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'lvchange' is used to alter a RAID 1 logical volume's write-mostly and
write-behind characteristics. The '--writemostly' parameter takes a
PV as an argument with an optional trailing character to specify whether
to set ('y'), unset ('n'), or toggle ('t') the value. If no trailing
character is given, it will set the flag.
Synopsis:
lvchange [--writemostly <PV>:{t|y|n}] [--writebehind <count>] vg/lv
Example:
lvchange --writemostly /dev/sdb1:y --writebehind 512 vg/raid1_lv
The last character in the 'lv_attr' field is used to show whether a device
has the WriteMostly flag set. It is signified with a 'w'. If the device
has failed, the 'p'artial flag has priority.
Example ("nosync" raid1 with mismatch_cnt and writemostly):
[~]# lvs -a --segment vg
LV VG Attr #Str Type SSize
raid1 vg Rwi---r-m 2 raid1 500.00m
[raid1_rimage_0] vg Iwi---r-- 1 linear 500.00m
[raid1_rimage_1] vg Iwi---r-w 1 linear 500.00m
[raid1_rmeta_0] vg ewi---r-- 1 linear 4.00m
[raid1_rmeta_1] vg ewi---r-- 1 linear 4.00m
Example (raid1 with mismatch_cnt, writemostly - but failed drive):
[~]# lvs -a --segment vg
LV VG Attr #Str Type SSize
raid1 vg rwi---r-p 2 raid1 500.00m
[raid1_rimage_0] vg Iwi---r-- 1 linear 500.00m
[raid1_rimage_1] vg Iwi---r-p 1 linear 500.00m
[raid1_rmeta_0] vg ewi---r-- 1 linear 4.00m
[raid1_rmeta_1] vg ewi---r-p 1 linear 4.00m
A new reportable field has been added for writebehind as well. If
write-behind has not been set or the LV is not RAID1, the field will
be blank.
Example (writebehind is set):
[~]# lvs -a -o name,attr,writebehind vg
LV Attr WBehind
lv rwi-a-r-- 512
[lv_rimage_0] iwi-aor-w
[lv_rimage_1] iwi-aor--
[lv_rmeta_0] ewi-aor--
[lv_rmeta_1] ewi-aor--
Example (writebehind is not set):
[~]# lvs -a -o name,attr,writebehind vg
LV Attr WBehind
lv rwi-a-r--
[lv_rimage_0] iwi-aor-w
[lv_rimage_1] iwi-aor--
[lv_rmeta_0] ewi-aor--
[lv_rmeta_1] ewi-aor--
Revert commit 31c24dd9f2. This commit
was used to force a RAID device-mapper table to be loaded into the
kernel despite the fact that it was identical to the one already
loaded. The effect allowed a RAID array with a transiently failed
device to refresh and reintegrate the failed device. This operation
is better done in the kernel on a 'resume'. Since,
'lvchange --refresh' already performs a suspend/resume cycle, the
above commit is not needed once the kernel change is made. Reverting
the commit removes an unnecessary (at least for now) change to the
device-mapper interface.
I've updated the dm_status_raid structure and dm_get_status_raid()
function to make it handle the new kernel status fields that will
be coming in dm-raid v1.5.0. It is backwards compatible with the
old status line - initializing the new fields to '0'. The new
structure is also more amenable to future changes. It includes a
'reserved' field that is currently initialized to zero but could
be used to hold flags describing new features. It also now uses
pointers for the character strings instead of attempting to allocate
their space along with the structure (causing the size of the
structure to be variable). This allows future fields to be appended.
The new fields that are available are:
- sync_action : shows what the sync thread in the kernel is doing
(idle, frozen, resync, recover, check, repair, or
reshape)
- mismatch_count: shows the number of discrepancies which were
found or repaired by a "check" or "repair"
process, respectively.
Previous commit included changes to WHATSNEW, but the code changes
were missing. Here is the description from the previous commit:
commit bbc6378b73
Author: Jonathan Brassow <jbrassow@redhat.com>
Date: Thu Feb 21 11:31:36 2013 -0600
RAID: Make 'lvchange --refresh' restore transiently failed RAID PVs
A new function (dm_tree_node_force_identical_table_reload) was added to
avoid the suppression of identical table reloads. This allows RAID LVs
to reload the on-disk superblock information that contains which devices
have failed and the bitmaps. If the failed device has returned, this has
the effect of restoring the device and initiating recovery. Without this
patch, the user had to completely deactivate their RAID LV and re-activate
it in order to restore the failed device. Now they simply need to
suspend and resume (which is done by 'lvchange --refresh').
The identical table suppression is only avoided if the LV is not PARTAIL
(i.e. all of it's devices can be seen and read by LVM) and the kernel
status of the array contains failed devices. In other words, the function
will only be called in the case where we may have success in restoring
a failed device in the array.
There's a possibility to interconnect the dm_config_node with an
ID, which in our case is used to reference the configuration
definition ID from config_settings.h. So simply interconnecting
struct dm_config_node with struct cfg_def_item.
This patch also adds support for enhanced config node output besides
existing "output line by line". This patch adds a possibility to
register a callback that gets called *before* the config node is
processed line by line (for example to include any headers on output)
and *after* the config node is processed line by line (to include any
footers on output). Also, it adds the config node reference itself
as the callback arg in addition to have a possibility to extract more
information from the config node itself if needed when processing the
output callback (e.g. the key name, the id, or whether this is a
section or a value etc...).
If the config node from lvm.conf/--config tree is recognized and valid,
it's always coupled with the config node definition ID from
config_settings.h:
struct dm_config_node {
int id;
const char *key;
struct dm_config_node *parent, *sib, *child;
struct dm_config_value *v;
}
For example if the dm_config_node *cn holds "devices/dev" configuration,
then the cn->id holds "devices_dev_CFG" ID from config_settings.h, -1 if
not found in config_settings.h and 0 if matching has not yet been done.
To support the enhanced config node output, a new structure has been
defined in libdevmapper to register it:
struct dm_config_node_out_spec {
dm_config_node_out_fn prefix_fn; /* called before processing config node lines */
dm_config_node_out_fn line_fn; /* called for each config node line */
dm_config_node_out_fn suffix_fn; /* called after processing config node lines */
};
Where dm_config_node_out_fn is:
typedef int (*dm_config_node_out_fn)(const struct dm_config_node *cn, const char *line, void *baton);
(so in comparison to existing callbacks for config node output, it has
an extra dm_config_node *cn arg in addition)
This patch also adds these functions to libdevmapper:
- dm_config_write_node_out
- dm_config_write_one_node_out
...which have exactly the same functionality as their counterparts
without the "out" suffix. The "*_out" functions adds the extra hooks
for enhanced config output (prefix_fn and suffix_fn mentioned above).
One can still use the old interface for config node output, this is
just an enhancement for those who'd like to modify the output more
extensively.
Export this functionality from libdevmapper just for
convenience and general use when reading boolean values
which could be defined either in a numeric way with 0/1
or by using strings with "true"/"false", "yes"/"no",
"on"/"off", "y"/"n".
Similar to the way thin* accesses its kernel status, we add a method
for RAID to grab the various values in its status output without the
higher levels (LVM) having to understand how to parse the output.
Added functions include:
- lib/activate/dev_manager.c:dev_manager_raid_status()
Pulls the status line from the kernel
- libdm/libdm-deptree.c:dm_get_status_raid()
Parses status line and puts components into dm_status_raid struct
- lib/activate/activate.c:lv_raid_dev_health()
Accesses dm_status_raid to deliver raid dev_health string
The new structure and functions can provide a more unified way to access
status information. ('lv_raid_percent' could switch to using these
functions, for example.)
Add log/debug_classes to lvm.conf to allow debug messages to be
classified and filtered at runtime.
The dm_errno field is only used by log_error(), so I've redefined it
for log_debug() messages to hold the message class.
By default, all existing messages appear, but we can add categories that
generate high volumes of data, such as logging all traffic to/from
lvmetad.
Just like we already have existing mangling support for
device-mapper names, we need exactly the same for device-mapper
UUIDs as their character whitelist is wider than what udev supports.
In case udev is used to create entries in /dev based on UUIDs
and these UUIDs contain characters not supported by udev,
we'll end up with incorrect /dev content for such devices.
