rbd: define rbd_update_mapping_size()

Encapsulate the code that handles updating the size of a mapping
after an rbd image has been refreshed.  This is done in anticipation
of the next patch, which will make this common code for format 1 and
2 images.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
rbd: define rbd_dev_v2_refresh()

Define a new function rbd_dev_v2_refresh() to update/refresh the
snapshot context for a format version 2 rbd image.  This function
will update anything that is not fixed for the life of an rbd
image--at the moment this is mainly the snapshot context and (for
a base mapping) the size.

Update rbd_refresh_header() so it selects which function to use
based on the image format.

Rename __rbd_refresh_header() to be rbd_dev_v1_refresh()
to be consistent with the naming of its version 2 counterpart.
Similarly rename rbd_refresh_header() to be rbd_dev_refresh().

Unrelated--we use rbd_image_format_valid() here.  Delete the other
use of it, which was primarily put in place to ensure that function
was referenced at the time it was defined.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
rbd: implement feature checks

Version 2 images have two sets of feature bit fields.  The first
indicates features possibly used by the image.  The second indicates
features that the client *must* support in order to use the image.

When an image (or snapshot) is first examined, we need to make sure
that the local implementation supports the image's required
features.  If not, fail the probe for the image.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
rbd: activate v2 image support

Now that v2 images support is fully implemented, have
rbd_dev_v2_probe() return 0 to indicate a successful probe.

(Note that an image that implements layering will fail
the probe early because of the feature chekc.)

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Btrfs: pass lockdep rwsem metadata to async commit transaction

The freeze rwsem is taken by sb_start_intwrite() and dropped during the
commit_ or end_transaction().  In the async case, that happens in a worker
thread.  Tell lockdep the calling thread is releasing ownership of the
rwsem and the async thread is picking it up.

XFS plays the same trick in fs/xfs/xfs_aops.c.

Signed-off-by: Sage Weil <sage@inktank.com>
Btrfs: do not take cleanup_work_sem in btrfs_run_delayed_iputs()

Josef has suggested that this is not necessary.  Removing it also avoids
this lockdep splat (after the new sb_internal locking stuff was added):

