1. 13 7月, 2015 2 次提交
  2. 01 7月, 2015 1 次提交
    • E
      fs: Add helper functions for permanently empty directories. · fbabfd0f
      Eric W. Biederman 提交于
      To ensure it is safe to mount proc and sysfs I need to check if
      filesystems that are mounted on top of them are mounted on truly empty
      directories.  Given that some directories can gain entries over time,
      knowing that a directory is empty right now is insufficient.
      
      Therefore add supporting infrastructure for permantently empty
      directories that proc and sysfs can use when they create mount points
      for filesystems and fs_fully_visible can use to test for permanently
      empty directories to ensure that nothing will be gained by mounting a
      fresh copy of proc or sysfs.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      fbabfd0f
  3. 24 6月, 2015 4 次提交
  4. 19 6月, 2015 1 次提交
    • D
      overlayfs: Make f_path always point to the overlay and f_inode to the underlay · 4bacc9c9
      David Howells 提交于
      Make file->f_path always point to the overlay dentry so that the path in
      /proc/pid/fd is correct and to ensure that label-based LSMs have access to the
      overlay as well as the underlay (path-based LSMs probably don't need it).
      
      Using my union testsuite to set things up, before the patch I see:
      
      	[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
      	[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
      	...
      	lr-x------. 1 root root 64 Jun  5 14:38 5 -> /a/foo107
      	[root@andromeda union-testsuite]# stat /mnt/a/foo107
      	...
      	Device: 23h/35d Inode: 13381       Links: 1
      	...
      	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
      	...
      	Device: 23h/35d Inode: 13381       Links: 1
      	...
      
      After the patch:
      
      	[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
      	[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
      	...
      	lr-x------. 1 root root 64 Jun  5 14:22 5 -> /mnt/a/foo107
      	[root@andromeda union-testsuite]# stat /mnt/a/foo107
      	...
      	Device: 23h/35d Inode: 40346       Links: 1
      	...
      	[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
      	...
      	Device: 23h/35d Inode: 40346       Links: 1
      	...
      
      Note the change in where /proc/$$/fd/5 points to in the ls command.  It was
      pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107
      (which is correct).
      
      The inode accessed, however, is the lower layer.  The union layer is on device
      25h/37d and the upper layer on 24h/36d.
      Signed-off-by: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      4bacc9c9
  5. 18 6月, 2015 1 次提交
    • T
      vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB · 46b15caa
      Tejun Heo 提交于
      FS_CGROUP_WRITEBACK indicates whether a file_system_type supports
      cgroup writeback; however, different super_blocks of the same
      file_system_type may or may not support cgroup writeback depending on
      filesystem options.  This patch replaces FS_CGROUP_WRITEBACK with a
      per-super_block flag.
      
      super_block->s_flags carries some internal flags in the high bits but
      it's exposd to userland through uapi header and running out of space
      anyway.  This patch adds a new field super_block->s_iflags to carry
      kernel-internal flags.  It is currently only used by the new
      SB_I_CGROUPWB flag whose concatenated and abbreviated name is for
      consistency with other super_block flags.
      
      ext2_fill_super() is updated to set SB_I_CGROUPWB.
      
      v2: Added super_block->s_iflags instead of stealing another high bit
          from sb->s_flags as suggested by Christoph and Jan.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Cc: linux-fsdevel@vger.kernel.org
      Cc: Christoph Hellwig <hch@infradead.org>
      Cc: Jan Kara <jack@suse.cz>
      Cc: linux-ext4@vger.kernel.org
      Reviewed-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      46b15caa
  6. 04 6月, 2015 2 次提交
    • D
      dax: expose __dax_fault for filesystems with locking constraints · ce5c5d55
      Dave Chinner 提交于
      Some filesystems cannot call dax_fault() directly because they have
      different locking and/or allocation constraints in the page fault IO
      path. To handle this, we need to follow the same model as the
      generic block_page_mkwrite code, where the internals are exposed via
      __block_page_mkwrite() so that filesystems can wrap the correct
      locking and operations around the outside. 
      
