[PATCH blivet/master 1/3] devicelibs.lvm: refactor _getConfigArgs()/lvm()

Anne Mulhern amulhern at redhat.com
Mon Sep 22 12:14:06 UTC 2014





----- Original Message -----
> From: "Will Woods" <wwoods at redhat.com>
> To: anaconda-patches at lists.fedorahosted.org
> Sent: Friday, September 19, 2014 6:18:36 PM
> Subject: [PATCH blivet/master 1/3] devicelibs.lvm: refactor	_getConfigArgs()/lvm()
> 
> Every place in devicelibs.lvm that executes lvm uses _getConfigArgs()[1]
> to help build the argument list. For the sake of consistency and
> simplicity, we could just call _getConfigArgs() from inside lvm().
> 
> (If we add a lvm_output() function to do the same for informational
> commands, then every call to the lvm binary uses _getConfigArgs().)
> 
> This also means we can pass the caller-requested arguments to
> _getConfigArgs(), and then it can examine them and automatically add
> appropriate config options.
> 
> For example: right now, the caller has to explicitly request
> read_only_locking whenever we're doing a call to one of the
> informational commands (lvs, pvs, vgs). This change lets
> _getConfigArgs() figure that out and add the arguments for read-only
> locking whenever it's appropriate.
> 
> [1] except thinsnapshotcreate(), but that was an oversight (which is
> therefore fixed by this commit)
> ---
>  blivet/devicelibs/lvm.py | 92
>  +++++++++++++++++++-----------------------------
>  1 file changed, 36 insertions(+), 56 deletions(-)
> 
> diff --git a/blivet/devicelibs/lvm.py b/blivet/devicelibs/lvm.py
> index 87d2639..949532c 100644
> --- a/blivet/devicelibs/lvm.py
> +++ b/blivet/devicelibs/lvm.py
> @@ -47,6 +47,9 @@ LVM_THINP_MAX_CHUNK_SIZE = Size("1 GiB")
>  
>  RAID_levels = raid.RAIDLevels(["raid0", "raid1", "linear"])
>  
> +# These LVM commands are read-only, so we can run them with read-only
> locking
> +READONLY_COMMANDS = ('lvs', 'pvs', 'vgs')
> +
>  def has_lvm():
>      if util.find_program_in_path("lvm"):
>          for line in open("/proc/devices").readlines():
> @@ -63,12 +66,11 @@ def has_lvm():
>  config_args_data = { "filterRejects": [],    # regular expressions to
>  reject.
>                       "filterAccepts": [] }   # regexp to accept
>  
> -def _getConfigArgs(**kwargs):
> +def _getConfigArgs(args):
>      """lvm command accepts lvm.conf type arguments preceded by --config. """
> +    cmd = args[0]
>      config_args = []
>  
> -    read_only_locking = kwargs.get("read_only_locking", False)
> -
>      filter_string = ""
>      rejects = config_args_data["filterRejects"]
>      for reject in rejects:
> @@ -87,7 +89,7 @@ def _getConfigArgs(**kwargs):
>      # "preferred_names", "filter", "cache_dir", "write_cache_state",
>      # "types", "sysfs_scan", "md_component_detection".  see man lvm.conf.
>      config_string = " devices { %s } " % (devices_string) # strings can be
>      added
> -    if read_only_locking:
> +    if cmd in READONLY_COMMANDS:
>          config_string += "global {locking_type=4} "
>      if config_string:
>          config_args = ["--config", config_string]
> @@ -205,17 +207,19 @@ def is_valid_thin_pool_chunk_size(size, discard=False):
>          return (size % LVM_THINP_MIN_CHUNK_SIZE == 0)
>  
>  def lvm(args):
> +    args += _getConfigArgs(args)
>      ret = util.run_program(["lvm"] + args)
>      if ret:
>          raise LVMError("running lvm " + " ".join(args) + " failed")
>  
> +def lvm_output(args):
> +    args += _getConfigArgs(args)
