| Message ID | 1318866452-30026-6-git-send-email-stefanha@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Oct 17, 2011 at 04:47:31PM +0100, Stefan Hajnoczi wrote: > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> > --- > block.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > trace-events | 1 + > 2 files changed, 70 insertions(+), 0 deletions(-) > > diff --git a/block.c b/block.c > index 0c22741..2aec6b4 100644 > --- a/block.c > +++ b/block.c > @@ -1409,6 +1409,55 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, > return 0; > } > > +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, > + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) > +{ > + void *bounce_buffer; > + struct iovec iov; > + QEMUIOVector bounce_qiov; > + int64_t cluster_sector_num; > + int cluster_nb_sectors; > + size_t skip_bytes; > + int ret; > + > + /* Cover entire cluster so no additional backing file I/O is required when > + * allocating cluster in the image file. > + */ > + round_to_clusters(bs, sector_num, nb_sectors, > + &cluster_sector_num, &cluster_nb_sectors); > + > + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, > + cluster_sector_num, cluster_nb_sectors); > + > + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; > + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); > + qemu_iovec_init_external(&bounce_qiov, &iov, 1); > + > + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + goto err; > + } > + > + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + /* It might be okay to ignore write errors for guest requests. If this > + * is a deliberate copy-on-read then we don't want to ignore the error. > + * Simply report it in all cases. > + */ > + goto err; > + } > + > + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; > + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, > + nb_sectors * BDRV_SECTOR_SIZE); > + > +err: > + qemu_vfree(bounce_buffer); > + return ret; > +} > + > /* > * Handle a read request in coroutine context > */ > @@ -1431,7 +1480,27 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, > } > > req = tracked_request_add(bs, sector_num, nb_sectors, false); The tracked request should include cluster round info?
On Mon, Oct 17, 2011 at 04:47:31PM +0100, Stefan Hajnoczi wrote: > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> > --- > block.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > trace-events | 1 + > 2 files changed, 70 insertions(+), 0 deletions(-) > > diff --git a/block.c b/block.c > index 0c22741..2aec6b4 100644 > --- a/block.c > +++ b/block.c > @@ -1409,6 +1409,55 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, > return 0; > } > > +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, > + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) > +{ > + void *bounce_buffer; > + struct iovec iov; > + QEMUIOVector bounce_qiov; > + int64_t cluster_sector_num; > + int cluster_nb_sectors; > + size_t skip_bytes; > + int ret; > + > + /* Cover entire cluster so no additional backing file I/O is required when > + * allocating cluster in the image file. > + */ > + round_to_clusters(bs, sector_num, nb_sectors, > + &cluster_sector_num, &cluster_nb_sectors); > + > + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, > + cluster_sector_num, cluster_nb_sectors); > + > + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; > + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); > + qemu_iovec_init_external(&bounce_qiov, &iov, 1); > + > + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + goto err; > + } > + > + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + /* It might be okay to ignore write errors for guest requests. If this > + * is a deliberate copy-on-read then we don't want to ignore the error. > + * Simply report it in all cases. > + */ > + goto err; > + } > + > + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; > + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, > + nb_sectors * BDRV_SECTOR_SIZE); > + > +err: > + qemu_vfree(bounce_buffer); > + return ret; > +} > + > /* > * Handle a read request in coroutine context > */ > @@ -1431,7 +1480,27 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, > } > > req = tracked_request_add(bs, sector_num, nb_sectors, false); > + > + if (bs->copy_on_read) { > + int pnum; > + > + /* TODO it is not safe to call bdrv_is_allocated() in coroutine context > + * because it's a synchronous interface. We probably want a > + * bdrv_co_is_allocated(). */ > + ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum); > + if (ret < 0) { > + goto out; > + } This lacks shared base image support, BTW (as in copy should be performed only if cluster not in destination chain). Could be added later.
On Tue, Oct 18, 2011 at 7:00 AM, Marcelo Tosatti <mtosatti@redhat.com> wrote: > On Mon, Oct 17, 2011 at 04:47:31PM +0100, Stefan Hajnoczi wrote: >> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> >> --- >> block.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> trace-events | 1 + >> 2 files changed, 70 insertions(+), 0 deletions(-) >> >> diff --git a/block.c b/block.c >> index 0c22741..2aec6b4 100644 >> --- a/block.c >> +++ b/block.c >> @@ -1409,6 +1409,55 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, >> return 0; >> } >> >> +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, >> + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) >> +{ >> + void *bounce_buffer; >> + struct iovec iov; >> + QEMUIOVector bounce_qiov; >> + int64_t cluster_sector_num; >> + int cluster_nb_sectors; >> + size_t skip_bytes; >> + int ret; >> + >> + /* Cover entire cluster so no additional backing file I/O is required when >> + * allocating cluster in the image file. >> + */ >> + round_to_clusters(bs, sector_num, nb_sectors, >> + &cluster_sector_num, &cluster_nb_sectors); >> + >> + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, >> + cluster_sector_num, cluster_nb_sectors); >> + >> + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; >> + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); >> + qemu_iovec_init_external(&bounce_qiov, &iov, 1); >> + >> + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, >> + &bounce_qiov); >> + if (ret < 0) { >> + goto err; >> + } >> + >> + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, >> + &bounce_qiov); >> + if (ret < 0) { >> + /* It might be okay to ignore write errors for guest requests. If this >> + * is a deliberate copy-on-read then we don't want to ignore the error. >> + * Simply report it in all cases. >> + */ >> + goto err; >> + } >> + >> + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; >> + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, >> + nb_sectors * BDRV_SECTOR_SIZE); >> + >> +err: >> + qemu_vfree(bounce_buffer); >> + return ret; >> +} >> + >> /* >> * Handle a read request in coroutine context >> */ >> @@ -1431,7 +1480,27 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, >> } >> >> req = tracked_request_add(bs, sector_num, nb_sectors, false); > > The tracked request should include cluster round info? When checking A and B for overlap, only one of them needs to be rounded in order for overlap detection to be correct. Therefore we can store the original request [start, length) in tracked_requests and only round the new request. Stefan
