linux-toradex.git/fs/btrfs/super.c, branch v4.9.105

btrfs: resume qgroup rescan on rw remount

2017-09-13T21:13:36+00:00

commit 6c6b5a39c4bf3dbd8cf629c9f5450e983c19dbb9 upstream.

Several distributions mount the "proper root" as ro during initrd and
then remount it as rw before pivot_root(2). Thus, if a rescan had been
aborted by a previous shutdown, the rescan would never be resumed.

This issue would manifest itself as several btrfs ioctl(2)s causing the
entire machine to hang when btrfs_qgroup_wait_for_completion was hit
(due to the fs_info->qgroup_rescan_running flag being set but the rescan
itself not being resumed). Notably, Docker's btrfs storage driver makes
regular use of BTRFS_QUOTA_CTL_DISABLE and BTRFS_IOC_QUOTA_RESCAN_WAIT
(causing this problem to be manifested on boot for some machines).

Cc: Jeff Mahoney 
Fixes: b382a324b60f ("Btrfs: fix qgroup rescan resume on mount")
Signed-off-by: Aleksa Sarai 
Reviewed-by: Nikolay Borisov 
Tested-by: Nikolay Borisov 
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

btrfs: convert pr_* to btrfs_* where possible

2016-09-26T17:37:04+00:00

For many printks, we want to know which file system issued the message.

This patch converts most pr_* calls to use the btrfs_* versions instead.
In some cases, this means adding plumbing to allow call sites access to
an fs_info pointer.

fs/btrfs/check-integrity.c is left alone for another day.

Signed-off-by: Jeff Mahoney 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba

btrfs: convert printk(KERN_* to use pr_* calls

2016-09-26T16:08:44+00:00

This patch converts printk(KERN_* style messages to use the pr_* versions.

One side effect is that anything that was KERN_DEBUG is now automatically
a dynamic debug message.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

btrfs: unsplit printed strings

2016-09-26T16:08:44+00:00

CodingStyle chapter 2:
"[...] never break user-visible strings such as printk messages,
because that breaks the ability to grep for them."

This patch unsplits user-visible strings.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

Btrfs: add a flags field to btrfs_fs_info

2016-09-26T15:59:49+00:00

We have a lot of random ints in btrfs_fs_info that can be put into flags.  This
is mostly equivalent with the exception of how we deal with quota going on or
off, now instead we set a flag when we are turning it on or off and deal with
that appropriately, rather than just having a pending state that the current
quota_enabled gets set to.  Thanks,

Signed-off-by: Josef Bacik 
Signed-off-by: David Sterba

btrfs: fix fsfreeze hang caused by delayed iputs deal

2016-08-25T10:58:26+00:00

When running fstests generic/068, sometimes we got below deadlock:
  xfs_io          D ffff8800331dbb20     0  6697   6693 0x00000080
  ffff8800331dbb20 ffff88007acfc140 ffff880034d895c0 ffff8800331dc000
  ffff880032d243e8 fffffffeffffffff ffff880032d24400 0000000000000001
  ffff8800331dbb38 ffffffff816a9045 ffff880034d895c0 ffff8800331dbba8
  Call Trace:
  [] schedule+0x35/0x80
  [] rwsem_down_read_failed+0xf2/0x140
  [] ? __filemap_fdatawrite_range+0xd1/0x100
  [] call_rwsem_down_read_failed+0x18/0x30
  [] ? btrfs_alloc_block_rsv+0x2c/0xb0 [btrfs]
  [] percpu_down_read+0x35/0x50
  [] __sb_start_write+0x2c/0x40
  [] start_transaction+0x2a5/0x4d0 [btrfs]
  [] btrfs_join_transaction+0x17/0x20 [btrfs]
  [] btrfs_evict_inode+0x3c4/0x5d0 [btrfs]
  [] evict+0xba/0x1a0
  [] iput+0x196/0x200
  [] btrfs_run_delayed_iputs+0x70/0xc0 [btrfs]
  [] btrfs_commit_transaction+0x928/0xa80 [btrfs]
  [] btrfs_freeze+0x30/0x40 [btrfs]
  [] freeze_super+0xf0/0x190
  [] do_vfs_ioctl+0x4a5/0x5c0
  [] ? do_audit_syscall_entry+0x66/0x70
  [] ? syscall_trace_enter_phase1+0x11f/0x140
  [] SyS_ioctl+0x79/0x90
  [] do_syscall_64+0x62/0x110
  [] entry_SYSCALL64_slow_path+0x25/0x25

>From this warning, freeze_super() already holds SB_FREEZE_FS, but
btrfs_freeze() will call btrfs_commit_transaction() again, if
btrfs_commit_transaction() finds that it has delayed iputs to handle,
it'll start_transaction(), which will try to get SB_FREEZE_FS lock
again, then deadlock occurs.

The root cause is that in btrfs, sync_filesystem(sb) does not make
sure all metadata is updated. There still maybe some codes adding
delayed iputs, see below sample race window:

         CPU1                                  |         CPU2
|-> freeze_super()                             |
    |-> sync_filesystem(sb);                   |
    |                                          |-> cleaner_kthread()
    |                                          |   |-> btrfs_delete_unused_bgs()
    |                                          |       |-> btrfs_remove_chunk()
    |                                          |           |-> btrfs_remove_block_group()
    |                                          |               |-> btrfs_add_delayed_iput()
    |                                          |
    |-> sb->s_writers.frozen = SB_FREEZE_FS;   |
    |-> sb_wait_write(sb, SB_FREEZE_FS);       |
    |   acquire SB_FREEZE_FS lock.             |
    |                                          |
    |-> btrfs_freeze()                         |
        |-> btrfs_commit_transaction()         |
            |-> btrfs_run_delayed_iputs()      |
            |   will handle delayed iputs,     |
            |   that means start_transaction() |
            |   will be called, which will try |
            |   to get SB_FREEZE_FS lock.      |

To fix this issue, introduce a "int fs_frozen" to record internally whether
fs has been frozen. If fs has been frozen, we can not handle delayed iputs.

Signed-off-by: Wang Xiaoguang 
Reviewed-by: David Sterba 
[ add comment to btrfs_freeze ]
Signed-off-by: David Sterba 

Signed-off-by: Chris Mason

btrfs: btrfs_abort_transaction, drop root parameter

2016-07-26T11:54:26+00:00

__btrfs_abort_transaction doesn't use its root parameter except to
obtain an fs_info pointer.  We can obtain that from trans->root->fs_info
for now and from trans->fs_info in a later patch.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

btrfs: tests, move initialization into tests/

2016-07-26T11:53:17+00:00

We have all these stubs that only exist because they're called from
btrfs_run_sanity_tests, which is a static inside super.c.  Let's just
move it all into tests/btrfs-tests.c and only have one stub.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

btrfs: btrfs_test_opt and friends should take a btrfs_fs_info

2016-07-26T11:53:16+00:00

btrfs_test_opt and friends only use the root pointer to access
the fs_info.  Let's pass the fs_info directly in preparation to
eliminate similar patterns all over btrfs.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba

btrfs: prefix fsid to all trace events

2016-07-26T11:53:16+00:00

When using trace events to debug a problem, it's impossible to determine
which file system generated a particular event.  This patch adds a
macro to prefix standard information to the head of a trace event.

The extent_state alloc/free events are all that's left without an
fs_info available.

Signed-off-by: Jeff Mahoney 
Signed-off-by: David Sterba