1. 08 2月, 2014 14 次提交
    • T
      kernfs: implement kernfs_get_parent(), kernfs_name/path() and friends · 3eef34ad
      Tejun Heo 提交于
      kernfs_node->parent and ->name are currently marked as "published"
      indicating that kernfs users may access them directly; however, those
      fields may get updated by kernfs_rename[_ns]() and unrestricted access
      may lead to erroneous values or oops.
      
      Protect ->parent and ->name updates with a irq-safe spinlock
      kernfs_rename_lock and implement the following accessors for these
      fields.
      
      * kernfs_name()		- format the node's name into the specified buffer
      * kernfs_path()		- format the node's path into the specified buffer
      * pr_cont_kernfs_name()	- pr_cont a node's name (doesn't need buffer)
      * pr_cont_kernfs_path()	- pr_cont a node's path (doesn't need buffer)
      * kernfs_get_parent()	- pin and return a node's parent
      
      All can be called under any context.  The recursive sysfs_pathname()
      in fs/sysfs/dir.c is replaced with kernfs_path() and
      sysfs_rename_dir_ns() is updated to use kernfs_get_parent() instead of
      dereferencing parent directly.
      
      v2: Dummy definition of kernfs_path() for !CONFIG_KERNFS was missing
          static inline making it cause a lot of build warnings.  Add it.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3eef34ad
    • T
      kernfs: implement kernfs_node_from_dentry(), kernfs_root_from_sb() and kernfs_rename() · 0c23b225
      Tejun Heo 提交于
      Implement helpers to determine node from dentry and root from
      super_block.  Also add a kernfs_rename_ns() wrapper which assumes NULL
      namespace.  These generally make sense and will be used by cgroup.
      
      v2: Some dummy implementations for !CONFIG_SYSFS was missing.  Fixed.
          Reported by kbuild test robot.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: kbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0c23b225
    • T
      kernfs: add kernfs_open_file->priv · 2536390d
      Tejun Heo 提交于
      Add a private data field to be used by kernfs file operations.  This
      generally makes sense and will be used by cgroup.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2536390d
    • T
      kernfs: implement kernfs_ops->atomic_write_len · 4d3773c4
      Tejun Heo 提交于
      A write to a kernfs_node is buffered through a kernel buffer.  Writes
      <= PAGE_SIZE are performed atomically, while larger ones are executed
      in PAGE_SIZE chunks.  While this is enough for sysfs, cgroup which is
      scheduled to be converted to use kernfs needs a bit more control over
      it.
      
      This patch adds kernfs_ops->atomic_write_len.  If not set (zero), the
      behavior stays the same.  If set, writes upto the size are executed
      atomically and larger writes are rejected with -E2BIG.
      
      A different implementation strategy would be allowing configuring
      chunking size while making the original write size available to the
      write method; however, such strategy, while being more complicated,
      doesn't really buy anything.  If the write implementation has to
      handle chunking, the specific chunk size shouldn't matter all that
      much.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      4d3773c4
    • T
      kernfs: allow nodes to be created in the deactivated state · d35258ef
      Tejun Heo 提交于
      Currently, kernfs_nodes are made visible to userland on creation,
      which makes it difficult for kernfs users to atomically succeed or
      fail creation of multiple nodes.  In addition, if something fails
      after creating some nodes, the created nodes might already be in use
      and their active refs need to be drained for removal, which has the
      potential to introduce tricky reverse locking dependency on active_ref
      depending on how the error path is synchronized.
      
      This patch introduces per-root flag KERNFS_ROOT_CREATE_DEACTIVATED.
      If set, all nodes under the root are created in the deactivated state
      and stay invisible to userland until explicitly enabled by the new
      kernfs_activate() API.  Also, nodes which have never been activated
      are guaranteed to bypass draining on removal thus allowing error paths
      to not worry about lockding dependency on active_ref draining.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d35258ef
    • T
      kernfs: implement kernfs_syscall_ops->remount_fs() and ->show_options() · 6a7fed4e
      Tejun Heo 提交于
      Add two super_block related syscall callbacks ->remount_fs() and
      ->show_options() to kernfs_syscall_ops.  These simply forward the
      matching super_operations.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6a7fed4e
    • T
      kernfs: rename kernfs_dir_ops to kernfs_syscall_ops · 90c07c89
      Tejun Heo 提交于
      We're gonna need non-dir syscall callbacks, which will make dir_ops a
      misnomer.  Let's rename kernfs_dir_ops to kernfs_syscall_ops.
      
      This is pure rename.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      90c07c89
    • T
      kernfs: invoke dir_ops while holding active ref of the target node · 07c7530d
      Tejun Heo 提交于
      kernfs_dir_ops are currently being invoked without any active
      reference, which makes it tricky for the invoked operations to
      determine whether the objects associated those nodes are safe to
      access and will remain that way for the duration of such operations.
      
      kernfs already has active_ref mechanism to deal with this which makes
      the removal of a given node the synchronization point for gating the
      file operations.  There's no reason for dir_ops to be any different.
      Update the dir_ops handling so that active_ref is held while the
      dir_ops are executing.  This guarantees that while a dir_ops is
      executing the target nodes stay alive.
      
