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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <libmount/libmount.h>
#include <sys/sysmacros.h>
#include "xlog.h"
#include "conffile.h"
#ifndef MOUNTINFO_PATH
#define MOUNTINFO_PATH "/proc/self/mountinfo"
#endif
#define CONF_NAME "nfsrahead"
#define NFS_DEFAULT_READAHEAD 128
/* Device information from the system */
struct device_info {
char *device_number;
dev_t dev;
char *mountpoint;
char *fstype;
};
/* Convert a string in the format n:m to a device number */
static int fill_device_number(struct device_info *info)
{
char *s = strdup(info->device_number), *p;
char *maj_s, *min_s;
unsigned int maj, min;
int err = -EINVAL;
maj_s = p = s;
for ( ; *p != ':' && *p != '\0'; p++)
;
if (*p == '\0')
goto out_free;
err = 0;
*p = '\0';
min_s = p + 1;
maj = strtol(maj_s, NULL, 10);
min = strtol(min_s, NULL, 10);
info->dev = makedev(maj, min);
out_free:
free(s);
return err;
}
#define sfree(ptr) if (ptr) free(ptr)
/* device_info maintenance */
static void init_device_info(struct device_info *di, const char *device_number)
{
di->device_number = strdup(device_number);
di->dev = 0;
di->mountpoint = NULL;
di->fstype = NULL;
}
static void free_device_info(struct device_info *di)
{
sfree(di->mountpoint);
sfree(di->fstype);
sfree(di->device_number);
}
static int get_mountinfo(const char *device_number, struct device_info *device_info, const char *mountinfo_path)
{
int ret = 0;
struct libmnt_table *mnttbl;
struct libmnt_fs *fs;
char *target;
init_device_info(device_info, device_number);
if ((ret = fill_device_number(device_info)) < 0)
goto out_free_device_info;
mnttbl = mnt_new_table();
if ((ret = mnt_table_parse_file(mnttbl, mountinfo_path)) < 0) {
xlog(D_GENERAL, "Failed to parse %s\n", mountinfo_path);
goto out_free_tbl;
}
if ((fs = mnt_table_find_devno(mnttbl, device_info->dev, MNT_ITER_FORWARD)) == NULL) {
ret = ENOENT;
goto out_free_tbl;
}
if ((target = (char *)mnt_fs_get_target(fs)) == NULL) {
ret = ENOENT;
goto out_free_fs;
}
device_info->mountpoint = strdup(target);
target = (char *)mnt_fs_get_fstype(fs);
if (target)
device_info->fstype = strdup(target);
out_free_fs:
mnt_free_fs(fs);
out_free_tbl:
mnt_free_table(mnttbl);
out_free_device_info:
free(device_info->device_number);
device_info->device_number = NULL;
return ret;
}
static int get_device_info(const char *device_number, struct device_info *device_info)
{
int ret = ENOENT;
for (int retry_count = 0; retry_count < 10 && ret != 0; retry_count++)
ret = get_mountinfo(device_number, device_info, MOUNTINFO_PATH);
return ret;
}
static int conf_get_readahead(const char *kind) {
int readahead = 0;
if((readahead = conf_get_num(CONF_NAME, kind, -1)) == -1)
readahead = conf_get_num(CONF_NAME, "default", NFS_DEFAULT_READAHEAD);
return readahead;
}
int main(int argc, char **argv)
{
int ret = 0, retry, opt;
struct device_info device;
unsigned int readahead = 128, log_level, log_stderr = 0;
log_level = D_ALL & ~D_GENERAL;
while((opt = getopt(argc, argv, "dF")) != -1) {
switch (opt) {
case 'd':
log_level = D_ALL;
break;
case 'F':
log_stderr = 1;
break;
}
}
conf_init_file(NFS_CONFFILE);
xlog_stderr(log_stderr);
xlog_syslog(~log_stderr);
xlog_config(log_level, 1);
xlog_open(CONF_NAME);
// xlog_err causes the system to exit
if ((argc - optind) != 1)
xlog_err("expected the device number of a BDI; is udev ok?");
for (retry = 0; retry <= 10; retry++ )
if ((ret = get_device_info(argv[optind], &device)) == 0)
break;
if (ret != 0) {
xlog(D_GENERAL, "unable to find device %s\n", argv[optind]);
goto out;
}
if (strncmp("nfs", device.fstype, 3) != 0) {
xlog(D_GENERAL,
"not setting readahead for non supported fstype %s on device %s\n",
device.fstype, argv[optind]);
ret = -EINVAL;
goto out;
}
readahead = conf_get_readahead(device.fstype);
xlog(D_FAC7, "setting %s readahead to %d\n", device.mountpoint, readahead);
printf("%d\n", readahead);
out:
free_device_info(&device);
return ret;
}
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