So we need to mangle them to a form that is supported by udev.
The mangling used for UUIDs follows the mangling used for names
(that is already supported and used throughout). That means,
setting the name mangling mode via dm_set_name_mangling_mode
affects mangling used for UUIDs in exactly the same manner.
It would be useless to add a new and separate
dm_set_uuid_mangling_mode fn, we'll reuse existing interface.
A regression introduced in 2.02.89 (11e520256b)
caused the lvm dumpconfig <node> to print out
the node as well as its subsequent siblings.
The information about "only_one" mode got lost.
Before this patch (just an example node):
# lvm dumpconfig global/use_lvmetad
use_lvmetad=1
thin_check_executable="/usr/sbin/thin_check"
thin_check_options="-q"
(...all nodes to the end of the section)
With this patch applied:
# lvm dumpconfig global/use_lvmetad
use_lvmetad=1
With latest changes in the udev, some deprecated functions were removed
from libudev amongst which there was the "udev_get_dev_path" function
we used to compare a device directory used in udev and directore set in
libdevmapper. The "/dev" is hardcoded in udev now (udev version >= 183).
Amongst other changes and from packager's point of view, it's also
important to note that the libudev development library ("libudev-devel")
could now be a part of the systemd development library ("systemd-devel")
because of the udev + systemd merge.
Should be faster then strncpy - since we could avoid clearing 4KB pages
with each strncpy(...,PATH_MAX).
Also it's easy to check whether string fit - and eventually avoid
to continue working we incomplete string.
If dm_task_get_name or dm_task_get_names gets called, these will return
unmangled form of the names so the name mangling stays totally transparent
to any libdevmapper user (unless DM_STRING_MANGLING_NONE is used in which
case the name is not touched and it is is returned as it is in kernel).
For example:
dmsetup create "a b" - will create a\x20b device in kernel and so udev will
create /dev/mapper/a\x20b
dm_task_get_name/names will still return "a b"
In AUTO mode, the libdevmapper user can still query the device by using
the mangled ("a\x20b") or unmangled form of the name when calling dm_task_set_name.
If mangled name is provided, it's detected and the name is kept as it is.
If unmangled name is provided, it will be mangled. IOW in AUTO mode it's
totally transparent and it should not require any changes in the code
using libdevmapper.
However, any libdevmapper user must be aware of the fact that the mangled form
of the name appears in /dev/mapper (udev just can't deal with those blacklisted
characters).
dm_task_get_name_mangled will always return mangled form of the name while
the dm_task_get_name_unmangled will always return unmangled form of the name
irrespective of the global setting (dm_set/get_name_mangling_mode).
This is handy in situations where we need to detect whether the name is already
mangled or not. Also display functions make use of it.
If dm_task_set_name/newname is called, the name provided will be
automatically translated to correct encoded form with the hex enconding
so any character not on udev whitelist will be mangled with \xNN
format where NN is hex value of the character used.
By default, the name mangling mode used is the one set during
configure with the '--with-default-name-mangling' option.
This option configures the default name mangling mode used, one of:
AUTO, NONE and HEX.
The name mangling is primarily used to support udev character whitelist
(0-9, A-Z, a-z, #*-.:=@_) so any character that is not on udev whitelist
will get translated into an encoded form \xNN where NN is the hex value
of the character.
It was not possible to pass down the DM_[FORCE|NO]SYNC flags to
'dm_tree_node_add_raid_target'. This meant that converting to 'raid1' from
'mirror' would cause a full resync. (It also meant that '--nosync' was
ineffective when creating a 'raid1' LV.)
I've taken the 'reserved' parameter in 'dm_tree_node_add_raid_target' and
used it for the "flags" parameter. Now it is possible to pass the sync
flags and any other flags that may come up.
This is accomplished by reading associated sysfs information. For a dm device,
this is /sys/dev/block/major:minor/dm/name (supported in kernel version >= 2.6.29,
for older kernels, the behaviour is the same as for non-dm devices).
For a non-dm device, this is a readlink on /sys/dev/block/major:minor, e.g.
/sys/dev/block/253:0 --> ../../devices/virtual/block/dm-0.
