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Commit Graph

12 Commits

Author SHA1 Message Date
David Teigland
5b3fbccab9 hints: check for malloc failure 2019-08-28 12:41:57 -05:00
David Teigland
12707adac8 hints: fix copy of filter
Only the first entry of the filter array was being
included in the copy of the filter, rather than the
entire thing.  The result is that hints would not be
refreshed if the filter was changed but the first
entry was unchanged.
2019-08-28 12:33:04 -05:00
David Teigland
677833ce6f lvmcache: renaming functions and variables
related to duplicates, no functional changes.
2019-08-16 13:26:11 -05:00
David Teigland
60bf9c9f33 hints: exclude md components
In some cases md components could be included in
the hints, so add a check to hint creation to make
sure they are excluded.
2019-05-21 11:58:01 -05:00
David Teigland
c3e385c108 hints: skip hint flock if nolocking option is set 2019-04-29 13:01:15 -05:00
David Teigland
8c87dda195 locking: unify global lock for flock and lockd
There have been two file locks used to protect lvm
"global state": "ORPHANS" and "GLOBAL".

Commands that used the ORPHAN flock in exclusive mode:
  pvcreate, pvremove, vgcreate, vgextend, vgremove,
  vgcfgrestore

Commands that used the ORPHAN flock in shared mode:
  vgimportclone, pvs, pvscan, pvresize, pvmove,
  pvdisplay, pvchange, fullreport

Commands that used the GLOBAL flock in exclusive mode:
  pvchange, pvscan, vgimportclone, vgscan

Commands that used the GLOBAL flock in shared mode:
  pvscan --cache, pvs

The ORPHAN lock covers the important cases of serializing
the use of orphan PVs.  It also partially covers the
reporting of orphan PVs (although not correctly as
explained below.)

The GLOBAL lock doesn't seem to have a clear purpose
(it may have eroded over time.)

Neither lock correctly protects the VG namespace, or
orphan PV properties.

To simplify and correct these issues, the two separate
flocks are combined into the one GLOBAL flock, and this flock
is used from the locking sites that are in place for the
lvmlockd global lock.

The logic behind the lvmlockd (distributed) global lock is
that any command that changes "global state" needs to take
the global lock in ex mode.  Global state in lvm is: the list
of VG names, the set of orphan PVs, and any properties of
orphan PVs.  Reading this global state can use the global lock
in sh mode to ensure it doesn't change while being reported.

The locking of global state now looks like:

lockd_global()
  previously named lockd_gl(), acquires the distributed
  global lock through lvmlockd.  This is unchanged.
  It serializes distributed lvm commands that are changing
  global state.  This is a no-op when lvmlockd is not in use.

lockf_global()
  acquires an flock on a local file.  It serializes local lvm
  commands that are changing global state.

lock_global()
  first calls lockf_global() to acquire the local flock for
  global state, and if this succeeds, it calls lockd_global()
  to acquire the distributed lock for global state.

Replace instances of lockd_gl() with lock_global(), so that the
existing sites for lvmlockd global state locking are now also
used for local file locking of global state.  Remove the previous
file locking calls lock_vol(GLOBAL) and lock_vol(ORPHAN).

The following commands which change global state are now
serialized with the exclusive global flock:

pvchange (of orphan), pvresize (of orphan), pvcreate, pvremove,
vgcreate, vgextend, vgremove, vgreduce, vgrename,
vgcfgrestore, vgimportclone, vgmerge, vgsplit

Commands that use a shared flock to read global state (and will
be serialized against the prior list) are those that use
process_each functions that are based on processing a list of
all VG names, or all PVs.  The list of all VGs or all PVs is
global state and the shared lock prevents those lists from
changing while the command is processing them.

The ORPHAN lock previously attempted to produce an accurate
listing of orphan PVs, but it was only acquired at the end of
the command during the fake vg_read of the fake orphan vg.
This is not when orphan PVs were determined; they were
determined by elimination beforehand by processing all real
VGs, and subtracting the PVs in the real VGs from the list
of all PVs that had been identified during the initial scan.
This is fixed by holding the single global lock in shared mode
while processing all VGs to determine the list of orphan PVs.
2019-04-29 13:01:05 -05:00
David Teigland
d0b869e46a hints: fix non-empty hints list when not using hints
When hints are invalid and ignored, the list of hints
could be non-empty (from additions before an invalid
hint was found).  This confused the calling code which
was checking for an empty list to see if hints were used.
Ensure the list is empty when hints are not used.
2019-04-11 11:58:51 -05:00
David Teigland
0cc80ccfd5 hints: fix case of error getting device size
When checking hints, if there's an error getting
the device size, that should be equivalent to
seeing zero size.
2019-04-11 10:32:28 -05:00
David Teigland
0aa51a2f61 hints: fix recreating hints from pvscan
When aay was included in the pvscan --cache command,
the activation part was complaining about the unusual
state of the hint file since it had been recreated
just prior.
2019-02-13 15:23:43 -06:00
David Teigland
5f102b3421 hints: invalidate when pvscan --cache sees a new PV
An idea from Zdenek for better ensuring valid hints by invalidating
them when pvscan --cache <device> sees a new PV, which is a case
where we know that hints should be invalidated.  This is triggered
from systemd/udev logic, and there may be some cases where it would
invalidate hints that the existing methods wouldn't detect.
2019-01-16 15:34:20 -06:00
David Teigland
7b5abc3fb1 hints: fix hint flock when using lvm shell
also cmd->use_hints needs to be set for each shell command
2019-01-15 12:23:16 -06:00
David Teigland
6620dc9475 add device hints to reduce scanning
Save the list of PVs in /run/lvm/hints.  These hints
are used to reduce scanning in a number of commands
to only the PVs on the system, or only the PVs in a
requested VG (rather than all devices on the system.)
2019-01-15 10:23:47 -06:00