      As kernfs_dir_ops doesn't have any in-kernel user at this point, this
      doesn't affect anybody.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      07c7530d
    • T
      sysfs, driver-core: remove unused {sysfs|device}_schedule_callback_owner() · ce8b04aa
      Tejun Heo 提交于
      All device_schedule_callback_owner() users are converted to use
      device_remove_file_self().  Remove now unused
      {sysfs|device}_schedule_callback_owner().
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      ce8b04aa
    • T
      kernfs, sysfs, driver-core: implement kernfs_remove_self() and its wrappers · 6b0afc2a
      Tejun Heo 提交于
      Sometimes it's necessary to implement a node which wants to delete
      nodes including itself.  This isn't straightforward because of kernfs
      active reference.  While a file operation is in progress, an active
      reference is held and kernfs_remove() waits for all such references to
      drain before completing.  For a self-deleting node, this is a deadlock
      as kernfs_remove() ends up waiting for an active reference that itself
      is sitting on top of.
      
      This currently is worked around in the sysfs layer using
      sysfs_schedule_callback() which makes such removals asynchronous.
      While it works, it's rather cumbersome and inherently breaks
      synchronicity of the operation - the file operation which triggered
      the operation may complete before the removal is finished (or even
      started) and the removal may fail asynchronously.  If a removal
      operation is immmediately followed by another operation which expects
      the specific name to be available (e.g. removal followed by rename
      onto the same name), there's no way to make the latter operation
      reliable.
      
      The thing is there's no inherent reason for this to be asynchrnous.
      All that's necessary to do this synchronous is a dedicated operation
      which drops its own active ref and deactivates self.  This patch
      implements kernfs_remove_self() and its wrappers in sysfs and driver
      core.  kernfs_remove_self() is to be called from one of the file
      operations, drops the active ref the task is holding, removes the self
      node, and restores active ref to the dead node so that the ref is
      balanced afterwards.  __kernfs_remove() is updated so that it takes an
      early exit if the target node is already fully removed so that the
      active ref restored by kernfs_remove_self() after removal doesn't
      confuse the deactivation path.
      
      This makes implementing self-deleting nodes very easy.  The normal
      removal path doesn't even need to be changed to use
      kernfs_remove_self() for the self-deleting node.  The method can
      invoke kernfs_remove_self() on itself before proceeding the normal
      removal path.  kernfs_remove() invoked on the node by the normal
      deletion path will simply be ignored.
      
      This will replace sysfs_schedule_callback().  A subtle feature of
      sysfs_schedule_callback() is that it collapses multiple invocations -
      even if multiple removals are triggered, the removal callback is run
      only once.  An equivalent effect can be achieved by testing the return
      value of kernfs_remove_self() - only the one which gets %true return
      value should proceed with actual deletion.  All other instances of
      kernfs_remove_self() will wait till the enclosing kernfs operation
      which invoked the winning instance of kernfs_remove_self() finishes
      and then return %false.  This trivially makes all users of
      kernfs_remove_self() automatically show correct synchronous behavior
      even when there are multiple concurrent operations - all "echo 1 >
      delete" instances will finish only after the whole operation is
      completed by one of the instances.
      
      Note that manipulation of active ref is implemented in separate public
      functions - kernfs_[un]break_active_protection().
      kernfs_remove_self() is the only user at the moment but this will be
      used to cater to more complex cases.
      
      v2: For !CONFIG_SYSFS, dummy version kernfs_remove_self() was missing
          and sysfs_remove_file_self() had incorrect return type.  Fix it.
          Reported by kbuild test bot.
      
      v3: kernfs_[un]break_active_protection() separated out from
          kernfs_remove_self() and exposed as public API.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: Alan Stern <stern@rowland.harvard.edu>
      Cc: kbuild test robot <fengguang.wu@intel.com>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6b0afc2a
    • T
      kernfs: remove KERNFS_REMOVED · 81c173cb
      Tejun Heo 提交于
      KERNFS_REMOVED is used to mark half-initialized and dying nodes so
      that they don't show up in lookups and deny adding new nodes under or
      renaming it; however, its role overlaps that of deactivation.
      
      It's necessary to deny addition of new children while removal is in
      progress; however, this role considerably intersects with deactivation
      - KERNFS_REMOVED prevents new children while deactivation prevents new
      file operations.  There's no reason to have them separate making
      things more complex than necessary.
      
      This patch removes KERNFS_REMOVED.
      