The last component of the path is a proper kernel name (block device name).
One can request to read only kernel names by setting the 'prefer_kernel_name'
argument if needed.
LVM- prefix.
Try harder not to leave stray empty devices around (locally or remotely) when
reverting changes after failures while there are inactive tables.
Add dm_get_status_thin_pool and dm_get_status_thin functions to
parse 'params' argument which is received via dm_get_next_target.
Returns filed structure allocated from given mempool.
Remove DM_THIN_ERROR_DEVICE_ID from API.
Remove API warning.
Drop code that was using DM_THIN_ERROR_DEVICE_ID (already commented)
Remove debug message which slipped in through some previous commit.
A little code shuffling and adding support for
DM_THIN_ERROR_DEVICE_ID which might be eventually be used
for activation of thin which is going to be deleted.
For now we do not need it lvm.
The current code does not always assign proper udev flags to sub-LVs (e.g.
mirror images and log LVs). This shows up especially during a splitmirror
operation in which an image is split off from a mirror to form a new LV.
A mirror with a disk log is actually composed of 4 different LVs: the 2
mirror images, the log, and the top-level LV that "glues" them all together.
When a 2-way mirror is split into two linear LVs, two of those LVs must be
removed. The segments of the image which is not split off to form the new
LV are transferred to the top-level LV. This is done so that the original
LV can maintain its major/minor, UUID, and name. The sub-lv from which the
segments were transferred gets an error segment as a transitory process
before it is eventually removed. (Note that if the error target was not put
in place, a resume_lv would result in two LVs pointing to the same segment!
If the machine crashes before the eventual removal of the sub-LV, the result
would be a residual LV with the same mapping as the original (now linear) LV.)
So, the two LVs that need to be removed are now the log device and the sub-LV
with the error segment. If udev_flags are not properly set, a resume will
cause the error LV to come up and be scanned by udev. This causes I/O errors.
Additionally, when udev scans sub-LVs (or former sub-LVs), it can cause races
when we are trying to remove those LVs. This is especially bad during failure
conditions.
When the mirror is suspended, the top-level along with its sub-LVs are
suspended. The changes (now 2 linear devices and the yet-to-be-removed log
and error LV) are committed. When the resume takes place on the original
LV, there are no longer links to the other sub-lvs through the LVM metadata.
The links are implicitly handled by querying the kernel for a list of
dependencies. This is done in the '_add_dev' function (which is recursively
called for each dependency found) - called through the following chain:
_add_dev
dm_tree_add_dev_with_udev_flags
<*** DM / LVM divide ***>
_add_dev_to_dtree
_add_lv_to_dtree
_create_partial_dtree
_tree_action
dev_manager_activate
_lv_activate_lv
_lv_resume
lv_resume_if_active
When udev flags are calculated by '_get_udev_flags', it is done by referencing
the 'logical_volume' structure. Those flags are then passed down into
'dm_tree_add_dev_with_udev_flags', which in turn passes them to '_add_dev'.
Unfortunately, when '_add_dev' is finding the dependencies, it has no way to
calculate their proper udev_flags. This is because it is below the DM/LVM
divide - it doesn't have access to the logical_volume structure. In fact,
'_add_dev' simply reuses the udev_flags given for the initial device! This
virtually guarentees the udev_flags are wrong for all the dependencies unless
they are reset by some other mechanism. The current code provides no such
mechanism. Even if '_add_new_lv_to_dtree' were called on the sub-devices -
which it isn't - entries already in the tree are simply passed over, failing
to reset any udev_flags. The solution must retain its implicit nature of
discovering dependencies and be able to go back over the dependencies found
to properly set the udev_flags.
My solution simply calls a new function before leaving '_add_new_lv_to_dtree'
that iterates over the dtree nodes to properly reset the udev_flags of any
children. It is important that this function occur after the '_add_dev' has
done its job of querying the kernel for a list of dependencies. It is this
list of children that we use to look up their respective LVs and properly
calculate the udev_flags.
This solution has worked for single machine, cluster, and cluster w/ exclusive
activation.
Make limits for thin data_block_size and device_id part of public API.
FIXME: read them possible from some kernel header file in the future ?
