03 Oct, 2012
1 commit
-
This patch re-adds the ability to optionally run in buffered FILEIO mode
(eg: w/o O_DSYNC) for device backends in order to once again use the
Linux buffered cache as a write-back storage mechanism.This logic was originally dropped with mainline v3.5-rc commit:
commit a4dff3043c231d57f982af635c9d2192ee40e5ae
Author: Nicholas Bellinger
Date: Wed May 30 16:25:41 2012 -0700target/file: Use O_DSYNC by default for FILEIO backends
This difference with this patch is that fd_create_virtdevice() now
forces the explicit setting of emulate_write_cache=1 when buffered FILEIO
operation has been enabled.(v2: Switch to FDBD_HAS_BUFFERED_IO_WCE + add more detailed
comment as requested by hch)Reported-by: Ferry
Cc: Christoph Hellwig
Cc:
Signed-off-by: Nicholas Bellinger
18 Sep, 2012
1 commit
-
This patch drops se_subsystem_api->[write_cache,fua_write]_emulated flags
set by viritual FILEIO/IBLOCK/RD_MCP backend drivers in favor of explict
TRANSPORT_PLUGIN_PHBA_PDEV checks to know when to fail if userspace is
attempting to set virtual emulation bits for an pSCSI (passthrough)
backend device.Reported-by: Christoph Hellwig
Cc: Christoph Hellwig
Signed-off-by: Nicholas Bellinger
02 Aug, 2012
1 commit
-
Pull second vfs pile from Al Viro:
"The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the
deadlock reproduced by xfstests 068), symlink and hardlink restriction
patches, plus assorted cleanups and fixes.Note that another fsfreeze deadlock (emergency thaw one) is *not*
dealt with - the series by Fernando conflicts a lot with Jan's, breaks
userland ABI (FIFREEZE semantics gets changed) and trades the deadlock
for massive vfsmount leak; this is going to be handled next cycle.
There probably will be another pull request, but that stuff won't be
in it."Fix up trivial conflicts due to unrelated changes next to each other in
drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c}* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
delousing target_core_file a bit
Documentation: Correct s_umount state for freeze_fs/unfreeze_fs
fs: Remove old freezing mechanism
ext2: Implement freezing
btrfs: Convert to new freezing mechanism
nilfs2: Convert to new freezing mechanism
ntfs: Convert to new freezing mechanism
fuse: Convert to new freezing mechanism
gfs2: Convert to new freezing mechanism
ocfs2: Convert to new freezing mechanism
xfs: Convert to new freezing code
ext4: Convert to new freezing mechanism
fs: Protect write paths by sb_start_write - sb_end_write
fs: Skip atime update on frozen filesystem
fs: Add freezing handling to mnt_want_write() / mnt_drop_write()
fs: Improve filesystem freezing handling
switch the protection of percpu_counter list to spinlock
nfsd: Push mnt_want_write() outside of i_mutex
btrfs: Push mnt_want_write() outside of i_mutex
fat: Push mnt_want_write() outside of i_mutex
...
01 Aug, 2012
1 commit
-
* set_fs(KERNEL_DS) + getname() is probably the weirdest implementation
of strdup() I've seen. Especially since they don't to copy it at all...
* filp_open() never returns NULL; it's ERR_PTR(-E...) on failure.
* file->f_dentry is never going to be NULL, TYVM.
* match_strdup() + snprintf() + kfree() is a bloody weird way to spell
match_strlcpy().Pox on cargo-cult programmers...