> +    return util.capture_output(["lvm"] + args)
> +
>  def pvcreate(device):
>      # we force dataalignment=1024k since we cannot get lvm to tell us what
>      # the pe_start will be in advance
> -    args = ["pvcreate"] + \
> -            _getConfigArgs() + \
> -            ["--dataalignment", "1024k"] + \
> -            [device]
> +    args = ["pvcreate", "--dataalignment", "1024k", device]
>  
>      try:
>          lvm(args)
> @@ -223,10 +227,9 @@ def pvcreate(device):
>          raise LVMError("pvcreate failed for %s: %s" % (device, msg))
>  
>  def pvresize(device, size):
> -    args = ["pvresize"] + \
> -            ["--setphysicalvolumesize", ("%dm" %
> size.convertTo(spec="mib"))] + \
> -            _getConfigArgs() + \
> -            [device]
> +    args = ["pvresize",
> +            "--setphysicalvolumesize", ("%dm" % size.convertTo(spec="mib")),
> +            device]
>  
>      try:
>          lvm(args)
> @@ -234,9 +237,7 @@ def pvresize(device, size):
>          raise LVMError("pvresize failed for %s: %s" % (device, msg))
>  
>  def pvremove(device):
> -    args = ["pvremove", "--force", "--force", "--yes"] + \
> -            _getConfigArgs() + \
> -            [device]
> +    args = ["pvremove", "--force", "--force", "--yes", device]
>  
>      try:
>          lvm(args)
> @@ -244,9 +245,7 @@ def pvremove(device):
>          raise LVMError("pvremove failed for %s: %s" % (device, msg))
>  
>  def pvscan(device):
> -    args = ["pvscan", "--cache",] + \
> -            _getConfigArgs() + \
> -            [device]
> +    args = ["pvscan", "--cache", device]
>  
>      try:
>          lvm(args)
> @@ -259,7 +258,7 @@ def pvmove(source, dest=None):
>          :param str source: pv device path to move extents off of
>          :keyword str dest: pv device path to move the extents onto
>      """
> -    args = ["pvmove"] + _getConfigArgs() + [source]
> +    args = ["pvmove", source]
>      if dest:
>          args.append(dest)
>  
> @@ -304,13 +303,12 @@ def pvinfo(device=None):
>              "--unit=k", "--nosuffix", "--nameprefixes",
>              "--unquoted", "--noheadings",
>              "-opv_name,pv_uuid,pe_start,vg_name,vg_uuid,vg_size,vg_free,"
> -            "vg_extent_size,vg_extent_count,vg_free_count,pv_count"] + \
> -            _getConfigArgs(read_only_locking=True)
> +            "vg_extent_size,vg_extent_count,vg_free_count,pv_count"]
>  
>      if device:
>          args.append(device)
>  
> -    buf = util.capture_output(["lvm"] + args)
> +    buf = lvm_output(args)
>      pvs = {}
>      for line in buf.splitlines():
>          info = parse_lvm_vars(line)
> @@ -326,7 +324,6 @@ def vgcreate(vg_name, pv_list, pe_size):
>      argv = ["vgcreate"]
>      if pe_size:
>          argv.extend(["-s", "%dm" % pe_size.convertTo(spec="mib")])
> -    argv.extend(_getConfigArgs())
>      argv.append(vg_name)
>      argv.extend(pv_list)
>  
> @@ -336,9 +333,7 @@ def vgcreate(vg_name, pv_list, pe_size):
>          raise LVMError("vgcreate failed for %s: %s" % (vg_name, msg))
>  
>  def vgremove(vg_name):
> -    args = ["vgremove", "--force"] + \
> -            _getConfigArgs() +\
> -            [vg_name]
> +    args = ["vgremove", "--force", vg_name]
>  
>      try:
>          lvm(args)
> @@ -346,9 +341,7 @@ def vgremove(vg_name):
>          raise LVMError("vgremove failed for %s: %s" % (vg_name, msg))
>  
>  def vgactivate(vg_name):
> -    args = ["vgchange", "-a", "y"] + \
