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Only lv_committed() now uses vg->vg_committed and it appears redundant
if its contents match the enclosing VG so don't waste cycles creating it
when that's known to be true when no write lock is held so the struct
won't get modified.
- Use 'lvmcache' consistently instead of 'metadata cache'
- Always use 5 characters for source line number
- Remember to convert uuids into printable form
- Use <no name> rather than (null) when VG has no name.
vgsplit shares the vg_rename code so that must only set the PV_MOVED_VG
flag introduced in commit 486ed10848
("vgmerge: Fix intermediate metadata corruption") on PVs that moved.
Replaced the confusing device error message "not found (or ignored by
filtering)" by either "not found" or "excluded by a filter".
(Later we should be able to say which filter.)
Left the the liblvm code paths alone.
vgmerge suffers from a similar problem to the one fixed in commit
8146548d25 ("vgsplit: Fix intermediate
metadata corruption.")
When merging, splitting or renaming VGs, use a new PV status flag
PV_MOVED_VG to mark the PVs that hold metadata with the old VG name and
use this to provide PV-level granularity instead of incorrectly assuming
all PVs in the VG are the same.
Warn about a PV that has the in-use flag set, but appears in
the orphan VG (no VG was found referencing it.)
There are a number of conditions that could lead to this:
. The PV was created with no mdas and is used in a VG with
other PVs (with metadata) that have not yet appeared on
the system. So, no VG metadata is found by lvm which
references the in-use PV with no mdas.
. vgremove could have failed after clearing mdas but
before clearing the in-use flag. In this case, the
in-use flag needs to be manually cleared on the PV.
. The PV may have damanged/unrecognized VG metadata
that lvm could not read.
. The PV may have no mdas, and the PVs with the metadata
may have damaged/unrecognized metadata.
A PV holding VG metadata that lvm can't understand
(e.g. damaged, checksum error, unrecognized flag)
will appear as an in-use orphan, and will be cleared
by this repair code. Disable this repair until the
code can keep track of these problematic PVs, and
distinguish them from actual in-use orphans.
_check_reappeared_pv() incorrectly clears the MISSING_PV flags of
PVs with unknown devices.
While one caller avoids passing such PVs into the function, the other
doesn't. Move the check inside the function so it's not forgotten.
Without this patch, if the normal VG reading code tries to repair
inconsistent metadata while there is an unknown PV, it incorrectly
considers the missing PVs no longer to be missing and produces
incorrect 'pvs' output omitting the missing PV, for example.
Easy reproducer:
Create a VG with 3 PVs pv1, pv2, pv3.
Hide pv2.
Run vgreduce --removemissing.
Reinstate the hidden PV pv2 and at the same time hide a different PV
pv3.
Run 'pvs' - incorrect output.
Run 'pvs' again - correct output.
See https://bugzilla.redhat.com/1434054
There are certain situations (not fully understood)
where is_missing_pv() is false, but pv->dev is NULL,
so this adds a check for NULL pv->dev after is_missing_pv()
to avoid a segfault.
Before, the automatic update from older to newer version of PV extension
header happened within vg_write call. This may have caused problems under
some circumnstances where there's a code in between vg_write and vg_commit
which may have failed. In such situation, we reverted precommitted metadata
and put back the state to working version of VG metadata.
However, we don't have revert for PV write operation at the moment. So
if we updated PV headers already and we reverted vg_write due to failure
in subsequent code (before vg_commit), we ended up with lost VG metadata
(because old metadata pointers got reset by the PV write operation).
To minimize problematic situations here, we should put vg_write and
vg_commit that is done after PV header rewrites as close to each
other as possible.
This patch moves the automatic PV header rewrite for new extension
header part from vg_write to _vg_read where it's done the same way
as we do any other VG repairs if detected during VG read operation
(under VG write lock).
Apply the same idea as vg_update.
