source3/smbd/oplock_linux.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kernel oplock processing for Linux
   4    Copyright (C) Andrew Tridgell 2000
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #define DBGC_CLASS DBGC_LOCKING
  21 #include "includes.h"
  22 #include "system/filesys.h"
  23 #include "smbd/smbd.h"
  24 #include "smbd/globals.h"
  25
  26 #if HAVE_KERNEL_OPLOCKS_LINUX
  27
  28 #ifndef F_SETLEASE
  29 #define F_SETLEASE      1024
  30 #endif
  31
  32 #ifndef F_GETLEASE
  33 #define F_GETLEASE      1025
  34 #endif
  35
  36 #ifndef CAP_LEASE
  37 #define CAP_LEASE 28
  38 #endif
  39
  40 #ifndef RT_SIGNAL_LEASE
  41 #define RT_SIGNAL_LEASE (SIGRTMIN+1)
  42 #endif
  43
  44 #ifndef F_SETSIG
  45 #define F_SETSIG 10
  46 #endif
  47
  48 /*
  49  * public function to get linux lease capability. Needed by some VFS modules (eg. gpfs.c)
  50  */
  51 void linux_set_lease_capability(void)
  52 {
  53         set_effective_capability(LEASE_CAPABILITY);
  54 }
  55
  56 /*
  57  * Call to set the kernel lease signal handler
  58  */
  59 int linux_set_lease_sighandler(int fd)
  60 {
  61         if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
  62                 DEBUG(3,("Failed to set signal handler for kernel lease\n"));
  63                 return -1;
  64         }
  65
  66         return 0;
  67 }
  68
  69 /****************************************************************************
  70  Call SETLEASE. If we get EACCES then we try setting up the right capability and
  71  try again.
  72  Use the SMB_VFS_LINUX_SETLEASE instead of this call directly.
  73 ****************************************************************************/
  74
  75 int linux_setlease(int fd, int leasetype)
  76 {
  77         int ret;
  78
  79         /* First set the signal handler. */
  80         if (linux_set_lease_sighandler(fd) == -1) {
  81                 return -1;
  82         }
  83         ret = fcntl(fd, F_SETLEASE, leasetype);
  84         if (ret == -1 && errno == EACCES) {
  85                 set_effective_capability(LEASE_CAPABILITY);
  86                 /*
  87                  * Bug 8974 - work around Linux kernel bug
  88                  * https://bugzilla.kernel.org/show_bug.cgi?id=43336.
  89                  * "fcntl(F_SETLEASE) resets signal number when
  90                  *  called multiple times"
  91                  */
  92                 if (linux_set_lease_sighandler(fd) == -1) {
  93                         return -1;
  94                 }
  95                 ret = fcntl(fd, F_SETLEASE, leasetype);
  96         }
  97
  98         return ret;
  99 }
 100
 101 /****************************************************************************
 102  * Deal with the Linux kernel <--> smbd
 103  * oplock break protocol.
 104 ****************************************************************************/
 105
 106 static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
 107                                         struct tevent_signal *se,
 108                                         int signum, int count,
 109                                         void *_info, void *private_data)
 110 {
 111         struct kernel_oplocks *ctx =
 112                 talloc_get_type_abort(private_data,
 113                 struct kernel_oplocks);
 114         struct smbd_server_connection *sconn =
 115                 talloc_get_type_abort(ctx->private_data,
 116                 struct smbd_server_connection);
 117         siginfo_t *info = (siginfo_t *)_info;
 118         int fd = info->si_fd;
 119         files_struct *fsp;
 120
 121         fsp = file_find_fd(sconn, fd);
 122         if (fsp == NULL) {
 123                 DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
 124                 return;
 125         }
 126         break_kernel_oplock(sconn->msg_ctx, fsp);
 127 }
 128
 129 /****************************************************************************
