Currently, file_ram_alloc() only works on directory - it creates a file
under @path and do mmap on it
This patch tries to allow it to work on file directly, if @path is a
directory it works as before, otherwise it treats @path as the target
file then directly allocate memory from it
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx>
---
exec.c | 80
++++++++++++++++++++++++++++++++++++++++++------------------------
1 file changed, 51 insertions(+), 29 deletions(-)
diff --git a/exec.c b/exec.c
index 9075f4d..db0fdaf 100644
--- a/exec.c
+++ b/exec.c
@@ -1174,14 +1174,60 @@ void qemu_mutex_unlock_ramlist(void)
}
#ifdef __linux__
+static bool path_is_dir(const char *path)
+{
+ struct stat fs;
+
+ return stat(path, &fs) == 0 && S_ISDIR(fs.st_mode);
+}
+
+static int open_ram_file_path(RAMBlock *block, const char *path,
size_t size)
+{
+ char *filename;
+ char *sanitized_name;
+ char *c;
+ int fd;
+
+ if (!path_is_dir(path)) {
+ int flags = (block->flags & RAM_SHARED) ? O_RDWR : O_RDONLY;
+
+ flags |= O_EXCL;
+ return open(path, flags);
+ }
+
+ /* Make name safe to use with mkstemp by replacing '/' with '_'. */
+ sanitized_name = g_strdup(memory_region_name(block->mr));
+ for (c = sanitized_name; *c != '\0'; c++) {
+ if (*c == '/') {
+ *c = '_';
+ }
+ }
+ filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path,
+ sanitized_name);
+ g_free(sanitized_name);
+ fd = mkstemp(filename);
+ if (fd >= 0) {
+ unlink(filename);
+ /*
+ * ftruncate is not supported by hugetlbfs in older
+ * hosts, so don't bother bailing out on errors.
+ * If anything goes wrong with it under other filesystems,
+ * mmap will fail.
+ */
+ if (ftruncate(fd, size)) {
+ perror("ftruncate");
+ }
+ }
+ g_free(filename);
+
+ return fd;
+}
+
static void *file_ram_alloc(RAMBlock *block,
ram_addr_t memory,
const char *path,
Error **errp)
{
- char *filename;
- char *sanitized_name;
- char *c;
void *area;
int fd;
uint64_t pagesize;
@@ -1212,38 +1258,14 @@ static void *file_ram_alloc(RAMBlock *block,
goto error;
}
- /* Make name safe to use with mkstemp by replacing '/' with '_'. */
- sanitized_name = g_strdup(memory_region_name(block->mr));
- for (c = sanitized_name; *c != '\0'; c++) {
- if (*c == '/')
- *c = '_';
- }
-
- filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path,
- sanitized_name);
- g_free(sanitized_name);
+ memory = ROUND_UP(memory, pagesize);
- fd = mkstemp(filename);
+ fd = open_ram_file_path(block, path, memory);
if (fd < 0) {
error_setg_errno(errp, errno,
"unable to create backing store for path
%s", path);
- g_free(filename);
goto error;
}
- unlink(filename);
- g_free(filename);
-
- memory = ROUND_UP(memory, pagesize);
-
- /*
- * ftruncate is not supported by hugetlbfs in older
- * hosts, so don't bother bailing out on errors.
- * If anything goes wrong with it under other filesystems,
- * mmap will fail.
- */
- if (ftruncate(fd, memory)) {
- perror("ftruncate");
- }
area = qemu_ram_mmap(fd, memory, pagesize, block->flags &
RAM_SHARED);
if (area == MAP_FAILED) {
