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Commit Graph

995 Commits

Author SHA1 Message Date
Bryn M. Reeves
c1bd76d6fc configure: check for -lm and log10 function
We already use -lm functions in a couple of places (these are
satisfied by gcc built-ins for most builds): add a configure.in
check and explicitly link to -lm.
2015-08-18 15:25:54 +01:00
Zdenek Kabelac
6e1feb0f73 cleanup: preserve constness of some pointers 2015-08-18 16:05:04 +02:00
Zdenek Kabelac
55a9262bdb cleanup: unused header files (Coverity) 2015-08-18 15:00:08 +02:00
Zdenek Kabelac
ba94d0f144 libdm: simplify dmstats formula.
Since we check for stats for not being 0,
simplify the operation and use a single division.
2015-08-18 15:00:08 +02:00
Bryn M. Reeves
074b5de771 libdm: check for zero in _nr_areas() (Coverity) 2015-08-17 18:37:16 +01:00
Bryn M. Reeves
8967776713 libdm: do not read region before checking dms for NULL (Coverity)
dm_stats_get_area_start() attempts to assign a region pointer from
a stats handle before checking it is non-NULL: move the assignment
after the test.
2015-08-17 18:37:16 +01:00
Alasdair G Kergon
be1db6b6c1 pre-release 2015-08-17 17:20:14 +01:00
Bryn M. Reeves
4227b2ebb4 libdm-stats: only return uint64_t when required
Several interfaced in libdm-stats return a uint64_t when it is
only used to signal success/failure: change all these uses to
return a simple int instead.
2015-08-17 16:59:52 +01:00
Bryn M. Reeves
427d0a5e92 libdm: ensure dm_stats_get_area_offset() returns a value 2015-08-17 14:40:48 +01:00
Zdenek Kabelac
79ea81b8a8 thin: restore transaction_id handling
Revert back to already existing behavior which has been slightly
modified by a900d150e4.

At the end however it seem to be equal to change TID right with first
metadata write.

Existing code missed handling for 'unused' thin-pool which would
require to also check empty message list for TID==0.

So with the fix we now again preserve 'active' thin-pool volume
when first thin volume is created - this property was lost and caused
problems in cluster, where the lock was hold, but volume was no longer
active on the node.

Another missing part was the proper support for already increased,
but unfinished TID change.

So going back here with existing logic -

TID is increased with first MDA update.

Code allows start with either same TID or (TID-1).

If there are messages, TID must be lower by 1 for sending,
otherwise messages were already posted.
2015-08-17 11:25:03 +02:00
Bryn M. Reeves
00ed523659 libdm: add dm_stats_get_{current_}area_offset()
Add a method to retrieve the offset of an area within the
containing region (rather than the offset within the containing
device returned by dm_stats_get_area_start()).

Although users of the library can calculate this themselves it is
better to provide this through a method call to avoid users making
assumptions about the structure of regions and areas.
2015-08-14 22:03:37 +01:00
Bryn M. Reeves
77fae3d852 libdm: ensure dm_stats_get_area_start includes region offset
The dm_stats_get_area_start (and its '_current_' variant) methods
are expected to return the start sector of the area in the
containing device.

Make sure the call adds region->start to the returned value.
2015-08-14 22:03:37 +01:00
Natanael Copa
4534f0fbcf libdm: do not in include internal bits/time.h header
Do not include bits/time.h as it is an internal libc header file.

A comment at the top of the glibc specific bits/time.h says:
"Never include this file directly; use <time.h> instead."

This fixes the following build error with musl libc:
libdm-timestamp.c:37:23: fatal error: bits/time.h: No such file or directory
---
Compile tested with Alpine Linx (musl libc) and ubuntu 15.04

 libdm/libdm-timestamp.c | 1 -
 1 file changed, 1 deletion(-)
2015-08-14 11:33:12 +01:00
Alasdair G Kergon
043fb32c4b dmsetup: Restructure arg handling.
Introduce enums and global variables to record cleanly which command we
are processing and eliminate the historically inconsistent use of the
shifted argv[0] and fix assorted bugs discovered along the way.

Add dm_report_is_empty() to indicate there is no data awaiting output
and use this to suppress dmsetup report headings when no data is output
so we don't get a stray line saying 'Help' at the end of reporting help.