Before doing the VG remove on disk, invalidate
the VG in lvmetad. After the VG is removed,
remove the VG in lvmetad. If the command fails
after removing the VG on disk, but before removing
the VG metadata from lvmetad, then a subsequent
command will see the INVALID flag and not use the
stale metadata from lvmetad.
Previously, a command sent lvmetad new VG metadata in vg_commit().
In vg_commit(), devices are suspended, so any memory allocation
done by the command while sending to lvmetad, or by lvmetad while
updating its cache could deadlock if memory reclaim was triggered.
Now lvmetad is updated in unlock_vg(), after devices are resumed.
The new method for updating VG metadata in lvmetad is in two phases:
1. In vg_write(), before devices are suspended, the command sends
lvmetad a short message ("set_vg_info") telling it what the new
VG seqno will be. lvmetad sees that the seqno is newer than
the seqno of its cached VG, so it sets the INVALID flag for the
cached VG. If sending the message to lvmetad fails, the command
fails before the metadata is committed and the change is not made.
If sending the message succeeds, vg_commit() is called.
2. In unlock_vg(), after devices are resumed, the command sends
lvmetad the standard vg_update message with the new metadata.
lvmetad sees that the seqno in the new metadata matches the
seqno it saved from set_vg_info, and knows it has the latest
copy, so it clears the INVALID flag for the cached VG.
If a command fails between 1 and 2 (after committing the VG on disk,
but before sending lvmetad the new metadata), the cached VG retains
the INVALID flag in lvmetad. A subsequent command will read the
cached VG from lvmetad, see the INVALID flag, ignore the cached
copy, read the VG from disk instead, update the lvmetad copy
with the latest copy from disk, (this clears the INVALID flag
in lvmetad), and use the correct VG metadata for the command.
(This INVALID mechanism already existed for use by lvmlockd.)
A number of places are working on a specific dev when they
call lvmcache_info_from_pvid() to look up an info struct
based on a pvid. In those cases, pass the dev being used
to lvmcache_info_from_pvid(). When a dev is specified,
lvmcache_info_from_pvid() will verify that the cached
info it's using matches the dev being processed before
returning the info. Calling code will not mistakenly
get info for the wrong dev when duplicate devs exist.
This confusion was happening when scanning labels when
duplicate devs existed. label_read for the first dev
would add an info struct to lvmcache for that dev/pvid.
label_read for the second dev would see the pvid in
lvmcache from first dev, and mistakenly conclude that
the label_read from the second dev can be skipped
because it's already been done. By verifying that the
dev for the cached pvid matches the dev being read,
this mismatch is avoided and the label is actually read
from the second duplicate.
This refactors the code for autoactivation. Previously,
as each PV was found, it would be sent to lvmetad, and
the VG would be autoactivated using a non-standard VG
processing function (the "activation_handler") called via
a function pointer from within the lvmetad notification path.
Now, any scanning that the command needs to do (scanning
only the named device args, or scanning all devices when
there are no args), is done first, before any activation
is attempted. During the scans, the VG names are saved.
After scanning is complete, process_each_vg is used to do
autoactivation of the saved VG names. This makes pvscan
activation much more similar to activation done with
vgchange or lvchange.
The separate autoactivate phase also means that if lvmetad
is disabled (either before or during the scan), the command
can continue with the activation step by simply not using
lvmetad and reverting to disk scanning to do the
activation.
Wait to compare and choose alternate duplicate devices until
after all devices are scanned. During scanning, the first
duplicate dev is kept in lvmcache, and others are kept in a
new list (_found_duplicate_devs).
After all devices are scanned, compare all the duplicates
available for a given PVID and decide which is best.
If the dev used in lvmcache is changed, drop the old dev
from lvmcache entirely and rescan the replacement dev.
Previously the VG metadata from the old dev was kept in
lvmcache and only the dev was replaced.
A new config setting devices/allow_changes_with_duplicate_pvs
can be set to 0 which disallows modifying a VG or activating
LVs in it when the VG contains PVs with duplicate devices.
