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recovery: write partitions more conservatively

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Write and verify partitions using write(2) and read(2) rather than the
stdio functions.  Read and write in 4kb blocks.  When writing, fsync()
every 1MB.

Bug: 9602014
Change-Id: Ie98ce38e857786fc0f4ebf36bb5ffc93b41bc96f
This commit is contained in:
Doug Zongker
2013-07-09 10:34:46 -07:00
parent 044a0b4d49
commit c870a99c4a
1 changed files with 45 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
applypatch/applypatch.c
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@@ -424,42 +424,50 @@ int WriteToPartition(unsigned char* data, size_t len,
{
size_t start = 0;
int success = 0;
FILE* f = fopen(partition, "r+b");
if (f == NULL) {
int fd = open(partition, O_RDWR);
if (fd < 0) {
printf("failed to open %s: %s\n", partition, strerror(errno));
return -1;
}
int attempt;
for (attempt = 0; attempt < 3; ++attempt) {
printf("write %s attempt %d start at %d\n", partition, attempt+1, start);
fseek(f, start, SEEK_SET);
for (attempt = 0; attempt < 10; ++attempt) {
off_t next_sync = start + (1<<20);
printf("raw write %s attempt %d start at %d\n", partition, attempt+1, start);
lseek(fd, start, SEEK_SET);
while (start < len) {
size_t to_write = len - start;
if (to_write > (1<<20)) to_write = 1<<20;
if (to_write > 4096) to_write = 4096;
if (fwrite(data+start, 1, to_write, f) != to_write) {
printf("short write writing to %s (%s)\n",
partition, strerror(errno));
return -1;
ssize_t written = write(fd, data+start, to_write);
if (written < 0) {
if (errno == EINTR) {
written = 0;
} else {
printf("failed write writing to %s (%s)\n",
partition, strerror(errno));
return -1;
}
}
start += to_write;
if (start < len) {
usleep(50000); // 50 ms
start += written;
if (start >= next_sync) {
fsync(fd);
next_sync = start + (1<<20);
}
}
fsync(fd);
// drop caches so our subsequent verification read
// won't just be reading the cache.
sync();
FILE* dc = fopen("/proc/sys/vm/drop_caches", "w");
fwrite("3\n", 2, 1, dc);
fclose(dc);
int dc = open("/proc/sys/vm/drop_caches", O_WRONLY);
write(dc, "3\n", 2);
close(dc);
sleep(1);
printf(" caches dropped\n");
// verify
fseek(f, 0, SEEK_SET);
lseek(fd, 0, SEEK_SET);
unsigned char buffer[4096];
start = len;
size_t p;
@@ -467,11 +475,23 @@ int WriteToPartition(unsigned char* data, size_t len,
size_t to_read = len - p;
if (to_read > sizeof(buffer)) to_read = sizeof(buffer);
if (fread(buffer, 1, to_read, f) != to_read) {
printf("short verify read %s at %d: %s\n",
partition, p, strerror(errno));
start = p;
break;
size_t so_far = 0;
while (so_far < to_read) {
ssize_t read_count = read(fd, buffer+so_far, to_read-so_far);
if (read_count < 0) {
if (errno == EINTR) {
read_count = 0;
} else {
printf("verify read error %s at %d: %s\n",
partition, p, strerror(errno));
return -1;
}
}
if (read_count < to_read) {
printf("short verify read %s at %d: %d %d %s\n",
partition, p, read_count, to_read, strerror(errno));
}
so_far += read_count;
}
if (memcmp(buffer, data+p, to_read)) {
@@ -486,6 +506,8 @@ int WriteToPartition(unsigned char* data, size_t len,
success = true;
break;
}
sleep(2);
}
if (!success) {
@@ -493,7 +515,7 @@ int WriteToPartition(unsigned char* data, size_t len,
return -1;
}
if (fclose(f) != 0) {
if (close(fd) != 0) {
printf("error closing %s (%s)\n", partition, strerror(errno));
return -1;
}