[lvm-devel] dev-prajnoha-selout - locking: Separate out flock and signal code.
Peter Rajnoha
prajnoha at fedoraproject.org
Fri May 9 06:56:07 UTC 2014
Gitweb: http://git.fedorahosted.org/git/?p=lvm2.git;a=commitdiff;h=29a3fbf067e1685ae7e202959a414e4b13f547c7
Commit: 29a3fbf067e1685ae7e202959a414e4b13f547c7
Parent: 239ba5bb04deccee83aa603efee11a9670f6f3fe
Author: Alasdair G Kergon <agk at redhat.com>
AuthorDate: Thu May 1 17:37:14 2014 +0100
Committer: Alasdair G Kergon <agk at redhat.com>
CommitterDate: Thu May 1 17:37:14 2014 +0100
locking: Separate out flock and signal code.
---
include/.symlinks.in | 6 +-
lib/Makefile.in | 2 +
lib/locking/file_locking.c | 231 +------------------------------------------
lib/misc/lvm-flock.c | 223 ++++++++++++++++++++++++++++++++++++++++++
lib/misc/lvm-flock.h | 22 ++++
lib/misc/lvm-signal.c | 56 +++++++++++
lib/misc/lvm-signal.h | 20 ++++
7 files changed, 333 insertions(+), 227 deletions(-)
diff --git a/include/.symlinks.in b/include/.symlinks.in
index 44076c8..ced2cb3 100644
--- a/include/.symlinks.in
+++ b/include/.symlinks.in
@@ -42,17 +42,19 @@
@top_builddir@/lib/misc/configure.h
@top_srcdir@/lib/misc/crc.h
@top_srcdir@/lib/misc/intl.h
- at top_srcdir@/lib/misc/util.h
@top_srcdir@/lib/misc/last-path-component.h
@top_srcdir@/lib/misc/lib.h
@top_srcdir@/lib/misc/lvm-exec.h
@top_srcdir@/lib/misc/lvm-file.h
+ at top_srcdir@/lib/misc/lvm-flock.h
@top_srcdir@/lib/misc/lvm-globals.h
+ at top_srcdir@/lib/misc/lvm-signal.h
@top_srcdir@/lib/misc/lvm-string.h
@top_builddir@/lib/misc/lvm-version.h
- at top_srcdir@/lib/misc/lvm-wrappers.h
@top_srcdir@/lib/misc/lvm-percent.h
+ at top_srcdir@/lib/misc/lvm-wrappers.h
@top_srcdir@/lib/misc/sharedlib.h
+ at top_srcdir@/lib/misc/util.h
@top_srcdir@/lib/properties/prop_common.h
@top_srcdir@/lib/report/properties.h
@top_srcdir@/lib/report/report.h
diff --git a/lib/Makefile.in b/lib/Makefile.in
index c3d4598..9f101f3 100644
--- a/lib/Makefile.in
+++ b/lib/Makefile.in
@@ -106,7 +106,9 @@ SOURCES =\
misc/crc.c \
misc/lvm-exec.c \
misc/lvm-file.c \
+ misc/lvm-flock.c \
misc/lvm-globals.c \
+ misc/lvm-signal.c \
misc/lvm-string.c \
misc/lvm-wrappers.c \
misc/lvm-percent.c \
diff --git a/lib/locking/file_locking.c b/lib/locking/file_locking.c
index 734e0b4..2f6716d 100644
--- a/lib/locking/file_locking.c
+++ b/lib/locking/file_locking.c
@@ -21,6 +21,7 @@
#include "defaults.h"
#include "lvm-file.h"
#include "lvm-string.h"
+#include "lvm-flock.h"
#include "lvmcache.h"
#include <limits.h>
@@ -30,237 +31,20 @@
#include <fcntl.h>
#include <signal.h>
-struct lock_list {
- struct dm_list list;
- int lf;
- char *res;
-};
-
-static struct dm_list _lock_list;
static char _lock_dir[PATH_MAX];
-static int _prioritise_write_locks;
static sig_t _oldhandler;
static sigset_t _fullsigset, _intsigset;
static volatile sig_atomic_t _handler_installed;
-/* Drop lock known to be shared with another file descriptor. */
-static void _drop_shared_flock(const char *file, int fd)
-{
- log_debug_locking("_drop_shared_flock %s.", file);
