/* Unix SMB/CIFS implementation. kernel oplock processing for Linux Copyright (C) Andrew Tridgell 2000 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #define DBGC_CLASS DBGC_LOCKING #include "includes.h" #if HAVE_KERNEL_OPLOCKS_LINUX /* these can be removed when they are in glibc headers */ struct cap_user_header { uint32 version; int pid; } header; struct cap_user_data { uint32 effective; uint32 permitted; uint32 inheritable; } data; extern int capget(struct cap_user_header * hdrp, struct cap_user_data * datap); extern int capset(struct cap_user_header * hdrp, const struct cap_user_data * datap); static SIG_ATOMIC_T signals_received; #define FD_PENDING_SIZE 100 static SIG_ATOMIC_T fd_pending_array[FD_PENDING_SIZE]; #ifndef F_SETLEASE #define F_SETLEASE 1024 #endif #ifndef F_GETLEASE #define F_GETLEASE 1025 #endif #ifndef CAP_LEASE #define CAP_LEASE 28 #endif #ifndef RT_SIGNAL_LEASE #define RT_SIGNAL_LEASE (SIGRTMIN+1) #endif #ifndef F_SETSIG #define F_SETSIG 10 #endif /**************************************************************************** Handle a LEASE signal, incrementing the signals_received and blocking the signal. ****************************************************************************/ static void signal_handler(int sig, siginfo_t *info, void *unused) { if (signals_received < FD_PENDING_SIZE - 1) { fd_pending_array[signals_received] = (SIG_ATOMIC_T)info->si_fd; signals_received++; } /* Else signal is lost. */ sys_select_signal(RT_SIGNAL_LEASE); } /**************************************************************************** Try to gain a linux capability. ****************************************************************************/ static void set_capability(unsigned capability) { #ifndef _LINUX_CAPABILITY_VERSION #define _LINUX_CAPABILITY_VERSION 0x19980330 #endif header.version = _LINUX_CAPABILITY_VERSION; header.pid = 0; if (capget(&header, &data) == -1) { DEBUG(3,("Unable to get kernel capabilities (%s)\n", strerror(errno))); return; } data.effective |= (1<<capability); if (capset(&header, &data) == -1) { DEBUG(3,("Unable to set %d capability (%s)\n", capability, strerror(errno))); } } /* Call to set the kernel lease signal handler */ int linux_set_lease_sighandler(int fd) { if (fcntl(fd, F_SETSIG, RT_SIGNAL_LEASE) == -1) { DEBUG(3,("Failed to set signal handler for kernel lease\n")); return -1; } return 0; } /**************************************************************************** Call SETLEASE. If we get EACCES then we try setting up the right capability and try again. Use the SMB_VFS_LINUX_SETLEASE instead of this call directly. ****************************************************************************/ int linux_setlease(int fd, int leasetype) { int ret; ret = fcntl(fd, F_SETLEASE, leasetype); if (ret == -1 && errno == EACCES) { set_capability(CAP_LEASE); ret = fcntl(fd, F_SETLEASE, leasetype); } return ret; } /**************************************************************************** * Deal with the Linux kernel <--> smbd * oplock break protocol. ****************************************************************************/ static files_struct *linux_oplock_receive_message(fd_set *fds) { int fd; files_struct *fsp; BlockSignals(True, RT_SIGNAL_LEASE); fd = fd_pending_array[0]; fsp = file_find_fd(fd); fd_pending_array[0] = (SIG_ATOMIC_T)-1; if (signals_received > 1) memmove(CONST_DISCARD(void *, &fd_pending_array[0]), CONST_DISCARD(void *, &fd_pending_array[1]), sizeof(SIG_ATOMIC_T)*(signals_received-1)); signals_received--; /* now we can receive more signals */ BlockSignals(False, RT_SIGNAL_LEASE); return fsp; } /**************************************************************************** Attempt to set an kernel oplock on a file. ****************************************************************************/ static BOOL linux_set_kernel_oplock(files_struct *fsp, int oplock_type) { if ( SMB_VFS_LINUX_SETLEASE(fsp,fsp->fh->fd, F_WRLCK) == -1) { DEBUG(3,("linux_set_kernel_oplock: Refused oplock on file %s, " "fd = %d, file_id = %s. (%s)\n", fsp->fsp_name, fsp->fh->fd, file_id_string_tos(&fsp->file_id), strerror(errno))); return False; } DEBUG(3,("linux_set_kernel_oplock: got kernel oplock on file %s, " "file_id = %s gen_id = %lu\n", fsp->fsp_name, file_id_string_tos(&fsp->file_id), fsp->fh->gen_id)); return True; } /**************************************************************************** Release a kernel oplock on a file. ****************************************************************************/ static void linux_release_kernel_oplock(files_struct *fsp) { if (DEBUGLVL(10)) { /* * Check and print out the current kernel * oplock state of this file. */ int state = fcntl(fsp->fh->fd, F_GETLEASE, 0); dbgtext("linux_release_kernel_oplock: file %s, file_id = %s " "gen_id = %lu has kernel oplock state " "of %x.\n", fsp->fsp_name, file_id_string_tos(&fsp->file_id), fsp->fh->gen_id, state ); } /* * Remove the kernel oplock on this file. */ if ( SMB_VFS_LINUX_SETLEASE(fsp,fsp->fh->fd, F_UNLCK) == -1) { if (DEBUGLVL(0)) { dbgtext("linux_release_kernel_oplock: Error when " "removing kernel oplock on file " ); dbgtext("%s, file_id = %s, gen_id = %lu. " "Error was %s\n", fsp->fsp_name, file_id_string_tos(&fsp->file_id), fsp->fh->gen_id, strerror(errno) ); } } } /**************************************************************************** See if a oplock message is waiting. ****************************************************************************/ static BOOL linux_oplock_msg_waiting(fd_set *fds) { return signals_received != 0; } /**************************************************************************** See if the kernel supports oplocks. ****************************************************************************/ static BOOL linux_oplocks_available(void) { int fd, ret; fd = open("/dev/null", O_RDONLY); if (fd == -1) return False; /* uggh! */ ret = fcntl(fd, F_GETLEASE, 0); close(fd); return ret == F_UNLCK; } /**************************************************************************** Setup kernel oplocks. ****************************************************************************/ struct kernel_oplocks *linux_init_kernel_oplocks(void) { static struct kernel_oplocks koplocks; struct sigaction act; if (!linux_oplocks_available()) { DEBUG(3,("Linux kernel oplocks not available\n")); return NULL; } ZERO_STRUCT(act); act.sa_handler = NULL; act.sa_sigaction = signal_handler; act.sa_flags = SA_SIGINFO; sigemptyset( &act.sa_mask ); if (sigaction(RT_SIGNAL_LEASE, &act, NULL) != 0) { DEBUG(0,("Failed to setup RT_SIGNAL_LEASE handler\n")); return NULL; } koplocks.receive_message = linux_oplock_receive_message; koplocks.set_oplock = linux_set_kernel_oplock; koplocks.release_oplock = linux_release_kernel_oplock; koplocks.msg_waiting = linux_oplock_msg_waiting; koplocks.notification_fd = -1; /* the signal can start off blocked due to a bug in bash */ BlockSignals(False, RT_SIGNAL_LEASE); DEBUG(3,("Linux kernel oplocks enabled\n")); return &koplocks; } #else void oplock_linux_dummy(void); void oplock_linux_dummy(void) {} #endif /* HAVE_KERNEL_OPLOCKS_LINUX */