      This is loosely based on a patch originally from Matthew Willcox.
      Unlike the original patch, it does not change ext4 code, error
      returns or unwritten extent conversion handling.  It also adds a
      __dax_mkwrite() wrapper for .page_mkwrite implementations to do the
      right thing, too.
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Reviewed-by: NJan Kara <jack@suse.cz>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      ce5c5d55
    • D
      dax: don't abuse get_block mapping for endio callbacks · e842f290
      Dave Chinner 提交于
      dax_fault() currently relies on the get_block callback to attach an
      io completion callback to the mapping buffer head so that it can
      run unwritten extent conversion after zeroing allocated blocks.
      
      Instead of this hack, pass the conversion callback directly into
      dax_fault() similar to the get_block callback. When the filesystem
      allocates unwritten extents, it will set the buffer_unwritten()
      flag, and hence the dax_fault code can call the completion function
      in the contexts where it is necessary without overloading the
      mapping buffer head.
      
      Note: The changes to ext4 to use this interface are suspect at best.
      In fact, the way ext4 did this end_io assignment in the first place
      looks suspect because it only set a completion callback when there
      wasn't already some other write() call taking place on the same
      inode. The ext4 end_io code looks rather intricate and fragile with
      all it's reference counting and passing to different contexts for
      modification via inode private pointers that aren't protected by
      locks...
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
      Acked-by: NJan Kara <jack@suse.cz>
      Signed-off-by: NDave Chinner <david@fromorbit.com>
      e842f290
  7. 02 6月, 2015 5 次提交
    • T
      writeback: implement unlocked_inode_to_wb transaction and use it for stat updates · 682aa8e1
      Tejun Heo 提交于
      The mechanism for detecting whether an inode should switch its wb
      (bdi_writeback) association is now in place.  This patch build the
      framework for the actual switching.
      
      This patch adds a new inode flag I_WB_SWITCHING, which has two
      functions.  First, the easy one, it ensures that there's only one
      switching in progress for a give inode.  Second, it's used as a
      mechanism to synchronize wb stat updates.
      
      The two stats, WB_RECLAIMABLE and WB_WRITEBACK, aren't event counters
      but track the current number of dirty pages and pages under writeback
      respectively.  As such, when an inode is moved from one wb to another,
      the inode's portion of those stats have to be transferred together;
      unfortunately, this is a bit tricky as those stat updates are percpu
      operations which are performed without holding any lock in some
      places.
      
      This patch solves the problem in a similar way as memcg.  Each such
      lockless stat updates are wrapped in transaction surrounded by
      unlocked_inode_to_wb_begin/end().  During normal operation, they map
      to rcu_read_lock/unlock(); however, if I_WB_SWITCHING is asserted,
      mapping->tree_lock is grabbed across the transaction.
      
      In turn, the switching path sets I_WB_SWITCHING and waits for a RCU
      grace period to pass before actually starting to switch, which
      guarantees that all stat update paths are synchronizing against
      mapping->tree_lock.
      
      This patch still doesn't implement the actual switching.
      
      v3: Updated on top of the recent cancel_dirty_page() updates.
          unlocked_inode_to_wb_begin() now nests inside
          mem_cgroup_begin_page_stat() to match the locking order.
      
      v2: The i_wb access transaction will be used for !stat accesses too.
          Function names and comments updated accordingly.
      
          s/inode_wb_stat_unlocked_{begin|end}/unlocked_inode_to_wb_{begin|end}/
          s/switch_wb/switch_wbs/
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Greg Thelen <gthelen@google.com>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      682aa8e1
    • T
      writeback: implement foreign cgroup inode detection · 2a814908
      Tejun Heo 提交于
      As concurrent write sharing of an inode is expected to be very rare
      and memcg only tracks page ownership on first-use basis severely
      confining the usefulness of such sharing, cgroup writeback tracks
      ownership per-inode.  While the support for concurrent write sharing
      of an inode is deemed unnecessary, an inode being written to by
      different cgroups at different points in time is a lot more common,
      and, more importantly, charging only by first-use can too readily lead
      to grossly incorrect behaviors (single foreign page can lead to
      gigabytes of writeback to be incorrectly attributed).
      
