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[Qemu-block] [PATCH v16 18/22] osdep: Add qemu_lock_fd and qemu_unlock_f
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH v16 18/22] osdep: Add qemu_lock_fd and qemu_unlock_fd |
Date: |
Tue, 2 May 2017 16:18:28 +0800 |
They are wrappers of POSIX fcntl "file private locking", with a
convenient "try lock" wrapper implemented with F_OFD_GETLK.
Signed-off-by: Fam Zheng <address@hidden>
Reviewed-by: Max Reitz <address@hidden>
---
include/qemu/osdep.h | 3 +++
util/osdep.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 122ff06..1c9f5e2 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -341,6 +341,9 @@ int qemu_close(int fd);
#ifndef _WIN32
int qemu_dup(int fd);
#endif
+int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
+int qemu_unlock_fd(int fd, int64_t start, int64_t len);
+int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
diff --git a/util/osdep.c b/util/osdep.c
index 06fb1cf..3de4a18 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -140,6 +140,54 @@ static int qemu_parse_fdset(const char *param)
{
return qemu_parse_fd(param);
}
+
+static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
+{
+#ifdef F_OFD_SETLK
+ int ret;
+ struct flock fl = {
+ .l_whence = SEEK_SET,
+ .l_start = start,
+ .l_len = len,
+ .l_type = fl_type,
+ };
+ ret = fcntl(fd, F_OFD_SETLK, &fl);
+ return ret == -1 ? -errno : 0;
+#else
+ return -ENOTSUP;
+#endif
+}
+
+int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive)
+{
+ return qemu_lock_fcntl(fd, start, len, exclusive ? F_WRLCK : F_RDLCK);
+}
+
+int qemu_unlock_fd(int fd, int64_t start, int64_t len)
+{
+ return qemu_lock_fcntl(fd, start, len, F_UNLCK);
+}
+
+int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive)
+{
+#ifdef F_OFD_SETLK
+ int ret;
+ struct flock fl = {
+ .l_whence = SEEK_SET,
+ .l_start = start,
+ .l_len = len,
+ .l_type = exclusive ? F_WRLCK : F_RDLCK,
+ };
+ ret = fcntl(fd, F_OFD_GETLK, &fl);
+ if (ret == -1) {
+ return -errno;
+ } else {
+ return fl.l_type == F_UNLCK ? 0 : -EAGAIN;
+ }
+#else
+ return -ENOTSUP;
+#endif
+}
#endif
/*
--
2.9.3
- [Qemu-block] [PATCH v16 12/22] iotests: 091: Quit QEMU before checking image, (continued)
- [Qemu-block] [PATCH v16 12/22] iotests: 091: Quit QEMU before checking image, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 13/22] iotests: 172: Use separate images for multiple devices, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 15/22] file-posix: Add 'locking' option, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 14/22] tests: Use null-co:// instead of /dev/null as the dummy image, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 16/22] tests: Disable image lock in test-replication, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 17/22] block: Reuse bs as backing hd for drive-backup sync=none, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 18/22] osdep: Add qemu_lock_fd and qemu_unlock_fd,
Fam Zheng <=
- [Qemu-block] [PATCH v16 19/22] osdep: Fall back to posix lock when OFD lock is unavailable, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 20/22] file-posix: Add image locking to perm operations, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 22/22] tests: Add POSIX image locking test case 182, Fam Zheng, 2017/05/02
- [Qemu-block] [PATCH v16 21/22] qemu-iotests: Add test case 153 for image locking, Fam Zheng, 2017/05/02
- Re: [Qemu-block] [PATCH v16 00/22] block: Image locking series, Kevin Wolf, 2017/05/02
- Re: [Qemu-block] [PATCH v16 00/22] block: Image locking series, Kevin Wolf, 2017/05/02