util-linux-mtab-lock.patch

   1 - Improved /etc/mtab lock
   2 - fix for the mount command and am-utils using different mtab locking
   3
   4 --- util-linux-2.12p/mount/fstab.c.mtab-lock    2005-03-22 14:05:22.481297072 +0100
   5 +++ util-linux-2.12p/mount/fstab.c      2005-03-22 14:50:55.719781664 +0100
   6 @@ -395,6 +395,7 @@
   7
   8  /* Flag for already existing lock file. */
   9  static int we_created_lockfile = 0;
  10 +static int lockfile_fd = -1;
  11
  12  /* Flag to indicate that signals have been set up. */
  13  static int signals_have_been_setup = 0;
  14 @@ -416,6 +417,8 @@
  15  void
  16  unlock_mtab (void) {
  17         if (we_created_lockfile) {
  18 +               close(lockfile_fd);
  19 +               lockfile_fd = -1;
  20                 unlink (MOUNTED_LOCK);
  21                 we_created_lockfile = 0;
  22         }
  23 @@ -443,7 +446,7 @@
  24
  25  void
  26  lock_mtab (void) {
  27 -       int tries = 3;
  28 +       int tries = 100000, i;
  29         char linktargetfile[MOUNTLOCK_LINKTARGET_LTH];
  30
  31         at_die = unlock_mtab;
  32 @@ -469,45 +472,48 @@
  33
  34         sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ());
  35
  36 +       i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
  37 +       if (i < 0) {
  38 +               int errsv = errno;
  39 +               /* linktargetfile does not exist (as a file)
  40 +                  and we cannot create it. Read-only filesystem?
  41 +                  Too many files open in the system?
  42 +                  Filesystem full? */
  43 +               die (EX_FILEIO, _("can't create lock file %s: %s "
  44 +                                                 "(use -n flag to override)"),
  45 +                        linktargetfile, strerror (errsv));
  46 +       }
  47 +       close(i);
  48 +
  49         /* Repeat until it was us who made the link */
  50         while (!we_created_lockfile) {
  51                 struct flock flock;
  52 -               int errsv, fd, i, j;
  53 -
  54 -               i = open (linktargetfile, O_WRONLY|O_CREAT, 0);
  55 -               if (i < 0) {
  56 -                       int errsv = errno;
  57 -                       /* linktargetfile does not exist (as a file)
  58 -                          and we cannot create it. Read-only filesystem?
  59 -                          Too many files open in the system?
  60 -                          Filesystem full? */
  61 -                       die (EX_FILEIO, _("can't create lock file %s: %s "
  62 -                            "(use -n flag to override)"),
  63 -                            linktargetfile, strerror (errsv));
  64 -               }
  65 -               close(i);
  66 +               int errsv, j;
  67
  68                 j = link(linktargetfile, MOUNTED_LOCK);
  69                 errsv = errno;
  70
  71 -               (void) unlink(linktargetfile);
  72 -
  73                 if (j == 0)
  74                         we_created_lockfile = 1;
  75
  76                 if (j < 0 && errsv != EEXIST) {
  77 +                       (void) unlink(linktargetfile);
  78                         die (EX_FILEIO, _("can't link lock file %s: %s "
  79                              "(use -n flag to override)"),
  80                              MOUNTED_LOCK, strerror (errsv));
  81                 }
  82
  83 -               fd = open (MOUNTED_LOCK, O_WRONLY);
  84 +               lockfile_fd = open (MOUNTED_LOCK, O_WRONLY);
  85
  86 -               if (fd < 0) {
  87 +               if (lockfile_fd < 0) {
  88                         int errsv = errno;
  89                         /* Strange... Maybe the file was just deleted? */
  90 -                       if (errno == ENOENT && tries-- > 0)
  91 +                       if (errno == ENOENT && tries-- > 0) {
  92 +                               if (tries % 200 == 0)
  93 +                                       usleep(30);
  94                                 continue;
  95 +                       }
  96 +                       (void) unlink(linktargetfile);
  97                         die (EX_FILEIO, _("can't open lock file %s: %s "
  98                              "(use -n flag to override)"),
  99                              MOUNTED_LOCK, strerror (errsv));
 100 @@ -520,7 +526,7 @@
 101
 102                 if (j == 0) {
 103                         /* We made the link. Now claim the lock. */
 104 -                       if (fcntl (fd, F_SETLK, &flock) == -1) {
 105 +                       if (fcntl (lockfile_fd, F_SETLK, &flock) == -1) {
 106                                 if (verbose) {
 107                                     int errsv = errno;
 108                                     printf(_("Can't lock lock file %s: %s\n"),
 109 @@ -528,13 +534,15 @@
 110                                 }
 111                                 /* proceed anyway */
 112                         }
 113 +                       (void) unlink(linktargetfile);
 114                 } else {
 115                         static int tries = 0;
 116
 117                         /* Someone else made the link. Wait. */
 118                         alarm(LOCK_TIMEOUT);
 119 -                       if (fcntl (fd, F_SETLKW, &flock) == -1) {
 120 +                       if (fcntl (lockfile_fd, F_SETLKW, &flock) == -1) {
 121                                 int errsv = errno;
 122 +                               (void) unlink(linktargetfile);
 123                                 die (EX_FILEIO, _("can't lock lock file %s: %s"),
 124                                      MOUNTED_LOCK, (errno == EINTR) ?
 125                                      _("timed out") : strerror (errsv));
 126 @@ -542,16 +550,18 @@
 127                         alarm(0);
 128                         /* Limit the number of iterations - maybe there
 129                            still is some old /etc/mtab~ */
 130 -                       if (tries++ > 3) {
 131 -                               if (tries > 5)
 132 -                                       die (EX_FILEIO, _("Cannot create link %s\n"
 133 -                                           "Perhaps there is a stale lock file?\n"),
 134 -                                            MOUNTED_LOCK);
 135 -                               sleep(1);
 136 -                       }
 137 +                       ++tries;
 138 +                       if (tries % 200 == 0)
 139 +                          usleep(30);
 140 +                       if (tries > 100000) {
 141 +                               (void) unlink(linktargetfile);
 142 +                               close(lockfile_fd);
 143 +                               die (EX_FILEIO, _("Cannot create link %s\n"
 144 +                                                 "Perhaps there is a stale lock file?\n"),
 145 +                                        MOUNTED_LOCK);
 146 +                       }
 147 +                       close(lockfile_fd);
 148                 }
 149 -
 150 -               close(fd);
 151         }
 152  }
 153