Define a report type (as the interface requires) so -o all selects
the right fields in splitname.  (A fix for stats list will follow.)

Exit immediately if no device is supplied to dmsetup wipe_table instead
of hitting errors later and failing.

Adjust the command name printed in usage/help output to match command
invoked (most of the time).
2015-08-13 22:30:39 +01:00
Bryn M. Reeves
99f55abc56 libdm: add dm_timestamp_copy() 2015-08-12 15:09:57 +01:00
Zdenek Kabelac
48ed8ac50c cleanup: indent 2015-08-12 14:33:16 +02:00
Zdenek Kabelac
79e9bde0ea libdm: rename to data_block_size
Use common name for pool device - as we use data_block_size
for thin pool metadata, use same name for cache_pool.

This change does not affect API.
2015-08-12 14:33:15 +02:00
Zdenek Kabelac
08f047eb51 libdm: cache target arg validation
Add some arg validation for dm_tree_node_add_cache_target().
2015-08-12 14:33:15 +02:00
Bryn M. Reeves
f072a76326 libdm-stats: backtrace if fclose fails (Coverity)
Since libdm-stats only uses fmemopen'd FILE objects the only way
that a close can fail is corruption of the memory containing the
FILE: check for this case and emit a backtrace if it occurs.

libdm/libdm-stats.c: 338 in _stats_parse_list()
libdm/libdm-stats.c: 341 in _stats_parse_list()
libdm/libdm-stats.c: 481 in _stats_parse_region()
libdm/libdm-stats.c: 487 in _stats_parse_region()
libdm/libdm-stats.c: 487 in _stats_parse_region()
 - Calling "fclose" without checking return value
2015-08-10 20:26:07 +01:00
Bryn M. Reeves
856f9cced8 libdm: simplify stats nr_areas calculation (Coverity)
Remove an unneccessary conditional operator and simplify the logic
in _nr_areas:

libdm/libdm-stats.c: 501 in _nr_areas() - Control flow issues  (DEADCODE)
2015-08-10 20:26:07 +01:00
Bryn M. Reeves
f9f5aac123 libdm: fix stats handle leak in dm_stats_create (Coverity)
Make sure the newly created handle is freed if we are unable to
also create the pool for it.

tools/dmsetup.c: 4255 in _stats_list() - Variable "dms" going out of scope leaks the storage it points to.
2015-08-10 20:20:30 +01:00
Bryn M. Reeves
1134de3c89 libdm: fix FILE leak in _program_id_from_proc() (Coverity)
Make sure comm is closed in the error path of _program_id_from_proc().

libdm/libdm-stats.c: 98 in dm_stats_create() - Variable "comm" going out of scope leaks the storage it points to.
2015-08-10 20:20:26 +01:00
Bryn M. Reeves
d62a8d2f15 dmstats: add libdm-stats library and 'dmsetup stats' command
Add the libdm-stats module to libdm: this implements a simple interface
for creating, managing and interrogating I/O statistics regions and
areas on device-mapper devices.

The library interface is documented in libdevmapper.h and provides a
'dm_stats' handle that is used to perform statistics operations and
obtain data.

Public methods are provided to create and destroy handles and to list,
create, and destroy statistics regions as well as to obtain and parse
counter data and calculate rate-based metrics.

This commit also adds a 'dmsetup stats' (aka 'dmstats') command with
'clear', 'create', 'delete', 'list', 'print', and 'report' sub-commands.

See the library documentation and the dmstats.8 manual page for detailed
API and command descriptions.
2015-08-09 14:37:58 +01:00
Bryn M. Reeves
3638c05ec9 libdm: do not attempt to output column headings with --rows
Columns-as-rows output does not use _report_headings(); don't
try to call it when rh->flags & DM_REPORT_OUTPUT_COLUMNS_AS_ROWS.
2015-08-08 17:48:30 +01:00
Bryn M. Reeves
54815fff06 libdm: remove report interval support
Don't do interval management and external timekeeping for stats in
dm_report: let applications handle this on their own.

Since this has not been included in a release remove it from the
library entirely and handle report timing directly inside dmsetup.
2015-08-08 11:48:12 +01:00
Bryn M. Reeves
666c77c0f2 libdm: add dm_report_column_headings
Add a function to print column headings regardless of whether they
have already been output. This will be used by dmstats to issue
periodic reminders of the column headings.

