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         siginfo_t *info = (siginfo_t *)_info;
 112         int fd = info->si_fd;
 113         files_struct *fsp;
 114
 115         fsp = file_find_fd(smbd_server_conn, fd);
 116         if (fsp == NULL) {
 117                 DEBUG(0,("linux_oplock_signal_handler: failed to find fsp for file fd=%d (file was closed ?)\n", fd ));
 118                 return;
 119         }
 120         break_kernel_oplock(fsp->conn->sconn->msg_ctx, fsp);
 121 }
 122
 123 /****************************************************************************
 124  Attempt to set an kernel oplock on a file.
 125 ****************************************************************************/
 126
 127 static bool linux_set_kernel_oplock(struct kernel_oplocks *ctx,
 128                                     files_struct *fsp, int oplock_type)
 129 {
 130         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_WRLCK) == -1) {
 131                 DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, "
 132                          "fd = %d, file_id = %s. (%s)\n",
 133                          fsp_str_dbg(fsp), fsp->fh->fd,
 134                          file_id_string_tos(&fsp->file_id),
 135                          strerror(errno)));
 136                 return False;
 137         }
 138
 139         DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, "
 140                  "file_id = %s gen_id = %lu\n",
 141                  fsp_str_dbg(fsp), file_id_string_tos(&fsp->file_id),
 142                  fsp->fh->gen_id));
 143
 144         return True;
 145 }
 146
 147 /****************************************************************************
 148  Release a kernel oplock on a file.
 149 ****************************************************************************/
 150
 151 static void linux_release_kernel_oplock(struct kernel_oplocks *ctx,
 152                                         files_struct *fsp, int oplock_type)
 153 {
 154         if (DEBUGLVL(10)) {
 155                 /*
 156                  * Check and print out the current kernel
 157                  * oplock state of this file.
 158                  */
 159                 int state = fcntl(fsp->fh->fd, F_GETLEASE, 0);
 160                 dbgtext("linux_release_kernel_oplock: file %s, file_id = %s "
 161                         "gen_id = %lu has kernel oplock state "
 162                         "of %x.\n", fsp_str_dbg(fsp),
 163                         file_id_string_tos(&fsp->file_id),
 164                         fsp->fh->gen_id, state );
 165         }
 166
 167         /*
 168          * Remove the kernel oplock on this file.
 169          */
 170         if ( SMB_VFS_LINUX_SETLEASE(fsp, F_UNLCK) == -1) {
 171                 if (DEBUGLVL(0)) {
 172                         dbgtext("linux_release_kernel_oplock: Error when "
 173                                 "removing kernel oplock on file " );
 174                         dbgtext("%s, file_id = %s, gen_id = %lu. "
 175                                 "Error was %s\n", fsp_str_dbg(fsp),
 176                                 file_id_string_tos(&fsp->file_id),
 177                                 fsp->fh->gen_id, strerror(errno) );
 178                 }
 179         }
 180 }
 181
 182 /****************************************************************************
 183  See if the kernel supports oplocks.
 184 ****************************************************************************/
 185
 186 static bool linux_oplocks_available(void)
 187 {
 188         int fd, ret;
 189         fd = open("/dev/null", O_RDONLY);
 190         if (fd == -1)
 191                 return False; /* uggh! */
 192         ret = fcntl(fd, F_GETLEASE, 0);
 193         close(fd);
 194         return ret == F_UNLCK;
 195 }
 196
 197 /****************************************************************************
 198  Setup kernel oplocks.
 199 ****************************************************************************/
 200
 201 static const struct kernel_oplocks_ops linux_koplocks = {
 202         .set_oplock                     = linux_set_kernel_oplock,
 203         .release_oplock                 = linux_release_kernel_oplock,
 204         .contend_level2_oplocks_begin   = NULL,
 205         .contend_level2_oplocks_end     = NULL,
 206 };
 207
 208 struct kernel_oplocks *linux_init_kernel_oplocks(TALLOC_CTX *mem_ctx)
 209 {
 210         struct kernel_oplocks *ctx;
 211         struct tevent_signal *se;
 212
 213         if (!linux_oplocks_available()) {
 214                 DEBUG(3,("Linux kernel oplocks not available\n"));
 215                 return NULL;
 216         }
 217
 218         ctx = talloc_zero(mem_ctx, struct kernel_oplocks);
 219         if (!ctx) {
 220                 DEBUG(0,("Linux Kernel oplocks talloc_Zero failed\n"));
 221                 return NULL;
 222         }
 223
 224         ctx->ops = &linux_koplocks;
 225
 226         se = tevent_add_signal(smbd_event_context(),
 227                                ctx,
 228                                RT_SIGNAL_LEASE, SA_SIGINFO,
 229                                linux_oplock_signal_handler,
 230                                ctx);
 231         if (!se) {
 232                 DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler"));
 233                 TALLOC_FREE(ctx);
 234                 return NULL;
 235         }
 236
 237         ctx->private_data = se;
 238
 239         DEBUG(3,("Linux kernel oplocks enabled\n"));
 240
 241         return ctx;
 242 }
 243 #else
 244  void oplock_linux_dummy(void);
 245
 246  void oplock_linux_dummy(void) {}
 247 #endif /* HAVE_KERNEL_OPLOCKS_LINUX */