xfs: stop the sync worker before xfs_unmountfs

Cancel work of the xfs_sync_worker before teardown of the log in
xfs_unmountfs.  This prevents occasional crashes on unmount like so:

PID: 21602  TASK: ee9df060  CPU: 0   COMMAND: "kworker/0:3"
 #0 [c5377d28] crash_kexec at c0292c94
 #1 [c5377d80] oops_end at c07090c2
 #2 [c5377d98] no_context at c06f614e
 #3 [c5377dbc] __bad_area_nosemaphore at c06f6281
 #4 [c5377df4] bad_area_nosemaphore at c06f629b
 #5 [c5377e00] do_page_fault at c070b0cb
 #6 [c5377e7c] error_code (via page_fault) at c070892c
    EAX: f300c6a8  EBX: f300c6a8  ECX: 000000c0  EDX: 000000c0  EBP: c5377ed0
    DS:  007b      ESI: 00000000  ES:  007b      EDI: 00000001  GS:  ffffad20
    CS:  0060      EIP: c0481ad0  ERR: ffffffff  EFLAGS: 00010246
 #7 [c5377eb0] atomic64_read_cx8 at c0481ad0
 #8 [c5377ebc] xlog_assign_tail_lsn_locked at f7cc7c6e [xfs]
 #9 [c5377ed4] xfs_trans_ail_delete_bulk at f7ccd520 [xfs]
#10 [c5377f0c] xfs_buf_iodone at f7ccb602 [xfs]
#11 [c5377f24] xfs_buf_do_callbacks at f7cca524 [xfs]
#12 [c5377f30] xfs_buf_iodone_callbacks at f7cca5da [xfs]
#13 [c5377f4c] xfs_buf_iodone_work at f7c718d0 [xfs]
#14 [c5377f58] process_one_work at c024ee4c
#15 [c5377f98] worker_thread at c024f43d
#16 [c5377fbc] kthread at c025326b
#17 [c5377fe8] kernel_thread_helper at c070e834

PID: 26653  TASK: e79143b0  CPU: 3   COMMAND: "umount"
 #0 [cde0fda0] __schedule at c0706595
 #1 [cde0fe28] schedule at c0706b89
 #2 [cde0fe30] schedule_timeout at c0705600
 #3 [cde0fe94] __down_common at c0706098
 #4 [cde0fec8] __down at c0706122
 #5 [cde0fed0] down at c025936f
 #6 [cde0fee0] xfs_buf_lock at f7c7131d [xfs]
 #7 [cde0ff00] xfs_freesb at f7cc2236 [xfs]
 #8 [cde0ff10] xfs_fs_put_super at f7c80f21 [xfs]
 #9 [cde0ff1c] generic_shutdown_super at c0333d7a
#10 [cde0ff38] kill_block_super at c0333e0f
#11 [cde0ff48] deactivate_locked_super at c0334218
#12 [cde0ff58] deactivate_super at c033495d
#13 [cde0ff68] mntput_no_expire at c034bc13
#14 [cde0ff7c] sys_umount at c034cc69
#15 [cde0ffa0] sys_oldumount at c034ccd4
#16 [cde0ffb0] system_call at c0707e66

commit 11159a05 added this to xfs_log_unmount and needs to be cleaned up
at a later date.

Signed-off-by: Ben Myers <bpm@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Make inode64 a remountable option

Actually, there is no reason about why a user must umount and mount a
XFS filesystem to enable 'inode64' option. So, this patch makes this a
remountable option.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: Fix m_agirotor reset during AG selection

xfs_ialloc_next_ag() currently resets m_agirotor when it is equal to
m_maxagi:

         if (++mp->m_agirotor == mp->m_maxagi)
	         mp->m_agirotor = 0;

But, if for some reason mp->m_maxagi changes to a lower value than
current m_agirotor, this condition will never be true, causing
m_agirotor to exceed the maximum allowed value (m_maxagi).

This implies mainly during lookups for xfs_perag structs in its radix
tree, since the agno value used for the lookup is based on m_agirotor.
An out-of-range m_agirotor may cause a lookup failure which in case will
return NULL.

As an example, the value of m_maxagi is decreased during
inode64->inode32 remount process, case where I've found this problem.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: make inode64 as the default allocation mode

since 64-bit inodes can be accessed while using inode32, and these can
also be used on 32-bit kernels, there is no reason to still keep inode32
as the default mount option.  If the filesystem cannot handle 64bit
inode numbers (i.e CONFIG_LBDAF is not enabled and BITS_PER_LONG == 32),
XFS_MOUNT_SMALL_INUMS will still be set by default, so inode64 is not an
unconditional default value.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: reduce code duplication handling inode32/64 options

Add xfs_set_inode32() to be used to enable inode32 allocation mode. this
will reduce the amount of duplicated code needed to mount/remount a
filesystem with inode32 option.  This patch also changes
xfs_set_inode64() to return the maximum AG number that inodes can be
allocated instead of set mp->m_maxagi by itself, so that the behaviour
is the same as xfs_set_inode32().  This simplifies code that calls these
functions and needs to know the maximum AG that inodes can be allocated
in.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: Fix mp->m_maxagi update during inode64 remount

With the changes made on xfs_set_inode64(), to make it behave as
xfs_set_inode32() (now leaving to the caller the responsibility to update
mp->m_maxagi), we use the return value of xfs_set_inode64() to update
mp->m_maxagi during remount.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: add inode64->inode32 transition into xfs_set_inode32()

To make inode32 a remountable option, xfs_set_inode32() should be able
to make a transition from inode64 option, disabling inode allocation on
higher AGs.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs: Make inode32 a remountable option

As inode64 is the default option now, and was also made remountable
previously, inode32 can also be remounted on-the-fly when it is needed.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>