> -            _getConfigArgs() + \
> -            [vg_name]
> +    args = ["vgchange", "-a", "y", vg_name]
>  
>      try:
>          lvm(args)
> @@ -356,9 +349,7 @@ def vgactivate(vg_name):
>          raise LVMError("vgactivate failed for %s: %s" % (vg_name, msg))
>  
>  def vgdeactivate(vg_name):
> -    args = ["vgchange", "-a", "n"] + \
> -            _getConfigArgs() + \
> -            [vg_name]
> +    args = ["vgchange", "-a", "n", vg_name]
>  
>      try:
>          lvm(args)
> @@ -380,7 +371,6 @@ def vgreduce(vg_name, pv, missing=False):
>              it from the VG. You must do that first by calling
>              :func:`.pvmove`.
>      """
>      args = ["vgreduce"]
> -    args.extend(_getConfigArgs())
>      if missing:
>          args.extend(["--removemissing", "--force", vg_name])
>      else:
> @@ -397,7 +387,7 @@ def vgextend(vg_name, pv):
>          :param str vg_name: the name of the VG
>          :param str pv: device path of PV to add
>      """
> -    args = ["vgextend"] + _getConfigArgs() + [vg_name, pv]
> +    args = ["vgextend", vg_name, pv]
>  
>      try:
>          lvm(args)
> @@ -412,10 +402,10 @@ def vginfo(vg_name):
>      """
>      args = ["vgs", "--noheadings", "--nosuffix", "--nameprefixes",
>      "--unquoted",
>              "--units", "m",
> -            "-o",
> "uuid,size,free,extent_size,extent_count,free_count,pv_count"] + \
> -            _getConfigArgs(read_only_locking=True) + [vg_name]
> +            "-o",
> "uuid,size,free,extent_size,extent_count,free_count,pv_count",
> +            vg_name]
>  
> -    buf = util.capture_output(["lvm"] + args)
> +    buf = lvm_output(args)
>      info = parse_lvm_vars(buf)
>      if len(info.keys()) != 7:
>          raise LVMError(_("vginfo failed for %s") % vg_name)
> @@ -434,12 +424,11 @@ def lvs(vg_name=None):
>      args = ["lvs",
>              "-a", "--unit", "k", "--nosuffix", "--nameprefixes",
>              "--unquoted", "--noheadings",
> -            "-ovg_name,lv_name,lv_uuid,lv_size,lv_attr,segtype"] + \
> -            _getConfigArgs(read_only_locking=True)
> +            "-ovg_name,lv_name,lv_uuid,lv_size,lv_attr,segtype"]
>      if vg_name:
>          args.append(vg_name)
>  
> -    buf = util.capture_output(["lvm"] + args)
> +    buf = lvm_output(args)
>      logvols = {}
>      for line in buf.splitlines():
>          info = parse_lvm_vars(line)
> @@ -454,10 +443,9 @@ def lvs(vg_name=None):
>  
>  def lvorigin(vg_name, lv_name):
>      args = ["lvs", "--noheadings", "-o", "origin"] + \
> -            _getConfigArgs(read_only_locking=True) + \
>              ["%s/%s" % (vg_name, lv_name)]
>  
> -    buf = util.capture_output(["lvm"] + args)
> +    buf = lvm_output(args)
>  
>      try:
>          origin = buf.splitlines()[0].strip()
> @@ -473,7 +461,6 @@ def lvcreate(vg_name, lv_name, size, pvs=None):
>              ["-L", "%dm" % size.convertTo(spec="mib")] + \
>              ["-n", lv_name] + \
>              ["-y"] + \
> -            _getConfigArgs() + \
>              [vg_name] + pvs
>  
>      try:
> @@ -486,7 +473,7 @@ def lvremove(vg_name, lv_name, force=False):
>      if force:
>          args.extend(["--force", "--yes"])
>  
> -    args += _getConfigArgs() + ["%s/%s" % (vg_name, lv_name)]
> +    args += ["%s/%s" % (vg_name, lv_name)]
>  
>      try:
>          lvm(args)
> @@ -496,7 +483,6 @@ def lvremove(vg_name, lv_name, force=False):
>  def lvresize(vg_name, lv_name, size):
>      args = ["lvresize"] + \