This patch removes a check for RH_HEADINGS_PRINTED from
_report_headings that prevents headings being displayed if the flag
is already set; this check is redundant since the only existing
caller (_output_as_columns()) already tests the flag before
calling the function.
2015-08-08 11:43:52 +01:00
Bryn M. Reeves
cafe145ba2 libdm: fix report rows and headings memory and state leaks
Not releasing objects back to the pool is fine for short-lived
pools since the memory will be freed when dm_pool_destroy() is
called.

Any pool that may be long-lived needs to be more careful to free
objects back to the pool to avoid leaking memory that will not be
reclaimed until the pool is destroyed at process exit time.

The report pool currently leaks each headings line and some row
data.

Although dm_report_output() tries to free the first allocated row
this may end up freeing a later row due to sorting of the row list
while reporting. Store a pointer to the first allocated row from
_do_report_obect() instead and free this at the end of
_output_as_columns(), _output_as_rows(), and dm_report_clear().

Also make sure to call dm_pool_free() for the headings line built
in _report_headings().

When dmstats is introduced it will maintain dm_report objects for
the whole lifetime of the process: without these changes a stats
report could leak around 600k in 10m (exact rate depends on field
selection and data values):

 top - 12:11:32 up 4 days,  3:16, 15 users,  load average: 0.01, 0.12, 0.14
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
 6473 root      20   0  130196   3124   2792 S   0.0  0.0   0:00.00 dmstats

 top - 12:22:04 up 4 days,  3:26, 15 users,  load average: 0.06, 0.11, 0.13
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
 6498 root      20   0  130836   3712   2752 S   0.0  0.0   0:00.60 dmstats

With this patch no increase in RSS is seen:

 top - 13:54:58 up 4 days,  4:59, 15 users,  load average: 0.12, 0.14, 0.14
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
13962 root      20   0  130196   2996   2688 S   0.0  0.0   0:00.00 dmstats

 top - 14:04:31 up 4 days,  5:09, 15 users,  load average: 1.02, 0.67, 0.36
  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
13962 root      20   0  130196   2996   2688 S   0.3  0.0   0:00.32 dmstats

This also affects report output for repeating reports in the
DM_REPORT_OUTPUT_COLUMNS_AS_ROWS case; row state is not fully cleared for
the next iteration leading to progressive growth of the heading width:

vg_hex-lv_home:vg_hex-lv_swap:vg_hex-lv_root:luks-79733921-3f68-4c92-9eb7-d0aca4c6ba3e:vg_hex-lv_images
253:253:253:253:253
2:0:1:4:3
L--w:L--w:L--w:L--w:L--w
1:2:1:1:1
3:1:1:1:2
0:0:0:0:0
LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiv08BCGvF4WsJSqWUDUt7qtf2hEmjtVvo:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiKf7XIiwdAYOJfaGhQe9fu26cTEICGgFS:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiEZj7ZXbmrWDuGhd7vvi88VF0NdTMG8iA:CRYPT-LUKS1-797339213f684c929eb7d0aca4c6ba3e-luks-79733921-3f68-4c92-9eb7-d0aca4c6ba3e:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOi2rKredlBPnw2X7v1BiCuEpFo6gaE7BRw

