initramfs: support initrd that is bigger than 2GiB

[mirror_ubuntu-bionic-kernel.git] / init / initramfs.c

diff --git a/init/initramfs.c b/init/initramfs.c
index a8497fab1c3d64950370fb54401493e9eeac0621..4f276b6a167b1ef518b98a7e68256f080b7f43ac 100644 (file)
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -19,6 +19,29 @@
 #include <linux/syscalls.h>
 #include <linux/utime.h>
 
+static ssize_t __init xwrite(int fd, const char *p, size_t count)
+{
+       ssize_t out = 0;
+
+       /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
+       while (count) {
+               ssize_t rv = sys_write(fd, p, count);
+
+               if (rv < 0) {
+                       if (rv == -EINTR || rv == -EAGAIN)
+                               continue;
+                       return out ? out : rv;
+               } else if (rv == 0)
+                       break;
+
+               p += rv;
+               out += rv;
+               count -= rv;
+       }
+
+       return out;
+}
+
 static __initdata char *message;
 static void __init error(char *x)
 {
@@ -346,7 +369,7 @@ static int __init do_name(void)
 static int __init do_copy(void)
 {
        if (count >= body_len) {
-               sys_write(wfd, victim, body_len);
+               xwrite(wfd, victim, body_len);
                sys_close(wfd);
                do_utime(vcollected, mtime);
                kfree(vcollected);
@@ -354,7 +377,7 @@ static int __init do_copy(void)
                state = SkipIt;
                return 0;
        } else {
-               sys_write(wfd, victim, count);
+               xwrite(wfd, victim, count);
                body_len -= count;
                eat(count);
                return 1;
@@ -603,8 +626,13 @@ static int __init populate_rootfs(void)
                fd = sys_open("/initrd.image",
                              O_WRONLY|O_CREAT, 0700);
                if (fd >= 0) {
-                       sys_write(fd, (char *)initrd_start,
-                                       initrd_end - initrd_start);
+                       ssize_t written = xwrite(fd, (char *)initrd_start,
+                                               initrd_end - initrd_start);
+
+                       if (written != initrd_end - initrd_start)
+                               pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
+                                      written, initrd_end - initrd_start);
+
                        sys_close(fd);
                        free_initrd();
                }