But we may need to support different values for different versions ?
Add dm_device_has_mounted_fs fn to check mounted filesystem on a device.
This requires sysfs directory to be correctly set via dm_set_sysfs_dir
(/sys by default). If sysfs dir is not used or it's set incorrectly,
dm_device_has_{holders,mounted_fs} will return 0!
Makes dumpconfig whole-section output wrong in a different way from before,
but we should be able to merge cft_cmdline properly into cmd->cft now and
remove cascade.
functionality. A number of bugs (copied and pasted all over the code) should
disappear:
- most string lookup based on dm_config_find_node would segfault when
encountering a non-zero integer (the intention there was to print an
error message instead)
- check for required sections in metadata would have been satisfied by
values as well (i.e. not sections)
- encountering a section in place of expected flag value would have
segfaulted (due to assumed but unchecked cn->v != NULL)
leaving behind the LVM-specific parts of the code (convenience wrappers that
handle `struct device` and `struct cmd_context`, basically). A number of
functions have been renamed (in addition to getting a dm_ prefix) -- namely,
all of the config interface now has a dm_config_ prefix.
This patch adds the ability to upconvert a raid1 array - say from 2-way to
3-way. It does not yet support upconverting linear to n-way.
The 'raid' device-mapper target allows for individual components (images) of
an array to be specified for rebuild. This mechanism is used when adding
new images to the array so that the new images can be resync'ed while the
rest of the images in the array can remain 'in-sync'. (There is no
mirror-on-mirror layering required.)
~> lvconvert --splitmirrors 1 --trackchanges vg/lv
The '--trackchanges' option allows a user the ability to use an image of
a RAID1 array for the purposes of temporary read-only access. The image
can be merged back into the array at a later time and only the blocks that
have changed in the array since the split will be resync'ed. This
operation can be thought of as a partial split. The image is never completely
extracted from the array, in that the array reserves the position the device
occupied and tracks the differences between the array and the split image via
a bitmap. The image itself is rendered read-only and the name (<LV>_rimage_*)
cannot be changed. The user can complete the split (permanently splitting the
image from the array) by re-issuing the 'lvconvert' command without the
'--trackchanges' argument and specifying the '--name' argument.
~> lvconvert --splitmirrors 1 --name my_split vg/lv
Merging the tracked image back into the array is done with the '--merge'
option (included in a follow-on patch).
~> lvconvert --merge vg/lv_rimage_<n>
The internal mechanics of this are relatively simple. The 'raid' device-
mapper target allows for the specification of an empty slot in an array
via '- -'. This is what will be used if a partial activation of an array
is ever required. (It would also be possible to use 'error' targets in
place of the '- -'.) If a RAID image is found to be both read-only and
visible, then it is considered separate from the array and '- -' is used
to hold it's position in the array. So, all that needs to be done to
temporarily split an image from the array /and/ cause the kernel target's
bitmap to track (aka "mark") changes made is to make the specified image
visible and read-only. To merge the device back into the array, the image
needs to be returned to the read/write state of the top-level LV and made
invisible.
Adding debuging functionality to lock and unlock memory pool.
2 ways to debug code:
crc - is default checksum/hash of the locked pool.
It gets slower when the pool is larger - so the check is only
made when VG is finaly released and it has been used more then
once.Thus the result is rather informative.
mprotect - quite fast all the time - but requires more memory and
currently it is using posix_memalign() - this could be
later modified to use dm_malloc() and align internally.
Tool segfaults when locked memory is modified and core
could be examined for faulty code section (backtrace).
Only fast memory pools could use mprotect for now -
so such debug builds cannot be combined with DEBUG_POOL.
Implementation described in doc/lvm2-raid.txt.
Basic support includes:
- ability to create RAID 1/4/5/6 arrays
- ability to delete RAID arrays
- ability to display RAID arrays
Notable missing features (not included in this patch):
- ability to clean-up/repair failures
- ability to convert RAID segment types
- ability to monitor RAID segment types
and use this for the LVM critical section logic. Also report an error if
code tries to load a table while any device is known to be in the
suspended state.