[  604.090449] ======================================================
[  604.114819] [ INFO: possible circular locking dependency detected ]
[  604.139262] 3.6.0-rc2-ceph-00144-g463b030 #1 Not tainted
[  604.162193] -------------------------------------------------------
[  604.186139] btrfs-cleaner/6669 is trying to acquire lock:
[  604.209555]  (sb_internal#2){.+.+..}, at: [<ffffffffa0042b84>] start_transaction+0x124/0x430 [btrfs]
[  604.257100]
[  604.257100] but task is already holding lock:
[  604.300366]  (&fs_info->cleanup_work_sem){.+.+..}, at: [<ffffffffa0048002>] btrfs_run_delayed_iputs+0x72/0x130 [btrfs]
[  604.352989]
[  604.352989] which lock already depends on the new lock.
[  604.352989]
[  604.427104]
[  604.427104] the existing dependency chain (in reverse order) is:
[  604.478493]
[  604.478493] -> #1 (&fs_info->cleanup_work_sem){.+.+..}:
[  604.529313]        [<ffffffff810b2c82>] lock_acquire+0xa2/0x140
[  604.559621]        [<ffffffff81632b69>] down_read+0x39/0x4e
[  604.589382]        [<ffffffffa004db98>] btrfs_lookup_dentry+0x218/0x550 [btrfs]
[  604.596161] btrfs: unlinked 1 orphans
[  604.675002]        [<ffffffffa006aadd>] create_subvol+0x62d/0x690 [btrfs]
[  604.708859]        [<ffffffffa006d666>] btrfs_mksubvol.isra.52+0x346/0x3a0 [btrfs]
[  604.772466]        [<ffffffffa006d7f2>] btrfs_ioctl_snap_create_transid+0x132/0x190 [btrfs]
[  604.842245]        [<ffffffffa006d8ae>] btrfs_ioctl_snap_create+0x5e/0x80 [btrfs]
[  604.912852]        [<ffffffffa00708ae>] btrfs_ioctl+0x138e/0x1990 [btrfs]
[  604.951888]        [<ffffffff8118e9b8>] do_vfs_ioctl+0x98/0x560
[  604.989961]        [<ffffffff8118ef11>] sys_ioctl+0x91/0xa0
[  605.026628]        [<ffffffff8163d569>] system_call_fastpath+0x16/0x1b
[  605.064404]
[  605.064404] -> #0 (sb_internal#2){.+.+..}:
[  605.126832]        [<ffffffff810b25e8>] __lock_acquire+0x1ac8/0x1b90
[  605.163671]        [<ffffffff810b2c82>] lock_acquire+0xa2/0x140
[  605.200228]        [<ffffffff8117dac6>] __sb_start_write+0xc6/0x1b0
[  605.236818]        [<ffffffffa0042b84>] start_transaction+0x124/0x430 [btrfs]
[  605.274029]        [<ffffffffa00431a3>] btrfs_start_transaction+0x13/0x20 [btrfs]
[  605.340520]        [<ffffffffa004ccfa>] btrfs_evict_inode+0x19a/0x330 [btrfs]
[  605.378720]        [<ffffffff811972c8>] evict+0xb8/0x1c0
[  605.416057]        [<ffffffff811974d5>] iput+0x105/0x210
[  605.452373]        [<ffffffffa0048082>] btrfs_run_delayed_iputs+0xf2/0x130 [btrfs]
[  605.521627]        [<ffffffffa003b5e1>] cleaner_kthread+0xa1/0x120 [btrfs]
[  605.560520]        [<ffffffff810791ee>] kthread+0xae/0xc0
[  605.598094]        [<ffffffff8163e744>] kernel_thread_helper+0x4/0x10
[  605.636499]
[  605.636499] other info that might help us debug this:
[  605.636499]
[  605.736504]  Possible unsafe locking scenario:
[  605.736504]
[  605.801931]        CPU0                    CPU1
[  605.835126]        ----                    ----
[  605.867093]   lock(&fs_info->cleanup_work_sem);
[  605.898594]                                lock(sb_internal#2);
[  605.931954]                                lock(&fs_info->cleanup_work_sem);
[  605.965359]   lock(sb_internal#2);
[  605.994758]
[  605.994758]  *** DEADLOCK ***
[  605.994758]
[  606.075281] 2 locks held by btrfs-cleaner/6669:
[  606.104528]  #0:  (&fs_info->cleaner_mutex){+.+...}, at: [<ffffffffa003b5d5>] cleaner_kthread+0x95/0x120 [btrfs]
[  606.165626]  #1:  (&fs_info->cleanup_work_sem){.+.+..}, at: [<ffffffffa0048002>] btrfs_run_delayed_iputs+0x72/0x130 [btrfs]
[  606.231297]
[  606.231297] stack backtrace:
[  606.287723] Pid: 6669, comm: btrfs-cleaner Not tainted 3.6.0-rc2-ceph-00144-g463b030 #1
[  606.347823] Call Trace:
[  606.376184]  [<ffffffff8162a77c>] print_circular_bug+0x1fb/0x20c
[  606.409243]  [<ffffffff810b25e8>] __lock_acquire+0x1ac8/0x1b90
[  606.441343]  [<ffffffffa0042b84>] ? start_transaction+0x124/0x430 [btrfs]
[  606.474583]  [<ffffffff810b2c82>] lock_acquire+0xa2/0x140
[  606.505934]  [<ffffffffa0042b84>] ? start_transaction+0x124/0x430 [btrfs]
[  606.539429]  [<ffffffff8132babd>] ? do_raw_spin_unlock+0x5d/0xb0
[  606.571719]  [<ffffffff8117dac6>] __sb_start_write+0xc6/0x1b0
[  606.603498]  [<ffffffffa0042b84>] ? start_transaction+0x124/0x430 [btrfs]
[  606.637405]  [<ffffffffa0042b84>] ? start_transaction+0x124/0x430 [btrfs]
[  606.670165]  [<ffffffff81172e75>] ? kmem_cache_alloc+0xb5/0x160
[  606.702144]  [<ffffffffa0042b84>] start_transaction+0x124/0x430 [btrfs]
[  606.735562]  [<ffffffffa00256a6>] ? block_rsv_add_bytes+0x56/0x80 [btrfs]
[  606.769861]  [<ffffffffa00431a3>] btrfs_start_transaction+0x13/0x20 [btrfs]
[  606.804575]  [<ffffffffa004ccfa>] btrfs_evict_inode+0x19a/0x330 [btrfs]
[  606.838756]  [<ffffffff81634c6b>] ? _raw_spin_unlock+0x2b/0x40
[  606.872010]  [<ffffffff811972c8>] evict+0xb8/0x1c0
[  606.903800]  [<ffffffff811974d5>] iput+0x105/0x210
[  606.935416]  [<ffffffffa0048082>] btrfs_run_delayed_iputs+0xf2/0x130 [btrfs]
[  606.970510]  [<ffffffffa003b5d5>] ? cleaner_kthread+0x95/0x120 [btrfs]
[  607.005648]  [<ffffffffa003b5e1>] cleaner_kthread+0xa1/0x120 [btrfs]
[  607.040724]  [<ffffffffa003b540>] ? btrfs_destroy_delayed_refs.isra.102+0x220/0x220 [btrfs]
[  607.104740]  [<ffffffff810791ee>] kthread+0xae/0xc0
[  607.137119]  [<ffffffff810b379d>] ? trace_hardirqs_on+0xd/0x10
[  607.169797]  [<ffffffff8163e744>] kernel_thread_helper+0x4/0x10
[  607.202472]  [<ffffffff81635430>] ? retint_restore_args+0x13/0x13
[  607.235884]  [<ffffffff81079140>] ? flush_kthread_work+0x1a0/0x1a0
[  607.268731]  [<ffffffff8163e740>] ? gs_change+0x13/0x13