      To resolve this issue, cgroup writeback detects the majority dirtier
      of an inode and will transfer the ownership to it.  To avoid
      unnnecessary oscillation, the detection mechanism keeps track of
      history and gives out the switch verdict only if the foreign usage
      pattern is stable over a certain amount of time and/or writeback
      attempts.
      
      The detection mechanism has fairly low space and computation overhead.
      It adds 8 bytes to struct inode (one int and two u16's) and minimal
      amount of calculation per IO.  The detection mechanism converges to
      the correct answer usually in several seconds of IO time when there's
      a clear majority dirtier.  Even when there isn't, it can reach an
      acceptable answer fairly quickly under most circumstances.
      
      Please see wb_detach_inode() for more details.
      
      This patch only implements detection.  Following patches will
      implement actual switching.
      
      v2: wbc_account_io() now checks whether the wbc is associated with a
          wb before dereferencing it.  This can happen when pageout() is
          writing pages directly without going through the usual writeback
          path.  As pageout() path is single-threaded, we don't want it to
          be blocked behind a slow cgroup and ultimately want it to delegate
          actual writing to the usual writeback path.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Wu Fengguang <fengguang.wu@intel.com>
      Cc: Greg Thelen <gthelen@google.com>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      2a814908
    • T
      writeback: make backing_dev_info host cgroup-specific bdi_writebacks · 52ebea74
      Tejun Heo 提交于
      For the planned cgroup writeback support, on each bdi
      (backing_dev_info), each memcg will be served by a separate wb
      (bdi_writeback).  This patch updates bdi so that a bdi can host
      multiple wbs (bdi_writebacks).
      
      On the default hierarchy, blkcg implicitly enables memcg.  This allows
      using memcg's page ownership for attributing writeback IOs, and every
      memcg - blkcg combination can be served by its own wb by assigning a
      dedicated wb to each memcg.  This means that there may be multiple
      wb's of a bdi mapped to the same blkcg.  As congested state is per
      blkcg - bdi combination, those wb's should share the same congested
      state.  This is achieved by tracking congested state via
      bdi_writeback_congested structs which are keyed by blkcg.
      
      bdi->wb remains unchanged and will keep serving the root cgroup.
      cgwb's (cgroup wb's) for non-root cgroups are created on-demand or
      looked up while dirtying an inode according to the memcg of the page
      being dirtied or current task.  Each cgwb is indexed on bdi->cgwb_tree
      by its memcg id.  Once an inode is associated with its wb, it can be
      retrieved using inode_to_wb().
      
      Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all
      pages will keep being associated with bdi->wb.
      
      v3: inode_attach_wb() in account_page_dirtied() moved inside
          mapping_cap_account_dirty() block where it's known to be !NULL.
          Also, an unnecessary NULL check before kfree() removed.  Both
          detected by the kbuild bot.
      
      v2: Updated so that wb association is per inode and wb is per memcg
          rather than blkcg.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: kbuild test robot <fengguang.wu@intel.com>
      Cc: Dan Carpenter <dan.carpenter@oracle.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      52ebea74
    • T
      writeback: add {CONFIG|BDI_CAP|FS}_CGROUP_WRITEBACK · 89e9b9e0
      Tejun Heo 提交于
      cgroup writeback requires support from both bdi and filesystem sides.
      Add BDI_CAP_CGROUP_WRITEBACK and FS_CGROUP_WRITEBACK to indicate
      support and enable BDI_CAP_CGROUP_WRITEBACK on block based bdi's by
      default.  Also, define CONFIG_CGROUP_WRITEBACK which is enabled if
      both MEMCG and BLK_CGROUP are enabled.
      
      inode_cgwb_enabled() which determines whether a given inode's both bdi
      and fs support cgroup writeback is added.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Jan Kara <jack@suse.cz>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      89e9b9e0
    • T
      bdi: make inode_to_bdi() inline · a212b105
      Tejun Heo 提交于
      Now that bdi definitions are moved to backing-dev-defs.h,
      backing-dev.h can include blkdev.h and inline inode_to_bdi() without
      worrying about introducing circular include dependency.  The function
      gets called from hot paths and fairly trivial.
      
