Check for empty blocks while importing an image.
When a read block only consists of zeroes, the import is simply
skipping the write. This way you non-sparse images will become sparse
rbd images.
v1 -> v2: fix a signedness warning
Signed-off-by: Christian Brunner <chb@xxxxxx>
---
src/rbd.cc | 44 ++++++++++++++++++++++++++------------------
1 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/src/rbd.cc b/src/rbd.cc
index 1a0c510..7d5a6aa 100644
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -512,7 +512,7 @@ static int do_import(librbd::RBD &rbd, librados::IoCtx& io_ctx,
while (cur_seg) {
bufferptr p(cur_seg);
//cerr << "reading " << cur_seg << " bytes at offset " << file_pos << std::endl;
- ssize_t rval;
+ ssize_t rval, i;
if(extent == 0 && fiemap->fm_extents[extent].fe_logical == 0) {
rval = TEMP_FAILURE_RETRY(::read(fd, p.c_str(), cur_seg));
} else {
@@ -528,23 +528,31 @@ static int do_import(librbd::RBD &rbd, librados::IoCtx& io_ctx,
r = 0;
goto done;
}
- bufferlist bl;
- bl.append(p);
- librbd::RBD::AioCompletion *completion = new librbd::RBD::AioCompletion(NULL, NULL);
- if (!completion) {
- r = -ENOMEM;
- goto done;
- }
- r = image.aio_write(file_pos, len, bl, completion);
- if (r < 0)
- goto done;
- completion->wait_for_complete();
- r = completion->get_return_value();
- completion->release();
- if (r < 0) {
- cerr << "error writing to image block" << std::endl;
- goto done;
- }
+
+ /* Skip empty blocks */
+ char *pcstr = p.c_str();
+ for (i=0 ; i < rval; i++) {
+ if (pcstr[i] != 0) {
+ bufferlist bl;
+ bl.append(p);
+ librbd::RBD::AioCompletion *completion = new librbd::RBD::AioCompletion(NULL, NULL);
+ if (!completion) {
+ r = -ENOMEM;
+ goto done;
+ }
+ r = image.aio_write(file_pos, len, bl, completion);
+ if (r < 0)
+ goto done;
+ completion->wait_for_complete();
+ r = completion->get_return_value();
+ completion->release();
+ if (r < 0) {
+ cerr << "error writing to image block" << std::endl;
+ goto done;
+ }
+ break;
+ }
+ }
file_pos += len;
cur_seg -= len;
--
1.7.1
--
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