>              ["--force", "-L", "%dm" % size.convertTo(spec="mib")] + \
> -            _getConfigArgs() + \
>              ["%s/%s" % (vg_name, lv_name)]
>  
>      try:
> @@ -510,7 +496,7 @@ def lvactivate(vg_name, lv_name, ignore_skip=False):
>      if ignore_skip:
>          args.append("-K")
>  
> -    args += _getConfigArgs() + ["%s/%s" % (vg_name, lv_name)]
> +    args += ["%s/%s" % (vg_name, lv_name)]
>  
>      try:
>          lvm(args)
> @@ -519,7 +505,6 @@ def lvactivate(vg_name, lv_name, ignore_skip=False):
>  
>  def lvdeactivate(vg_name, lv_name):
>      args = ["lvchange", "-a", "n"] + \
> -            _getConfigArgs() + \
>              ["%s/%s" % (vg_name, lv_name)]
>  
>      try:
> @@ -536,8 +521,7 @@ def lvsnapshotmerge(vg_name, lv_name):
>              how merge is handled by lvm.
>  
>      """
> -    args = ["lvconvert", "--merge", "%s/%s" % (vg_name, lv_name)]
> -    args += _getConfigArgs() + [lv_name]
> +    args = ["lvconvert", "--merge", "%s/%s" % (vg_name, lv_name), lv_name]
>  
>      try:
>          lvm(args)
> @@ -552,7 +536,7 @@ def lvsnapshotcreate(vg_name, snap_name, size,
> origin_name):
>          :param str origin_name: the name of the origin logical volume
>      """
>      args = ["lvcreate", "-s", "-L", "%dm" % size.convertTo(spec="MiB"),
> -            "-n", snap_name] + _getConfigArgs() + ["%s/%s" % (vg_name,
> origin_name)]
> +            "-n", snap_name, "%s/%s" % (vg_name, origin_name)]
>  
>      try:
>          lvm(args)
> @@ -571,8 +555,6 @@ def thinpoolcreate(vg_name, lv_name, size,
> metadatasize=None, chunksize=None):
>          # default unit is KiB
>          args += ["--chunksize", "%d" % chunksize.convertTo(spec="kib")]
>  
> -    args += _getConfigArgs()
> -
>      try:
>          lvm(args)
>      except LVMError as msg:
> @@ -581,8 +563,7 @@ def thinpoolcreate(vg_name, lv_name, size,
> metadatasize=None, chunksize=None):
>  def thinlvcreate(vg_name, pool_name, lv_name, size):
>      args = ["lvcreate", "--thinpool", "%s/%s" % (vg_name, pool_name),
>              "--virtualsize", "%dm" % size.convertTo(spec="MiB"),
> -            "-n", lv_name] + \
> -            _getConfigArgs()
> +            "-n", lv_name]
>  
>      try:
>          lvm(args)
> @@ -606,10 +587,9 @@ def thinsnapshotcreate(vg_name, snap_name, origin_name,
> pool_name=None):
>  
>  def thinlvpoolname(vg_name, lv_name):
>      args = ["lvs", "--noheadings", "-o", "pool_lv"] + \
> -            _getConfigArgs(read_only_locking=True) + \
>              ["%s/%s" % (vg_name, lv_name)]
>  
> -    buf = util.capture_output(["lvm"] + args)
> +    buf = lvm_output(args)
>  
>      try:
>          pool = buf.splitlines()[0].strip()
> --
> 1.9.3
> 
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> anaconda-patches mailing list
> anaconda-patches at lists.fedorahosted.org
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> 


Moving _getConfigArgs() into lvm seems fine with me.

But, better to extend lvm() in a principled manner than to invent new method lvm_output.
Seems more consistent w/ idea of moving _getConfigArgs() call into lvm(), anyway.
See example in mdraid.py.

Fine w/ READONLY_COMMANDS change, generally, but think variable READONLY_COMMANDS should be local to _getConfigArgs(),
not file global.

Please make sure to verify relevant tests succeed, you need to be root to run the majority.

- mulhern


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