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 "smbd/globals.h"
  23
  24 #if HAVE_KERNEL_OPLOCKS_LINUX
  25
  26 #ifndef F_SETLEASE
  27 #define F_SETLEASE      1024
  28 #endif
  29
  30 #ifndef F_GETLEASE
  31 #define F_GETLEASE      1025
  32 #endif
  33
  34 #ifndef CAP_LEASE
  35 #define CAP_LEASE 28
  36 #endif
  37
  38 #ifndef RT_SIGNAL_LEASE
  39 #define RT_SIGNAL_LEASE (SIGRTMIN+1)
  40 #endif
  41
  42 #ifndef F_SETSIG
  43 #define F_SETSIG 10
  44 #endif
  45
  46 /*
  47  * public function to get linux lease capability. Needed by some VFS modules (eg. gpfs.c)
  48  */
  49 void linux_set_lease_capability(void)
  50 {
  51         set_effective_capability(LEASE_CAPABILITY);
  52 }
  53
  54 /*
  55  * Call to set the kernel lease signal handler
  56  */
  57 int linux_set_lease_sighandler(int fd)
  58 {
  59         if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) {
  60                 DEBUG(3,("Failed to set signal handler for kernel lease\n"));
  61                 return -1;
  62         }
  63
  64         return 0;
  65 }
  66
  67 /****************************************************************************
  68  Call SETLEASE. If we get EACCES then we try setting up the right capability and
  69  try again.
  70  Use the SMB_VFS_LINUX_SETLEASE instead of this call directly.
  71 ****************************************************************************/
  72
  73 int linux_setlease(int fd, int leasetype)
  74 {
  75         int ret;
  76
  77         ret = fcntl(fd, F_SETLEASE, leasetype);
  78         if (ret == -1 && errno == EACCES) {
  79                 set_effective_capability(LEASE_CAPABILITY);
  80                 ret = fcntl(fd, F_SETLEASE, leasetype);
  81         }
  82
  83         return ret;
  84 }
  85
  86 /****************************************************************************
  87  * Deal with the Linux kernel <--> smbd
  88  * oplock break protocol.
  89 ****************************************************************************/
  90
  91 static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
  92                                         struct tevent_signal *se,
  93                                         int signum, int count,
  94                                         void *_info, void *private_data)
  95 {
  96         siginfo_t *info = (siginfo_t *)_info;
  97         int fd = info->si_fd;
  98         files_struct *fsp;
  99
 100         fsp = file_find_fd(fd);
 101         break_kernel_oplock(smbd_messaging_context(), fsp);
 102 }
 103
 104 /****************************************************************************
 105  Attempt to set an kernel oplock on a file.
 106 ****************************************************************************/
 107
 108 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 109                                     files_struct *fsp, int oplock_type)
 110 {
 111         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 112                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 113                          "fd = %d, file_id = %s. (%s)\n",
 114                          fsp->fsp_name, fsp->fh->fd,
 115                          file_id_string_tos(&fsp->file_id),
 116                          strerror(errno)));
 117                 return False;
 118         }
 119
 120         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 121                  "file_id = %s gen_id = %lu\n",
 122                  fsp->fsp_name, file_id_string_tos(&fsp->file_id),
 123                  fsp->fh->gen_id));
 124
 125         return True;
 126 }
 127
 128 /****************************************************************************
 129  Release a kernel oplock on a file.
 130 ****************************************************************************/
 131
 132 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 133                                         files_struct *fsp, int oplock_type)
 134 {
 135         if (DEBUGLVL(10)) {
 136                 /*
 137                  * Check and print out the current kernel
 138                  * oplock state of this file.
 139                  */
 140                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 141                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 142                         "gen_id = %lu has kernel oplock state "
 143                         "of %x.\n", fsp->fsp_name, file_id_string_tos(&fsp->file_id),
 144                         fsp->fh->gen_id, state );
 145         }
 146
 147         /*
 148          * Remove the kernel oplock on this file.
 149          */
 150         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 151                 if (DEBUGLVL(0)) {
 152                         dbgtext("linux_release_kernel_oplock: Error when "
 153                                 "removing kernel oplock on file " );
 154                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 155                                 "Error was %s\n", fsp->fsp_name,
 156                                 file_id_string_tos(&fsp->file_id),
 157                                 fsp->fh->gen_id, strerror(errno) );
 158                 }
 159         }
 160 }
 161
 162 /****************************************************************************
 163  See if the kernel supports oplocks.
 164 ****************************************************************************/
 165
 166 static bool linux_oplocks_available(void)
 167 {
 168         int fd, ret;
 169         fd = open("/dev/null", O_RDONLY);
 170         if (fd == -1)
 171                 return False; /* uggh! */
 172         ret = fcntl(fd, F_GETLEASE, 0);
 173         close(fd);
 174         return ret == F_UNLCK;
 175 }
 176
 177 /****************************************************************************
 178  Setup kernel oplocks.
 179 ****************************************************************************/
 180
 181 static const struct kernel_oplocks_ops linux_koplocks = {
 182         .set_oplock                     = linux_set_kernel_oplock,
 183         .release_oplock                 = linux_release_kernel_oplock,
 184         .contend_level2_oplocks_begin   = NULL,
 185         .contend_level2_oplocks_end     = NULL,
 186 };
 187
 188 struct kernel_oplocks *linux_init_kernel_oplocks(TALLOC_CTX *mem_ctx)
 189 {
 190         struct kernel_oplocks *ctx;
 191         struct tevent_signal *se;
 192
 193         if (!linux_oplocks_available()) {
 194                 DEBUG(3,("Linux kernel oplocks not available\n"));
 195                 return NULL;
 196         }
 197
 198         ctx = talloc_zero(mem_ctx, struct kernel_oplocks);
 199         if (!ctx) {
 200                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 201                 return NULL;
 202         }
 203
 204         ctx->ops = &linux_koplocks;
 205
 206         se = tevent_add_signal(smbd_event_context(),
 207                                ctx,
 208                                RT_SIGNAL_LEASE, SA_SIGINFO,
 209                                linux_oplock_signal_handler,
 210                                ctx);
 211         if (!se) {
 212                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 213                 TALLOC_FREE(ctx);
 214                 return NULL;
 215         }
 216
 217         ctx->private_data = se;
 218
 219         DEBUG(3,("Linux kernel oplocks enabled\n"));
 220
 221         return ctx;
 222 }
 223 #else
 224  void oplock_linux_dummy(void);
 225
 226  void oplock_linux_dummy(void) {}
 227 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */