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Using log_warn to report missing symlinks as warning, since the command
itself returns as successful, we should not produce log_error().
log_warn is better fit here.
Cosmetic, since r is already 0 for the error path, no need to assign it there,
and r is assigned to 1 after switch command.
Also makes the code more readable.
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.
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.
~> 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.
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
We've used udev fallback code till now to check whether udev
created/removed the entries in /dev correctly and if not,
a repair was done (giving a warning messagea about that).
This patch adds a possibility to enable this additional check
and subsequent fallback only when required (debugging purposes
mostly) and trust udev completely.
So let's disable the fallback code by default and add a new
configuration option "activation/udev_fallback".
(The original code for creating the nodes will still be used
in case the device directory that is set in lvm.conf differs
from the one that udev uses and also when activation/udev_rules
is set to 0 - otherwise we would end up with no nodes/symlinks
at all)
To avoid modification of 'read-only' volume group structure
add a new structure to pass local data around the code for LV
activation.
As origin_only is one such flag - replace this parameter with new
struct lv_activate_opts.
More parameters might eventually become part of lv_activate_opts.
are affected by the move. (Currently it's possible for I/O to become
trapped between suspended devices amongst other problems.
The current fix was selected so as to minimise the testing surface. I
hope eventually to replace it with a cleaner one that extends the
deptree code.
Some lvconvert scenarios still suffer from related problems.
LVM doesn't behave correctly if running as non-root user,
there is warning when it detects it.
Despite this, it produces many error messages, saying nothing.
See https://bugzilla.redhat.com/show_bug.cgi?id=620571
This patch fixes two things:
1) Removes eror message from device_is_usable() which has no
information value anyway (real warning is printed inside it).
2) it fixes device-mapper initialization, if we support
core dm module autoload and device node is present, it should
fail early and not try recreate existing and correct node.
(non-root == permission denied here)
N.B. In future code should support user roles, some more
drastic checks in code are probably contraproductive now.
activated.
In order to achieve this, we need to be able to query whether
the origin is active exclusively (a condition of being able to
add an exclusive snapshot).
Once we are able to query the exclusive activation of an LV, we
can safely create/activate the snapshot.
A change to 'hold_lock' was also made so that a request to aquire
a WRITE lock did not replace an EX lock, which is already a form
of write lock.
Stop calling fs_unlock() from lv_de/activate().
Start using internal lvm fs cookie for dm_tree.
Stop directly calling dm_udev_wait() and
dm_tree_set/get_cookie() from activate code -
it's now called through fs_unlock() function.
Add lvm_do_fs_unlock()
Call fs_unlock() when unlocking vg where implicit unlock solves the
problem also for cluster - thus no extra command for clustering
environment is required - only lvm_do_fs_unlock() function is added
to call lvm's fs_unlock() while holding lvm_lock mutex in clvmd.
Add fs_unlock() also to set_lv() so the command waits until devices
are ready for regular open (i.e. wiping its begining).
Move fs_unlock() prototype to activation.h to keep fs.h private
in lib/activate dir and not expose other functions from this header.
A merged snapshot's DM device is made to use the "error" target as part
of lvm's transaction to merge a snapshot. This snapshot merge use-case
aside, any device using the error target shouldn't be scanned.
page.
Add ->target_name to segtype_handler to allow a more specific target
name to be returned based on the state of the segment.
Result of trying to merge a snapshot using a kernel that doesn't have
the snapshot-merge target:
Before:
# lvconvert --merge vg/snap
Can't expand LV lv: snapshot target support missing from kernel?
Failed to suspend origin lv
After:
# lvconvert --merge vg/snap
Can't process LV lv: snapshot-merge target support missing from kernel?
Failed to suspend origin lv
Unable to merge LV "snap" into it's origin.
to block when a mirror under a snapshot suffers a failure.
The problem has to do with label scanning. When a mirror suffers
a failure, the kernel blocks I/O to prevent corruption. When
LVM attempts to repair the mirror, it scans the devices on the
system for LVM labels. While mirrors are skipped during this
scanning process, snapshot-origins are not. When the origin is
scanned, it kicks up I/O to the mirror (which is blocked)
underneath - causing the label scan (an thus the repair operation)
to hang.
This patch simply bypasses snapshot-origin devices when doing
labels scans (while ignore_suspended_devices() is set). This
fixes the issue.
Ignore snapshots when performing mirror recovery beneath an origin.
Pass LCK_ORIGIN_ONLY flag around cluster.
Add suspend_lv_origin and resume_lv_origin using LCK_ORIGIN_ONLY.
Adding function _add_partial_replicator_to_dtree() to create
partial tree for Replicator target.
Using dm_tree_node_set_presuspend_node() for Replicator.
This should avoid various races between dmeventd on multiple nodes
in cluster where one node already repairing device and another
run full scan and locks the device.
There's no need for foreign udev rules to touch LVM reserved devices
(snapshot, pvmove, _mlog, _mimage, _vorigin) even if they happen to
be visible. The same applies for /dev/disk content - no need to create
any content for these devices (and so no need to run any "blkid" etc.).
This also prevents setting any inotify "watch" from udev rules on such
devices that is a source of race conditions (the rules need to honor
DM_UDEV_DISABLE_OTHER_RULES_FLAG for this to work though).
Internally, we used DM names instead of UUIDs while processing event
handlers. This caused problems while trying to vgrename a VG with active LVs
where the names are being changed and so the devices were not found then.
