From 5bdb6bc091a0270912974583a7dabe94f5b8a1ef Mon Sep 17 00:00:00 2001

From: Eduardo Otubo <otubo@redhat.com>

Date: Wed, 18 Mar 2020 14:11:23 +0100

Subject: [PATCH] Do not use fallocate in swap file creation on xfs. (#70)

Message-id: <20200318141123.30265-1-otubo@redhat.com>

Patchwork-id: 94377

O-Subject: [RHEL-7.9 cloud-init PATCH] Do not use fallocate in swap file creation on xfs. (#70)

Bugzilla: 1772505

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

RH-Acked-by: Vitaly Kuznetsov <vkuznets@redhat.com>

commit 6603706eec1c39d9d591c8ffa0ef7171b74d84d6

Author: Eduardo Otubo <otubo@redhat.com>

Date:   Thu Jan 23 17:41:48 2020 +0100

    Do not use fallocate in swap file creation on xfs. (#70)

    When creating a swap file on an xfs filesystem, fallocate cannot be used.

    Doing so results in failure of swapon and a message like:

     swapon: swapfile has holes

    The solution here is to maintain a list (currently containing only XFS)

    of filesystems where fallocate cannot be used. The, on those fileystems

    use the slower but functional 'dd' method.

    Signed-off-by: Eduardo Otubo <otubo@redhat.com>

    Co-authored-by: Adam Dobrawy <naczelnik@jawnosc.tk>

    Co-authored-by:  Scott Moser <smoser@brickies.net>

    Co-authored-by: Daniel Watkins <daniel@daniel-watkins.co.uk>

    LP: #1781781

Signed-off-by: Eduardo Otubo <otubo@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 cloudinit/config/cc_mounts.py                      | 67 ++++++++++++++++------

 .../unittests/test_handler/test_handler_mounts.py  | 12 ++++

 2 files changed, 62 insertions(+), 17 deletions(-)

diff --git a/cloudinit/config/cc_mounts.py b/cloudinit/config/cc_mounts.py

index c741c74..4293844 100644

--- a/cloudinit/config/cc_mounts.py

+++ b/cloudinit/config/cc_mounts.py

@@ -223,13 +223,58 @@ def suggested_swapsize(memsize=None, maxsize=None, fsys=None):

     return size

+def create_swapfile(fname, size):

+    """Size is in MiB."""

+

+    errmsg = "Failed to create swapfile '%s' of size %dMB via %s: %s"

+

+    def create_swap(fname, size, method):

+        LOG.debug("Creating swapfile in '%s' on fstype '%s' using '%s'",

+                  fname, fstype, method)

+

+        if method == "fallocate":

+            cmd = ['fallocate', '-l', '%dM' % size, fname]

+        elif method == "dd":

+            cmd = ['dd', 'if=/dev/zero', 'of=%s' % fname, 'bs=1M',

+                   'count=%d' % size]

+

+        try:

+            util.subp(cmd, capture=True)

+        except util.ProcessExecutionError as e:

+            LOG.warning(errmsg, fname, size, method, e)

+            util.del_file(fname)

+

+    swap_dir = os.path.dirname(fname)

+    util.ensure_dir(swap_dir)

+

+    fstype = util.get_mount_info(swap_dir)[1]

+

+    if fstype in ("xfs", "btrfs"):

+        create_swap(fname, size, "dd")

+    else:

+        try:

+            create_swap(fname, size, "fallocate")

+        except util.ProcessExecutionError as e:

+            LOG.warning(errmsg, fname, size, "dd", e)

+            LOG.warning("Will attempt with dd.")

+            create_swap(fname, size, "dd")

+

+    util.chmod(fname, 0o600)

+    try:

+        util.subp(['mkswap', fname])

+    except util.ProcessExecutionError:

+        util.del_file(fname)

+        raise

+

+

 def setup_swapfile(fname, size=None, maxsize=None):

     """

     fname: full path string of filename to setup

     size: the size to create. set to "auto" for recommended

     maxsize: the maximum size

     """

-    tdir = os.path.dirname(fname)

+    swap_dir = os.path.dirname(fname)

+    mibsize = str(int(size / (2 ** 20)))

     if str(size).lower() == "auto":

         try:

             memsize = util.read_meminfo()['total']

@@ -237,28 +282,16 @@ def setup_swapfile(fname, size=None, maxsize=None):

             LOG.debug("Not creating swap: failed to read meminfo")

             return

-        util.ensure_dir(tdir)

-        size = suggested_swapsize(fsys=tdir, maxsize=maxsize,

+        util.ensure_dir(swap_dir)

+        size = suggested_swapsize(fsys=swap_dir, maxsize=maxsize,

                                   memsize=memsize)

     if not size:

         LOG.debug("Not creating swap: suggested size was 0")

         return

-    mbsize = str(int(size / (2 ** 20)))

-    msg = "creating swap file '%s' of %sMB" % (fname, mbsize)

-    try:

-        util.ensure_dir(tdir)

-        util.log_time(LOG.debug, msg, func=util.subp,

-                      args=[['sh', '-c',

-                             ('rm -f "$1" && umask 0066 && '

-                              '{ fallocate -l "${2}M" "$1" || '

-                              'dd if=/dev/zero "of=$1" bs=1M "count=$2"; } && '

-                              'mkswap "$1" || { r=$?; rm -f "$1"; exit $r; }'),

-                             'setup_swap', fname, mbsize]])

-

-    except Exception as e:

-        raise IOError("Failed %s: %s" % (msg, e))

+    util.log_time(LOG.debug, msg="Setting up swap file", func=create_swapfile,

+                  args=[fname, mibsize])

     return fname

diff --git a/tests/unittests/test_handler/test_handler_mounts.py b/tests/unittests/test_handler/test_handler_mounts.py

index 0fb160b..7bcefa0 100644

--- a/tests/unittests/test_handler/test_handler_mounts.py

+++ b/tests/unittests/test_handler/test_handler_mounts.py

@@ -181,6 +181,18 @@ class TestFstabHandling(test_helpers.FilesystemMockingTestCase):

         return dev

+    def test_swap_integrity(self):

+        '''Ensure that the swap file is correctly created and can

+        swapon successfully. Fixing the corner case of:

+        kernel: swapon: swapfile has holes'''

+

+        fstab = '/swap.img swap swap defaults 0 0\n'

+

+        with open(cc_mounts.FSTAB_PATH, 'w') as fd:

+            fd.write(fstab)

+        cc = {'swap': ['filename: /swap.img', 'size: 512', 'maxsize: 512']}

+        cc_mounts.handle(None, cc, self.mock_cloud, self.mock_log, [])

+

     def test_fstab_no_swap_device(self):

         '''Ensure that cloud-init adds a discovered swap partition

         to /etc/fstab.'''

-- 

1.8.3.1