Am 17.10.2011 17:47, schrieb Stefan Hajnoczi: > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> > --- > block.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > trace-events | 1 + > 2 files changed, 70 insertions(+), 0 deletions(-) > > diff --git a/block.c b/block.c > index 0c22741..2aec6b4 100644 > --- a/block.c > +++ b/block.c > @@ -1409,6 +1409,55 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, > return 0; > } > > +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, > + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) > +{ > + void *bounce_buffer; I think the bounce buffer deserves a comment. It may not be obvious for everyone why it's needed. > + struct iovec iov; > + QEMUIOVector bounce_qiov; > + int64_t cluster_sector_num; > + int cluster_nb_sectors; > + size_t skip_bytes; > + int ret; > + > + /* Cover entire cluster so no additional backing file I/O is required when > + * allocating cluster in the image file. > + */ > + round_to_clusters(bs, sector_num, nb_sectors, > + &cluster_sector_num, &cluster_nb_sectors); > + > + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, > + cluster_sector_num, cluster_nb_sectors); > + > + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; > + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); > + qemu_iovec_init_external(&bounce_qiov, &iov, 1); > + > + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + goto err; > + } > + > + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, > + &bounce_qiov); > + if (ret < 0) { > + /* It might be okay to ignore write errors for guest requests. If this > + * is a deliberate copy-on-read then we don't want to ignore the error. > + * Simply report it in all cases. > + */ > + goto err; > + } > + > + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; > + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, > + nb_sectors * BDRV_SECTOR_SIZE); > + > +err: > + qemu_vfree(bounce_buffer); > + return ret; > +} > + > /* > * Handle a read request in coroutine context > */ > @@ -1431,7 +1480,27 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, > } > > req = tracked_request_add(bs, sector_num, nb_sectors, false); > + > + if (bs->copy_on_read) { > + int pnum; > + > + /* TODO it is not safe to call bdrv_is_allocated() in coroutine context > + * because it's a synchronous interface. We probably want a > + * bdrv_co_is_allocated(). */ > + ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum); I think I already said it in a reply to another patch, but for the record: We need bdrv_co_is_allocated() before this can be merged. Kevin
diff --git a/block.c b/block.c index 0c22741..2aec6b4 100644 --- a/block.c +++ b/block.c @@ -1409,6 +1409,55 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, return 0; } +static int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) +{ + void *bounce_buffer; + struct iovec iov; + QEMUIOVector bounce_qiov; + int64_t cluster_sector_num; + int cluster_nb_sectors; + size_t skip_bytes; + int ret; + + /* Cover entire cluster so no additional backing file I/O is required when + * allocating cluster in the image file. + */ + round_to_clusters(bs, sector_num, nb_sectors, + &cluster_sector_num, &cluster_nb_sectors); + + trace_bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, + cluster_sector_num, cluster_nb_sectors); + + iov.iov_len = cluster_nb_sectors * BDRV_SECTOR_SIZE; + iov.iov_base = bounce_buffer = qemu_blockalign(bs, iov.iov_len); + qemu_iovec_init_external(&bounce_qiov, &iov, 1); + + ret = bs->drv->bdrv_co_readv(bs, cluster_sector_num, cluster_nb_sectors, + &bounce_qiov); + if (ret < 0) { + goto err; + } + + ret = bs->drv->bdrv_co_writev(bs, cluster_sector_num, cluster_nb_sectors, + &bounce_qiov); + if (ret < 0) { + /* It might be okay to ignore write errors for guest requests. If this + * is a deliberate copy-on-read then we don't want to ignore the error. + * Simply report it in all cases. + */ + goto err; + } + + skip_bytes = (sector_num - cluster_sector_num) * BDRV_SECTOR_SIZE; + qemu_iovec_from_buffer(qiov, bounce_buffer + skip_bytes, + nb_sectors * BDRV_SECTOR_SIZE); + +err: + qemu_vfree(bounce_buffer); + return ret; +} + /* * Handle a read request in coroutine context */ @@ -1431,7 +1480,27 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, } req = tracked_request_add(bs, sector_num, nb_sectors, false); + + if (bs->copy_on_read) { + int pnum; + + /* TODO it is not safe to call bdrv_is_allocated() in coroutine context + * because it's a synchronous interface. We probably want a + * bdrv_co_is_allocated(). */ + ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum); + if (ret < 0) { + goto out; + } + + if (!ret || pnum != nb_sectors) { + ret = bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, qiov); + goto out; + } + } + ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); + +out: tracked_request_remove(req); return ret; } diff --git a/trace-events b/trace-events index 63d8c8e..7e52ed6 100644 --- a/trace-events +++ b/trace-events @@ -68,6 +68,7 @@ bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d" bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d" bdrv_co_io_em(void *bs, int64_t sector_num, int nb_sectors, int is_write, void *acb) "bs %p sector_num %"PRId64" nb_sectors %d is_write %d acb %p" +bdrv_co_copy_on_readv(void *bs, int64_t sector_num, int nb_sectors, int64_t cluster_sector_num, int cluster_nb_sectors) "bs %p sector_num %"PRId64" nb_sectors %d cluster_sector_num %"PRId64" cluster_nb_sectors %d" # hw/virtio-blk.c virtio_blk_req_complete(void *req, int status) "req %p status %d"
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> --- block.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ trace-events | 1 + 2 files changed, 70 insertions(+), 0 deletions(-)