In order to re-attach, it's necessary to know the exact image
source for local images.
For later remote images, more information is expected to be recorded.
Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
---
v3:
- should record realpath() in recovery files.
mount/main.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 88 insertions(+), 7 deletions(-)
diff --git a/mount/main.c b/mount/main.c
index d82e526..9123618 100644
--- a/mount/main.c
+++ b/mount/main.c
@@ -300,6 +300,71 @@ out_closefd:
return err;
}
+static char *erofsmount_write_recovery_info(const char *source)
+{
+ char recp[] = "/var/run/erofs/mountnbd_XXXXXX";
+ char *realp;
+ int fd, err;
+ FILE *f;
+
+ fd = mkstemp(recp);
+ if (fd < 0 && errno == ENOENT) {
+ err = mkdir("/var/run/erofs", 0700);
+ if (err)
+ return ERR_PTR(-errno);
+ fd = mkstemp(recp);
+ }
+ if (fd < 0)
+ return ERR_PTR(-errno);
+
+ f = fdopen(fd, "w+");
+ if (!f) {
+ close(fd);
+ return ERR_PTR(-errno);
+ }
+
+ realp = realpath(source, NULL);
+ if (!realp) {
+ fclose(f);
+ return ERR_PTR(-errno);
+ }
+ /* TYPE<LOCAL> <SOURCE PATH>\n(more..) */
+ err = fprintf(f, "LOCAL %s\n", realp) < 0;
+ fclose(f);
+ free(realp);
+ if (err)
+ return ERR_PTR(-ENOMEM);
+ return strdup(recp) ?: ERR_PTR(-ENOMEM);
+}
+
+static int erofsmount_nbd_fix_backend_linkage(int num, char **recp)
+{
+ char *newrecp;
+ int err;
+
+ newrecp = erofs_nbd_get_identifier(num);
+ if (!IS_ERR(newrecp)) {
+ err = strlen(newrecp);
+ if (newrecp[err - 1] == '\n')
+ newrecp[err - 1] = '\0';
+ err = strcmp(newrecp, *recp) ? -EFAULT : 0;
+ free(newrecp);
+ return err;
+ }
+
+ if (asprintf(&newrecp, "/var/run/erofs/mountnbd_nbd%d", num) <= 0)
+ return -ENOMEM;
+
+ if (rename(*recp, newrecp) < 0) {
+ err = -errno;
+ free(newrecp);
+ return err;
+ }
+ free(*recp);
+ *recp = newrecp;
+ return 0;
+}
+
static int erofsmount_startnbd_nl(pid_t *pid, const char *source)
{
struct erofsmount_nbd_ctx ctx = {};
@@ -318,26 +383,42 @@ static int erofsmount_startnbd_nl(pid_t *pid, const char
*source)
return err;
}
if ((*pid = fork()) == 0) {
+ char *recp;
+
/* Otherwise, NBD disconnect sends SIGPIPE, skipping cleanup */
if (signal(SIGPIPE, SIG_IGN) == SIG_ERR) {
close(ctx.vd.fd);
exit(EXIT_FAILURE);
}
-
+ recp = erofsmount_write_recovery_info(source);
+ if (IS_ERR(recp)) {
+ close(ctx.vd.fd);
+ exit(EXIT_FAILURE);
+ }
num = -1;
- err = erofs_nbd_nl_connect(&num, 9, INT64_MAX >> 9, NULL);
+ err = erofs_nbd_nl_connect(&num, 9, INT64_MAX >> 9, recp);
if (err >= 0) {
ctx.sk.fd = err;
- err = write(pipefd[1], &num, sizeof(int));
- if (err >= sizeof(int)) {
+ err = erofsmount_nbd_fix_backend_linkage(num, &recp);
+ if (err) {
+ close(ctx.sk.fd);
+ } else {
+ err = write(pipefd[1], &num, sizeof(int));
+ if (err < 0)
+ err = -errno;
close(pipefd[1]);
close(pipefd[0]);
- err =
(int)(uintptr_t)erofsmount_nbd_loopfn(&ctx);
- exit(err ? EXIT_FAILURE : EXIT_SUCCESS);
+ if (err >= sizeof(int)) {
+ err =
(int)(uintptr_t)erofsmount_nbd_loopfn(&ctx);
+ goto out_fork;
+ }
}
}
close(ctx.vd.fd);
- exit(EXIT_FAILURE);
+out_fork:
+ (void)unlink(recp);
+ free(recp);
+ exit(err ? EXIT_FAILURE : EXIT_SUCCESS);
}
close(pipefd[1]);
err = read(pipefd[0], &num, sizeof(int));
--
2.43.0