Signed-off-by: Al Viro
17 Jul, 2012
3 commits
-
Add spc_ops->execute_sync_cache() caller for ->execute_cmd() setup,
and update IBLOCK + FILEIO backends to use it.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
Remove the execute_cmd method in struct se_subsystem_api, and always use the
one directly in struct se_cmd. To make life simpler for SBC virtual backends
a struct spc_ops that is passed to sbc_parse_cmd is added. For now it
only contains an execute_rw member, but more will follow with the subsequent
commits.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
Instead of trying to handle all SCSI command sets in one function
(transport_generic_cmd_sequencer) call out to the backend driver to perform
this functionality. For pSCSI a copy of the existing code is used, but for
all virtual backends we can use a new parse_sbc_cdb helper is used to
provide a simple SBC emulation.For now this setups means a fair amount of duplication between pSCSI and the
SBC library, but patches later in this series will sort out that problem.(nab: Fix up build failure in target_core_pscsi.c)
Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger
03 Jun, 2012
1 commit
-
Convert to use O_DSYNC for all cases at FILEIO backend creation time to
avoid the extra syncing of pure timestamp updates with legacy O_SYNC during
default operation as recommended by hch. Continue to do this independently of
Write Cache Enable (WCE) bit, as WCE=0 is currently the default for all backend
devices and enabled by user on per device basis via attrib/emulate_write_cache.This patch drops the now unnecessary fd_buffered_io= token usage that was
originally signalling when to explictly disable O_SYNC at backend creation
time for buffered I/O operation. This can end up being dangerous for a number
of reasons during physical node failure, so go ahead and drop this option
for now when O_DSYNC is used as the default.Also allow explict FUA WRITEs -> vfs_fsync_range() call to function in
fd_execute_cmd() independently of WCE bit setting.Reported-by: Christoph Hellwig
Cc: Linus Torvalds
Cc:
Signed-off-by: Nicholas Bellinger
22 May, 2012
1 commit
-
Pull scsi-target changes from Nicholas Bellinger:
"There has been lots of work in existing code in a number of areas this
past cycle. The major highlights have been:* Removal of transport_do_task_sg_chain() from core + fabrics
(Roland)
* target-core: Removal of se_task abstraction from target-core and
enforce hw_max_sectors for pSCSI backends (hch)
* Re-factoring of iscsi-target tx immediate/response queues (agrover)
* Conversion of iscsi-target back to using target core memory
allocation logic (agrover)We've had one last minute iscsi-target patch go into for-next to
address a nasty regression bug related to the target core allocation
logic conversion from agrover that is not included in friday's
linux-next build, but has been included in this series.On the new fabric module code front for-3.5, here is a brief status
update for the three currently in flight this round:* usb-gadget target driver:
Sebastian Siewior's driver for supporting usb-gadget target mode
operation. This will be going out as a separate PULL request from
target-pending/usb-target-merge with subsystem maintainer ACKs. There
is one minor target-core patch in this series required to function.* sbp ieee-1394/firewire target driver:
Chris Boot's driver for supportting the Serial Block Protocol (SBP)
across IEEE-1394 Firewire hardware. This will be going out as a
separate PULL request from target-pending/sbp-target-merge with two
additional drivers/firewire/ patches w/ subsystem maintainer ACKs.* qla2xxx LLD target mode infrastructure changes + tcm_qla2xxx:
The Qlogic >= 24xx series HW target mode LLD infrastructure patch-set
and tcm_qla2xxx fabric driver. Support for FC target mode using
qla2xxx LLD code has been officially submitted by Qlogic to James
below, and is currently outstanding but not yet merged into
scsi.git/for-next..[PATCH 00/22] qla2xxx: Updates for scsi "misc" branch
http://www.spinics.net/lists/linux-scsi/msg59350.htmlNote there are *zero* direct dependencies upon this for-next series
for the qla2xxx LLD target + tcm_qla2xxx patches submitted above, and
over the last days the target mode team has been tracking down an
tcm_qla2xxx specific active I/O shutdown bug that appears to now be
almost squashed for 3.5-rc-fixes."* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending: (47 commits)
iscsi-target: Fix iov_count calculation bug in iscsit_allocate_iovecs
iscsi-target: remove dead code in iscsi_check_valuelist_for_support
target: Handle ATA_16 passthrough for pSCSI backend devices
target: Add MI_REPORT_TARGET_PGS ext. header + implict_trans_secs attribute
target: Fix MAINTENANCE_IN service action CDB checks to use lower 5 bits
target: add support for the WRITE_VERIFY command
target: make target_put_session void
target: cleanup transport_execute_tasks()
target: Remove max_sectors device attribute for modern se_task less code
target: lock => unlock typo in transport_lun_wait_for_tasks
target: Enforce hw_max_sectors for SCF_SCSI_DATA_SG_IO_CDB
target: remove the t_se_count field in struct se_cmd
target: remove the t_task_cdbs_ex_left field in struct se_cmd
target: remove the t_task_cdbs_left field in struct se_cmd
target: remove struct se_task
target: move the state and execute lists to the command
target: simplify command to task linkage
target: always allocate a single task
target: replace ->execute_task with ->execute_cmd
target: remove the task_sectors field in struct se_task
...
18 May, 2012
1 commit
-
This patch fixes a bug in the handling of FILEIO w/ underlying block_device
resize operations where the original fd_dev->fd_dev_size was incorrectly being
used in fd_get_blocks() for READ_CAPACITY response payloads.This patch avoids using fd_dev->fd_dev_size for FILEIO devices with
an underlying block_device, and instead changes fd_get_blocks() to
get the sector count directly from i_size_read() as recommended by hch.Reported-by: Christoph Hellwig
Cc:
Signed-off-by: Nicholas Bellinger
07 May, 2012
4 commits
-
We can use struct se_cmd for everything it did. Make sure to pass the S/G
list and data direction to the execution function to ease adding back BIDI
support later on.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
Make CDB emulation work on commands instead of tasks again as a preparation
of removing tasks completely.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
Now that we don't split commands the size field in the task is always
equivalent to the one in the CDB, even in cases where we have two tasks
due to a BIDI transfer. Just refer the the size in the command instead
of duplicating it in the task.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
Now that we don't split commands the lba field in the task is always
equivalent to the one in the CDB, even in cases where we have two tasks
due to a BIDI transfer. Just refer the the lba in the command instead
of duplicating it in the task.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger
15 Apr, 2012
1 commit
-
This patch includes the handful of squashed patches for target/iscsi from
Andy's original series into lio-core/master code:*) Make iscsit_add_reject static
*) Remove unused data_offset_end from iscsi_datain_req
*) Remove "#if 0" stubs
*) Rename iscsi_datain_req to cmd_datain_node
*) Cleanups for built_r2ts_for_cmd()
*) Cleanups for Cleanup build_sendtargets_response()Signed-off-by: Andy Grover
Signed-off-by: Nicholas Bellinger
14 Dec, 2011
3 commits
-
A reader should spend an extra moment whenever noticing a cast,
because either something special is going on that deserves extra
attention or, as is all too often the case, the code is wrong.These casts, afaics, have all been useless. They cast a foo* to a
foo*, cast a void* to the assigned type, cast a foo* to void*, before
assigning it to a void* variable, etc.In a few cases I also removed an additional &...[0], which is equally
useless.Lastly I added three FIXMEs where, to the best of my judgement, the
code appears to have a bug. It would be good if someone could check
these.Signed-off-by: Joern Engel
Signed-off-by: Nicholas Bellinger -
The command
| echo rd_pages=32768 > ramdisk/controlDoes not work because it writes "rd_pages=32768\n" and the parser which
matches for "rd_pages=%d" does not recognize it due to the \n. One way
of fixing this would be using "echo -n" instead.
This patch adds \n to the list of separators so we don't have to use the
-n argument which I find is more convinient.Signed-off-by: Sebastian Andrzej Siewior
Signed-off-by: Nicholas Bellinger -
This reorganized the headers under include/target into:
- target_core_base.h stays as is with all target-wide data stuctures and defines
- target_core_backend.h contains the whole interface to I/O backends
- target_core_fabric.h contains the whole interface to fabric modulesExcept for those only the various configfs macro headers stay around.
Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger
06 Dec, 2011
3 commits
-
This patch changes fileio to use for_each_sg() when walking se_task->task_sg
memory passed into from loopback LLD struct scsi_cmnd scatterlist memory.This addresses an issue where FILEIO backends with loopback where hitting the
following OOPs with mkfs.ext2:|kernel BUG at include/linux/scatterlist.h:97!
|invalid opcode: 0000 [#1] PREEMPT SMP
|Modules linked in: sd_mod tcm_loop target_core_stgt scsi_tgt target_core_pscsi target_core_file target_core_iblock target_core_mod configfs scsi_mod
|
|Pid: 671, comm: LIO_fileio Not tainted 3.1.0-rc10+ #139 Bochs Bochs
|EIP: 0060:[] EFLAGS: 00010202 CPU: 0
|EIP is at fd_do_task+0x396/0x420 [target_core_file]
| [] __transport_execute_tasks+0xd4/0x190 [target_core_mod]
| [] transport_execute_tasks+0x3c/0xf0 [target_core_mod]
|EIP: [] fd_do_task+0x396/0x420 [target_core_file] SS:ESP 0068:dea47e90Signed-off-by: Sebastian Andrzej Siewior
Cc: Christoph Hellwig
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger -
And use a SCF_FUA flag instead.
Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
This patch removes legacy usage of PYX_TRANSPORT_* return codes in a number
of locations and addresses cases where transport_generic_request_failure()
was returning the incorrect sense upon CHECK_CONDITION status after the
v3.1 converson to use errno return codes.This includes the conversion of transport_generic_request_failure() to
process cmd->scsi_sense_reason and handle extra TCM_RESERVATION_CONFLICT
before calling transport_send_check_condition_and_sense() to queue up
response status. It also drops PYX_TRANSPORT_OUT_OF_MEMORY_RESOURCES legacy
usgae, and returns TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE w/ a response
for these cases.transport_generic_allocate_tasks(), transport_generic_new_cmd(), backend
SCF_SCSI_DATA_SG_IO_CDB ->do_task(), and emulated ->execute_task() have
all been updated to set se_cmd->scsi_sense_reason and return errno codes
universally upon failure. This includes cmd->scsi_sense_reason assignment
in target_core_alua.c, target_core_pr.c and target_core_cdb.c emulation code.Finally it updates fabric modules to remove the legacy usage, and for
TFO->new_cmd_map() callers forwards return values outside of fabric code.
iscsi-target has also been updated to remove a handful of special cases
related to the cleanup and signaling QUEUE_FULL handling w/ ft_write_pending()(v2: Drop extra SCF_SCSI_CDB_EXCEPTION check during failure from
transport_generic_new_cmd, and re-add missing task->task_error_status
assignment in transport_complete_task)Cc: Christoph Hellwig
Cc: stable@kernel.org
Signed-off-by: Nicholas Bellinger
01 Nov, 2011
1 commit
-
Signed-off-by: Paul Gortmaker
24 Oct, 2011
3 commits
-
Remove the dpo_emulated, fua_write_emulated, fua_read_emulated and
write_cache_emulated methods, and replace them with a simple bitfields in
se_subsystem_api in those cases where they ever returned one.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
The most commonly used file, iblock and rd backends have no use for
a per-task CDB and thus don't need a method to copy it into their
otherwise unused CDB fields.Signed-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
This is a squashed version of the following se_task cleanup patches:
target: remove the unused task_state_flags field in se_task
target: remove the unused se_obj_ptr field in se_task
target: remove the se_dev field in se_taskSigned-off-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger
11 Oct, 2011
1 commit
-
It was pointed out by 'make versioncheck' that some includes of
linux/version.h are not needed in drivers/target/.
This patch removes them.Signed-off-by: Jesper Juhl
Signed-off-by: Nicholas Bellinger
22 Jul, 2011
4 commits
-
This patch contains the squashed version of forth round series cleanups
from Andy and Christoph following the post heavy lifting in the preceeding:
'Eliminate usage of struct se_mem' and 'Make all control CDBs scatter-gather'
changes. This also includes a conversion of target core and the v3.0
mainline fabric modules (loopback and tcm_fc) to use pr_debug and the
CONFIG_DYNAMIC_DEBUG infrastructure!These have been squashed into this third and final round for v3.1.
target: Remove ifdeffed code in t_g_process_write
target: Remove direct ramdisk code
target: Rename task_sg_num to task_sg_nents
target: Remove custom debug macros for pr_debug. Use pr_err().
