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[Qemu-block] [PATCH v5 08/27] osdep: Add qemu_lock_fd and qemu_unlock_fd
From: |
Fam Zheng |
Subject: |
[Qemu-block] [PATCH v5 08/27] osdep: Add qemu_lock_fd and qemu_unlock_fd |
Date: |
Tue, 17 May 2016 15:35:17 +0800 |
They are wrappers of POSIX fcntl "file private locking".
Signed-off-by: Fam Zheng <address@hidden>
---
include/qemu/osdep.h | 2 ++
util/osdep.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 1e3221c..81913a7 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -265,6 +265,8 @@ int qemu_madvise(void *addr, size_t len, int advice);
int qemu_open(const char *name, int flags, ...);
int qemu_close(int fd);
+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);
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
diff --git a/util/osdep.c b/util/osdep.c
index d56d071..9e5d7fa 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -236,6 +236,37 @@ int qemu_close(int fd)
return close(fd);
}
+static int qemu_lock_fcntl(int fd, int64_t start, int64_t len, int fl_type)
+{
+#ifdef F_OFD_SETLK
+ struct flock fl = (struct flock) {
+ .l_whence = SEEK_SET,
+ /* Locking byte 1 avoids interfereing with virtlockd. */
+ .l_start = start,
+ .l_len = len,
+ .l_type = fl_type,
+ };
+ if (fcntl(fd, F_OFD_SETLK, &fl) == -1) {
+ return -errno;
+ } else {
+ return 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);
+}
+
/*
* A variant of write(2) which handles partial write.
*
--
2.8.2
- [Qemu-block] [PATCH v5 05/27] block: Add bdrv_image_locked, (continued)
[Qemu-block] [PATCH v5 08/27] osdep: Add qemu_lock_fd and qemu_unlock_fd,
Fam Zheng <=
[Qemu-block] [PATCH v5 11/27] raw-posix: Implement .bdrv_lockf, Fam Zheng, 2016/05/17
[Qemu-block] [PATCH v5 09/27] osdep: Introduce qemu_dup, Fam Zheng, 2016/05/17
[Qemu-block] [PATCH v5 10/27] raw-posix: Use qemu_dup, Fam Zheng, 2016/05/17
[Qemu-block] [PATCH v5 12/27] gluster: Implement .bdrv_lockf, Fam Zheng, 2016/05/17
[Qemu-block] [PATCH v5 13/27] qemu-io: Add "-L" option for BDRV_O_NO_LOCK, Fam Zheng, 2016/05/17