Commit dc5f690b authored by Max Reitz's avatar Max Reitz
Browse files

qemu-img: Expose PreallocMode for resizing 



Add a --preallocation command line option to qemu-img resize which can
be used to set the PreallocMode parameter of blk_truncate().

While touching this code, fix the fact that we did not handle errors
returned by blk_getlength().

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Message-id: 20170613202107.10125-5-mreitz@redhat.com
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
parent 3a691c50

qemu-img.c

+30 −3
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include "qemu/osdep.h"

#include "qemu-version.h"

#include "qapi/error.h"

#include "qapi/util.h"

#include "qapi-visit.h"

#include "qapi/qobject-output-visitor.h"

#include "qapi/qmp/qerror.h"
@@ -62,6 +63,7 @@ enum { 
    OPTION_NO_DRAIN = 262,

    OPTION_TARGET_IMAGE_OPTS = 263,

    OPTION_SIZE = 264,

    OPTION_PREALLOCATION = 265,

};



typedef enum OutputFormat {
@@ -3408,9 +3410,10 @@ static int img_resize(int argc, char **argv) 
    Error *err = NULL;

    int c, ret, relative;

    const char *filename, *fmt, *size;

    int64_t n, total_size;

    int64_t n, total_size, current_size;

    bool quiet = false;

    BlockBackend *blk = NULL;

    PreallocMode prealloc = PREALLOC_MODE_OFF;

    QemuOpts *param;



    static QemuOptsList resize_options = {
@@ -3444,6 +3447,7 @@ static int img_resize(int argc, char **argv) 
            {"help", no_argument, 0, 'h'},

            {"object", required_argument, 0, OPTION_OBJECT},

            {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},

            {"preallocation", required_argument, 0, OPTION_PREALLOCATION},

            {0, 0, 0, 0}

        };

        c = getopt_long(argc, argv, ":f:hq",
@@ -3478,6 +3482,15 @@ static int img_resize(int argc, char **argv) 
        case OPTION_IMAGE_OPTS:

            image_opts = true;

            break;

        case OPTION_PREALLOCATION:

            prealloc = qapi_enum_parse(PreallocMode_lookup, optarg,

                                       PREALLOC_MODE__MAX, PREALLOC_MODE__MAX,

                                       NULL);

            if (prealloc == PREALLOC_MODE__MAX) {

                error_report("Invalid preallocation mode '%s'", optarg);

                return 1;

            }

            break;

        }

    }

    if (optind != argc - 1) {
@@ -3526,8 +3539,16 @@ static int img_resize(int argc, char **argv) 
        goto out;

    }



    current_size = blk_getlength(blk);

    if (current_size < 0) {

        error_report("Failed to inquire current image length: %s",

                     strerror(-current_size));

        ret = -1;

        goto out;

    }



    if (relative) {

        total_size = blk_getlength(blk) + n * relative;

        total_size = current_size + n * relative;

    } else {

        total_size = n;

    }
@@ -3537,7 +3558,13 @@ static int img_resize(int argc, char **argv) 
        goto out;

    }



    ret = blk_truncate(blk, total_size, PREALLOC_MODE_OFF, &err);

    if (total_size <= current_size && prealloc != PREALLOC_MODE_OFF) {

        error_report("Preallocation can only be used for growing images");

        ret = -1;

        goto out;

    }



    ret = blk_truncate(blk, total_size, prealloc, &err);

    if (!ret) {

        qprintf(quiet, "Image resized.\n");

    } else {

qemu-img.texi

+6 −1
Original line number Diff line number Diff line
@@ -529,7 +529,7 @@ qemu-img rebase -b base.img diff.qcow2 
At this point, @code{modified.img} can be discarded, since

@code{base.img + diff.qcow2} contains the same information.



@item resize @var{filename} [+ | -]@var{size}

@item resize [--preallocation=@var{prealloc}] @var{filename} [+ | -]@var{size}



Change the disk image as if it had been created with @var{size}.
@@ -541,6 +541,11 @@ After using this command to grow a disk image, you must use file system and 
partitioning tools inside the VM to actually begin using the new space on the

device.



When growing an image, the @code{--preallocation} option may be used to specify

how the additional image area should be allocated on the host.  See the format

description in the @code{NOTES} section which values are allowed.  Using this

option may result in slightly more data being allocated than necessary.



@item amend [-p] [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}



Amends the image format specific @var{options} for the image file