(If the variety of problems these changes are showing up can't be fixed
before the next release, the error messages can be reduced to debug
level.)
dm_hash binary functions takes void* key - so there is no need to cast
pointers to char* (also the hash key does not have trailing '\0').
This is slight API change, but presents no change for the API user side
it just allows to write code easier as the casting could be removed.
As dm_report_field_string() doesn't modify content of data pointer,
it can be marked as const.
It's slight API change - but doesn't require any change on the user side
and supports wider range of arguments without const casting.
(i.e. we may use as paramater const lv struct this way: &lv->name)
Add new function dm_task_set_add_node() to select between 2 types
of node creation in device directory.
DM_ADD_NODE_ON_RESUME is now default and ensures node is created on
resume. Old original behavior is accessible with DM_ADD_NODE_ON_CREATE.
In this case node would be created during dmsetup create --notable.
For the user 2 new options for dmsetup create are added:
[{--addnodeonresume | --addnodeoncreate }]
Properly working node creation on resume is needed for proper operation
stacking and ability to correctly check in which state the device should
after whole udev transation.
As 'const' types are also passed to macro dm_list_struct_base -
keep offset calculation with const char pointers.
Fixes several gcc constness warnings.
Change API interface to accept even completely const array patterns.
This should present no change for libdm users and allows to pass
pattern arrays without cast to const char **.
Detect existence of new SELinux selabel interface during configure.
Use new dm_prepare_selinux_context instead of dm_set_selinux_context.
We should set the SELinux context before the actual file system object creation.
The new dm_prepare_selinux_context function sets this using the selabel_lookup
fn in conjuction with the setfscreatecon fn. If selinux/label.h interface
(that should be a part of the selinux library) is not found during configure,
we fallback to the original matchpathcon function instead.
Rather than hard code the size of the field, use a #define, so we can re-use.
The #define will be needed in a future patch when we extend the reporting
infrastructure to have 'get' and 'set' functions for each field, allowing
lvm2app functions which query any report field. In order to provide a
generic lookup based on the field id, we will define a type containing this
field id, and thus, we will need to re-use the length of this string as
it's defined inside libdevmapper.h.
mirrors, we must also check that the log daemon (cmirrord) is running.
The log module can be auto-loaded, but the daemon cannot be
"auto-started". Failing to check for the daemon produces cryptic
messages that customers have a hard time deciphering. (The system
messages do report that the log daemon is not running, but people
don't seem to find this message easily.)
Here are examples of what is printed when the module is available,
but the log daemon has not been started.
[root@bp-01 LVM2]# lvcreate -m1 -l1 -n lv vg
Shared cluster mirrors are not available.
[root@bp-01 LVM2]# lvcreate -m1 -l1 -n lv vg -v
Setting logging type to disk
Finding volume group "vg"
Archiving volume group "vg" metadata (seqno 3).
Creating logical volume lv
Executing: /sbin/modprobe dm-log-userspace
Cluster mirror log daemon is not running
Shared cluster mirrors are not available.
Creating volume group backup "/etc/lvm/backup/vg" (seqno 4).
Switch dmeventd to use dm_create_lockfile and drop duplicate code.
Allow clvmd pidfile to be configurable.
Switch cmirrord and clvmd to use dm_create_lockfile.
Introducing dm_tree_node_set_presuspend_node() for presuspending child
node (i.e. replicator control target) before deactivation of parent node
(i.e. replicator-dev target).
This patch presents no functional change to current dtree - only
replicator target currently sets presuspend node for dev nodes.
This rule appeared in udev v152 and it helps us to support spurious events
where we didn't have any flags set (events originated in udevadm trigger
or the watch rule). These flags are important to direct the rule application.
Now, with the help of this rule, we can regenerate old udev db content.
To implement this correctly, we need to flag all proper DM udev events with
DM_UDEV_PRIMARY_SOURCE_FLAG. That happens automatically for all ioctls
generating events originated in libdevmapper.
