[PATCH 7/9] virfdstream: Allow sparse stream vol-download

When handling sparse stream, a thread is executed. This thread runs a read() or write() loop (depending what API is called; in this case it's virStorageVolDownload() and this the thread run read() loop). The read() is handled in virFDStreamThreadDoRead() which is then data/hole section aware, meaning it uses virFileInData() to detect data and hole sections and sends TYPE_DATA or TYPE_HOLE virStream messages accordingly. However, virFileInData() does not work with block devices. Simply because block devices don't have data and hole sections. But we can use new virFileInDataDetectZeroes() which is block device friendly for that. Partially resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1852528 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/util/virfdstream.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/src/util/virfdstream.c b/src/util/virfdstream.c index 1c32be47a9..b5406fe690 100644 --- a/src/util/virfdstream.c +++ b/src/util/virfdstream.c @@ -396,6 +396,7 @@ struct _virFDStreamThreadData { size_t length; bool doRead; bool sparse; + bool isBlock; int fdin; char *fdinname; int fdout; @@ -419,6 +420,7 @@ virFDStreamThreadDataFree(virFDStreamThreadDataPtr data) static ssize_t virFDStreamThreadDoRead(virFDStreamDataPtr fdst, bool sparse, + bool isBlock, const int fdin, const int fdout, const char *fdinname, @@ -435,8 +437,13 @@ virFDStreamThreadDoRead(virFDStreamDataPtr fdst, ssize_t got; if (sparse && *dataLen == 0) { - if (virFileInData(fdin, &inData, &sectionLen) < 0) - goto error; + if (isBlock) { + if (virFileInDataDetectZeroes(fdin, &inData, &sectionLen) < 0) + goto error; + } else { + if (virFileInData(fdin, &inData, &sectionLen) < 0) + goto error; + } if (length && sectionLen > length - total) @@ -575,6 +582,7 @@ virFDStreamThread(void *opaque) virStreamPtr st = data->st; size_t length = data->length; bool sparse = data->sparse; + bool isBlock = data->isBlock; int fdin = data->fdin; char *fdinname = data->fdinname; int fdout = data->fdout; @@ -611,7 +619,7 @@ virFDStreamThread(void *opaque) } if (doRead) - got = virFDStreamThreadDoRead(fdst, sparse, + got = virFDStreamThreadDoRead(fdst, sparse, isBlock, fdin, fdout, fdinname, fdoutname, length, total, @@ -1289,6 +1297,7 @@ virFDStreamOpenFileInternal(virStreamPtr st, threadData->st = virObjectRef(st); threadData->length = length; threadData->sparse = sparse; + threadData->isBlock = !!S_ISBLK(sb.st_mode); if ((oflags & O_ACCMODE) == O_RDONLY) { threadData->fdin = fd; -- 2.26.2