      * Instead of KERNFS_REMOVED, each node now starts its life
        deactivated.  This means that we now use both atomic_add() and
        atomic_sub() on KN_DEACTIVATED_BIAS, which is INT_MIN.  The compiler
        generates an overflow warnings when negating INT_MIN as the negation
        can't be represented as a positive number.  Nothing is actually
        broken but let's bump BIAS by one to avoid the warnings for archs
        which negates the subtrahend..
      
      * A new helper kernfs_active() which tests whether kn->active >= 0 is
        added for convenience and lockdep annotation.  All KERNFS_REMOVED
        tests are replaced with negated kernfs_active() tests.
      
      * __kernfs_remove() is updated to deactivate, but not drain, all nodes
        in the subtree instead of setting KERNFS_REMOVED.  This removes
        deactivation from kernfs_deactivate(), which is now renamed to
        kernfs_drain().
      
      * Sanity check on KERNFS_REMOVED in kernfs_put() is replaced with
        checks on the active ref.
      
      * Some comment style updates in the affected area.
      
      v2: Reordered before removal path restructuring.  kernfs_active()
          dropped and kernfs_get/put_active() used instead.  RB_EMPTY_NODE()
          used in the lookup paths.
      
      v3: Reverted most of v2 except for creating a new node with
          KN_DEACTIVATED_BIAS.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      81c173cb
    • T
      kernfs: remove KERNFS_ACTIVE_REF and add kernfs_lockdep() · 182fd64b
      Tejun Heo 提交于
      There currently are two mechanisms gating active ref lockdep
      annotations - KERNFS_LOCKDEP flag and KERNFS_ACTIVE_REF type mask.
      The former disables lockdep annotations in kernfs_get/put_active()
      while the latter disables all of kernfs_deactivate().
      
      While KERNFS_ACTIVE_REF also behaves as an optimization to skip the
      deactivation step for non-file nodes, the benefit is marginal and it
      needlessly diverges code paths.  Let's drop KERNFS_ACTIVE_REF.
      
      While at it, add a test helper kernfs_lockdep() to test KERNFS_LOCKDEP
      flag so that it's more convenient and the related code can be compiled
      out when not enabled.
      
      v2: Refreshed on top of ("kernfs: make kernfs_deactivate() honor
          KERNFS_LOCKDEP flag").  As the earlier patch already added
          KERNFS_LOCKDEP tests to kernfs_deactivate(), those additions are
          dropped from this patch and the existing ones are simply converted
          to kernfs_lockdep().
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      182fd64b
    • T
      kernfs: remove kernfs_addrm_cxt · 988cd7af
      Tejun Heo 提交于
      kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were
      added because there were operations which should be performed outside
      kernfs_mutex after adding and removing kernfs_nodes.  The necessary
      operations were recorded in kernfs_addrm_cxt and performed by
      kernfs_addrm_finish(); however, after the recent changes which
      relocated deactivation and unmapping so that they're performed
      directly during removal, the only operation kernfs_addrm_finish()
      performs is kernfs_put(), which can be moved inside the removal path
      too.
      
      This patch moves the kernfs_put() of the base ref to __kernfs_remove()
      and remove kernfs_addrm_cxt and kernfs_addrm_start/finish().
      
      * kernfs_add_one() is updated to grab and release kernfs_mutex itself.
        sysfs_addrm_start/finish() invocations around it are removed from
        all users.
      
      * __kernfs_remove() puts an unlinked node directly instead of chaining
        it to kernfs_addrm_cxt.  Its callers are updated to grab and release
        kernfs_mutex instead of calling kernfs_addrm_start/finish() around
        it.
      
      v2: Rebased on top of "kernfs: associate a new kernfs_node with its
          parent on creation" which dropped @parent from kernfs_add_one().
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      988cd7af
    • T
      kernfs: replace kernfs_node->u.completion with kernfs_root->deactivate_waitq · abd54f02
      Tejun Heo 提交于
      kernfs_node->u.completion is used to notify deactivation completion
      from kernfs_put_active() to kernfs_deactivate().  We now allow
      multiple racing removals of the same node and the current removal
      scheme is no longer correct - kernfs_remove() invocation may return
      before the node is properly deactivated if it races against another
      removal.  The removal path will be restructured to address the issue.
      
      To help such restructure which requires supporting multiple waiters,
      this patch replaces kernfs_node->u.completion with
      kernfs_root->deactivate_waitq.  This makes deactivation event
      notifications share a per-root waitqueue_head; however, the wait path
      is quite cold and this will also allow shaving one pointer off
      kernfs_node.
      
      v2: Refreshed on top of ("kernfs: make kernfs_deactivate() honor
          KERNFS_LOCKDEP flag").
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      abd54f02
  2. 01 2月, 2014 1 次提交
  3. 31 1月, 2014 5 次提交
  4. 30 1月, 2014 4 次提交
  5. 29 1月, 2014 2 次提交
  6. 28 1月, 2014 14 次提交