      This patch makes inode_to_bdi() and sb_is_blkdev_sb() that the
      function calls inline.  blockdev_superblock and noop_backing_dev_info
      are EXPORT_GPL'd to allow the inline functions to be used from
      modules.
      
      While at it, make sb_is_blkdev_sb() return bool instead of int.
      
      v2: Fixed typo in description as suggested by Jan.
      Signed-off-by: NTejun Heo <tj@kernel.org>
      Reviewed-by: NJens Axboe <axboe@kernel.dk>
      Cc: Christoph Hellwig <hch@infradead.org>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      a212b105
  8. 20 5月, 2015 1 次提交
    • J
      block: export blkdev_reread_part() and __blkdev_reread_part() · be324177
      Jarod Wilson 提交于
      This patch exports blkdev_reread_part() for block drivers, also
      introduce __blkdev_reread_part().
      
      For some drivers, such as loop, reread of partitions can be run
      from the release path, and bd_mutex may already be held prior to
      calling ioctl_by_bdev(bdev, BLKRRPART, 0), so introduce
      __blkdev_reread_part for use in such cases.
      
      CC: Christoph Hellwig <hch@lst.de>
      CC: Jens Axboe <axboe@kernel.dk>
      CC: Tejun Heo <tj@kernel.org>
      CC: Alexander Viro <viro@zeniv.linux.org.uk>
      CC: Markus Pargmann <mpa@pengutronix.de>
      CC: Stefan Weinhuber <wein@de.ibm.com>
      CC: Stefan Haberland <stefan.haberland@de.ibm.com>
      CC: Sebastian Ott <sebott@linux.vnet.ibm.com>
      CC: Fabian Frederick <fabf@skynet.be>
      CC: Ming Lei <ming.lei@canonical.com>
      CC: David Herrmann <dh.herrmann@gmail.com>
      CC: Andrew Morton <akpm@linux-foundation.org>
      CC: Peter Zijlstra <peterz@infradead.org>
      CC: nbd-general@lists.sourceforge.net
      CC: linux-s390@vger.kernel.org
      Reviewed-by: NChristoph Hellwig <hch@lst.de>
      Signed-off-by: NJarod Wilson <jarod@redhat.com>
      Signed-off-by: NMing Lei <ming.lei@canonical.com>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      be324177
  9. 15 5月, 2015 2 次提交
  10. 14 5月, 2015 1 次提交
    • E
      mnt: Refactor the logic for mounting sysfs and proc in a user namespace · 1b852bce
      Eric W. Biederman 提交于
      Fresh mounts of proc and sysfs are a very special case that works very
      much like a bind mount.  Unfortunately the current structure can not
      preserve the MNT_LOCK... mount flags.  Therefore refactor the logic
      into a form that can be modified to preserve those lock bits.
      
      Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount
      of the filesystem be fully visible in the current mount namespace,
      before the filesystem may be mounted.
      
      Move the logic for calling fs_fully_visible from proc and sysfs into
      fs/namespace.c where it has greater access to mount namespace state.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      1b852bce
  11. 11 5月, 2015 5 次提交
  12. 25 4月, 2015 2 次提交
    • E
      fix I_DIO_WAKEUP definition · ac74d8d6
      Eric Sandeen 提交于
      I_DIO_WAKEUP is never directly used, but fix it up anyway.
      Signed-off-by: NEric Sandeen <sandeen@redhat.com>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      ac74d8d6
    • J
      direct-io: only inc/dec inode->i_dio_count for file systems · fe0f07d0
      Jens Axboe 提交于
      do_blockdev_direct_IO() increments and decrements the inode
      ->i_dio_count for each IO operation. It does this to protect against
      truncate of a file. Block devices don't need this sort of protection.
      