:::::vg_hex-lv_home:vg_hex-lv_swap:vg_hex-lv_root:luks-79733921-3f68-4c92-9eb7-d0aca4c6ba3e:vg_hex-lv_images
:::::253:253:253:253:253
:::::2:0:1:4:3
:::::L--w:L--w:L--w:L--w:L--w
:::::1:2:1:1:1
:::::3:1:1:1:2
:::::0:0:0:0:0
:::::LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiv08BCGvF4WsJSqWUDUt7qtf2hEmjtVvo:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiKf7XIiwdAYOJfaGhQe9fu26cTEICGgFS:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOiEZj7ZXbmrWDuGhd7vvi88VF0NdTMG8iA:CRYPT-LUKS1-797339213f684c929eb7d0aca4c6ba3e-luks-79733921-3f68-4c92-9eb7-d0aca4c6ba3e:LVM-9t8ITqLZa6AuuyVoz5Olp1KwF9ZDBfOi2rKredlBPnw2X7v1BiCuEpFo6gaE7BRw
2015-08-08 11:35:10 +01:00
Bryn M. Reeves
974e7b9220 libdm: ensure new dm_timestamp objects are initialized
Allocate a dm_timestamp with dm_zalloc() to ensure the memory is
initialized to a known state.
2015-08-08 10:42:14 +01:00
Alasdair G Kergon
559ca8bc65 dmsetup: Report timestamps of ioctls with -vvv.
If enabled, record timestamp immediately after the ioctl() returns.
2015-08-05 08:28:35 +01:00
Alasdair G Kergon
2f334afb98 libdm: Whitespace. 2015-08-05 05:21:58 +01:00
Alasdair G Kergon
88551add97 libdm: Whitespace. 2015-08-05 05:11:42 +01:00
Alasdair G Kergon
23e8e849e4 libdm: Sort new exported symbols. 2015-08-05 05:07:45 +01:00
Peter Rajnoha
6ac5689ce4 report: also recognize variants without underscores for <prefix>_all fields
For example: "pvs -o pv_all" and pvs -o pvall" are same.
2015-08-04 09:03:31 +02:00
Peter Rajnoha
71dbe47619 report: update comment for _is_same_field fn 2015-08-03 16:47:02 +02:00
Peter Rajnoha
a5b476a7d3 report: recognize report field name variants without any underscores too
Whenver reporting field name is registered with libdevmapper and if
the field name contains any number of underscores ('_'), libdm
can now automatically recognize any of its variant without any
underscores used.

For example:

..for underscores in prefixes:
  pvs -o pv_name
  pvs -o name
  pvs -o pvname (newly recognized besides pvname)

..for underscores in the name:
  lvs -o cache_mode
  lvs -o cachemode

..or even multiple underscores:
  pvs -o pv___na___me

It's all variant of the same field name.
2015-08-03 16:29:50 +02:00
Bryn M. Reeves
a161e29c59 dmsetup: Add --count and --interval to reports.
For example, to monitor active devices every second you can now run
dmsetup info -c --count 0.
2015-07-31 21:59:34 +01:00
Alasdair G Kergon
3cd644aeb5 libdm: Require librt for new dm_timestamp. 2015-07-29 19:30:22 +01:00
Alasdair G Kergon
a28fb37b9e libdm: Add dm_timestamp functions. 2015-07-29 19:21:07 +01:00
Alasdair G Kergon
a5491d3698 dmsetup: Accept vg/lv name format.
If there is exactly one / which is not the first character, check
for /dev/vg/lv (as dm_dir()/../$name i.e. /dev/mapper/../vg/lv.)
2015-07-29 12:24:36 +01:00
Alasdair G Kergon
af1c7bf0c7 libdm: Add dm_size_to_string to libdevmapper.
Moved out from lib/display and a little documentation added.
It's tuned to LVM's requirements historically and its behaviour
might not always be what you would expect.
2015-07-27 21:30:20 +01:00
Alasdair G Kergon
1612c570b6 libdm: Use wrappers for all malloc functions.
Move the DEBUG_MEM decision inside libdevmapper.so instead of exposing
it in libdevmapper.h which causes failures if the binary and library
were compiled with opposite debugging settings.
2015-07-22 23:11:48 +01:00
Zdenek Kabelac
c45e6e3c78 cleanup: avoid double assign
Variable n1 is assigned without using n1 before.
2015-07-15 13:10:22 +02:00
Peter Rajnoha
3ec4813ba2 coverity: fix missing initialization
... Using uninitialized value "lockd_state" when calling "lockd_vg"
(even though lockd_vg assigns 0 to the lockd_state, but it looks at
previous state of lockd_state just before that so we need to have
that properly initialized!)

libdm/libdm-report.c:2934: uninit_use_in_call: Using uninitialized value "tm". Field "tm.tm_gmtoff" is uninitialized when calling "_get_final_time".

daemons/lvmlockd/lvmlockctl.c:273: uninit_use_in_call: Using uninitialized element of array "r_name" when calling "format_info_r_action". (just added FIXME as this looks unfinished?)
2015-07-08 14:53:30 +02:00
Jonathan Brassow
4daea88516 clean-up: typos s/bellow/below/ 2015-07-06 10:15:11 -05:00
Alasdair G Kergon
810ab095e6 macros: Wrap PRI with FMT.
Create a set of wrappers with embedded % such as
  #define FMTu64 "%" PRIu64
2015-07-06 15:09:17 +01:00
Zdenek Kabelac
a900d150e4 thin: move pool messaging from resume to suspend
Existing messaging intarface for thin-pool has a few 'weak' points:

* Message were posted with each 'resume' operation, thus not allowing
activation of thin-pool with the existing state.

