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-rw-r--r--exec.c107
1 files changed, 64 insertions, 43 deletions
diff --git a/exec.c b/exec.c
index f09dd4e928..3380836748 100644
--- a/exec.c
+++ b/exec.c
@@ -1233,19 +1233,17 @@ void qemu_mutex_unlock_ramlist(void)
#define HUGETLBFS_MAGIC 0x958458f6
-static long gethugepagesize(const char *path, Error **errp)
+static long gethugepagesize(int fd)
{
struct statfs fs;
int ret;
do {
- ret = statfs(path, &fs);
+ ret = fstatfs(fd, &fs);
} while (ret != 0 && errno == EINTR);
if (ret != 0) {
- error_setg_errno(errp, errno, "failed to get page size of file %s",
- path);
- return 0;
+ return -1;
}
return fs.f_bsize;
@@ -1256,60 +1254,79 @@ static void *file_ram_alloc(RAMBlock *block,
const char *path,
Error **errp)
{
- struct stat st;
+ bool unlink_on_error = false;
char *filename;
char *sanitized_name;
char *c;
void *area;
int fd;
- uint64_t hpagesize;
- Error *local_err = NULL;
-
- hpagesize = gethugepagesize(path, &local_err);
- if (local_err) {
- error_propagate(errp, local_err);
- goto error;
- }
- block->mr->align = hpagesize;
-
- if (memory < hpagesize) {
- error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
- "or larger than huge page size 0x%" PRIx64,
- memory, hpagesize);
- goto error;
- }
+ int64_t hpagesize;
if (kvm_enabled() && !kvm_has_sync_mmu()) {
error_setg(errp,
"host lacks kvm mmu notifiers, -mem-path unsupported");
- goto error;
+ return NULL;
}
- if (!stat(path, &st) && S_ISDIR(st.st_mode)) {
- /* 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 = '_';
- }
+ for (;;) {
+ fd = open(path, O_RDWR);
+ if (fd >= 0) {
+ /* @path names an existing file, use it */
+ break;
}
+ if (errno == ENOENT) {
+ /* @path names a file that doesn't exist, create it */
+ fd = open(path, O_RDWR | O_CREAT | O_EXCL, 0644);
+ if (fd >= 0) {
+ unlink_on_error = true;
+ break;
+ }
+ } else if (errno == EISDIR) {
+ /* @path names a directory, create a file there */
+ /* 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);
+ 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);
+ fd = mkstemp(filename);
+ if (fd >= 0) {
+ unlink(filename);
+ g_free(filename);
+ break;
+ }
+ g_free(filename);
}
- g_free(filename);
- } else {
- fd = open(path, O_RDWR | O_CREAT, 0644);
+ if (errno != EEXIST && errno != EINTR) {
+ error_setg_errno(errp, errno,
+ "can't open backing store %s for guest RAM",
+ path);
+ goto error;
+ }
+ /*
+ * Try again on EINTR and EEXIST. The latter happens when
+ * something else creates the file between our two open().
+ */
}
- if (fd < 0) {
- error_setg_errno(errp, errno,
- "unable to create backing store for hugepages");
+ hpagesize = gethugepagesize(fd);
+ if (hpagesize < 0) {
+ error_setg_errno(errp, errno, "can't get page size for %s",
+ path);
+ goto error;
+ }
+ block->mr->align = hpagesize;
+
+ if (memory < hpagesize) {
+ error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
+ "or larger than page size 0x%" PRIx64,
+ memory, hpagesize);
goto error;
}
@@ -1328,7 +1345,7 @@ static void *file_ram_alloc(RAMBlock *block,
area = qemu_ram_mmap(fd, memory, hpagesize, block->flags & RAM_SHARED);
if (area == MAP_FAILED) {
error_setg_errno(errp, errno,
- "unable to map backing store for hugepages");
+ "unable to map backing store for guest RAM");
close(fd);
goto error;
}
@@ -1341,6 +1358,10 @@ static void *file_ram_alloc(RAMBlock *block,
return area;
error:
+ if (unlink_on_error) {
+ unlink(path);
+ }
+ close(fd);
return NULL;
}
#endif