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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 04 of 21] blktap3/drivers: Introduce locking functionality
This patch copies files lock.[ch] from blktap2, with minor changes coming
from blktap2.5. I haven't looked thoroughly into them, they seem to implement
some kind of locking functionality.
Signed-off-by: Thanos Makatos <thanos.makatos@xxxxxxxxxx>
diff --git a/tools/blktap2/drivers/lock.c b/tools/blktap3/drivers/lock.c
copy from tools/blktap2/drivers/lock.c
copy to tools/blktap3/drivers/lock.c
--- a/tools/blktap2/drivers/lock.c
+++ b/tools/blktap3/drivers/lock.c
@@ -41,10 +41,9 @@
#include <time.h>
#include <dirent.h>
#include <limits.h>
+#include "blktap3.h"
#include "lock.h"
-#define unlikely(x) __builtin_expect(!!(x), 0)
-
/* format: xenlk.hostname.uuid.<xf><rw>*/
#define LF_POSTFIX ".xenlk"
#define LFXL_FORMAT LF_POSTFIX ".%s.%s.x%s"
@@ -106,7 +105,8 @@ static char *create_lockfn_link(char *fn
return lockfn_link;
}
-static int NFSnormalizedStatTime(char *fn, struct stat *statnow, int *reterrno)
+static int NFSnormalizedStatTime(char *fn, struct stat *statnow,
+ int *reterrno)
{
int result = LOCK_OK;
int uniq;
@@ -121,13 +121,20 @@ static int NFSnormalizedStatTime(char *f
srandom((int)time(0) ^ pid);
uniq = random() % 0xffffff;
buf = malloc(strlen(fn) + 24);
- if (unlikely(!buf)) { result = LOCK_ENOMEM; goto finish; }
+ if (unlikely(!buf)) {
+ result = LOCK_ENOMEM;
+ goto finish;
+ }
strcpy(buf, fn);
sprintf(buf + strlen(buf), ".xen%08d.tmp", uniq);
fd = open(buf, O_WRONLY | O_CREAT, 0644);
- if (fd == -1) { *reterrno = errno; result = LOCK_EOPEN; goto finish; }
+ if (fd == -1) {
+ *reterrno = errno;
+ result = LOCK_EOPEN;
+ goto finish;
+ }
clstat = close(fd);
if (unlikely(clstat == -1)) {
LOG("fail on close\n");
@@ -144,7 +151,7 @@ finish:
return result;
}
-static int writer_eval(char *name, int readonly)
+static int writer_eval(char *name, int readonly __attribute__((unused)))
{
return name[strlen(name)-1] == 'w';
}
@@ -173,8 +180,10 @@ static int lock_holder(char *fn, char *l
*ioerror = 0;
*elt = 0;
- if (!dirname) goto finish;
- if (!uname) goto finish;
+ if (!dirname)
+ goto finish;
+ if (!uname)
+ goto finish;
/* get directory */
ptr = strrchr(lockfn, '/');
@@ -207,9 +216,12 @@ static int lock_holder(char *fn, char *l
char *p1 = strrchr(fn, '/');
char *p2 = strrchr(lockfn, '/');
char *p3 = strrchr(lockfn_link, '/');
- if (p1) p1+=1;
- if (p2) p2+=1;
- if (p3) p3+=1;
+ if (p1)
+ p1 += 1;
+ if (p2)
+ p2 += 1;
+ if (p3)
+ p3 += 1;
if (strcmp(dptr->d_name, p1 ? p1 : fn) &&
strcmp(dptr->d_name, p2 ? p2 : lockfn) &&
strcmp(dptr->d_name, p3 ? p3 : lockfn_link) &&
@@ -250,7 +262,7 @@ static int lock_holder(char *fn, char *l
}
}
dptr = readdir(pd);
- if (!dptr && errno) {
+ if (!dptr && !errno) {
*ioerror = EIO;
}
}
@@ -265,7 +277,8 @@ finish:
return (*ioerror) ? 1 : status;
}
-int lock(char *fn_to_lock, char *uuid, int force, int readonly, int
*lease_time, int *retstatus)
+int lock(char *fn_to_lock, char *uuid, int force, int readonly,
+ int *lease_time, int *retstatus)
{
char *lockfn = 0;
char *lockfn_xlink = 0;
@@ -296,15 +309,27 @@ int lock(char *fn_to_lock, char *uuid, i
/* build lock file strings */
lockfn = create_lockfn(fn_to_lock);
- if (unlikely(!lockfn)) { status = ENOMEM; *retstatus = LOCK_ENOMEM;
goto finish; }
+ if (unlikely(!lockfn)) {
+ status = ENOMEM;