target: Remove custom debug macros in mainline fabrics
target: Set WSNZ=1 in block limits VPD. Abort if WRITE_SAME sectors = 0
target: Remove transport do_se_mem_map callback
target: Further simplify transport_free_pages
target: Redo task allocation return value handling
target: Remove extra parentheses
target: change alloc_task call to take *cdb, not *cmd(nab: Fix bogus struct file assignments in fd_do_readv and fd_do_writev)
Signed-off-by: Andy Grover
Reviewed-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
This patch contains a squashed version of third round series cleanups,
improvements ,and simplfications from Andy and Christoph ahead of the
heavy lifting between round 3 -> 4 for the target core SGL conversion.This include cleanups to the main target I/O path and other miscellaneous
updates.target: Replace custom sgbuf functions with lib funcs
target: Simplify sector limiting code
target: get_cdb should never return NULL
target: Simplify transport_memcpy_se_mem_read_contig
target: Use assignment rather than increment for t_task_cdbs
target: Don't pass dma_size to generic_get_mem
target: Pass sg with type scatterlist in transport_map_sg_to_mem
target: Move task_sg_num next to task_sg in struct se_task
target: inline struct se_transport_task into struct se_cmd
target: Change name & semantics of transport_get_sectors()
target: Remove unused members of se_cmd
target: Rename se_cmd.t_task_cdbs to t_task_list_num
target: Fix some spelling
target: Remove unused var from transport_generic_do_tmr
target: map_sg_to_mem: return sg_count in return value
target/pscsi: Use min_t for sector limits
target/pscsi: Unused param for pscsi_get_bio()
target: Rename get_cdb_count to allocate_tasks
target: Make transport_generic_new_cmd() available for iscsi-target
target: Remove fabric callback to allocate iovecs
target: Fix transport_generic_new_cmd WRITE comment(hch: Use __GFP_ZERO usage for alloc_pages() usage)
Signed-off-by: Andy Grover
Reviewed-by: Christoph Hellwig
Signed-off-by: Nicholas Bellinger -
This patch contains the squashed version of second round of target core
cleanups and simplifications and Andy and Co. It also contains a handful
of fixes to address bugs the original series and other minor cleanups.Here is the condensed shortlog:
target: Remove unneeded casts to void*
target: Rename get_lun_for_{cmd,tmr} to lookup_{cmd,tmr}_lun
target: Make t_task a member of se_cmd, not a pointer
target: Handle functions returning "-2"
target: Use cmd->se_dev over cmd->se_lun->lun_se_dev
target: Embed qr in struct se_cmd
target: Replace embedded struct se_queue_req with a list_head
target: Rename list_heads that are nodes in struct se_cmd to "*_node"
target: Fold transport_device_setup_cmd() into lookup_{tmr,cmd}_lun()
target: Make t_mem_list and t_mem_list_bidi members of t_task
target: Add comment & cleanup transport_map_sg_to_mem()
target: Remove unneeded checks in transport_free_pages()(Roland: Fix se_queue_req removal leftovers OOPs)
(nab: Fix transport_lookup_tmr_lun failure case)
(nab: Fix list_empty(&cmd->t_task.t_mem_bidi_list) inversion bugs)Signed-off-by: Andy Grover
Signed-off-by: Roland Dreier
Signed-off-by: Nicholas Bellinger -
This patch contains the squashed version of a number of cleanups and
minor fixes from Andy's initial series (round 1) for target core this
past spring. The condensed log looks like:target: use errno values instead of returning -1 for everything
target: Rename transport_calc_sg_num to transport_init_task_sg
target: Fix leak in error path in transport_init_task_sg
target/pscsi: Remove pscsi_get_sh() usage
target: Make two runtime checks into WARN_ONs
target: Remove hba queue depth and convert to spin_lock_irq usage
target: dev->dev_status_queue_obj is unused
target: Make struct se_queue_req.cmd type struct se_cmd *
target: Remove __transport_get_qr_from_queue()
