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Commit Graph

123 Commits

Author SHA1 Message Date
Bryn M. Reeves
ab1b54c3e3 libdm: fix dm_stats leak in dm_stats_create()
The histogram changes adds a new error path to dm_stats_create().
Make sure that the dm_stats handle is properly destroyed if we fail
to create the histogram pool and check for failures setting the
program_id.
2015-09-07 12:08:34 +01:00
Bryn M. Reeves
0f5933ecc1 libdm: handle pool errors in dm_histogram_to_string() 2015-09-07 12:01:20 +01:00
Bryn M. Reeves
e75b4bc2df libdm: check dm_pool_begin_object() return value. 2015-09-07 11:52:54 +01:00
Bryn M. Reeves
36b09fd147 libdm: add missing error handling in _stats_parse_histogram()
Since we are growing an object in the histogram pool the return
value of dm_pool_grow_object() must be checked and error paths need
to abandon the object before returning.
2015-09-07 11:44:53 +01:00
Alasdair G Kergon
fb12308416 style: Standardise some error paths. 2015-09-05 23:56:30 +01:00
Bryn M. Reeves
cdca2782d2 libdm: fix uninitialized variable warnings on older gcc
Older versions of gcc aren't able to track the assignments of
local variables as well as the latest versions leading to spurious
warnings like:

libdm-stats.c:2183: warning: "len" may be used uninitialized in this
function
libdm-stats.c:2177: warning: "minwidth" may be used uninitialized in
this function

Both of these variables are in fact assigned in all possible paths
through the function and later compilers do not produce these
warnings.

There's no reason to not initialize these variables though and
it makes the function slightly easier to follow.

Also fix one use of 'unsigned' for a nr_bins value.
2015-09-04 11:46:48 +01:00
Bryn M. Reeves
f09e4f7b10 libdm: allow formatting histogram strings with no whitespace
Allow dm_histogram_to_string() to format histogram strings with
no whitespace by passing a width value less than zero.
2015-09-03 22:04:10 +01:00
Bryn M. Reeves
a0cf3d47f1 libdm: add latency histogram support
Add support for creating, parsing, and reporting dm-stats latency
histograms on kernels that support precise_timestamps.

Histograms are specified as a series of time values that give the
boundaries of the bins into which I/O counts accumulate (with
implicit lower and upper bounds on the first and last bins).

A new type, struct dm_histogram, is introduced to represent
histogram values and bin boundaries.

The boundary values may be given as either a string of values (with
optional unit suffixes) or as a zero terminated array of uint64_t
values expressing boundary times in nanoseconds.

A new bounds argument is added to dm_stats_create_region() which
accepts a pointer to a struct dm_histogram initialised with bounds
values.

Histogram data associated with a region is parsed during a call to
dm_stats_populate() and used to build a table of histogram values
that are pointed to from the containing area's counter set. The
histogram for a specified area may then be obtained and interogated
for values and properties.

This relies on kernel support to provide the boundary values in
a @stats_list response: this will be present in 4.3 and 4.2-stable. A
check for a minimum driver version of 4.33.0 is implemented to ensure
that this is present (4.32.0 has the necessary precise_timestamps and
histogram features but is unable to report these via @stats_list).

Access methods are provided to retrieve histogram values and bounds
as well as simple string representations of the counts and bin
boundaries.  Methods are also available to return the total count
for a histogram and the relative value (as a dm_percent_t) of a
specified bin.
2015-09-02 20:48:59 +01:00
Bryn M. Reeves
567189cc76 libdm: add per region precise timestamps property methods 2015-08-24 20:03:21 +01:00
Bryn M. Reeves
f4262026b6 libdm: add precise timestamps support to libdm-stats
Add support for the kernel precise_timestamps feature. This allows
regions to be created using counters with nanosecond precision.

A new dm_stats method, dm_stats_set_precise_timestamps() causes all
future regions created with this handle to attempt to enable precise
counters.
2015-08-24 20:03:21 +01:00
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
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
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
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