The patch also contains a little bit of refactoring, moving "build_dlid" code
found in dev_manager.c to "build_dm_uuid", now in lvm-string.c (so we have
build_dm_uuid and build_dm_name at one place).
lvm2 devices have always UUID set even if imported from lvm1 metadata.
Patch removes name argument from dev_manager_info call and converts
all activation related calls to use query by UUID.
Also it simplifies mknode call (which is the only user on mknodes parameter).
Add a merging snapshot to the deptree, using the "error" target, rather
than avoid adding it entirely. This allows proper cleanup of the -cow
device without having to rename the -cow to use the origin's name as a
prefix.
Move the preloading of the origin LV, after a merge, from
lv_remove_single() to vg_remove_snapshot(). Having vg_remove_snapshot()
preload the origin allows the -cow device to be released so that it can
be removed via deactivate_lv(). lv_remove_single()'s deactivate_lv()
reliably removes the -cow device because the associated snapshot LV,
that is to be removed when a snapshot-merge completes, is always added
to the deptree (and kernel -- via "error" target).
Now when the snapshot LV is removed both the -cow and -real devices
get removed using uuid rather than device name. This paves the way
for us to switch over to info-by-uuid queries.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
We unfortunately don't yet _know_, in dev_manager_snapshot_percent(), if
a snapshot-merge target is active (activation is deferred if dev is
open); so we can't short-circuit origin devices based purely on existing
LVM LV attributes.
Set 'fail_if_percent_unsupported' in dev_manager_snapshot_percent() for
a merging origin LV, otherwise passing unsupported LV types to _percent
will lead to a default successful return with percent_range as
PERCENT_100.
For a merging origin, PERCENT_100 will result in a polldaemon that runs
infinitely (because completion is PERCENT_0).
When activating a merging origin it is valid, and expected, to not have
a node in the deptree for both the origin and its merging snapshot. The
_cached_info() caller is only concerned with whether a device is open.
If there isn't a node in the tree the associated device is definitely
not open.
In dev_manager_info 0 means error and 1 info is returned,
not that device exists (that value is part of info struct).
Fix query by uuid only (no name) which returns 0 when device
does not exist.
'const'. Be consistent with its use (and dev_manager_snapshot_percent()).
Pass 'lv' from dev_manager_snapshot_percent() to _percent() to
_percent_run(). _percent_run() always dereferenced 'lv' (when
initializing segh) even though it may have been NULL (as was the case
until now for dev_manager_snapshot_percent()).
If a "snapshot-origin" LV (snapshot-merge whose merge was deferred
becuase it was open) was passed to _percent_run() it would always return
100%.
Update _percent_run() to NOT return PERCENT_100 et. al. if
->target_percent() wasn't ever called and supplied 'lv' is a merging
origin. A default return of 100% does not work for snapshot-merge.
Also tweak a related lvconvert log_error() to include "Aborting merge."
If either the origin or snapshot that is to be merged is open the merge
will not start; only the merge metadata will be written. The merge will
start on the next activation of the origin (or via lvchange --refresh)
IFF both the origin and snapshot are closed.
Merge on activate is particularly important if we want to merge over a
mounted filesystem that cannot be unmounted (until next boot) --- for
example root.
"snapshot-merge" target based on whether the LV is a merging snapshot.
When activating a snapshot-merge target do not attempt to monitor the
LV for events; the polldaemon will monitor the snapshot as it is
merged.
Allow "snapshot-merge" target's usage to be parsed via standard
"snapshot" methods.
NOTE: follow on fixes to the _percent_run change are still needed
- 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).
During vgreduce is failed mirror image replaced with error segment,
this segmant type has always area_count == 0.
Current code expects that there is at least one area with device,
patch fixes it by additional check (fixes segfault during vgreduce).
Also do not calculate readahead in every lv_info call, we only need
to cache PV readahead before activation calls which locks memory.
When we are stacking LV over device, which has for some reason
increased read_ahead (e.g. MD RAID), the read_ahead hint
for libdevmapper is wrong (it is zero).
If the calculated read_ahead hint is zero, patch uses read_ahead of underlying device
(if first segment is PV) when setting DM_READ_AHEAD_MINIMUM_FLAG.
Because we are using dev-cache, it also store this value to cache for future use
(if several LVs are over one PV, BLKRAGET is called only once for underlying device.)
This should fix all the reamining problems with readahead mismatch reported
for DM over MD configurations (and similar cases).
Check for major/minor collision is added in _add_dev_to_dtree()
where we already read info by uuid,
so in the case of requesting major/minor it queries device-mapper
by major/minor for device availability.
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=204992
Add --config for overriding most config file settings from cmdline.
Quote arguments when printing command line.
Remove linefeed from 'initialising logging' message.
Add 'Completed' debug message.
Don't attempt library exit after reloading config files.
Always compile with libdevmapper, even if device-mapper is disabled.
Fix some memory leaks in error paths found by coverity.
Use C99 struct initialisers.
Move DEFS into configure.h.
Clean-ups to remove miscellaneous compiler warnings.
and further reduce the number of ioctl calls made.
o Metadata area struct change.
o Make config file accessible to activation functions & get stripe_filler
from it.
o Allow kernel to return snapshot status as a fraction or a percentage.
Clear many compiler warnings (i386) & associated bugs - hopefully without
introducing too many new bugs:-) (Same exercise required for other archs.)
Default compilation has optimisation - or else use ./configure --enable-debug
