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-rw-r--r--tools/nfsrahead/main.c192
1 files changed, 192 insertions, 0 deletions
diff --git a/tools/nfsrahead/main.c b/tools/nfsrahead/main.c
new file mode 100644
index 0000000..8a11cf1
--- /dev/null
+++ b/tools/nfsrahead/main.c
@@ -0,0 +1,192 @@
+#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 || device.fstype == NULL) {
+ 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;
+}