/* Unix SMB/CIFS implementation. DMAPI Support routines Copyright (C) James Peach 2006 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/>. */ #include "includes.h" #undef DBGC_CLASS #define DBGC_CLASS DBGC_DMAPI #ifndef USE_DMAPI uint32 dmapi_file_flags(const char * const path) { return 0; } bool dmapi_have_session(void) { return False; } const void * dmapi_get_current_session(void) { return NULL; } #else /* USE_DMAPI */ #ifdef HAVE_XFS_DMAPI_H #include <xfs/dmapi.h> #elif defined(HAVE_SYS_DMI_H) #include <sys/dmi.h> #elif defined(HAVE_SYS_JFSDMAPI_H) #include <sys/jfsdmapi.h> #elif defined(HAVE_SYS_DMAPI_H) #include <sys/dmapi.h> #elif defined(HAVE_DMAPI_H) #include <dmapi.h> #endif #define DMAPI_SESSION_NAME "samba" #define DMAPI_TRACE 10 static dm_sessid_t samba_dmapi_session = DM_NO_SESSION; static unsigned session_num; /* Initialise DMAPI session. The session is persistant kernel state, so it might already exist, in which case we merely want to reconnect to it. This function should be called as root. */ static int dmapi_init_session(void) { char buf[DM_SESSION_INFO_LEN]; size_t buflen; uint nsessions = 5; dm_sessid_t *sessions = NULL; char *version; char *session_name; TALLOC_CTX *tmp_ctx = talloc_new(NULL); int i, err; if (session_num == 0) { session_name = DMAPI_SESSION_NAME; } else { session_name = talloc_asprintf(tmp_ctx, "%s%u", DMAPI_SESSION_NAME, session_num); } if (session_name == NULL) { DEBUG(0,("Out of memory in dmapi_init_session\n")); talloc_free(tmp_ctx); return -1; } if (dm_init_service(&version) < 0) { DEBUG(0, ("dm_init_service failed - disabling DMAPI\n")); talloc_free(tmp_ctx); return -1; } ZERO_STRUCT(buf); /* Fetch kernel DMAPI sessions until we get any of them */ do { dm_sessid_t *new_sessions; nsessions *= 2; new_sessions = TALLOC_REALLOC_ARRAY(tmp_ctx, sessions, dm_sessid_t, nsessions); if (new_sessions == NULL) { talloc_free(tmp_ctx); return -1; } sessions = new_sessions; err = dm_getall_sessions(nsessions, sessions, &nsessions); } while (err == -1 && errno == E2BIG); if (err == -1) { DEBUGADD(DMAPI_TRACE, ("failed to retrieve DMAPI sessions: %s\n", strerror(errno))); talloc_free(tmp_ctx); return -1; } /* Look through existing kernel DMAPI sessions to find out ours */ for (i = 0; i < nsessions; ++i) { err = dm_query_session(sessions[i], sizeof(buf), buf, &buflen); buf[sizeof(buf) - 1] = '\0'; if (err == 0 && strcmp(session_name, buf) == 0) { samba_dmapi_session = sessions[i]; DEBUGADD(DMAPI_TRACE, ("attached to existing DMAPI session " "named '%s'\n", buf)); break; } } /* No session already defined. */ if (samba_dmapi_session == DM_NO_SESSION) { err = dm_create_session(DM_NO_SESSION, session_name, &samba_dmapi_session); if (err < 0) { DEBUGADD(DMAPI_TRACE, ("failed to create new DMAPI session: %s\n", strerror(errno))); samba_dmapi_session = DM_NO_SESSION; talloc_free(tmp_ctx); return -1; } DEBUG(0, ("created new DMAPI session named '%s' for %s\n", session_name, version)); } if (samba_dmapi_session != DM_NO_SESSION) { set_effective_capability(DMAPI_ACCESS_CAPABILITY); } /* Note that we never end the DMAPI session. It gets re-used if possiblie. DMAPI session is a kernel resource that is usually lives until server reboot and doesn't get destroed when an application finishes. However, we free list of references to DMAPI sessions we've got from the kernel as it is not needed anymore once we have found (or created) our session. */ talloc_free(tmp_ctx); return 0; } /* Return a pointer to our DMAPI session, if available. This assumes that you have called dmapi_have_session() first. */ const void *dmapi_get_current_session(void) { if (samba_dmapi_session == DM_NO_SESSION) { return NULL; } return (void *)&samba_dmapi_session; } /* dmapi_have_session() must be the first DMAPI call you make in Samba. It will initialize DMAPI, if available, and tell you if you can get a