-
- if (close(fd) < 0)
- log_sys_debug("close", file);
-}
-
-static void _undo_flock(const char *file, int fd)
-{
- struct stat buf1, buf2;
-
- log_debug_locking("_undo_flock %s", file);
- if (!flock(fd, LOCK_NB | LOCK_EX) &&
- !stat(file, &buf1) &&
- !fstat(fd, &buf2) &&
- is_same_inode(buf1, buf2))
- if (unlink(file))
- log_sys_debug("unlink", file);
-
- if (close(fd) < 0)
- log_sys_debug("close", file);
-}
-
-static int _release_lock(const char *file, int unlock)
-{
- struct lock_list *ll;
- struct dm_list *llh, *llt;
-
- dm_list_iterate_safe(llh, llt, &_lock_list) {
- ll = dm_list_item(llh, struct lock_list);
-
- if (!file || !strcmp(ll->res, file)) {
- dm_list_del(llh);
- if (unlock) {
- log_very_verbose("Unlocking %s", ll->res);
- if (flock(ll->lf, LOCK_NB | LOCK_UN))
- log_sys_debug("flock", ll->res);
- _undo_flock(ll->res, ll->lf);
- } else
- _drop_shared_flock(ll->res, ll->lf);
-
- dm_free(ll->res);
- dm_free(llh);
-
- if (file)
- return 1;
- }
- }
-
- return 0;
-}
-
static void _fin_file_locking(void)
{
- _release_lock(NULL, 1);
+ release_flocks(1);
}
static void _reset_file_locking(void)
{
- _release_lock(NULL, 0);
-}
-
-static void _remove_ctrl_c_handler(void)
-{
- siginterrupt(SIGINT, 0);
- if (!_handler_installed)
- return;
-
- _handler_installed = 0;
-
- sigprocmask(SIG_SETMASK, &_fullsigset, NULL);
- if (signal(SIGINT, _oldhandler) == SIG_ERR)
- log_sys_error("signal", "_remove_ctrl_c_handler");
-}
-
-static void _trap_ctrl_c(int sig __attribute__((unused)))
-{
- _remove_ctrl_c_handler();
- log_error("CTRL-c detected: giving up waiting for lock");
-}
-
-static void _install_ctrl_c_handler(void)
-{
- _handler_installed = 1;
-
- if ((_oldhandler = signal(SIGINT, _trap_ctrl_c)) == SIG_ERR) {
- _handler_installed = 0;
- return;
- }
-
- sigprocmask(SIG_SETMASK, &_intsigset, NULL);
- siginterrupt(SIGINT, 1);
-}
-
-static int _do_flock(const char *file, int *fd, int operation, uint32_t nonblock)
-{
- int r = 1;
- int old_errno;
- struct stat buf1, buf2;
-
- log_debug_locking("_do_flock %s %c%c", file,
- operation == LOCK_EX ? 'W' : 'R', nonblock ? ' ' : 'B');
- do {
- if ((*fd > -1) && close(*fd))
- log_sys_debug("close", file);
-
- if ((*fd = open(file, O_CREAT | O_APPEND | O_RDWR, 0777)) < 0) {
- log_sys_error("open", file);
- return 0;
- }
-
- if (nonblock)
- operation |= LOCK_NB;
- else
- _install_ctrl_c_handler();
-
- r = flock(*fd, operation);
- old_errno = errno;
- if (!nonblock)
- _remove_ctrl_c_handler();
-
- if (r) {
- errno = old_errno;
- log_sys_error("flock", file);
- if (close(*fd))
- log_sys_debug("close", file);
- *fd = -1;
- return 0;
- }
-
- if (!stat(file, &buf1) && !fstat(*fd, &buf2) &&
- is_same_inode(buf1, buf2))
- return 1;
- } while (!nonblock);
-
- return_0;
-}
-
-#define AUX_LOCK_SUFFIX ":aux"
-
-static int _do_write_priority_flock(const char *file, int *fd, int operation, uint32_t nonblock)
-{
- int r, fd_aux = -1;
- char *file_aux = alloca(strlen(file) + sizeof(AUX_LOCK_SUFFIX));
-
- strcpy(file_aux, file);
- strcat(file_aux, AUX_LOCK_SUFFIX);
-
- if ((r = _do_flock(file_aux, &fd_aux, LOCK_EX, 0))) {
- if (operation == LOCK_EX) {
- r = _do_flock(file, fd, operation, nonblock);
- _undo_flock(file_aux, fd_aux);
- } else {
- _undo_flock(file_aux, fd_aux);
- r = _do_flock(file, fd, operation, nonblock);
- }
- }
-
- return r;
-}
-
-static int _lock_file(const char *file, uint32_t flags)
-{
- int operation;
- uint32_t nonblock = flags & LCK_NONBLOCK;
- int r;
-
- struct lock_list *ll;
- char state;
-
- switch (flags & LCK_TYPE_MASK) {
- case LCK_READ:
- operation = LOCK_SH;
- state = 'R';
- break;
- case LCK_WRITE:
- operation = LOCK_EX;
- state = 'W';
- break;
- case LCK_UNLOCK:
- return _release_lock(file, 1);
- default:
- log_error("Unrecognised lock type: %d", flags & LCK_TYPE_MASK);
- return 0;
- }
-
- if (!(ll = dm_malloc(sizeof(struct lock_list))))
- return_0;
-
- if (!(ll->res = dm_strdup(file))) {
- dm_free(ll);
- return_0;
- }
-
- ll->lf = -1;
-
- log_very_verbose("Locking %s %c%c", ll->res, state,
- nonblock ? ' ' : 'B');
-
- (void) dm_prepare_selinux_context(file, S_IFREG);
- if (_prioritise_write_locks)
- r = _do_write_priority_flock(file, &ll->lf, operation, nonblock);
- else
- r = _do_flock(file, &ll->lf, operation, nonblock);
- (void) dm_prepare_selinux_context(NULL, 0);
-
- if (r)
- dm_list_add(&_lock_list, &ll->list);
- else {
- dm_free(ll->res);
- dm_free(ll);
- stack;
- }
-
- return r;
+ release_flocks(0);
}
static int _file_lock_resource(struct cmd_context *cmd, const char *resource,
@@ -298,7 +82,7 @@ static int _file_lock_resource(struct cmd_context *cmd, const char *resource,
return 0;
}
- if (!_lock_file(lockfile, flags))
+ if (!lock_file(lockfile, flags))
return_0;
break;
case LCK_LV:
@@ -352,6 +136,8 @@ int init_file_locking(struct locking_type *locking, struct cmd_context *cmd,
int r;
const char *locking_dir;
+ init_flock(cmd);
+
locking->lock_resource = _file_lock_resource;
locking->reset_locking = _reset_file_locking;
locking->fin_locking = _fin_file_locking;
@@ -366,9 +152,6 @@ int init_file_locking(struct locking_type *locking, struct cmd_context *cmd,
strcpy(_lock_dir, locking_dir);
- _prioritise_write_locks =
- find_config_tree_bool(cmd, global_prioritise_write_locks_CFG, NULL);
-
(void) dm_prepare_selinux_context(_lock_dir, S_IFDIR);
r = dm_create_dir(_lock_dir);
(void) dm_prepare_selinux_context(NULL, 0);
@@ -380,8 +163,6 @@ int init_file_locking(struct locking_type *locking, struct cmd_context *cmd,
if ((access(_lock_dir, R_OK | W_OK | X_OK) == -1) && (errno == EROFS))
return 0;
- dm_list_init(&_lock_list);
-
if (sigfillset(&_intsigset) || sigfillset(&_fullsigset)) {
log_sys_error_suppress(suppress_messages, "sigfillset",
"init_file_locking");
diff --git a/lib/misc/lvm-flock.c b/lib/misc/lvm-flock.c
new file mode 100644
index 0000000..ca05e1c
--- /dev/null
+++ b/lib/misc/lvm-flock.c
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
+ * Copyright (C) 2004-2014 Red Hat, Inc. All rights reserved.
