Re: [libvirt] [PATCHv3 4/4] storage: probe qcow2 volumes in gluster pool

Putting together pieces from previous patches, it is now possible for 'virsh dumpxml --pool gluster volname' to report metadata

about a qcow2 file stored on gluster. The backing file is still treated as raw; to fix that, more patches are needed to make the storage backing chain analysis recursive rather than halting at a network protocol name, but that work will not need any further calls into libgfapi so much as just reusing this code, and that should be the only code outside of the storage driver that needs any help from libgfapi. Any additional use of libgfapi within libvirt should only be needed for implementing storage pool APIs such as volume creation or resizing, where backing chain analysis should be unaffected. * src/storage/storage_backend_gluster.c (virStorageBackendGlusterOpen): Make relative name handling easier. (virStorageBackendGlusterReadHeader): New helper function. (virStorageBackendGlusterRefreshVol): Probe non-raw files. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/storage/storage_backend_gluster.c | 87 +++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c index bc90de9..69e8e61 100644 --- a/src/storage/storage_backend_gluster.c +++ b/src/storage/storage_backend_gluster.c

@@ -124,6 +130,37 @@ error: } +static int

+virStorageBackendGlusterReadHeader(glfs_fd_t *fd, + const char *name, + int maxlen, + char **buf) +{ + char *s; + size_t nread = 0;

+ + if (VIR_ALLOC_N(*buf, maxlen) < 0) + return -1; + + s = *buf; + while (maxlen) { + ssize_t r = glfs_read(fd, s, maxlen, 0); + if (r < 0 && errno == EINTR) + continue; + if (r < 0) { + VIR_FREE(*buf); + virReportSystemError(errno, _("unable to read '%s'"), name); + return r; + } + if (r == 0) + return nread; + buf += r; + maxlen -= r; + nread += r; + } + return nread; +} + /* Populate *volptr for the given name and stat information, or leave * it NULL if the entry should be skipped (such as "."). Return 0 on * success, -1 on failure. */

@@ -162,11 +203,57 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state, } state->uri->path = tmp; + if (!(fd = glfs_open(state->vol, name, O_RDONLY| O_NONBLOCK | O_NOCTTY))) { + if ((errno == ENOENT || errno == ELOOP) && + S_ISLNK(st->st_mode)) { + VIR_WARN("ignoring dangling symlink '%s'", name); + ret = 0; + } else { + virReportSystemError(errno, _("cannot open volume '%s'"), name); + } + goto cleanup; + }

+ + if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0) + goto cleanup; + + if ((vol->target.format = virStorageFileProbeFormatFromBuf(name, + header, + len)) < 0 || + !(meta = virStorageFileGetMetadataFromBuf(name, header, len, + vol->target.format))) + goto cleanup;

+ + if (meta->backingStore) { + vol->backingStore.path = meta->backingStore; + meta->backingStore = NULL; + vol->backingStore.format = meta->backingStoreFormat; + if (vol->backingStore.format < 0) + vol->backingStore.format = VIR_STORAGE_FILE_RAW; + } + if (meta->capacity) + vol->capacity = meta->capacity; + if (meta->encrypted) { + if (VIR_ALLOC(vol->target.encryption) < 0) + goto cleanup; + if (vol->target.format == VIR_STORAGE_FILE_QCOW || + vol->target.format == VIR_STORAGE_FILE_QCOW2) + vol->target.encryption->format = VIR_STORAGE_ENCRYPTION_FORMAT_QCOW; + } + vol->target.features = meta->features; + meta->features = NULL; + vol->target.compat = meta->compat; + meta->compat = NULL; + *volptr = vol; vol = NULL; ret = 0; cleanup: + virStorageFileFreeMetadata(meta); virStorageVolDefFree(vol); + if (fd) + glfs_close(fd); + VIR_FREE(header); return ret; }