Re: [libvirt] [PATCHv4 8/8] storage: probe qcow2 volumes in gluster pool

Putting together pieces from previous patches, it is now possible for 'virsh vol-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 (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 | 76 ++++++++++++++++++++++++++++++++++- 1 file changed, 75 insertions(+), 1 deletion(-) diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c index e935583..b239880 100644 --- a/src/storage/storage_backend_gluster.c +++ b/src/storage/storage_backend_gluster.c @@ -147,6 +147,37 @@ error: } +static ssize_t +virStorageBackendGlusterReadHeader(glfs_fd_t *fd, + const char *name, + ssize_t 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; + }

@@ -208,15 +243,54 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state, goto cleanup; } - /* FIXME - must open files to determine if they are non-raw */ vol->type = VIR_STORAGE_VOL_NETWORK; vol->target.format = VIR_STORAGE_FILE_RAW; + if (!(fd = glfs_open(state->vol, name, O_RDONLY| O_NONBLOCK | O_NOCTTY))) { + /* A dangling symlink now implies a TOCTTOU race; report it. */ + virReportSystemError(errno, _("cannot open volume '%s'"), name); + goto cleanup; + }