+ *retstatus = LOCK_ENOMEM;
+ goto finish;
+ }
lockfn_xlink = create_lockfn_link(fn_to_lock, LFXL_FORMAT,
uuid, readonly);
- if (unlikely(!lockfn_xlink)) { status = ENOMEM; *retstatus =
LOCK_ENOMEM; goto finish; }
+ if (unlikely(!lockfn_xlink)) {
+ status = ENOMEM;
+ *retstatus = LOCK_ENOMEM;
+ goto finish;
+ }
lockfn_flink = create_lockfn_link(fn_to_lock, LFFL_FORMAT, uuid,
readonly);
- if (unlikely(!lockfn_flink)) { status = ENOMEM; *retstatus =
LOCK_ENOMEM; goto finish; }
+ if (unlikely(!lockfn_flink)) {
+ status = ENOMEM;
+ *retstatus = LOCK_ENOMEM;
+ goto finish;
+ }
try_again:
if (retry_attempts++ > RETRY_MAX) {
@@ -454,8 +479,7 @@ skip:
}
tmpstat = unlink(lockfn_xlink);
if (unlikely(tmpstat == -1)) {
- LOG("error removing linked lock file %s",
- lockfn_xlink);
+ LOG("error removing linked lock file %s", lockfn_xlink);
}
XSLEEP;
status = LOCK_ESTAT;
@@ -470,8 +494,7 @@ skip:
status = 0;
tmpstat = unlink(lockfn_xlink);
if (unlikely(tmpstat == -1)) {
- LOG("error removing linked lock file %s",
- lockfn_xlink);
+ LOG("error removing linked lock file %s", lockfn_xlink);
}
goto finish;
} else {
@@ -483,8 +506,7 @@ skip:
}
tmpstat = unlink(lockfn_xlink);
if (unlikely(tmpstat == -1)) {
- LOG("error removing linked lock file %s",
- lockfn_xlink);
+ LOG("error removing linked lock file %s", lockfn_xlink);
}
XSLEEP;
*retstatus = LOCK_EINODE;
@@ -554,8 +576,8 @@ finish:
}
*retstatus = LOCK_EHELD_RD;
}
- if (established_lease_time) *lease_time =
- established_lease_time;
+ if (established_lease_time)
+ *lease_time = established_lease_time;
}
skip_scan:
@@ -573,10 +595,12 @@ skip_scan:
failed_write = write(fd, lockfn_flink,
strlen(lockfn_flink)) !=
strlen(lockfn_flink);
- if (failed_write) status = errno;
+ if (failed_write)
+ status = errno;
failed_write |= write(fd, tmpbuf, strlen(tmpbuf)) !=
strlen(tmpbuf);
- if (failed_write) status = errno;
+ if (failed_write)
+ status = errno;
if (failed_write) {
clstat = close(fd);
if (unlikely(clstat == -1)) {
@@ -605,8 +629,7 @@ skip_scan:
/* remove exclusive lock, final read/write locks will hold */
tmpstat = unlink(lockfn);
if (unlikely(tmpstat == -1)) {
- LOG("error removing exclusive lock file %s",
- lockfn);
+ LOG("error removing exclusive lock file %s", lockfn);
}
free(lockfn);
@@ -614,7 +637,8 @@ skip_scan:
free(lockfn_flink);
/* set lease time to -1 if error, so no one is apt to use it */
- if (*retstatus < 0) *lease_time = -1;
+ if (*retstatus < 0)
+ *lease_time = -1;
LOG("returning status %d, errno=%d\n", status, errno);
return status;
@@ -633,7 +657,10 @@ int unlock(char *fn_to_unlock, char *uui
lockfn_link = create_lockfn_link(fn_to_unlock, LFFL_FORMAT, uuid,
readonly);
- if (unlikely(!lockfn_link)) { *status = LOCK_ENOMEM; goto finish; }
+ if (unlikely(!lockfn_link)) {
+ *status = LOCK_ENOMEM;
+ goto finish;
+ }
if (unlink(lockfn_link) == -1) {
LOG("error removing linked lock file %s", lockfn_link);
@@ -686,7 +713,10 @@ int lock_delta(char *fn, int *ret_lease,
ptr += 1;
}
pd = opendir(dirname);
- if (!pd) { reterrno = errno; goto finish; }
+ if (!pd) {
+ reterrno = errno;
+ goto finish;
+ }
dptr = readdir(pd);
while (dptr) {
@@ -703,8 +733,7 @@ int lock_delta(char *fn, int *ret_lease,
strcat(fpath, "/");
strcat(fpath, dptr->d_name);
if (lstat(fpath, &statbuf) != -1) {
- int diff = (int)statnow.st_mtime -
- (int)statbuf.st_mtime;
+ int diff = (int) statnow.st_mtime - (int) statbuf.st_mtime;