      For a capable multiqueue setup, this atomic int is the only shared
      state between applications accessing the device for O_DIRECT, and it
      presents a scaling wall for that. In my testing, as much as 30% of
      system time is spent incrementing and decrementing this value. A mixed
      read/write workload improved from ~2.5M IOPS to ~9.6M IOPS, with
      better latencies too. Before:
      
      clat percentiles (usec):
       |  1.00th=[   33],  5.00th=[   34], 10.00th=[   34], 20.00th=[   34],
       | 30.00th=[   34], 40.00th=[   34], 50.00th=[   35], 60.00th=[   35],
       | 70.00th=[   35], 80.00th=[   35], 90.00th=[   37], 95.00th=[   80],
       | 99.00th=[   98], 99.50th=[  151], 99.90th=[  155], 99.95th=[  155],
       | 99.99th=[  165]
      
      After:
      
      clat percentiles (usec):
       |  1.00th=[   95],  5.00th=[  108], 10.00th=[  129], 20.00th=[  149],
       | 30.00th=[  155], 40.00th=[  161], 50.00th=[  167], 60.00th=[  171],
       | 70.00th=[  177], 80.00th=[  185], 90.00th=[  201], 95.00th=[  270],
       | 99.00th=[  390], 99.50th=[  398], 99.90th=[  418], 99.95th=[  422],
       | 99.99th=[  438]
      
      In other setups, Robert Elliott reported seeing good performance
      improvements:
      
      https://lkml.org/lkml/2015/4/3/557
      
      The more applications accessing the device, the worse it gets.
      
      Add a new direct-io flags, DIO_SKIP_DIO_COUNT, which tells
      do_blockdev_direct_IO() that it need not worry about incrementing
      or decrementing the inode i_dio_count for this caller.
      
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Cc: Elliott, Robert (Server Storage) <elliott@hp.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Signed-off-by: NJens Axboe <axboe@fb.com>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      fe0f07d0
  13. 17 4月, 2015 2 次提交
    • A
      proc: show locks in /proc/pid/fdinfo/X · 6c8c9031
      Andrey Vagin 提交于
      Let's show locks which are associated with a file descriptor in
      its fdinfo file.
      
      Currently we don't have a reliable way to determine who holds a lock.  We
      can find some information in /proc/locks, but PID which is reported there
      can be wrong.  For example, a process takes a lock, then forks a child and
      dies.  In this case /proc/locks contains the parent pid, which can be
      reused by another process.
      
      $ cat /proc/locks
      ...
      6: FLOCK  ADVISORY  WRITE 324 00:13:13431 0 EOF
      ...
      
      $ ps -C rpcbind
        PID TTY          TIME CMD
        332 ?        00:00:00 rpcbind
      
      $ cat /proc/332/fdinfo/4
      pos:	0
      flags:	0100000
      mnt_id:	22
      lock:	1: FLOCK  ADVISORY  WRITE 324 00:13:13431 0 EOF
      
      $ ls -l /proc/332/fd/4
      lr-x------ 1 root root 64 Mar  5 14:43 /proc/332/fd/4 -> /run/rpcbind.lock
      
      $ ls -l /proc/324/fd/
      total 0
      lrwx------ 1 root root 64 Feb 27 14:50 0 -> /dev/pts/0
      lrwx------ 1 root root 64 Feb 27 14:50 1 -> /dev/pts/0
      lrwx------ 1 root root 64 Feb 27 14:49 2 -> /dev/pts/0
      
      You can see that the process with the 324 pid doesn't hold the lock.
      
      This information is required for proper dumping and restoring file
      locks.
      Signed-off-by: NAndrey Vagin <avagin@openvz.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Alexander Viro <viro@zeniv.linux.org.uk>
      Acked-by: NJeff Layton <jlayton@poochiereds.net>
      Acked-by: N"J. Bruce Fields" <bfields@fieldses.org>
      Acked-by: NCyrill Gorcunov <gorcunov@openvz.org>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Joe Perches <joe@perches.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6c8c9031
    • K
      mm: rcu-protected get_mm_exe_file() · 90f31d0e
      Konstantin Khlebnikov 提交于
      This patch removes mm->mmap_sem from mm->exe_file read side.
      Also it kills dup_mm_exe_file() and moves exe_file duplication into
      dup_mmap() where both mmap_sems are locked.
      
      [akpm@linux-foundation.org: fix comment typo]
      Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
      Cc: Davidlohr Bueso <dbueso@suse.de>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      90f31d0e
  14. 16 4月, 2015 2 次提交
  15. 12 4月, 2015 9 次提交