- add DM_UDEV_DISABLE_LIBRARY_FALLBACK udev flag to rely on udev only
- export dm_udev_create_cookie function to create new cookies on demand
- add --udevcookie, udevcreatecookie and udevreleasecookie for dmsetup
(to support "udev transactions" where one cookie value can be used for
several dmsetup calls)
- don't use DM_UDEV_DISABLE_CHECKING env. var. anymore and set the state
automatically (based on udev and libdevmapper dev path comparison)
Introduces new libdevmapper function dm_tree_node_add_snapshot_merge_target
Verifies that the kernel (dm-snapshot) provides the 'snapshot-merge'
target.
Activate origin LV as snapshot-merge target. Using snapshot-origin
target would be pointless because the origin contains volatile data
while a merge is in progress.
Because snapshot-merge target is activated in place of the
snapshot-origin target it must be resumed after all other snapshots
(just like snapshot-origin does) --- otherwise small window for data
corruption would exist.
Ideally the merging snapshot would not be activated at all but if it is
to be activated (because snapshot was already active) it _must_ be done
after the snapshot-merge. This insures that DM's snapshot-merge target
will perform exception handover in the proper order (new->resume before
old->resume). DM's snapshot-merge does support handover if the reverse
sequence is used (old->resume before new->resume) but DM will fail to
resume the old snapshot; leaving it suspended.
To insure the proper activation sequence dm_tree_activate_children() was
updated to accommodate an additional 'activation_priority' level. All
regular snapshots are 0, snapshot-merge is 1, and merging snapshot is 2.
Sometimes it is really needed to switch off udev checking and the warnings we show when
we detect that udev has not done its job right - the messages like "Udev should have done
this and that. Falling back to direct node creation/removal. " etc.
This would be especially handy while setting DM_DEV_DIR env var that could be set to a
different location than standard /dev (udev can't create nodes/symlinks out of that one
directory that is configured into udevd). The exact same situation happens while we're
running our tests.
This provides better support for environments where udev rules are installed
but udev_sync is not compiled in (however, using udev_sync is highly
recommended). It also provides consistent and expected functionality even
when '--noudevsync' option is used.
There is still requirement for kernel >= 2.6.31 for the flags to work though
(it uses DM cookies to pass the flags into the kernel and set them in udev
event environment that we can read in udev rules).
'last_rule' option has been removed from udev (version >= 147).
From now on, we require foreign rules to check and honor
ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG} instead. Foreign
rules should be skipped totally when this flag is set.
- we have these levels when the udev rules are processed:
10-dm.rules --> [11-dm-<subsystem>.rules] --> [12-dm-permissions.rules] -->
13-dm-disk.rules --> [...all the other foreign rules...] --> 95-dm-notify.rules
- each level can be disabled now by
DM_UDEV_DISABLE_{DM, SUBSYSTEM, DISK, OTHER}_RULES_FLAG
- add DM_UDEV_DISABLE_DM_RULES_FLAG to disable 10-dm.rules
- add DM_UDEV_DISABLE_OTHER_RULES_FLAG to disable all the other (non-dm) rules.
We cutoff these rules by using the 'last_rule', so this one should really be
used with great care and in well-founded situations. We use this for lvm's
hidden and layer devices now.
- add a parameter for add_dev_node, rm_dev_node and rename_dev_node so it's
possible to switch on/off udev checks
- use DM_UDEV_DISABLE_DM_RULES_FLAG and DM_UDEV_DISABLE_SUBSYSTEM_RULES_FLAG
if there's no cookie set and we have resume, remove and rename ioctl.
This could happen when someone uses the libdevmapper that is compiled with
udev_sync but the software does not make use of it. This way we can switch
off the rules and fallback to libdevmapper node creation so there's no
udev/libdevmapper race.
Is an application uses query and set major:minor
to device, it should not fallback to default major by default.
Add new function whoich allows that (and use it in lvm2).
- it can support multiple segments, but note that
to work properly, correct IV (initialization vector)
offset parameter must be set properly.
Because most usage of IV start offset is when we join
several crypto segments together (so iv_offset is the segment
start offset), DM_CRYPT_IV_DEFAULT is defined to simplify
the process.
Function accepts the string in cipher agrument (already
including chainmode and iv type; chainmode and iv parameters are NULL
in this case) or user can provide split parameters which will
join into dm-crypt cipher specification "cipher-chainmode-iv".
All these parameters must be supplied in correct dm-crypt format.