+ *
+ * This file is part of LVM2.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "lib.h"
+#include "config.h"
+#include "lvm-file.h"
+#include "lvm-flock.h"
+#include "lvm-signal.h"
+#include "locking.h"
+
+#include <sys/file.h>
+#include <fcntl.h>
+
+struct lock_list {
+ struct dm_list list;
+ int lf;
+ char *res;
+};
+
+static struct dm_list _lock_list;
+static int _prioritise_write_locks;
+
+/* Drop lock known to be shared with another file descriptor. */
+static void _drop_shared_flock(const char *file, int fd)
+{
+ log_debug_locking("_drop_shared_flock %s.", file);
+
+ if (close(fd) < 0)
+ log_sys_debug("close", file);
+}
+
+static void _undo_flock(const char *file, int fd)
+{
+ struct stat buf1, buf2;
+
+ log_debug_locking("_undo_flock %s", file);
+ if (!flock(fd, LOCK_NB | LOCK_EX) &&
+ !stat(file, &buf1) &&
+ !fstat(fd, &buf2) &&
+ is_same_inode(buf1, buf2))
+ if (unlink(file))
+ log_sys_debug("unlink", file);
+
+ if (close(fd) < 0)
+ log_sys_debug("close", file);
+}
+
+static int _release_lock(const char *file, int unlock)
+{
+ struct lock_list *ll;
+ struct dm_list *llh, *llt;
+
+ dm_list_iterate_safe(llh, llt, &_lock_list) {
+ ll = dm_list_item(llh, struct lock_list);
+
+ if (!file || !strcmp(ll->res, file)) {
+ dm_list_del(llh);
+ if (unlock) {
+ log_very_verbose("Unlocking %s", ll->res);
+ if (flock(ll->lf, LOCK_NB | LOCK_UN))
+ log_sys_debug("flock", ll->res);
+ _undo_flock(ll->res, ll->lf);
+ } else
+ _drop_shared_flock(ll->res, ll->lf);
+
+ dm_free(ll->res);
+ dm_free(llh);
+
+ if (file)
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+void release_flocks(int unlock)
+{
+ _release_lock(NULL, unlock);
+}
+
+static int _do_flock(const char *file, int *fd, int operation, uint32_t nonblock)
+{
+ int r = 1;
+ int old_errno;
+ struct stat buf1, buf2;
+
+ log_debug_locking("_do_flock %s %c%c", file,
+ operation == LOCK_EX ? 'W' : 'R', nonblock ? ' ' : 'B');
+ do {
+ if ((*fd > -1) && close(*fd))
+ log_sys_debug("close", file);
+
+ if ((*fd = open(file, O_CREAT | O_APPEND | O_RDWR, 0777)) < 0) {
+ log_sys_error("open", file);
+ return 0;
+ }
+
+ if (nonblock)
+ operation |= LOCK_NB;
+ else
+ install_ctrl_c_handler();
+
+ r = flock(*fd, operation);
+ old_errno = errno;
+ if (!nonblock)
+ remove_ctrl_c_handler();
+
+ if (r) {
+ errno = old_errno;
+ log_sys_error("flock", file);
+ if (close(*fd))
+ log_sys_debug("close", file);
+ *fd = -1;
+ return 0;
+ }
+
+ if (!stat(file, &buf1) && !fstat(*fd, &buf2) &&
+ is_same_inode(buf1, buf2))
+ return 1;
+ } while (!nonblock);
+
+ return_0;
+}
+
+#define AUX_LOCK_SUFFIX ":aux"
+
+static int _do_write_priority_flock(const char *file, int *fd, int operation, uint32_t nonblock)
+{
+ int r, fd_aux = -1;
+ char *file_aux = alloca(strlen(file) + sizeof(AUX_LOCK_SUFFIX));
+
+ strcpy(file_aux, file);
+ strcat(file_aux, AUX_LOCK_SUFFIX);
+
+ if ((r = _do_flock(file_aux, &fd_aux, LOCK_EX, 0))) {
+ if (operation == LOCK_EX) {
+ r = _do_flock(file, fd, operation, nonblock);
+ _undo_flock(file_aux, fd_aux);
+ } else {
+ _undo_flock(file_aux, fd_aux);
+ r = _do_flock(file, fd, operation, nonblock);
+ }
+ }
+
+ return r;
+}
+
+int lock_file(const char *file, uint32_t flags)
+{
+ int operation;
+ uint32_t nonblock = flags & LCK_NONBLOCK;
+ int r;
+
+ struct lock_list *ll;
+ char state;
+
+ switch (flags & LCK_TYPE_MASK) {
