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         /* First set the signal handler. */
  78         if (linux_set_lease_sighandler(fd) == -1) {
  79                 return -1;
  80         }
  81         ret = fcntl(fd, F_SETLEASE, leasetype);
  82         if (ret == -1 && errno == EACCES) {
  83                 set_effective_capability(LEASE_CAPABILITY);
  84                 /*
  85                  * Bug 8974 - work around Linux kernel bug
  86                  * https://bugzilla.kernel.org/show_bug.cgi?id=43336.
  87                  * "fcntl(F_SETLEASE) resets signal number when
  88                  *  called multiple times"
  89                  */
  90                 if (linux_set_lease_sighandler(fd) == -1) {
  91                         return -1;
  92                 }
  93                 ret = fcntl(fd, F_SETLEASE, leasetype);
  94         }
  95
  96         return ret;
  97 }
  98
  99 /****************************************************************************
 100  * Deal with the Linux kernel <--> smbd
 101  * oplock break protocol.
 102 ****************************************************************************/
 103
 104 static void linux_oplock_signal_handler(struct tevent_context *ev_ctx,
 105                                         struct tevent_signal *se,
 106                                         int signum, int count,
 107                                         void *_info, void *private_data)
 108 {
 109         siginfo_t *info = (siginfo_t *)_info;
 110         int fd = info->si_fd;
 111         files_struct *fsp;
 112
 113         fsp = file_find_fd(fd);
 114         if (fsp == NULL) {
 115                 DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
 116                 return;
 117         }
 118         break_kernel_oplock(smbd_messaging_context(), fsp);
 119 }
 120
 121 /****************************************************************************
 122  Attempt to set an kernel oplock on a file.
 123 ****************************************************************************/
 124
 125 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 126                                     files_struct *fsp, int oplock_type)
 127 {
 128         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 129                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 130                          "fd = %d, file_id = %s. (%s)\n",
 131                          fsp_str_dbg(fsp), fsp->fh->fd,
 132                          file_id_string_tos(&fsp->file_id),
 133                          strerror(errno)));
 134                 return False;
 135         }
 136
 137         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 138                  "file_id = %s gen_id = %lu\n",
 139                  fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
 140                  fsp->fh->gen_id));
 141
 142         return True;
 143 }
 144
 145 /****************************************************************************
 146  Release a kernel oplock on a file.
 147 ****************************************************************************/
 148
 149 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 150                                         files_struct *fsp, int oplock_type)
 151 {
 152         if (DEBUGLVL(10)) {
 153                 /*
 154                  * Check and print out the current kernel
 155                  * oplock state of this file.
 156                  */
 157                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 158                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 159                         "gen_id = %lu has kernel oplock state "
 160                         "of %x.\n", fsp_str_dbg(fsp),
 161                         file_id_string_tos(&fsp->file_id),
 162                         fsp->fh->gen_id, state );
 163         }
 164
 165         /*
 166          * Remove the kernel oplock on this file.
 167          */
 168         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 169                 if (DEBUGLVL(0)) {
 170                         dbgtext("linux_release_kernel_oplock: Error when "
 171                                 "removing kernel oplock on file " );
 172                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 173                                 "Error was %s\n", fsp_str_dbg(fsp),
 174                                 file_id_string_tos(&fsp->file_id),
 175                                 fsp->fh->gen_id, strerror(errno) );
 176                 }
 177         }
 178 }
 179
 180 /****************************************************************************
 181  See if the kernel supports oplocks.
 182 ****************************************************************************/
 183
 184 static bool linux_oplocks_available(void)
 185 {
 186         int fd, ret;
 187         fd = open("/dev/null", O_RDONLY);
 188         if (fd == -1)
 189                 return False; /* uggh! */
 190         ret = fcntl(fd, F_GETLEASE, 0);
 191         close(fd);
 192         return ret == F_UNLCK;
 193 }
 194
 195 /****************************************************************************
 196  Setup kernel oplocks.
 197 ****************************************************************************/
 198
 199 static const struct kernel_oplocks_ops linux_koplocks = {
 200         .set_oplock                     = linux_set_kernel_oplock,
 201         .release_oplock                 = linux_release_kernel_oplock,
 202         .contend_level2_oplocks_begin   = NULL,
 203         .contend_level2_oplocks_end     = NULL,
 204 };
 205
 206 struct kernel_oplocks *linux_init_kernel_oplocks(TALLOC_CTX *mem_ctx)
 207 {
 208         struct kernel_oplocks *ctx;
 209         struct tevent_signal *se;
 210
 211         if (!linux_oplocks_available()) {
 212                 DEBUG(3,("Linux kernel oplocks not available\n"));
 213                 return NULL;
 214         }
 215
 216         ctx = talloc_zero(mem_ctx, struct kernel_oplocks);
 217         if (!ctx) {
 218                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 219                 return NULL;
 220         }
 221
 222         ctx->ops = &linux_koplocks;
 223
 224         se = tevent_add_signal(smbd_event_context(),
 225                                ctx,
 226                                RT_SIGNAL_LEASE, SA_SIGINFO,
 227                                linux_oplock_signal_handler,
 228                                ctx);
 229         if (!se) {
 230                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 231                 TALLOC_FREE(ctx);
 232                 return NULL;
 233         }
 234
 235         ctx->private_data = se;
 236
 237         DEBUG(3,("Linux kernel oplocks enabled\n"));
 238
 239         return ctx;
 240 }
 241 #else
 242  void oplock_linux_dummy(void);
 243
 244  void oplock_linux_dummy(void) {}
 245 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */