() as it's no longer required with
      the automount code.
      
      This reverts the non-helper-function parts of
      051d3812, which breaks union mounts.
      
      Reported-by: vaurora@redhat.com
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      87556ef1
    • Ian Kent's avatar
      autofs4: Bump version · 1972580b
      Ian Kent authored
      Increase the autofs module sub-version so we can tell what kernel
      implementation is being used from user space debug logging.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      1972580b
    • Ian Kent's avatar
      autofs4: Add v4 pseudo direct mount support · dd89f90d
      Ian Kent authored
      Version 4 of autofs provides a pseudo direct mount implementation
      that relies on directories at the leaves of a directory tree under
      an indirect mount to trigger mounts.
      
      This patch adds support for that functionality.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      dd89f90d
    • Ian Kent's avatar
      autofs4: Fix wait validation · 9e3fea16
      Ian Kent authored
      It is possible for the check in wait.c:validate_request() to return
      an incorrect result if the dentry that was mounted upon has changed
      during the callback.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      9e3fea16
    • Ian Kent's avatar
      autofs4: Clean up autofs4_free_ino() · 66511493
      Ian Kent authored
      When this function is called the local reference count does't need to
      be updated since the dentry is going away and dput definitely must
      not be called here.
      
      Also the autofs info struct field inode isn't used so remove it.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      66511493
    • Ian Kent's avatar
      autofs4: Clean up dentry operations · 71e469db
      Ian Kent authored
      There are now two distinct dentry operations uses. One for dentrys
      that trigger mounts and one for dentrys that do not.
      
      Rationalize the use of these dentry operations and rename them to
      reflect their function.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      71e469db
    • Ian Kent's avatar
      autofs4: Clean up inode operations · e61da20a
      Ian Kent authored
      Since the use of ->follow_link() has been eliminated there is no
      need to separate the indirect and direct inode operations.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      e61da20a
    • Ian Kent's avatar
      autofs4: Remove unused code · 8c13a676
      Ian Kent authored
      Remove code that is not used due to the use of ->d_automount()
      and ->d_manage().
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      8c13a676
    • Ian Kent's avatar
      autofs4: Add d_manage() dentry operation · b5b80177
      Ian Kent authored
      This patch required a previous patch to add the ->d_automount()
      dentry operation.
      
      Add a function to use the newly defined ->d_manage() dentry operation
      for blocking during mount and expire.
      
      Whether the VFS calls the dentry operations d_automount() and d_manage()
      is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs
      uses the d_automount() operation to callback to user space to request
      mount operations and the d_manage() operation to block walks into mounts
      that are under construction or destruction.
      
      In order to prevent these functions from being called unnecessarily the
      DMANAGED_* flags are cleared for cases which would cause this. In the
      common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both
      set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is
      cleared upon successful mount request completion and set during expire
      runs, both during the dentry expire check, and if selected for expire,
      is left set until a subsequent successful mount request completes.
      
      The exception to this is the so-called rootless multi-mount which has
      no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag
      is cleared upon successful mount request completion as well and set
      again after a successful expire.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      b5b80177
    • Ian Kent's avatar
      autofs4: Add d_automount() dentry operation · 10584211
      Ian Kent authored
      Add a function to use the newly defined ->d_automount() dentry operation
      for triggering mounts instead of doing the user space callback in ->lookup()
      and ->d_revalidate().
      
      Note, to be useful the subsequent patch to add the ->d_manage() dentry
      operation is also needed so the discussion of functionality is deferred to
      that patch.
      Signed-off-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      10584211
    • David Howells's avatar
      Remove the automount through follow_link() kludge code from pathwalk · db372915
      David Howells authored
      Remove the automount through follow_link() kludge code from pathwalk in favour
      of using d_automount().
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Acked-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      db372915
    • David Howells's avatar
      CIFS: Use d_automount() rather than abusing follow_link() · 01c64fea
      David Howells authored
      Make CIFS use the new d_automount() dentry operation rather than abusing
      follow_link() on directories.
      
      [NOTE: THIS IS UNTESTED!]
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Cc: Steve French <sfrench@samba.org>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      01c64fea
    • David Howells's avatar
      NFS: Use d_automount() rather than abusing follow_link() · 36d43a43
      David Howells authored
      Make NFS use the new d_automount() dentry operation rather than abusing
      follow_link() on directories.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Acked-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
      Acked-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      36d43a43
    • David Howells's avatar
      AFS: Use d_automount() rather than abusing follow_link() · d18610b0
      David Howells authored
      Make AFS use the new d_automount() dentry operation rather than abusing
      follow_link() on directories.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      d18610b0
    • David Howells's avatar
      Add an AT_NO_AUTOMOUNT flag to suppress terminal automount · 6f45b656
      David Howells authored
      Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of automount
      point directories.  This can be used by fstatat() users to permit the
      gathering of attributes on an automount point and also prevent
      mass-automounting of a directory of automount points by ls.
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Acked-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      6f45b656
    • David Howells's avatar
      Add a dentry op to allow processes to be held during pathwalk transit · cc53ce53
      David Howells authored
      Add a dentry op (d_manage) to permit a filesystem to hold a process and make it
      sleep when it tries to transit away from one of that filesystem's directories
      during a pathwalk.  The operation is keyed off a new dentry flag
      (DCACHE_MANAGE_TRANSIT).
      
      The filesystem is allowed to be selective about which processes it holds and
      which it permits to continue on or prohibits from transiting from each flagged
      directory.  This will allow autofs to hold up client processes whilst letting
      its userspace daemon through to maintain the directory or the stuff behind it
      or mounted upon it.
      
      The ->d_manage() dentry operation:
      
      	int (*d_manage)(struct path *path, bool mounting_here);
      
      takes a pointer to the directory about to be transited away from and a flag
      indicating whether the transit is undertaken by do_add_mount() or
      do_move_mount() skipping through a pile of filesystems mounted on a mountpoint.
      
      It should return 0 if successful and to let the process continue on its way;
      -EISDIR to prohibit the caller from skipping to overmounted filesystems or
      automounting, and to use this directory; or some other error code to return to
      the user.
      
      ->d_manage() is called with namespace_sem writelocked if mounting_here is true
      and no other locks held, so it may sleep.  However, if mounting_here is true,
      it may not initiate or wait for a mount or unmount upon the parameter
      directory, even if the act is actually performed by userspace.
      
      Within fs/namei.c, follow_managed() is extended to check with d_manage() first
      on each managed directory, before transiting away from it or attempting to
      automount upon it.
      
      follow_down() is renamed follow_down_one() and should only be used where the
      filesystem deliberately intends to avoid management steps (e.g. autofs).
      
      A new follow_down() is added that incorporates the loop done by all other
      callers of follow_down() (do_add/move_mount(), autofs and NFSD; whilst AFS, NFS
      and CIFS do use it, their use is removed by converting them to use
      d_automount()).  The new follow_down() calls d_manage() as appropriate.  It
      also takes an extra parameter to indicate if it is being called from mount code
      (with namespace_sem writelocked) which it passes to d_manage().  follow_down()
      ignores automount points so that it can be used to mount on them.
      
      __follow_mount_rcu() is made to abort rcu-walk mode if it hits a directory with
      DCACHE_MANAGE_TRANSIT set on the basis that we're probably going to have to
      sleep.  It would be possible to enter d_manage() in rcu-walk mode too, and have
      that determine whether to abort or not itself.  That would allow the autofs
      daemon to continue on in rcu-walk mode.
      
      Note that DCACHE_MANAGE_TRANSIT on a directory should be cleared when it isn't
      required as every tranist from that directory will cause d_manage() to be
      invoked.  It can always be set again when necessary.
      
      ==========================
      WHAT THIS MEANS FOR AUTOFS
      ==========================
      
      Autofs currently uses the lookup() inode op and the d_revalidate() dentry op to
      trigger the automounting of indirect mounts, and both of these can be called
      with i_mutex held.
      
      autofs knows that the i_mutex will be held by the caller in lookup(), and so
      can drop it before invoking the daemon - but this isn't so for d_revalidate(),
      since the lock is only held on _some_ of the code paths that call it.  This
      means that autofs can't risk dropping i_mutex from its d_revalidate() function
      before it calls the daemon.
      
      The bug could manifest itself as, for example, a process that's trying to
      validate an automount dentry that gets made to wait because that dentry is
      expired and needs cleaning up:
      
      	mkdir         S ffffffff8014e05a     0 32580  24956
      	Call Trace:
      	 [<ffffffff885371fd>] :autofs4:autofs4_wait+0x674/0x897
      	 [<ffffffff80127f7d>] avc_has_perm+0x46/0x58
      	 [<ffffffff8009fdcf>] autoremove_wake_function+0x0/0x2e
      	 [<ffffffff88537be6>] :autofs4:autofs4_expire_wait+0x41/0x6b
      	 [<ffffffff88535cfc>] :autofs4:autofs4_revalidate+0x91/0x149
      	 [<ffffffff80036d96>] __lookup_hash+0xa0/0x12f
      	 [<ffffffff80057a2f>] lookup_create+0x46/0x80
      	 [<ffffffff800e6e31>] sys_mkdirat+0x56/0xe4
      
      versus the automount daemon which wants to remove that dentry, but can't
      because the normal process is holding the i_mutex lock:
      
      	automount     D ffffffff8014e05a     0 32581      1              32561
      	Call Trace:
      	 [<ffffffff80063c3f>] __mutex_lock_slowpath+0x60/0x9b
      	 [<ffffffff8000ccf1>] do_path_lookup+0x2ca/0x2f1
      	 [<ffffffff80063c89>] .text.lock.mutex+0xf/0x14
      	 [<ffffffff800e6d55>] do_rmdir+0x77/0xde
      	 [<ffffffff8005d229>] tracesys+0x71/0xe0
      	 [<ffffffff8005d28d>] tracesys+0xd5/0xe0
      
      which means that the system is deadlocked.
      
      This patch allows autofs to hold up normal processes whilst the daemon goes
      ahead and does things to the dentry tree behind the automouter point without
      risking a deadlock as almost no locks are held in d_manage() and none in
      d_automount().
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Was-Acked-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      cc53ce53
    • David Howells's avatar
      Add a dentry op to handle automounting rather than abusing follow_link() · 9875cf80
      David Howells authored
      Add a dentry op (d_automount) to handle automounting directories rather than
      abusing the follow_link() inode operation.  The operation is keyed off a new
      dentry flag (DCACHE_NEED_AUTOMOUNT).
      
      This also makes it easier to add an AT_ flag to suppress terminal segment
      automount during pathwalk and removes the need for the kludge code in the
      pathwalk algorithm to handle directories with follow_link() semantics.
      
      The ->d_automount() dentry operation:
      
      	struct vfsmount *(*d_automount)(struct path *mountpoint);
      
      takes a pointer to the directory to be mounted upon, which is expected to
      provide sufficient data to determine what should be mounted.  If successful, it
      should return the vfsmount struct it creates (which it should also have added
      to the namespace using do_add_mount() or similar).  If there's a collision with
      another automount attempt, NULL should be returned.  If the directory specified
      by the parameter should be used directly rather than being mounted upon,
      -EISDIR should be returned.  In any other case, an error code should be
      returned.
      
      The ->d_automount() operation is called with no locks held and may sleep.  At
      this point the pathwalk algorithm will be in ref-walk mode.
      
      Within fs/namei.c itself, a new pathwalk subroutine (follow_automount()) is
      added to handle mountpoints.  It will return -EREMOTE if the automount flag was
      set, but no d_automount() op was supplied, -ELOOP if we've encountered too many
      symlinks or mountpoints, -EISDIR if the walk point should be used without
      mounting and 0 if successful.  The path will be updated to point to the mounted
      filesystem if a successful automount took place.
      
      __follow_mount() is replaced by follow_managed() which is more generic
      (especially with the patch that adds ->d_manage()).  This handles transits from
      directories during pathwalk, including automounting and skipping over
      mountpoints (and holding processes with the next patch).
      
      __follow_mount_rcu() will jump out of RCU-walk mode if it encounters an
      automount point with nothing mounted on it.
      
      follow_dotdot*() does not handle automounts as you don't want to trigger them
      whilst following "..".
      
      I've also extracted the mount/don't-mount logic from autofs4 and included it
      here.  It makes the mount go ahead anyway if someone calls open() or creat(),
      tries to traverse the directory, tries to chdir/chroot/etc. into the directory,
      or sticks a '/' on the end of the pathname.  If they do a stat(), however,
      they'll only trigger the automount if they didn't also say O_NOFOLLOW.
      
      I've also added an inode flag (S_AUTOMOUNT) so that filesystems can mark their
      inodes as automount points.  This flag is automatically propagated to the
      dentry as DCACHE_NEED_AUTOMOUNT by __d_instantiate().  This saves NFS and could
      save AFS a private flag bit apiece, but is not strictly necessary.  It would be
      preferable to do the propagation in d_set_d_op(), but that doesn't normally
      have access to the inode.
      
      [AV: fixed breakage in case if __follow_mount_rcu() fails and nameidata_drop_rcu()
      succeeds in RCU case of do_lookup(); we need to fall through to non-RCU case after
      that, rather than just returning with ungrabbed *path]
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Was-Acked-by: default avatarIan Kent <raven@themaw.net>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      9875cf80
    • Al Viro's avatar
      do_lookup() fix · 1a8edf40
      Al Viro authored
      do_lookup() has a path leading from LOOKUP_RCU case to non-RCU
      crossing of mountpoints, which breaks things badly.  If we
      hit need_revalidate: and do nothing in there, we need to come
      back into LOOKUP_RCU half of things, not to done: in non-RCU
      one.
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      1a8edf40
  3. 15 Jan, 2011 1 commit