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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.
Supply offset to start of variable data area (so struct size can change
without breaking backward compatibility)
Add command that just returns the driver version