target: Rename se_dev->g_se_dev_list to se_dev_node
target: Remove struct se_global
target: Simplify scsi mib index table code
target: Make dev_queue_obj a member of se_device instead of a pointer
target: remove extraneous returns at end of void functions
target: Ensure transport_dump_vpd_ident_type returns null-terminated str
target: Function pointers don't need to use '&' to be assigned
target: Fix comment in __transport_execute_tasks()
target: Misc style cleanups
target: rename struct pr_reservation_template to pr_reservation
target: Remove #defines that just perform indirection
target: Inline transport_get_task_from_execute_queue()
target: Minor header comment fixesSigned-off-by: Andy Grover
Signed-off-by: Nicholas Bellinger
31 Mar, 2011
1 commit
-
Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: Lucas De Marchi
24 Mar, 2011
3 commits
-
This patch fixes a token typo for the TCM/FILEIO match_table_t used
for toggling O_SYNC usage for individual struct file backend access.Reported-by: Christophe Fergeau
Signed-off-by: Nicholas A. Bellinger
Signed-off-by: James Bottomley -
This patch converts the target_core_store_dev_enable() -> struct
se_subsystem_api->create_virtdevice() call to return proper ERR_PTR values
back up to configfs logic during backend dependent struct se_device ENABLE
exception conditions.Along with the change to target_core_configfs.c, this includes converting IBLOCK,
FILEIO, pSCSI, and RAMDISK_* backend subsystem plugins to obtain upper level
PTR_ERR return codes (where available), and return via ERR_PTR during a
*_create_virtdev() failure.Reported-by: Fubo Chen
Signed-off-by: Nicholas A. Bellinger
Signed-off-by: James Bottomley -
match_strdup() dynamically allocates memory and it is the responsabillity
of the caller to free that memory. The following three cases:drivers/target/target_core_file.c:fd_set_configfs_dev_params()
drivers/target/target_core_iblock.c:iblock_set_configfs_dev_params()
drivers/target/target_core_configfs.c:target_core_dev_pr_store_attr_res_aptpl_metadata()should be kfree()'ing the allocated memory once it is no longer needed.
It also makes sure to return -ENOMEM if the memory allocation in match_strdup()
should fail. For target_core_configfs.c, this patch adds kfree()'s around
Opt_initiator_fabric, Opt_initiator_node, Opt_initiator_sid, Opt_sa_res_key,
Opt_target_fabric, and Opt_target_node for the Persistent Reservations
Activate Persistence across Target Power Loss (APTPL=1) token parsing.Signed-off-by: Jesper Juhl
Signed-off-by: Nicholas A. Bellinger
Signed-off-by: James Bottomley
02 Mar, 2011
1 commit
-
These were missed the last time I cleaned this up
globally, because of code moving around or new code
getting merged.Signed-off-by: Arnd Bergmann
15 Jan, 2011
1 commit
-
LIO target is a full featured in-kernel target framework with the
following feature set:High-performance, non-blocking, multithreaded architecture with SIMD
support.Advanced SCSI feature set:
* Persistent Reservations (PRs)
* Asymmetric Logical Unit Assignment (ALUA)
* Protocol and intra-nexus multiplexing, load-balancing and failover (MC/S)
* Full Error Recovery (ERL=0,1,2)
* Active/active task migration and session continuation (ERL=2)
* Thin LUN provisioning (UNMAP and WRITE_SAMExx)Multiprotocol target plugins
Storage media independence:
* Virtualization of all storage media; transparent mapping of IO to LUNs
* No hard limits on number of LUNs per Target; maximum LUN size ~750 TB
* Backstores: SATA, SAS, SCSI, BluRay, DVD, FLASH, USB, ramdisk, etc.Standards compliance:
* Full compliance with IETF (RFC 3720)
* Full implementation of SPC-4 PRs and ALUASignificant code cleanups done by Christoph Hellwig.
[jejb: fix up for new block bdev exclusive interface. Minor fixes from
Randy Dunlap and Dan Carpenter.]
Signed-off-by: Nicholas A. Bellinger
Signed-off-by: James Bottomley