* Acceleration skipped suspend step has not worked in cluster,
since clvmd resumes only nodes which are suspended (have proper lock
state).

* Resume may fail and code is not really designed to 'fail' in this
phase (generic rule here is resume DOES NOT fail unless something serious
is wrong and lvm2 tool usually doesn't handle recovery path in this case.)

* Full thin-pool suspend happened, when taken a thin-volume snapshot.

With this patch the new method relocates message passing into suspend
state.

This has a few drawbacks with current API, but overal it performs
better and gives are more posibilities to deal with errors.

Patch introduces a new logic for 'origin-only' suspend of thin-pool and
this also relates to thin-volume when taking snapshot.

When suspend_origin_only operation is invoked on a pool with
queued messages then only those messages are posted to thin-pool and
actual suspend of thin pool and data and metadata volume is skipped.

This makes taking a snapshot of thin-volume lighter operation and
avoids blocking of other unrelated active thin volumes.

Also fail now happens in 'suspend' state where the 'Fail' is more expected
and it is better handled through error paths.

Activation of thin-pool is now not sending any message and leaves upto a tool
to decided later how to finish unfinished double-commit transaction.

Problem which needs some API improvements relates to the lvm2 tree
construction. For the suspend tree we do not add target table line
into the tree, but only a device is inserted into a tree.
Current mechanism to attach messages for thin-pool requires the libdm
to know about thin-pool target, so lvm2 currently takes assumption, node
is really a thin-pool and fills in the table line for this node (which
should be ensured by the PRELOAD phase, but it's a misuse of internal API)
we would possibly need to be able to attach message to 'any' node.

Other thing to notice - current messaging interface in thin-pool
target requires to suspend thin volume origin first and then send
a create message, but this could not have any 'nice' solution on lvm2
side and IMHO we should introduce something like 'create_after_resume'
message.

Patch also changes the moment, where lvm2 transaction id is increased.
Now it happens only after successful finish of kernel transaction id
change. This change was needed to handle properly activation of pool,
which is in the middle of unfinished transaction, and also this corrects
usage of thin-pool by external apps like Docker.
2015-07-03 16:13:14 +02:00
Zdenek Kabelac
5bef18f2eb libdm: support for posting messages in suspend
Add support for sending message in suspend tree for thin-pools.
When this operation is requested whole subtree suspend is then skipped.

This is experimantal support for new lvm2 code for sending message
in suspend phase where 'thin-pool origin-only suspend' will send
messages instead of really suspending thin-pool tree.

When suspening thin volume origin-only - only thin volume is suspended,
then messages are posted and thin-pool suspend is skipped.
2015-07-03 16:13:14 +02:00
Peter Rajnoha
9cee94372a report: select: add handler to recognize fuzzy time specification
Recognize date and time specification within selection criteria
that is formulated in a more free-form way besides to the original
basic YYYY-MM-DD HH:MM format that libdevmapper supports.

Currently, this free-form format is recognized for lv_time field.

Users are able to use expressions from this set:
  - weekday names ("Sunday" - "Saturday" or abbreviated as "Sun" - "Sat")
  - labels for points in time ("noon", "midnight")
  - labels for a day relative to current day ("today", "yesterday")
  - points back in time with relative offset from today (N is a number)
    ( "N" "seconds"/"minutes"/"hours"/"days"/"weeks"/"years" "ago")
    ( "N" "secs"/"mins"/"hrs" ... "ago")
    ( "N" "s"/"m"/"h" ... "ago")
  - time specification either in hh:mm:ss format or with AM/PM suffixes
  - month names ("January" - "December" or abbreviated as "Jan" - "Dec")

For example:

$ date
Fri Jul  3 10:11:13 CEST 2015

$ lvmconfig --type full report/time_format
time_format="%a %Y-%m-%d %T %z %Z [%s]"

