Commit eeb6b45d authored by Jeff Cody's avatar Jeff Cody Committed by Kevin Wolf
Browse files

block: raw-posix image file reopen 



This is derived from the Supriya Kannery's reopen patches.

This contains the raw-posix driver changes for the bdrv_reopen_*
functions.  All changes are staged into a temporary scratch buffer
during the prepare() stage, and copied over to the live structure
during commit().  Upon abort(), all changes are abandoned, and the
live structures are unmodified.

The _prepare() will create an extra fd - either by means of a dup,
if possible, or opening a new fd if not (for instance, access
control changes).  Upon _commit(), the original fd is closed and
the new fd is used.  Upon _abort(), the duplicate/new fd is closed.

Signed-off-by: default avatarJeff Cody <jcody@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 3d1807ac

block/raw-posix.c

+114 −0
Original line number Diff line number Diff line
@@ -138,6 +138,14 @@ typedef struct BDRVRawState { 
#endif

} BDRVRawState;



typedef struct BDRVRawReopenState {

    int fd;

    int open_flags;

#ifdef CONFIG_LINUX_AIO

    int use_aio;

#endif

} BDRVRawReopenState;



static int fd_open(BlockDriverState *bs);

static int64_t raw_getlength(BlockDriverState *bs);
@@ -290,6 +298,109 @@ static int raw_open(BlockDriverState *bs, const char *filename, int flags) 
    return raw_open_common(bs, filename, flags, 0);

}



static int raw_reopen_prepare(BDRVReopenState *state,

                              BlockReopenQueue *queue, Error **errp)

{

    BDRVRawState *s;

    BDRVRawReopenState *raw_s;

    int ret = 0;



    assert(state != NULL);

    assert(state->bs != NULL);



    s = state->bs->opaque;



    state->opaque = g_malloc0(sizeof(BDRVRawReopenState));

    raw_s = state->opaque;



#ifdef CONFIG_LINUX_AIO

    raw_s->use_aio = s->use_aio;



    /* we can use s->aio_ctx instead of a copy, because the use_aio flag is

     * valid in the 'false' condition even if aio_ctx is set, and raw_set_aio()

     * won't override aio_ctx if aio_ctx is non-NULL */

    if (raw_set_aio(&s->aio_ctx, &raw_s->use_aio, state->flags)) {

        return -1;

    }

#endif



    raw_parse_flags(state->flags, &raw_s->open_flags);



    raw_s->fd = -1;



    int fcntl_flags = O_APPEND | O_ASYNC | O_NONBLOCK;

#ifdef O_NOATIME

    fcntl_flags |= O_NOATIME;

#endif



    if ((raw_s->open_flags & ~fcntl_flags) == (s->open_flags & ~fcntl_flags)) {

        /* dup the original fd */

        /* TODO: use qemu fcntl wrapper */

#ifdef F_DUPFD_CLOEXEC

        raw_s->fd = fcntl(s->fd, F_DUPFD_CLOEXEC, 0);

#else

        raw_s->fd = dup(s->fd);

        if (raw_s->fd != -1) {

            qemu_set_cloexec(raw_s->fd);

        }

#endif

        if (raw_s->fd >= 0) {

            ret = fcntl_setfl(raw_s->fd, raw_s->open_flags);

            if (ret) {

                qemu_close(raw_s->fd);

                raw_s->fd = -1;

            }

        }

    }



    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */

    if (raw_s->fd == -1) {

        assert(!(raw_s->open_flags & O_CREAT));

        raw_s->fd = qemu_open(state->bs->filename, raw_s->open_flags);

        if (raw_s->fd == -1) {

            ret = -1;

        }

    }

    return ret;

}





static void raw_reopen_commit(BDRVReopenState *state)

{

    BDRVRawReopenState *raw_s = state->opaque;

    BDRVRawState *s = state->bs->opaque;



    s->open_flags = raw_s->open_flags;



    qemu_close(s->fd);

    s->fd = raw_s->fd;

#ifdef CONFIG_LINUX_AIO

    s->use_aio = raw_s->use_aio;

#endif



    g_free(state->opaque);

    state->opaque = NULL;

}





static void raw_reopen_abort(BDRVReopenState *state)

{

    BDRVRawReopenState *raw_s = state->opaque;



     /* nothing to do if NULL, we didn't get far enough */

    if (raw_s == NULL) {

        return;

    }



    if (raw_s->fd >= 0) {

        qemu_close(raw_s->fd);

        raw_s->fd = -1;

    }

    g_free(state->opaque);

    state->opaque = NULL;

}





/* XXX: use host sector size if necessary with:

#ifdef DIOCGSECTORSIZE

        {
@@ -740,6 +851,9 @@ static BlockDriver bdrv_file = { 
    .instance_size = sizeof(BDRVRawState),

    .bdrv_probe = NULL, /* no probe for protocols */

    .bdrv_file_open = raw_open,

    .bdrv_reopen_prepare = raw_reopen_prepare,

    .bdrv_reopen_commit = raw_reopen_commit,

    .bdrv_reopen_abort = raw_reopen_abort,

    .bdrv_close = raw_close,

    .bdrv_create = raw_create,

    .bdrv_co_discard = raw_co_discard,