Set to 1 is the old behavior which allowed the VG to be
changed.
The logic for which of two devs is preferred has changed.
The primary goal is to choose a device that is currently
in use if the other isn't, e.g. by an active LV.
. prefer dev with fs mounted if the other doesn't, else
. prefer dev that is dm if the other isn't, else
. prefer dev in subsystem if the other isn't
If neither device is preferred by these rules, then don't
change devices in lvmcache, leaving the one that was found
first.
The previous logic for preferring a device was:
. prefer dev in subsystem if the other isn't, else
. prefer dev without holders if the other has holders, else
. prefer dev that is dm if the other isn't
Checking for devices uses is_missing_pv() to check
if there is a device for the PV. is_missing_pv()
is based on the MISSING_PV flag, which does not
always correspond to !pv->dev. When using lvmetad,
a command like:
pvs --config 'devices/filter=["a|/dev/sdb|", "r|.*|"]'
will cause a number of PVs to have NULL pv->dev, but
not the MISSING_PV flag. So, NULL pv->dev needs to
also be checked.
[0] fedora/~ # pvs --config 'devices/filter=["a|/dev/sda|", "r|.*|"]'
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Couldn't find device for segment belonging to fedora/root while checking used and assumed devices.
WARNING: Couldn't find device for segment belonging to fedora/swap while checking used and assumed devices.
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
[unknown] fedora lvm2 a-m 19.49g 0
Probably not worth mentioning "segments" here, just state that devices
for an LV can't be all found during the check - it's less mysterious for
user then:
[0] fedora/~ # pvs --config 'devices/filter=["a|/dev/sda|", "r|.*|"]'
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Couldn't find all devices for LV fedora/root while checking used and assumed devices.
WARNING: Couldn't find all devices for LV fedora/swap while checking used and assumed devices.
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
[unknown] fedora lvm2 a-m 19.49g 0
When checking assumed PVs against real devices used for LVs and if
there's no device assigned for an assumed PV (e.g. due to filters),
do log_warn instead of log_error and continue checking LV segments
and associated assumed PVs further, just like we do log_warn elsewhere
in this situation.
This way user will see the warning for each LV which couldn't be
checked completely against real PVs used. Before, we logged only
the very first occurence of missing device for an LV in a VG and we
returned from the function doing this check for all the LVs in VG
immediately which may be a bit misleading because it didn't tell
user about all the other LVs and whether they could be checked
or not.
For example, we have this setup:
[0] fedora/~ # pvs
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
/dev/vda2 fedora lvm2 a-- 19.49g 0
[0] fedora/~ # lvs -o+devices
LV VG Attr LSize Devices
root fedora -wi-ao---- 19.00g /dev/vda2(0)
swap fedora -wi-ao---- 500.00m /dev/vda2(4864)
Before this patch (only the very first LV in a VG is logged to have a
problem while checking used and assumed devices):
[0] fedora/~ # pvs --config 'devices/filter=["a|/dev/sda|", "r|.*|"]'
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
Couldn't find device for segment belonging to fedora/root while checking used and assumed devices.
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
[unknown] fedora lvm2 a-m 19.49g 0
With this patch applied (all LVs where we hit problem while checking
used and assumed devices are logged and it's warning, not error):
[0] fedora/~ # pvs --config 'devices/filter=["a|/dev/sda|", "r|.*|"]'
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Device for PV Qcxpcy-XgtP-UD3s-PmG0-qLyE-Z0ho-DYsxoz not found or rejected by a filter.
WARNING: Couldn't find device for segment belonging to fedora/root while checking used and assumed devices.
WARNING: Couldn't find device for segment belonging to fedora/swap while checking used and assumed devices.
PV VG Fmt Attr PSize PFree
/dev/sda lvm2 --- 128.00m 128.00m
[unknown] fedora lvm2 a-m 19.49g 0
The lvmetad connection is created within the
init_connections() path during command startup,
rather than via the old lvmetad_active() check.
The old lvmetad_active() checks are replaced
with lvmetad_used() which is a simple check that
tests if the command is using/connected to lvmetad.
The old lvmetad_set_active(cmd, 0) calls, which
stopped the command from using lvmetad (to revert to
disk scanning), are replaced with lvmetad_make_unused(cmd).
It's possible for an LVM LV to use a device during activation which
then differs from device which LVM assumes based on metadata later on.
For example, such device mismatch can occur if LVM doesn't have
complete view of devices during activation or if filters are
misbehaving or they're incorrectly set during activation.
This patch adds code that can detect this mismatch by creating
VG UUID and LV UUID index while scanning devices for device cache.
The VG UUID index maps VG UUID to a device list. Each device in the
list has a device layered above as a holder which is an LVM LV device
and for which we know the VG UUID (and similarly for LV UUID index).
We can acquire VG and LV UUID by reading /sys/block/<dm_dev_name>/dm/uuid.
So these indices represent the actual state of PV device use in
the system by LVs and then we compare that to what LVM assumes
based on metadata.
For example:
[0] fedora/~ # lsblk /dev/sdq /dev/sdr /dev/sds /dev/sdt
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdq 65:0 0 104M 0 disk
|-vg-lvol0 253:2 0 200M 0 lvm
`-mpath_dev1 253:3 0 104M 0 mpath
sdr 65:16 0 104M 0 disk
`-mpath_dev1 253:3 0 104M 0 mpath
sds 65:32 0 104M 0 disk
|-vg-lvol0 253:2 0 200M 0 lvm
`-mpath_dev2 253:4 0 104M 0 mpath
sdt 65:48 0 104M 0 disk
`-mpath_dev2 253:4 0 104M 0 mpath
In this case the vg-lvol0 is mapped onto sdq and sds becauset this is
what was available and seen during activation. Then later on, sdr and
sdt appeared and mpath devices were created out of sdq+sdr (mpath_dev1)
and sds+sdt (mpath_dev2). Now, LVM assumes (correctly) that mpath_dev1
and mpath_dev2 are the PVs that should be used, not the mpath
components (sdq/sdr, sds/sdt).
[0] fedora/~ # pvs
Found duplicate PV xSUix1GJ2SK82ACFuKzFLAQi8xMfFxnO: using /dev/mapper/mpath_dev1 not /dev/sdq
Using duplicate PV /dev/mapper/mpath_dev1 from subsystem DM, replacing /dev/sdq
Found duplicate PV MvHyMVabtSqr33AbkUrobq1LjP8oiTRm: using /dev/mapper/mpath_dev2 not /dev/sds
Using duplicate PV /dev/mapper/mpath_dev2 from subsystem DM, ignoring /dev/sds
WARNING: Device mismatch detected for vg/lvol0 which is accessing /dev/sdq, /dev/sds instead of /dev/mapper/mpath_dev1, /dev/mapper/mpath_dev2.
PV VG Fmt Attr PSize PFree
/dev/mapper/mpath_dev1 vg lvm2 a-- 100.00m 0
/dev/mapper/mpath_dev2 vg lvm2 a-- 100.00m 0
There's a window between doing VG read and checking PV device size
against real device size. If the device is removed in this window,
the dev cache still holds struct device and pv->dev still references
that and that PV is not marked as missing. However, if we're trying
to get size for such device, the open fails because that device
doesn't exists anymore.
We called existing pv_dev_size in _check_pv_dev_sizes fn. But
pv_dev_size assigned a size of 0 if the dev_get_size it called failed
(because the device is gone).
So call the dev_get_size directly and check for the return code
in _check_pv_dev_sizes and go further only if we really know the
device size. This is to avoid confusing warning messages like:
Device /dev/sdd1 has size of 0 sectors which is smaller than corresponding PV size of 31455207 sectors. Was device resized?
One or more devices used as PVs in VG helter_skelter have changed sizes.
