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  1. 19 Oct, 2018 1 commit
  3. 02 Oct, 2018 1 commit
  5. 05 Sep, 2018 1 commit
  7. 14 Aug, 2018 5 commits
  9. 23 May, 2018 1 commit
  11. 04 Apr, 2018 1 commit
  13. 23 Jan, 2018 2 commits
  15. 16 Nov, 2017 1 commit
  17. 05 Oct, 2017 2 commits
  19. 06 Apr, 2017 3 commits
  21. 08 Mar, 2017 1 commit
  23. 10 Jan, 2017 4 commits
  25. 06 Dec, 2016 1 commit
  27. 15 Sep, 2016 2 commits
  29. 18 Aug, 2016 2 commits
  31. 16 May, 2016 1 commit
    • Jan Kara's avatar
      ext4: fix races between page faults and hole punching · c882bba8
      Jan Kara authored 
      BugLink: http://bugs.launchpad.net/bugs/1578798

commit ea3d7209

 upstream.

Currently, page faults and hole punching are completely unsynchronized.
This can result in page fault faulting in a page into a range that we
are punching after truncate_pagecache_range() has been called and thus
we can end up with a page mapped to disk blocks that will be shortly
freed. Filesystem corruption will shortly follow. Note that the same
race is avoided for truncate by checking page fault offset against
i_size but there isn't similar mechanism available for punching holes.

Fix the problem by creating new rw semaphore i_mmap_sem in inode and
grab it for writing over truncate, hole punching, and other functions
removing blocks from extent tree and for read over page faults. We
cannot easily use i_data_sem for this since that ranks below transaction
start and we need something ranking above it so that it can be held over
the whole truncate / hole punching operation. Also remove various
workarounds we had in the code to reduce race window when page fault
could have created pages with stale mapping information.
Signed-off-by: default avatarJan Kara <jack@suse.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      c882bba8
  33. 21 Apr, 2016 2 commits
  35. 06 Apr, 2016 2 commits
    • Seth Forshee's avatar
      UBUNTU: SAUCE: ext4: Add module parameter to enable user namespace mounts · 41d8f9b2
      Seth Forshee authored 
      
This is still an experimental feature, so disable it by default
and allow it only when the system administrator supplies the
userns_mounts=true module parameter.
Signed-off-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
      41d8f9b2
    • Seth Forshee's avatar
      UBUNTU: SAUCE: ext4: Add support for unprivileged mounts from user namespaces · 7a5ab85b
      Seth Forshee authored 
      
Support unprivileged mounting of ext4 volumes from user
namespaces. This requires the following changes:

 - Perform all uid and gid conversions to/from disk relative to
   s_user_ns. In many cases this will already be handled by the
   vfs helper functions. This also requires updates to handle
   cases where ids may not map into s_user_ns.

 - Update most capability checks to check for capabilities in
   s_user_ns rather than init_user_ns. These mostly reflect
   changes to the filesystem that a user in s_user_ns could
   already make externally by virtue of having write access to
   the backing device.

 - Restrict unsafe options in either the mount options or the
   ext4 superblock. Currently the only concerning option is
   errors=panic, and this is made to require CAP_SYS_ADMIN in
   init_user_ns.

 - Verify that unprivileged users have the required access to the
   journal device at the path passed via the journal_path mount
   option.

   Note that for the journal_path and the journal_dev mount
   options, and for external journal devices specified in the
   ext4 superblock, devcgroup restrictions will be enforced by
   __blkdev_get(), (via blkdev_get_by_dev()), ensuring that the
   user has been granted appropriate access to the block device.

 - Set the FS_USERNS_MOUNT flag on the filesystem types supported
   by ext4.

sysfs attributes for ext4 mounts remain writable only by real
root.
Signed-off-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
      7a5ab85b
  37. 16 Nov, 2015 1 commit
    • Dan Williams's avatar
      ext2, ext4: warn when mounting with dax enabled · ef83b6e8
      Dan Williams authored 
      
Similar to XFS warn when mounting DAX while it is still considered under
development.  Also, aspects of the DAX implementation, for example
synchronization against multiple faults and faults causing block
allocation, depend on the correct implementation in the filesystem.  The
maturity of a given DAX implementation is filesystem specific.

Cc: <stable@vger.kernel.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: linux-ext4@vger.kernel.org
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: default avatarDave Chinner <david@fromorbit.com>
Acked-by: default avatarJan Kara <jack@suse.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
      ef83b6e8
  39. 07 Nov, 2015 1 commit
    • Mel Gorman's avatar
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep... · d0164adc
      Mel Gorman authored 
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for backgrou...
      d0164adc
  41. 19 Oct, 2015 2 commits
  43. 18 Oct, 2015 1 commit
    • Daeho Jeong's avatar
      ext4, jbd2: ensure entering into panic after recording an error in superblock · 4327ba52
      Daeho Jeong authored 
      
If a EXT4 filesystem utilizes JBD2 journaling and an error occurs, the
journaling will be aborted first and the error number will be recorded
into JBD2 superblock and, finally, the system will enter into the
panic state in "errors=panic" option.  But, in the rare case, this
sequence is little twisted like the below figure and it will happen
that the system enters into panic state, which means the system reset
in mobile environment, before completion of recording an error in the
journal superblock. In this case, e2fsck cannot recognize that the
filesystem failure occurred in the previous run and the corruption
wouldn't be fixed.

Task A                        Task B
ext4_handle_error()
-> jbd2_journal_abort()
  -> __journal_abort_soft()
    -> __jbd2_journal_abort_hard()
    | -> journal->j_flags |= JBD2_ABORT;
    |
    |                         __ext4_abort()
    |                         -> jbd2_journal_abort()
    |                         | -> __journal_abort_soft()
    |                         |   -> if (journal->j_flags & JBD2_ABORT)
    |                         |           return;
    |                         -> panic()
    |
    -> jbd2_journal_update_sb_errno()
Tested-by: default avatarHobin Woo <hobin.woo@samsung.com>
Signed-off-by: default avatarDaeho Jeong <daeho.jeong@samsung.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
      4327ba52
  45. 17 Oct, 2015 2 commits
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