$ lvs
  LV    VG     Time
  lvol0 vg     Fri 2014-08-22 21:25:41 +0200 CEST [1408735541]
  lvol2 vg     Sun 2015-04-26 14:52:20 +0200 CEST [1430052740]
  root  fedora Wed 2015-05-27 08:09:21 +0200 CEST [1432706961]
  swap  fedora Wed 2015-05-27 08:09:21 +0200 CEST [1432706961]
  lvol1 vg     Tue 2015-06-30 03:25:43 +0200 CEST [1435627543]
  lvol3 vg     Tue 2015-06-30 14:52:23 +0200 CEST [1435668743]
  lvol6 vg     Wed 2015-07-01 13:35:56 +0200 CEST [1435750556]
  lvol4 vg     Thu 2015-07-02 12:12:02 +0200 CEST [1435831922]
  lvol5 vg     Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

$ lvs -S 'time=yesterday'
  LV    VG   Time
  lvol4 vg   Thu 2015-07-02 12:12:02 +0200 CEST [1435831922]
  lvol5 vg   Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

$ lvs -S 'time since "June 30"'
  LV    VG   Time
  lvol1 vg   Tue 2015-06-30 03:25:43 +0200 CEST [1435627543]
  lvol3 vg   Tue 2015-06-30 14:52:23 +0200 CEST [1435668743]
  lvol6 vg   Wed 2015-07-01 13:35:56 +0200 CEST [1435750556]
  lvol4 vg   Thu 2015-07-02 12:12:02 +0200 CEST [1435831922]
  lvol5 vg   Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

$ lvs -S 'time since "noon June 30"'
  LV    VG   Time
  lvol3 vg   Tue 2015-06-30 14:52:23 +0200 CEST [1435668743]
  lvol6 vg   Wed 2015-07-01 13:35:56 +0200 CEST [1435750556]
  lvol4 vg   Thu 2015-07-02 12:12:02 +0200 CEST [1435831922]
  lvol5 vg   Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

$ lvs -S 'time since "2 July 9AM"'
  LV    VG   Time
  lvol4 vg   Thu 2015-07-02 12:12:02 +0200 CEST [1435831922]
  lvol5 vg   Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

$ lvs -S 'time since "2 July 1PM"'
  LV    VG   Time
  lvol5 vg   Thu 2015-07-02 14:30:32 +0200 CEST [1435840232]

...and so on.
2015-07-03 10:51:31 +02:00
Peter Rajnoha
3b1422c45c report: call appropriate handler to evaluate fuzzy reserved names and dynamic reserved values
Wire the dm_report_reserved_handler instance call in reporting/selection
infrastructure to handle reserved value actions (currently only
DM_REPORT_RESERVED_PARSE_FUZZY_NAME and DM_REPORT_RESERVED_GET_DYNAMIC_VALUE
actions).
2015-07-03 10:47:38 +02:00
Peter Rajnoha
335707b0e2 report: add infrastructure to recognize fuzzy reserved names and returning dynamic reserved values
With fuzzy names we mean the names for which it's hard or even impossible
to enumerate all possible variations of the name - the name needs to
be evaluated. An example of fuzzy name is a name which has a base
(substring) which matches and it can contain arbitrary variations
around this base. We can cover human language better with fuzzy
names as people may use several different names (or sentences) to
denote the same thing.

With dynamic values we mean the values which are not constants
and they need to be evaluated in runtime. An example of dynamic
value is a value which depends on current system state (e.g. time,
current configuration or any other state which may change and it
needs runtime evaluation).

There's a handler that can be registered with reporting/selection
using dm_report_reserved_handler instance. This is a central point
in which the computation/evaluation happens when processing reserved
values. Currently, there are two actions declared:

  DM_REPORT_RESERVED_PARSE_FUZZY_NAME
  (translates fuzzy name into canonical name)

  DM_REPORT_RESERVED_GET_DYNAMIC_VALUE
  (gets value for canonical name)

The handler is then registered as value in struct
dm_report_reserved_value (see explaining comments besided
the struct dm_report_reserved_value in libdevmapper.h).

Also, this patch provides support for simple caching of values
used during report/selection via dm_report_value_cache_{set,get}.
This is supposed to be used mainly in the dm_report_reserved_handler
instances to save values among calls so all the handler calls work
with the same base value used in computation/evaluation and/or
possibly to save resources if the evaluation is more time-consuming.
The cache is attached to the dm_report handle and so the cache is
dropped one dm_report is dropped.
2015-07-03 10:47:09 +02:00