Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
1 年多 前同步成功

通知 163
Star 36
Fork 7
cloud-kernel
cloud-kernel
切换分支/标签
  1. 23 1月, 2019 35 次提交
  3. 17 1月, 2019 5 次提交
    • G
      Linux 4.19.16 · 9c5931b6
      由 Greg Kroah-Hartman 提交于
      9c5931b6
    • F
      Btrfs: use nofs context when initializing security xattrs to avoid deadlock · 7a1b9b76
      由 Filipe Manana 提交于 
      commit 827aa18e7b903c5ff3b3cd8fec328a99b1dbd411 upstream.

When initializing the security xattrs, we are holding a transaction handle
therefore we need to use a GFP_NOFS context in order to avoid a deadlock
with reclaim in case it's triggered.

Fixes: 39a27ec1 ("btrfs: use GFP_KERNEL for xattr and acl allocations")
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      7a1b9b76
    • F
      Btrfs: fix deadlock when enabling quotas due to concurrent snapshot creation · 79aa5c0d
      由 Filipe Manana 提交于 
      commit 9a6f209e36500efac51528132a3e3083586eda5f upstream.

If the quota enable and snapshot creation ioctls are called concurrently
we can get into a deadlock where the task enabling quotas will deadlock
on the fs_info->qgroup_ioctl_lock mutex because it attempts to lock it
twice, or the task creating a snapshot tries to commit the transaction
while the task enabling quota waits for the former task to commit the
transaction while holding the mutex. The following time diagrams show how
both cases happen.

First scenario:

           CPU 0                                    CPU 1

 btrfs_ioctl()
  btrfs_ioctl_quota_ctl()
   btrfs_quota_enable()
    mutex_lock(fs_info->qgroup_ioctl_lock)
    btrfs_start_transaction()

                                             btrfs_ioctl()
                                              btrfs_ioctl_snap_create_v2
                                               create_snapshot()
                                                --> adds snapshot to the
                                                    list pending_snapshots
                                                    of the current
                                                    transaction

    btrfs_commit_transaction()
     create_pending_snapshots()
       create_pending_snapshot()
        qgroup_account_snapshot()
         btrfs_qgroup_inherit()
	   mutex_lock(fs_info->qgroup_ioctl_lock)
	    --> deadlock, mutex already locked
	        by this task at
		btrfs_quota_enable()

Second scenario:

           CPU 0                                    CPU 1

 btrfs_ioctl()
  btrfs_ioctl_quota_ctl()
   btrfs_quota_enable()
    mutex_lock(fs_info->qgroup_ioctl_lock)
    btrfs_start_transaction()

                                             btrfs_ioctl()
                                              btrfs_ioctl_snap_create_v2
                                               create_snapshot()
                                                --> adds snapshot to the
                                                    list pending_snapshots
                                                    of the current
                                                    transaction

                                                btrfs_commit_transaction()
                                                 --> waits for task at
                                                     CPU 0 to release
                                                     its transaction
                                                     handle

    btrfs_commit_transaction()
     --> sees another task started
         the transaction commit first
     --> releases its transaction
         handle
     --> waits for the transaction
         commit to be completed by
         the task at CPU 1

                                                 create_pending_snapshot()
                                                  qgroup_account_snapshot()
                                                   btrfs_qgroup_inherit()
                                                    mutex_lock(fs_info->qgroup_ioctl_lock)
                                                     --> deadlock, task at CPU 0
                                                         has the mutex locked but
                                                         it is waiting for us to
                                                         finish the transaction
                                                         commit

So fix this by setting the quota enabled flag in fs_info after committing
the transaction at btrfs_quota_enable(). This ends up serializing quota
enable and snapshot creation as if the snapshot creation happened just
before the quota enable request. The quota rescan task, scheduled after
committing the transaction in btrfs_quote_enable(), will do the accounting.

Fixes: 6426c7ad ("btrfs: qgroup: Fix qgroup accounting when creating snapshot")
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      79aa5c0d
    • F
      Btrfs: fix access to available allocation bits when starting balance · 829431a2
      由 Filipe Manana 提交于 
      commit 5a8067c0d17feb7579db0476191417b441a8996e upstream.

The available allocation bits members from struct btrfs_fs_info are
protected by a sequence lock, and when starting balance we access them
incorrectly in two different ways:

1) In the read sequence lock loop at btrfs_balance() we use the values we
   read from fs_info->avail_*_alloc_bits and we can immediately do actions
   that have side effects and can not be undone (printing a message and
   jumping to a label). This is wrong because a retry might be needed, so
   our actions must not have side effects and must be repeatable as long
   as read_seqretry() returns a non-zero value. In other words, we were
   essentially ignoring the sequence lock;

2) Right below the read sequence lock loop, we were reading the values
   from avail_metadata_alloc_bits and avail_data_alloc_bits without any
   protection from concurrent writers, that is, reading them outside of
   the read sequence lock critical section.

So fix this by making sure we only read the available allocation bits
while in a read sequence lock critical section and that what we do in the
critical section is repeatable (has nothing that can not be undone) so
that any eventual retry that is needed is handled properly.

Fixes: de98ced9 ("Btrfs: use seqlock to protect fs_info->avail_{data, metadata, system}_alloc_bits")
Fixes: 14506127 ("btrfs: fix a bogus warning when converting only data or metadata")
Reviewed-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      829431a2
    • W
      arm64: compat: Don't pull syscall number from regs in arm_compat_syscall · 6c9a2046
      由 Will Deacon 提交于 
      commit 53290432145a8eb143fe29e06e9c1465d43dc723 upstream.

The syscall number may have been changed by a tracer, so we should pass
the actual number in from the caller instead of pulling it from the
saved r7 value directly.

Cc: <stable@vger.kernel.org>
Cc: Pi-Hsun Shih <pihsun@chromium.org>
Reviewed-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      6c9a2046