initramfs: support initrd that is bigger than 2GiB

When initrd (compressed or not) is used, kernel report data corrupted with
/dev/ram0.

The root cause:
During initramfs checking, if it is initrd, it will be transferred to
/initrd.image with sys_write.
sys_write only support 2G-4K write, so if the initrd ram is more than
that, /initrd.image will not complete at all.

Add local xwrite to loop calling sys_write to workaround the problem.

Also need to use xwrite in write_buffer() to handle:
image is uncompressed cpio and there is one big file (>2G) in it.
   unpack_to_rootfs ===> write_buffer ===> actions[]/do_copy

At the same time, we don't need to worry about sys_read/sys_write in
do_mounts_rd.c::crd_load.  As decompressor will have fill/flush and local
buffer that is smaller than 2G.

Test with uncompressed initrd, and compressed ones with gz, bz2, lzma,xz,
lzop.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: "Daniel M. Weeks" <dan@danweeks.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 4 deletions

diff --git a/init/initramfs.c b/init/initramfs.c
index a8497fab1c3d..4f276b6a167b 100644
--- 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();
                 }