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btrfs-progs: add helper to read zone size from sysfs 

Sysfs hides the zone size of a block device in the queue/chunk_sectors
file, so add a helper that will read it for us when given the short
device name (that can be found in FSID/devices).

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2021-06-24 22:38:59 +02:00
parent e25c8f00a3
commit 3d52313591
2 changed files with 59 additions and 0 deletions
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58
common/device-utils.c
View File

@ -17,17 +17,20 @@
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/statfs.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dirent.h>
#include <blkid/blkid.h>
#include <linux/limits.h>
#include "kernel-lib/sizes.h"
#include "kernel-shared/disk-io.h"
#include "kernel-shared/zoned.h"
#include "common/device-utils.h"
#include "common/path-utils.h"
#include "common/internal.h"
#include "common/messages.h"
#include "common/utils.h"
@ -392,3 +395,58 @@ u64 device_get_zone_unusable(int fd, u64 flags)
return unusable;
}
/*
* Read information about zone size of the given device (short @name) from a
* given filesystem fd
*/
u64 device_get_zone_size(int fd, const char *name)
{
DIR *dir;
struct dirent *de;
int sysfs_fd;
u64 ret = 0;
sysfs_fd = sysfs_open_fsid_dir(fd, "devices");
if (sysfs_fd < 0)
return 0;
dir = fdopendir(sysfs_fd);
if (!dir) {
ret = 0;
goto out;
}
while (1) {
int queue_fd;
char queue[PATH_MAX];
char buf[128] = {0};
de = readdir(dir);
if (!de) {
ret = 0;
break;
}
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
continue;
if (strcmp(name, de->d_name) != 0)
continue;
path_cat3_out(queue, "devices", de->d_name, "queue/chunk_sectors");
/* /sys/fs/btrfs/FSID/devices/NAME/queue/chunk_sectors */
queue_fd = sysfs_open_fsid_file(fd, queue);
if (queue_fd < 0) {
ret = 0;
break;
}
sysfs_read_file(queue_fd, buf, sizeof(buf));
ret = atoll(buf);
close(queue_fd);
break;
}
closedir(dir);
out:
close(sysfs_fd);
return ret;
}

1
common/device-utils.h
View File

@ -40,6 +40,7 @@ u64 device_get_partition_size(const char *dev);
u64 device_get_partition_size_fd(int fd);
int device_get_queue_param(const char *file, const char *param, char *buf, size_t len);
u64 device_get_zone_unusable(int fd, u64 flags);
u64 device_get_zone_size(int fd, const char *name);
/*
* Updates to devices with btrfs-specific changs
*/