 130  Attempt to set an kernel oplock on a file.
 131 ****************************************************************************/
 132
 133 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 134                                     files_struct *fsp, int oplock_type)
 135 {
 136         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 137                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 138                          "fd = %d, file_id = %s. (%s)\n",
 139                          fsp_str_dbg(fsp), fsp->fh->fd,
 140                          file_id_string_tos(&fsp->file_id),
 141                          strerror(errno)));
 142                 return False;
 143         }
 144
 145         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 146                  "file_id = %s gen_id = %lu\n",
 147                  fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
 148                  fsp->fh->gen_id));
 149
 150         return True;
 151 }
 152
 153 /****************************************************************************
 154  Release a kernel oplock on a file.
 155 ****************************************************************************/
 156
 157 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 158                                         files_struct *fsp, int oplock_type)
 159 {
 160         if (DEBUGLVL(10)) {
 161                 /*
 162                  * Check and print out the current kernel
 163                  * oplock state of this file.
 164                  */
 165                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 166                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 167                         "gen_id = %lu has kernel oplock state "
 168                         "of %x.\n", fsp_str_dbg(fsp),
 169                         file_id_string_tos(&fsp->file_id),
 170                         fsp->fh->gen_id, state );
 171         }
 172
 173         /*
 174          * Remove the kernel oplock on this file.
 175          */
 176         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 177                 if (DEBUGLVL(0)) {
 178                         dbgtext("linux_release_kernel_oplock: Error when "
 179                                 "removing kernel oplock on file " );
 180                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 181                                 "Error was %s\n", fsp_str_dbg(fsp),
 182                                 file_id_string_tos(&fsp->file_id),
 183                                 fsp->fh->gen_id, strerror(errno) );
 184                 }
 185         }
 186 }
 187
 188 /****************************************************************************
 189  See if the kernel supports oplocks.
 190 ****************************************************************************/
 191
 192 static bool linux_oplocks_available(void)
 193 {
 194         int fd, ret;
 195         fd = open("/dev/null", O_RDONLY);
 196         if (fd == -1)
 197                 return False; /* uggh! */
 198         ret = fcntl(fd, F_GETLEASE, 0);
 199         close(fd);
 200         return ret == F_UNLCK;
 201 }
 202
 203 /****************************************************************************
 204  Setup kernel oplocks.
 205 ****************************************************************************/
 206
 207 static const struct kernel_oplocks_ops linux_koplocks = {
 208         .set_oplock                     = linux_set_kernel_oplock,
 209         .release_oplock                 = linux_release_kernel_oplock,
 210         .contend_level2_oplocks_begin   = NULL,
 211         .contend_level2_oplocks_end     = NULL,
 212 };
 213
 214 struct kernel_oplocks *linux_init_kernel_oplocks(struct smbd_server_connection *sconn)
 215 {
 216         struct kernel_oplocks *ctx;
 217         struct tevent_signal *se;
 218
 219         if (!linux_oplocks_available()) {
 220                 DEBUG(3,("Linux kernel oplocks not available\n"));
 221                 return NULL;
 222         }
 223
 224         ctx = talloc_zero(sconn, struct kernel_oplocks);
 225         if (!ctx) {
 226                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 227                 return NULL;
 228         }
 229
 230         ctx->ops = &linux_koplocks;
 231         ctx->private_data = sconn;
 232
 233         se = tevent_add_signal(sconn->ev_ctx,
 234                                ctx,
 235                                RT_SIGNAL_LEASE, SA_SIGINFO,
 236                                linux_oplock_signal_handler,
 237                                ctx);
 238         if (!se) {
 239                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 240                 TALLOC_FREE(ctx);
 241                 return NULL;
 242         }
 243
 244         DEBUG(3,("Linux kernel oplocks enabled\n"));
 245
 246         return ctx;
 247 }
 248 #else
 249  void oplock_linux_dummy(void);
 250
 251  void oplock_linux_dummy(void) {}
 252 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */