Mountpoint crossing is similar to following procfs symlinks - we do
not get ->d_revalidate() called for dentry we have arrived at, with
unpleasant consequences for NFS4.

Simple way to reproduce the problem in mainline:

    cat >/tmp/a.c <<'EOF'
    #include <unistd.h>
    #include <fcntl.h>
    #include <stdio.h>
    main()
    {
            struct flock fl = {.l_type = F_RDLCK, .l_whence = SEEK_SET, .l_len = 1};
            if (fcntl(0, F_SETLK, &fl))
                    perror("setlk");
    }
    EOF
    cc /tmp/a.c -o /tmp/test

then on nfs4:

    mount --bind file1 file2
    /tmp/test < file1		# ok
    /tmp/test < file2		# spews "setlk: No locks available"...

What happens is the missing call of ->d_revalidate() after mountpoint
crossing and that's where NFS4 would issue OPEN request to server.

The fix is simple - treat mountpoint crossing the same way we deal with
following procfs-style symlinks.  I.e.  set LOOKUP_JUMPED...

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* git://git.samba.org/sfrench/cifs-2.6:
  CIFS: Cleanup byte-range locking code style
  CIFS: Simplify setlk error handling for mandatory locking

* git://git.infradead.org/mtd-2.6: (226 commits)
  mtd: tests: annotate as DANGEROUS in Kconfig
  mtd: tests: don't use mtd0 as a default
  mtd: clean up usage of MTD_DOCPROBE_ADDRESS
  jffs2: add compr=lzo and compr=zlib options
  jffs2: implement mount option parsing and compression overriding
  mtd: nand: initialize ops.mode
  mtd: provide an alias for the redboot module name
  mtd: m25p80: don't probe device which has status of 'disabled'
  mtd: nand_h1900 never worked
  mtd: Add DiskOnChip G3 support
  mtd: m25p80: add EON flash EN25Q32B into spi flash id table
  mtd: mark block device queue as non-rotational
  mtd: r852: make r852_pm_ops static
  mtd: m25p80: add support for at25df321a spi data flash
  mtd: mxc_nand: preset_v1_v2: unlock all NAND flash blocks
  mtd: nand: switch `check_pattern()' to standard `memcmp()'
  mtd: nand: invalidate cache on unaligned reads
  mtd: nand: do not scan bad blocks with NAND_BBT_NO_OOB set
  mtd: nand: wait to set BBT version
  mtd: nand: scrub BBT on ECC errors
  ...

Fix up trivial conflicts:
 - arch/arm/mach-at91/board-usb-a9260.c
	Merged into board-usb-a926x.c
 - drivers/mtd/maps/lantiq-flash.c
	add_mtd_partitions -> mtd_device_register vs changed to use
	mtd_device_parse_register.

* 'linux-next' of git://git.infradead.org/ubifs-2.6:
  UBIFS: fix the dark space calculation
  UBIFS: introduce a helper to dump scanning info

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (114 commits)
  Btrfs: check for a null fs root when writing to the backup root log
  Btrfs: fix race during transaction joins
  Btrfs: fix a potential btrfs_bio leak on scrub fixups
  Btrfs: rename btrfs_bio multi -> bbio for consistency
  Btrfs: stop leaking btrfs_bios on readahead
  Btrfs: stop the readahead threads on failed mount
  Btrfs: fix extent_buffer leak in the metadata IO error handling
  Btrfs: fix the new inspection ioctls for 32 bit compat
  Btrfs: fix delayed insertion reservation
  Btrfs: ClearPageError during writepage and clean_tree_block
  Btrfs: be smarter about committing the transaction in reserve_metadata_bytes
  Btrfs: make a delayed_block_rsv for the delayed item insertion
  Btrfs: add a log of past tree roots
  btrfs: separate superblock items out of fs_info
  Btrfs: use the global reserve when truncating the free space cache inode
  Btrfs: release metadata from global reserve if we have to fallback for unlink
  Btrfs: make sure to flush queued bios if write_cache_pages waits
  Btrfs: fix extent pinning bugs in the tree log
  Btrfs: make sure btrfs_remove_free_space doesn't leak EAGAIN
  Btrfs: don't wait as long for more batches during SSD log commit
  ...

* 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: (230 commits)
  Revert "tracing: Include module.h in define_trace.h"
  irq: don't put module.h into irq.h for tracking irqgen modules.
  bluetooth: macroize two small inlines to avoid module.h
  ip_vs.h: fix implicit use of module_get/module_put from module.h
  nf_conntrack.h: fix up fallout from implicit moduleparam.h presence
  include: replace linux/module.h with "struct module" wherever possible
  include: convert various register fcns to macros to avoid include chaining
  crypto.h: remove unused crypto_tfm_alg_modname() inline
  uwb.h: fix implicit use of asm/page.h for PAGE_SIZE
  pm_runtime.h: explicitly requires notifier.h
  linux/dmaengine.h: fix implicit use of bitmap.h and asm/page.h
  miscdevice.h: fix up implicit use of lists and types
  stop_machine.h: fix implicit use of smp.h for smp_processor_id
  of: fix implicit use of errno.h in include/linux/of.h
  of_platform.h: delete needless include <linux/module.h>
  acpi: remove module.h include from platform/aclinux.h
  miscdevice.h: delete unnecessary inclusion of module.h
  device_cgroup.h: delete needless include <linux/module.h>
  net: sch_generic remove redundant use of <linux/module.h>
  net: inet_timewait_sock doesnt need <linux/module.h>
  ...

Fix up trivial conflicts (other header files, and  removal of the ab3550 mfd driver) in
 - drivers/media/dvb/frontends/dibx000_common.c
 - drivers/media/video/{mt9m111.c,ov6650.c}
 - drivers/mfd/ab3550-core.c
 - include/linux/dmaengine.h

* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: Add a 'reason' to wb_writeback_work
  writeback: send work item to queue_io, move_expired_inodes
  writeback: trace event balance_dirty_pages
  writeback: trace event bdi_dirty_ratelimit
  writeback: fix ppc compile warnings on do_div(long long, unsigned long)
  writeback: per-bdi background threshold
  writeback: dirty position control - bdi reserve area
  writeback: control dirty pause time
  writeback: limit max dirty pause time
  writeback: IO-less balance_dirty_pages()
  writeback: per task dirty rate limit
  writeback: stabilize bdi->dirty_ratelimit
  writeback: dirty rate control
  writeback: add bg_threshold parameter to __bdi_update_bandwidth()
  writeback: dirty position control
  writeback: account per-bdi accumulated dirtied pages

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph/super.c: quiet sparse noise
  ceph/mds_client.c: quiet sparse noise
  ceph: use new D_COMPLETE dentry flag
  ceph: clear parent D_COMPLETE flag when on dentry prune

During log replay, can commit the transaction before the fs_root
pointers are setup, so we have to make sure they are not null before
trying to use them.

Signed-off-by: Chris Mason <chris.mason@oracle.com>