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         ret = fcntl(fd, F_SETLEASE, leasetype);
  80         if (ret == -1 && errno == EACCES) {
  81                 set_effective_capability(LEASE_CAPABILITY);
  82                 ret = fcntl(fd, F_SETLEASE, leasetype);
  83         }
  84
  85         return ret;
  86 }
  87
  88 /****************************************************************************
  89  * Deal with the Linux kernel <--> smbd
  90  * oplock break protocol.
  91 ****************************************************************************/
  92
  93 static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
  94                                         struct tevent_signal *se,
  95                                         int signum, int count,
  96                                         void *_info, void *private_data)
  97 {
  98         siginfo_t *info = (siginfo_t *)_info;
  99         int fd = info->si_fd;
 100         files_struct *fsp;
 101
 102         fsp = file_find_fd(smbd_server_conn, fd);
 103         if (fsp == NULL) {
 104                 DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
 105                 return;
 106         }
 107         break_kernel_oplock(fsp->conn->sconn->msg_ctx, fsp);
 108 }
 109
 110 /****************************************************************************
 111  Attempt to set an kernel oplock on a file.
 112 ****************************************************************************/
 113
 114 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 115                                     files_struct *fsp, int oplock_type)
 116 {
 117         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 118                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 119                          "fd = %d, file_id = %s. (%s)\n",
 120                          fsp_str_dbg(fsp), fsp->fh->fd,
 121                          file_id_string_tos(&fsp->file_id),
 122                          strerror(errno)));
 123                 return False;
 124         }
 125
 126         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 127                  "file_id = %s gen_id = %lu\n",
 128                  fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
 129                  fsp->fh->gen_id));
 130
 131         return True;
 132 }
 133
 134 /****************************************************************************
 135  Release a kernel oplock on a file.
 136 ****************************************************************************/
 137
 138 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 139                                         files_struct *fsp, int oplock_type)
 140 {
 141         if (DEBUGLVL(10)) {
 142                 /*
 143                  * Check and print out the current kernel
 144                  * oplock state of this file.
 145                  */
 146                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 147                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 148                         "gen_id = %lu has kernel oplock state "
 149                         "of %x.\n", fsp_str_dbg(fsp),
 150                         file_id_string_tos(&fsp->file_id),
 151                         fsp->fh->gen_id, state );
 152         }
 153
 154         /*
 155          * Remove the kernel oplock on this file.
 156          */
 157         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 158                 if (DEBUGLVL(0)) {
 159                         dbgtext("linux_release_kernel_oplock: Error when "
 160                                 "removing kernel oplock on file " );
 161                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 162                                 "Error was %s\n", fsp_str_dbg(fsp),
 163                                 file_id_string_tos(&fsp->file_id),
 164                                 fsp->fh->gen_id, strerror(errno) );
 165                 }
 166         }
 167 }
 168
 169 /****************************************************************************
 170  See if the kernel supports oplocks.
 171 ****************************************************************************/
 172
 173 static bool linux_oplocks_available(void)
 174 {
 175         int fd, ret;
 176         fd = open("/dev/null", O_RDONLY);
 177         if (fd == -1)
 178                 return False; /* uggh! */
 179         ret = fcntl(fd, F_GETLEASE, 0);
 180         close(fd);
 181         return ret == F_UNLCK;
 182 }
 183
 184 /****************************************************************************
 185  Setup kernel oplocks.
 186 ****************************************************************************/
 187
 188 static const struct kernel_oplocks_ops linux_koplocks = {
 189         .set_oplock                     = linux_set_kernel_oplock,
 190         .release_oplock                 = linux_release_kernel_oplock,
 191         .contend_level2_oplocks_begin   = NULL,
 192         .contend_level2_oplocks_end     = NULL,
 193 };
 194
 195 struct kernel_oplocks *linux_init_kernel_oplocks(TALLOC_CTX *mem_ctx)
 196 {
 197         struct kernel_oplocks *ctx;
 198         struct tevent_signal *se;
 199
 200         if (!linux_oplocks_available()) {
 201                 DEBUG(3,("Linux kernel oplocks not available\n"));
 202                 return NULL;
 203         }
 204
 205         ctx = talloc_zero(mem_ctx, struct kernel_oplocks);
 206         if (!ctx) {
 207                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 208                 return NULL;
 209         }
 210
 211         ctx->ops = &linux_koplocks;
 212
 213         se = tevent_add_signal(server_event_context(),
 214                                ctx,
 215                                RT_SIGNAL_LEASE, SA_SIGINFO,
 216                                linux_oplock_signal_handler,
 217                                ctx);
 218         if (!se) {
 219                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 220                 TALLOC_FREE(ctx);
 221                 return NULL;
 222         }
 223
 224         ctx->private_data = se;
 225
 226         DEBUG(3,("Linux kernel oplocks enabled\n"));
 227
 228         return ctx;
 229 }
 230 #else
 231  void oplock_linux_dummy(void);
 232
 233  void oplock_linux_dummy(void) {}
 234 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */