Limit setting the readahead for nfs devices. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1946283 Signed-off-by: Thiago Becker <tbecker@xxxxxxxxxx> --- tools/nfsrahead/Makefile.am | 1 + tools/nfsrahead/main.c | 130 ++++++++++++++++++++++++++++++++++++ 2 files changed, 131 insertions(+) diff --git a/tools/nfsrahead/Makefile.am b/tools/nfsrahead/Makefile.am index b598bec3..afccc520 100644 --- a/tools/nfsrahead/Makefile.am +++ b/tools/nfsrahead/Makefile.am @@ -1,5 +1,6 @@ libexec_PROGRAMS = nfsrahead nfsrahead_SOURCES = main.c +nfsrahead_LDFLAGS= -lmount udev_rulesdir = /etc/udev/rules.d udev_rules_DATA = 99-nfs_bdi.rules diff --git a/tools/nfsrahead/main.c b/tools/nfsrahead/main.c index e454108e..2cf77424 100644 --- a/tools/nfsrahead/main.c +++ b/tools/nfsrahead/main.c @@ -1,7 +1,137 @@ #include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include <errno.h> + +#include <libmount/libmount.h> +#include <sys/sysmacros.h> + +#ifndef MOUNTINFO_PATH +#define MOUNTINFO_PATH "/proc/self/mountinfo" +#endif + +/* 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 dev_t dev_from_arg(const char *device_number) +{ + char *s = strdup(device_number), *p; + char *maj_s, *min_s; + unsigned int maj, min; + dev_t dev; + + maj_s = p = s; + for ( ; *p != ':'; p++) + ; + + *p = '\0'; + min_s = p + 1; + + maj = strtol(maj_s, NULL, 10); + min = strtol(min_s, NULL, 10); + + dev = makedev(maj, min); + + free(s); + return dev; +} + +#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 = dev_from_arg(device_number); + 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); + + mnttbl = mnt_new_table(); + + if ((ret = mnt_table_parse_file(mnttbl, mountinfo_path)) < 0) + 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); + 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; +} int main(int argc, char **argv, char **envp) { + int ret = 0; + struct device_info device; unsigned int readahead = 128; + + if (argc != 2) { + return -EINVAL; + } + + if ((ret = get_device_info(argv[1], &device)) != 0) { + goto out; + } + + if (strncmp("nfs", device.fstype, 3) != 0) { + ret = -EINVAL; + goto out; + } + + info("Setting %s readahead to 128\n", device.mountpoint); + printf("%d\n", readahead); + +out: + free_device_info(&device); + return ret; } -- 2.35.1