/* adjust diff if someone updated the lock
between now and when we created the "now"
file
@@ -744,10 +773,12 @@ finish:
free(uname);
/* returns smallest lock time, or error */
- if (result == INT_MAX) result = LOCK_ENOLOCK;
+ if (result == INT_MAX)
+ result = LOCK_ENOLOCK;
/* set lease time to -1 if error, so no one is apt to use it */
- if ((result < 0) || reterrno) *max_lease = -1;
+ if ((result < 0) || reterrno)
+ *max_lease = -1;
*ret_lease = result;
return reterrno;
}
@@ -769,7 +800,8 @@ static void usage(char *prg)
printf(" t : test the file (after random locks)\n");
printf(" r : random lock tests (must ^C)\n");
printf(" u : unlock, readonly? uniqID (default is PID)\n");
- printf(" l : lock, readonly? force?, uniqID (default is PID),
lease time\n");
+ printf
+ (" l : lock, readonly? force?, uniqID (default is PID), lease
time\n");
}
static void test_file(char *fn)
@@ -792,6 +824,7 @@ static void test_file(char *fn)
}
prev_count = count + 1;
}
+ fclose(fptr);
}
static void random_locks(char *fn)
@@ -841,10 +874,10 @@ static void random_locks(char *fn)
int bw = bytes-2;
while (bw &&
filebuf[bw]!='\n')
bw--;
- if (!bw) bw = -1;
+ if (!bw)
+ bw = -1;
sscanf(&filebuf[bw+1],
- "%d %d %d",
- &count, &dummy, &dummy);
+ "%d %d %d", &count, &dummy, &dummy);
count += 1;
}
lseek(fd, 0, SEEK_END);
@@ -919,15 +952,27 @@ int main(int argc, char *argv[])
} else if (!strcmp(argv[1],"p")) {
perf_lock(argv[2], argc < 3 ? 100000 : atoi(argv[3]));
} else if (!strcmp(argv[1],"l")) {
- if (argc < 4) force = 0; else force = atoi(argv[3]);
- if (argc < 5) readonly = 0; else readonly = atoi(argv[4]);
- if (argc >= 6) ptr = argv[5];
- if (argc == 7) lease = atoi(argv[6]);
+ if (argc < 4)
+ force = 0;
+ else
+ force = atoi(argv[3]);
+ if (argc < 5)
+ readonly = 0;
+ else
+ readonly = atoi(argv[4]);
+ if (argc >= 6)
+ ptr = argv[5];
+ if (argc == 7)
+ lease = atoi(argv[6]);
status = lock(argv[2], ptr, readonly, force, &lease,
&intstatus);
printf("lock status = %d\n", status);
} else if (!strcmp(argv[1],"u") ) {
- if (argc < 5) readonly = 0; else readonly = atoi(argv[3]);
- if (argc == 5) ptr = argv[4];
+ if (argc < 5)
+ readonly = 0;
+ else
+ readonly = atoi(argv[3]);
+ if (argc == 5)
+ ptr = argv[4];
status = unlock(argv[2], ptr, readonly, &intstatus);
printf("unlock status = %d\n", intstatus);
} else {
@@ -949,17 +994,19 @@ static void usage(char *prg)
" unlock <filename> <r|w> <uniqid>\n"
" lock <filename> <r|w> <0|1> <uniqid> <leasetime>\n", prg);
printf(" delta : get time since lock last refreshed\n");
- printf(" returns delta time and max lease time in
seconds\n");
+ printf
+ (" returns delta time and max lease time in seconds\n");
printf(" unlock: unlock request filename, r|w, uniqID\n");
printf(" returns status (success is 0)\n");
- printf(" lock : lock request filename, r|w, force?, uniqID,
lease time request\n");
- printf(" returns status (success is 0) and established
lease time in seconds\n");
+ printf
+ (" lock : lock request filename, r|w, force?, uniqID, lease
time request\n");
+ printf
+ (" returns status (success is 0) and established lease
time in seconds\n");
}
int main(int argc, char *argv[])
{
int status = 0;
- int dlock;
char *ptr;
int force;
int readonly;
diff --git a/tools/blktap2/drivers/lock.h b/tools/blktap3/drivers/lock.h
copy from tools/blktap2/drivers/lock.h
copy to tools/blktap3/drivers/lock.h
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