+ case LCK_READ:
+ operation = LOCK_SH;
+ state = 'R';
+ break;
+ case LCK_WRITE:
+ operation = LOCK_EX;
+ state = 'W';
+ break;
+ case LCK_UNLOCK:
+ return _release_lock(file, 1);
+ default:
+ log_error("Unrecognised lock type: %d", flags & LCK_TYPE_MASK);
+ return 0;
+ }
+
+ if (!(ll = dm_malloc(sizeof(struct lock_list))))
+ return_0;
+
+ if (!(ll->res = dm_strdup(file))) {
+ dm_free(ll);
+ return_0;
+ }
+
+ ll->lf = -1;
+
+ log_very_verbose("Locking %s %c%c", ll->res, state,
+ nonblock ? ' ' : 'B');
+
+ (void) dm_prepare_selinux_context(file, S_IFREG);
+ if (_prioritise_write_locks)
+ r = _do_write_priority_flock(file, &ll->lf, operation, nonblock);
+ else
+ r = _do_flock(file, &ll->lf, operation, nonblock);
+ (void) dm_prepare_selinux_context(NULL, 0);
+
+ if (r)
+ dm_list_add(&_lock_list, &ll->list);
+ else {
+ dm_free(ll->res);
+ dm_free(ll);
+ stack;
+ }
+
+ return r;
+}
+
+void init_flock(struct cmd_context *cmd)
+{
+ dm_list_init(&_lock_list);
+
+ _prioritise_write_locks =
+ find_config_tree_bool(cmd, global_prioritise_write_locks_CFG, NULL);
+}
diff --git a/lib/misc/lvm-flock.h b/lib/misc/lvm-flock.h
new file mode 100644
index 0000000..5e8aefd
--- /dev/null
+++ b/lib/misc/lvm-flock.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2014 Red Hat, Inc. All rights reserved.
+ *
+ * This file is part of LVM2.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _LVM_SIGNAL_H
+# define _LVM_SIGNAL_H
+
+void init_flock(struct cmd_context *cmd);
+int lock_file(const char *file, uint32_t flags);
+void release_flocks(int unlock);
+
+#endif /* _LVM_SIGNAL_H */
diff --git a/lib/misc/lvm-signal.c b/lib/misc/lvm-signal.c
new file mode 100644
index 0000000..927e839
--- /dev/null
+++ b/lib/misc/lvm-signal.c
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
+ * Copyright (C) 2004-2014 Red Hat, Inc. All rights reserved.
+ *
+ * This file is part of LVM2.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "lib.h"
+#include "lvm-signal.h"
+
+#include <signal.h>
+
+static sig_t _oldhandler;
+static sigset_t _fullsigset, _intsigset;
+static volatile sig_atomic_t _handler_installed;
+
+void remove_ctrl_c_handler(void)
+{
+ siginterrupt(SIGINT, 0);
+ if (!_handler_installed)
+ return;
+
+ _handler_installed = 0;
+
+ sigprocmask(SIG_SETMASK, &_fullsigset, NULL);
+ if (signal(SIGINT, _oldhandler) == SIG_ERR)
+ log_sys_error("signal", "_remove_ctrl_c_handler");
+}
+
+static void _trap_ctrl_c(int sig __attribute__((unused)))
+{
+ remove_ctrl_c_handler();
+
+ log_error("CTRL-c detected: giving up waiting for lock");
+}
+
+void install_ctrl_c_handler(void)
+{
+ _handler_installed = 1;
+
+ if ((_oldhandler = signal(SIGINT, _trap_ctrl_c)) == SIG_ERR) {
+ _handler_installed = 0;
+ return;
+ }
+
+ sigprocmask(SIG_SETMASK, &_intsigset, NULL);
+ siginterrupt(SIGINT, 1);
+}
diff --git a/lib/misc/lvm-signal.h b/lib/misc/lvm-signal.h
new file mode 100644
index 0000000..ce9d2e9
--- /dev/null
+++ b/lib/misc/lvm-signal.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
+ * Copyright (C) 2004-2014 Red Hat, Inc. All rights reserved.
+ *
+ * This file is part of LVM2.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _LVM_SIGNAL_H
+# define _LVM_SIGNAL_H
+void remove_ctrl_c_handler(void);
+void install_ctrl_c_handler(void);
+#endif
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