Signed-off-by: Sage Weil <sage@inktank.com>
Btrfs: set journal_info in async trans commit worker

We expect current->journal_info to point to the trans handle we are
committing.

Signed-off-by: Sage Weil <sage@inktank.com>
Btrfs: move the sb_end_intwrite until after the throttle logic

Sage reported the following lockdep backtrace

=====================================
[ BUG: bad unlock balance detected! ]
3.6.0-rc2-ceph-00171-gc7ed62d #1 Not tainted
-------------------------------------
btrfs-cleaner/7607 is trying to release lock (sb_internal) at:
[<ffffffffa00422ae>] btrfs_commit_transaction+0xa6e/0xb20 [btrfs]
but there are no more locks to release!

other info that might help us debug this:
1 lock held by btrfs-cleaner/7607:
 #0:  (&fs_info->cleaner_mutex){+.+...}, at: [<ffffffffa003b405>] cleaner_kthread+0x95/0x120 [btrfs]

stack backtrace:
Pid: 7607, comm: btrfs-cleaner Not tainted 3.6.0-rc2-ceph-00171-gc7ed62d #1
Call Trace:
 [<ffffffffa00422ae>] ? btrfs_commit_transaction+0xa6e/0xb20 [btrfs]
 [<ffffffff810afa9e>] print_unlock_inbalance_bug+0xfe/0x110
 [<ffffffff810b289e>] lock_release_non_nested+0x1ee/0x310
 [<ffffffff81172f9b>] ? kmem_cache_free+0x7b/0x160
 [<ffffffffa004106c>] ? put_transaction+0x8c/0x130 [btrfs]
 [<ffffffffa00422ae>] ? btrfs_commit_transaction+0xa6e/0xb20 [btrfs]
 [<ffffffff810b2a95>] lock_release+0xd5/0x220
 [<ffffffff81173071>] ? kmem_cache_free+0x151/0x160
 [<ffffffff8117d9ed>] __sb_end_write+0x7d/0x90
 [<ffffffffa00422ae>] btrfs_commit_transaction+0xa6e/0xb20 [btrfs]
 [<ffffffff81079850>] ? __init_waitqueue_head+0x60/0x60
 [<ffffffff81634c6b>] ? _raw_spin_unlock+0x2b/0x40
 [<ffffffffa0042758>] __btrfs_end_transaction+0x368/0x3c0 [btrfs]
 [<ffffffffa0042808>] btrfs_end_transaction_throttle+0x18/0x20 [btrfs]
 [<ffffffffa00318f0>] btrfs_drop_snapshot+0x410/0x600 [btrfs]
 [<ffffffff8132babd>] ? do_raw_spin_unlock+0x5d/0xb0
 [<ffffffffa00430ef>] btrfs_clean_old_snapshots+0xaf/0x150 [btrfs]
 [<ffffffffa003b405>] ? cleaner_kthread+0x95/0x120 [btrfs]
 [<ffffffffa003b419>] cleaner_kthread+0xa9/0x120 [btrfs]
 [<ffffffffa003b370>] ? btrfs_destroy_delayed_refs.isra.102+0x220/0x220 [btrfs]
 [<ffffffff810791ee>] kthread+0xae/0xc0
 [<ffffffff810b379d>] ? trace_hardirqs_on+0xd/0x10
 [<ffffffff8163e744>] kernel_thread_helper+0x4/0x10
 [<ffffffff81635430>] ? retint_restore_args+0x13/0x13
 [<ffffffff81079140>] ? flush_kthread_work+0x1a0/0x1a0
 [<ffffffff8163e740>] ? gs_change+0x13/0x13

This is because the throttle stuff can commit the transaction, which expects to
be the one stopping the intwrite stuff, but we've already done it in the
__btrfs_end_transaction.  Moving the sb_end_intewrite after this logic makes the
lockdep go away.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>