| Message ID | 20170313214045.26857-7-mreitz@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Mar 13, 2017 at 10:40:38PM +0100, Max Reitz wrote: > This patch adds two new parameters to the preallocate() function so we > will be able to use it not just for preallocating a new image but also > for preallocated image growth. > > The offset parameter allows the caller to specify a virtual offset from > which to start preallocating. For newly created images this is always 0, > but for preallocating growth this will be the old image length. > > The new_length parameter specifies the supposed new length of the image > (basically the "end offset" for preallocation). During image truncation, > bdrv_getlength() will return the old image length so we cannot rely on > its return value then. You documented the arguments in the commit description. Please move them into doc comments.
On 20.03.2017 12:04, Stefan Hajnoczi wrote: > On Mon, Mar 13, 2017 at 10:40:38PM +0100, Max Reitz wrote: >> This patch adds two new parameters to the preallocate() function so we >> will be able to use it not just for preallocating a new image but also >> for preallocated image growth. >> >> The offset parameter allows the caller to specify a virtual offset from >> which to start preallocating. For newly created images this is always 0, >> but for preallocating growth this will be the old image length. >> >> The new_length parameter specifies the supposed new length of the image >> (basically the "end offset" for preallocation). During image truncation, >> bdrv_getlength() will return the old image length so we cannot rely on >> its return value then. > > You documented the arguments in the commit description. Please move > them into doc comments. Yeah, right, new_length is not really a super self-explaining name... I'll add a comment. Max
diff --git a/block/qcow2.c b/block/qcow2.c index 210646b60f..9abdf9e0fb 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2034,17 +2034,16 @@ static int qcow2_change_backing_file(BlockDriverState *bs, return qcow2_update_header(bs); } -static int preallocate(BlockDriverState *bs) +static int preallocate(BlockDriverState *bs, int64_t offset, int64_t new_length) { uint64_t bytes; - uint64_t offset; uint64_t host_offset = 0; unsigned int cur_bytes; int ret; QCowL2Meta *meta; - bytes = bdrv_getlength(bs); - offset = 0; + assert(offset <= new_length); + bytes = new_length - offset; while (bytes) { cur_bytes = MIN(bytes, INT_MAX); @@ -2313,7 +2312,7 @@ static int qcow2_create2(const char *filename, int64_t total_size, if (prealloc != PREALLOC_MODE_OFF) { BDRVQcow2State *s = blk_bs(blk)->opaque; qemu_co_mutex_lock(&s->lock); - ret = preallocate(blk_bs(blk)); + ret = preallocate(blk_bs(blk), 0, total_size); qemu_co_mutex_unlock(&s->lock); if (ret < 0) { error_setg_errno(errp, -ret, "Could not preallocate metadata");
This patch adds two new parameters to the preallocate() function so we will be able to use it not just for preallocating a new image but also for preallocated image growth. The offset parameter allows the caller to specify a virtual offset from which to start preallocating. For newly created images this is always 0, but for preallocating growth this will be the old image length. The new_length parameter specifies the supposed new length of the image (basically the "end offset" for preallocation). During image truncation, bdrv_getlength() will return the old image length so we cannot rely on its return value then. Signed-off-by: Max Reitz <mreitz@redhat.com> --- block/qcow2.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)