DMAPI session. This should be called in the client-specific child process. */ bool dmapi_have_session(void) { static bool initialized; if (!initialized) { initialized = true; become_root(); dmapi_init_session(); unbecome_root(); } return samba_dmapi_session != DM_NO_SESSION; } /* only call this when you get back an EINVAL error indicating that the session you are using is invalid. This destroys the existing session and creates a new one. */ bool dmapi_new_session(void) { if (dmapi_have_session()) { /* try to destroy the old one - this may not succeed */ dm_destroy_session(samba_dmapi_session); } samba_dmapi_session = DM_NO_SESSION; become_root(); session_num++; dmapi_init_session(); unbecome_root(); return samba_dmapi_session != DM_NO_SESSION; } /* only call this when exiting from master smbd process. DMAPI sessions are long-lived kernel resources we ought to share across smbd processes. However, we must free them when all smbd processes are finished to allow other subsystems clean up properly. Not freeing DMAPI session blocks certain HSM implementations from proper shutdown. */ bool dmapi_destroy_session(void) { if (samba_dmapi_session != DM_NO_SESSION) { become_root(); if (0 == dm_destroy_session(samba_dmapi_session)) { session_num--; samba_dmapi_session = DM_NO_SESSION; } else { DEBUG(0,("Couldn't destroy DMAPI session: %s\n", strerror(errno))); } unbecome_root(); } return samba_dmapi_session == DM_NO_SESSION; } /* This is default implementation of dmapi_file_flags() that is called from VFS is_offline() call to know whether file is offline. For GPFS-specific version see modules/vfs_tsmsm.c. It might be that approach on quering existence of a specific attribute that is used in vfs_tsmsm.c will work with other DMAPI-based HSM implementations as well. */ uint32 dmapi_file_flags(const char * const path) { int err; dm_eventset_t events = {0}; uint nevents; dm_sessid_t dmapi_session; const void *dmapi_session_ptr; void *dm_handle = NULL; size_t dm_handle_len = 0; uint32 flags = 0; dmapi_session_ptr = dmapi_get_current_session(); if (dmapi_session_ptr == NULL) { return 0; } dmapi_session = *(dm_sessid_t *)dmapi_session_ptr; if (dmapi_session == DM_NO_SESSION) { return 0; } /* AIX has DMAPI but no POSIX capablities support. In this case, * we need to be root to do DMAPI manipulations. */ #ifndef HAVE_POSIX_CAPABILITIES become_root(); #endif err = dm_path_to_handle(CONST_DISCARD(char *, path), &dm_handle, &dm_handle_len); if (err < 0) { DEBUG(DMAPI_TRACE, ("dm_path_to_handle(%s): %s\n", path, strerror(errno))); if (errno != EPERM) { goto done; } /* Linux capabilities are broken in that changing our * user ID will clobber out effective capabilities irrespective * of whether we have set PR_SET_KEEPCAPS. Fortunately, the * capabilities are not removed from our permitted set, so we * can re-acquire them if necessary. */ set_effective_capability(DMAPI_ACCESS_CAPABILITY); err = dm_path_to_handle(CONST_DISCARD(char *, path), &dm_handle, &dm_handle_len); if (err < 0) { DEBUG(DMAPI_TRACE, ("retrying dm_path_to_handle(%s): %s\n", path, strerror(errno))); goto done; } } err = dm_get_eventlist(dmapi_session, dm_handle, dm_handle_len, DM_NO_TOKEN, DM_EVENT_MAX, &events, &nevents); if (err < 0) { DEBUG(DMAPI_TRACE, ("dm_get_eventlist(%s): %s\n", path, strerror(errno))); dm_handle_free(dm_handle, dm_handle_len); goto done; } /* We figure that the only reason a DMAPI application would be * interested in trapping read events is that part of the file is * offline. */ DEBUG(DMAPI_TRACE, ("DMAPI event list for %s\n", path)); if (DMEV_ISSET(DM_EVENT_READ, events)) { flags = FILE_ATTRIBUTE_OFFLINE; } dm_handle_free(dm_handle, dm_handle_len); if (flags & FILE_ATTRIBUTE_OFFLINE) { DEBUG(DMAPI_TRACE, ("%s is OFFLINE\n", path)); } done: #ifndef HAVE_POSIX_CAPABILITIES unbecome_root(); #endif return flags; } #endif /* USE_DMAPI */