How can I resize a fat32 file system in an LVM partition?

Question

Simple enough: I have an LVM partition (e.g. /dev/mapper/foo-fat) that contains a Fat32 file system. Prior to reducing the size of this LVM partition (which I'll do with lvmreduce), I want to reduce the size of the Fat32 filesystem it contains.

It looks like parted should be able to do it, but I can't find the magic invocation to make it work.

Stefano Sanfilippo · Accepted Answer · 2013-05-04T22:06:43.693

3

Use fatresize (manpage) and then proceed with lvresize.

To avoid truncating the FS, you should first shrink the VFAT volume a few hundreds (to be safe) megabytes more than wanted, then resize the LVM container and finally grow the volume to fill the LVM partition.

Besides, this question does not belong to StackOverflow but to ServerFault.

edited May 04 '13 at 22:06

answered May 04 '13 at 21:57

Stefano Sanfilippo

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Haven't tested it, but this looks like a viable answer. – Edward Falk Jun 17 '15 at 01:47
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I don't think ths would work. fatresize just uses libparted and libparted can only work with partitions inside MBR or GPT, not LVM. – Andrius Štikonas Apr 16 '18 at 11:05

score 3 · Answer 2 · answered Dec 24 '10 at 23:22

3

No answers + deadline to meet = write it myself.

For future reference, it was only a few lines of code, using libparted. For readability, I've omitted error checking, etc. Caller is responsible for ensuring there's enough space in the partition for the new filesystem size.

#include <parted/parted.h>

int
resize_filesystem(const char *device, PedSector newsize)
{
        PedDevice *dev = NULL;
        PedGeometry *geom = NULL;
        PedGeometry *new_geom = NULL;
        PedFileSystem *fs = NULL;
        int rc = 0;

        dev = ped_device_get(device);
        ped_device_open(dev);

        geom = ped_geometry_new(dev, 0LL, dev->length);

        fs = ped_file_system_open(geom);

        new_geom = ped_geometry_new(dev, 0LL, newsize / dev->sector_size);

        ped_file_system_resize(fs, new_geom, NULL);

        ped_file_system_close(fs);
        ped_geometry_destroy(geom);
        ped_geometry_destroy(new_geom);
        ped_device_close(dev);

        return rc;
}

answered Dec 24 '10 at 23:22

Edward Falk

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Of course, if someone has a solution using the parted program, I'd still like to hear it. – Edward Falk Dec 24 '10 at 23:23
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One thing I learned the hard way: the file system MUST be clean before running this code. Run dosfsck first before doing this. – Edward Falk Jan 20 '11 at 22:29
If I am correct, there is a StackOverflow FAQ while encourages users NOT to answer and accept their own question :) – Bill May 04 '13 at 22:31
No, actually you get a badge for it. – Edward Falk May 05 '13 at 01:42
@Bill http://stackoverflow.com/help/self-answer – Samuel Harmer Jun 13 '15 at 10:22

score 0 · Answer 3 · answered Dec 24 '10 at 23:24

0

This appears to be what you want, http://www.gnu.org/software/parted/manual/html_chapter/parted_2.html#SEC25

answered Dec 24 '10 at 23:24

jcopenha

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Yes, that was the first thing I tried, but it wants to have access to the device's partition table so it can resize the partition as well as the filesystem. But I'm running under LVM and there *is* no partition table and I'll be using LVM to resize the actual partition. I only wanted to resize the filesystem without mucking about with the underlying partition. The parted command-line program apparently doesn't support this. – Edward Falk Dec 25 '10 at 18:19

How can I resize a fat32 file system in an LVM partition?

3 Answers3