zfs-patches/0011-Remove-vn_rename-and-vn_remove-dependency.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Brian Behlendorf <behlendorf1@llnl.gov>
   3 Date: Thu, 19 Oct 2017 10:06:55 -0700
   4 Subject: [PATCH] Remove vn_rename and vn_remove dependency
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   8
   9 The only place vn_rename and vn_remove are used is when writing
  10 out an updated pool configuration file.  By truncating the file
  11 instead of renaming and removing it we can avoid having to implement
  12 these interfaces entirely.  Functionally an empty cache file is
  13 treated the same as a missing cache file.  This is particularly
  14 advantageous because the Linux kernel has never provided a way
  15 to reliably implement vn_rename and vn_remove.
  16
  17 The cachefile_004_pos.ksh test case was updated to understand
  18 that an empty cache file is the same as a missing one.
  19
  20 The zfs-import-* systemd service files were not updated to use
  21 ConditionFileNotEmpty in place of ConditionPathExists.  This
  22 means that after exporting all pools and rebooting new pools
  23 will not the scanned for on the next boot.  This small change
  24 should not impact normal usage since pools are not exported
  25 as part of a normal shutdown.
  26
  27 Documentation was updated accordingly.
  28
  29 Reviewed-by: George Melikov <mail@gmelikov.ru>
  30 Reviewed-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com>
  31 Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
  32 Closes zfsonlinux/spl#648
  33 Closes #6753
  34 (cherry picked from commit 5d62588032aa1d13d7f789cf564a0d20c77a5762)
  35 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  36 ---
  37  module/zfs/spa_config.c                            | 34 ++++++++++++++++++----
  38  man/man8/zpool.8                                   |  2 +-
  39  .../functional/cachefile/cachefile_004_pos.ksh     |  6 ++--
  40  3 files changed, 32 insertions(+), 10 deletions(-)
  41
  42 diff --git a/module/zfs/spa_config.c b/module/zfs/spa_config.c
  43 index 5b792b868..fea239014 100644
  44 --- a/module/zfs/spa_config.c
  45 +++ b/module/zfs/spa_config.c
  46 @@ -147,6 +147,26 @@ out:
  47         kobj_close_file(file);
  48  }
  49
  50 +static int
  51 +spa_config_remove(spa_config_dirent_t *dp)
  52 +{
  53 +#if defined(__linux__) && defined(_KERNEL)
  54 +       int error, flags = FWRITE | FTRUNC;
  55 +       uio_seg_t seg = UIO_SYSSPACE;
  56 +       vnode_t *vp;
  57 +
  58 +       error = vn_open(dp->scd_path, seg, flags, 0644, &vp, 0, 0);
  59 +       if (error == 0) {
  60 +               (void) VOP_FSYNC(vp, FSYNC, kcred, NULL);
  61 +               (void) VOP_CLOSE(vp, 0, 1, 0, kcred, NULL);
  62 +       }
  63 +
  64 +       return (error);
  65 +#else
  66 +       return (vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE));
  67 +#endif
  68 +}
  69 +
  70  static int
  71  spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl)
  72  {
  73 @@ -161,7 +181,10 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl)
  74          * If the nvlist is empty (NULL), then remove the old cachefile.
  75          */
  76         if (nvl == NULL) {
  77 -               err = vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE);
  78 +               err = spa_config_remove(dp);
  79 +               if (err == ENOENT)
  80 +                       err = 0;
  81 +
  82                 return (err);
  83         }
  84
  85 @@ -174,9 +197,9 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl)
  86  #if defined(__linux__) && defined(_KERNEL)
  87         /*
  88          * Write the configuration to disk.  Due to the complexity involved
  89 -        * in performing a rename from within the kernel the file is truncated
  90 -        * and overwritten in place.  In the event of an error the file is
  91 -        * unlinked to make sure we always have a consistent view of the data.
  92 +        * in performing a rename and remove from within the kernel the file
  93 +        * is instead truncated and overwritten in place.  This way we always
  94 +        * have a consistent view of the data or a zero length file.
  95          */
  96         err = vn_open(dp->scd_path, UIO_SYSSPACE, oflags, 0644, &vp, 0, 0);
  97         if (err == 0) {
  98 @@ -186,9 +209,8 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl)
  99                         err = VOP_FSYNC(vp, FSYNC, kcred, NULL);
 100
 101                 (void) VOP_CLOSE(vp, oflags, 1, 0, kcred, NULL);
 102 -
 103                 if (err)
 104 -                       (void) vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE);
 105 +                       (void) spa_config_remove(dp);
 106         }
 107  #else
 108         /*
 109 diff --git a/man/man8/zpool.8 b/man/man8/zpool.8
 110 index 328ba3dce..22579101a 100644
 111 --- a/man/man8/zpool.8
 112 +++ b/man/man8/zpool.8
 113 @@ -655,7 +655,7 @@ Because the kernel destroys and recreates this file when pools are added and
 114  removed, care should be taken when attempting to access this file.
 115  When the last pool using a
 116  .Sy cachefile
 117 -is exported or destroyed, the file is removed.
 118 +is exported or destroyed, the file will be empty.
 119  .It Sy comment Ns = Ns Ar text
 120  A text string consisting of printable ASCII characters that will be stored
 121  such that it is available even if the pool becomes faulted.
 122 diff --git a/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh b/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh
 123 index ae54a9365..e0b81e166 100755
 124 --- a/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh
 125 +++ b/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh
 126 @@ -98,13 +98,13 @@ log_must zpool set cachefile=$CPATH2 $TESTPOOL1
 127  log_must pool_in_cache $TESTPOOL1 $CPATH2
 128  log_must zpool set cachefile=$CPATH2 $TESTPOOL2
 129  log_must pool_in_cache $TESTPOOL2 $CPATH2
 130 -if [[ -f $CPATH1 ]]; then
 131 +if [[ -s $CPATH1 ]]; then
 132         log_fail "Verify set when cachefile is set on pool."
 133  fi
 134
 135  log_must zpool export $TESTPOOL1
 136  log_must zpool export $TESTPOOL2
 137 -if [[ -f $CPATH2 ]]; then
 138 +if [[ -s $CPATH2 ]]; then
 139         log_fail "Verify export when cachefile is set on pool."
 140  fi
 141
 142 @@ -117,7 +117,7 @@ log_must pool_in_cache $TESTPOOL2 $CPATH2
 143
 144  log_must zpool destroy $TESTPOOL1
 145  log_must zpool destroy $TESTPOOL2
 146 -if [[ -f $CPATH2 ]]; then
 147 +if [[ -s $CPATH2 ]]; then
 148         log_fail "Verify destroy when cachefile is set on pool."
 149  fi
 150
 151 --
 152 2.14.2
 153