[PATCH] initramfs: Support initrd that is bigger then 2G.

Yinghai Lu
2014-06-20T02:12:39Z

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 sys_write_large to loop calling sys_write to workaround the
problem.

Also need to use that in write_buffer path for cpio that have file is
more than file.

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 that
means it will allocate buffer and buffer is smaller than 2G.

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

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
init/initramfs.c | 33 +++++++++++++++++++++++++++++----
1 file changed, 29 insertions(+), 4 deletions(-)

Index: linux-2.6/init/initramfs.c
===================================================================
--- linux-2.6.orig/init/initramfs.c
+++ linux-2.6/init/initramfs.c
@@ -19,6 +19,26 @@
#include <linux/syscalls.h>
#include <linux/utime.h>

+static long __init sys_write_large(unsigned int fd, char *p,
+ size_t count)
+{
+ ssize_t left = count;
+ long written;
+
+ /* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
+ while (left > 0) {
+ written = sys_write(fd, p, left);
+
+ if (written <= 0)
+ break;
+
+ left -= written;
+ p += written;
+ }
+
+ return (written < 0) ? written : count;
+}
+
static __initdata char *message;
static void __init error(char *x)
{
@@ -346,7 +366,7 @@ static int __init do_name(void)
static int __init do_copy(void)
{
if (count >= body_len) {
- sys_write(wfd, victim, body_len);
+ sys_write_large(wfd, victim, body_len);
sys_close(wfd);
do_utime(vcollected, mtime);
kfree(vcollected);
@@ -354,7 +374,7 @@ static int __init do_copy(void)
state = SkipIt;
return 0;
} else {
- sys_write(wfd, victim, count);
+ sys_write_large(wfd, victim, count);
body_len -= count;
eat(count);
return 1;
@@ -604,8 +624,13 @@ 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);
+ long written = sys_write_large(fd, (char *)initrd_start,
+ initrd_end - initrd_start);
+
+ if (written != initrd_end - initrd_start)
+ pr_err("/initrd.image: incomplete write (%ld != %ld)\n",
+ written, initrd_end - initrd_start);
+
sys_close(fd);
free_initrd();
}