| Message ID | 1478851210-6251-6-git-send-email-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
>>> On 11.11.16 at 09:00, <JGross@suse.com> wrote: > --- a/xen/include/public/io/xs_wire.h > +++ b/xen/include/public/io/xs_wire.h > @@ -50,6 +50,9 @@ enum xsd_sockmsg_type > XS_SET_TARGET, > XS_RESTRICT, > XS_RESET_WATCHES, > + XS_DIRECTORY_PART, > + > + XS_NEXT_ENTRY, /* First unused type. */ What is this needed for? Jan
On 11/11/16 11:09, Jan Beulich wrote: >>>> On 11.11.16 at 09:00, <JGross@suse.com> wrote: >> --- a/xen/include/public/io/xs_wire.h >> +++ b/xen/include/public/io/xs_wire.h >> @@ -50,6 +50,9 @@ enum xsd_sockmsg_type >> XS_SET_TARGET, >> XS_RESTRICT, >> XS_RESET_WATCHES, >> + XS_DIRECTORY_PART, >> + >> + XS_NEXT_ENTRY, /* First unused type. */ > > What is this needed for? Patch 7. I didn't want to modify the same enum twice in the same series. In case you'd prefer to add XS_NEXT_ENTRY in patch 7 I'd be happy to move it. Juergen
>>> On 11.11.16 at 11:43, <JGross@suse.com> wrote: > On 11/11/16 11:09, Jan Beulich wrote: >>>>> On 11.11.16 at 09:00, <JGross@suse.com> wrote: >>> --- a/xen/include/public/io/xs_wire.h >>> +++ b/xen/include/public/io/xs_wire.h >>> @@ -50,6 +50,9 @@ enum xsd_sockmsg_type >>> XS_SET_TARGET, >>> XS_RESTRICT, >>> XS_RESET_WATCHES, >>> + XS_DIRECTORY_PART, >>> + >>> + XS_NEXT_ENTRY, /* First unused type. */ >> >> What is this needed for? > > Patch 7. I didn't want to modify the same enum twice in the same series. > In case you'd prefer to add XS_NEXT_ENTRY in patch 7 I'd be happy to > move it. Yes please. Additions should be made where they are needed; please don't forget that series' may be committed in pieces. Also judging about the chosen name (which I consider somewhat odd - I'd have expected something like XS_TYPE_COUNT) is easier when one sees the intended use. Jan
On 11/11/16 12:12, Jan Beulich wrote: >>>> On 11.11.16 at 11:43, <JGross@suse.com> wrote: >> On 11/11/16 11:09, Jan Beulich wrote: >>>>>> On 11.11.16 at 09:00, <JGross@suse.com> wrote: >>>> --- a/xen/include/public/io/xs_wire.h >>>> +++ b/xen/include/public/io/xs_wire.h >>>> @@ -50,6 +50,9 @@ enum xsd_sockmsg_type >>>> XS_SET_TARGET, >>>> XS_RESTRICT, >>>> XS_RESET_WATCHES, >>>> + XS_DIRECTORY_PART, >>>> + >>>> + XS_NEXT_ENTRY, /* First unused type. */ >>> >>> What is this needed for? >> >> Patch 7. I didn't want to modify the same enum twice in the same series. >> In case you'd prefer to add XS_NEXT_ENTRY in patch 7 I'd be happy to >> move it. > > Yes please. Additions should be made where they are needed; > please don't forget that series' may be committed in pieces. Also > judging about the chosen name (which I consider somewhat odd - > I'd have expected something like XS_TYPE_COUNT) is easier when > one sees the intended use. Okay to both (moving and renaming to your suggested name). Juergen
On Fri, Nov 11, 2016 at 09:00:03AM +0100, Juergen Gross wrote: > As the payload size for one xenstore wire command is limited to 4096 > bytes it is impossible to read the children names of a node with a > large number of children (e.g. /local/domain in case of a host with > more than about 2000 domains). This effectively limits the maximum > number of domains a host can support. > > In order to support such long directory outputs add a new wire command > XS_DIRECTORY_PART which will return only some entries in each call and > can be called in a loop to get all entries. > > Input data are the path of the node and the byte offset into the child > list where returned data should start. > > Output is the generation count of the node (which will change each time > the node is being modified) and a list of child names starting with > the specified index. The end of the list is indicated by an empty > child name. It is the responsibility of the caller to check for data > consistency by comparing the generation counts of all returned data > sets to be the same for one node. > > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> (with Jan's comment addressed)
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c index 95d6d7d..e4e09fa 100644 --- a/tools/xenstore/xenstored_core.c +++ b/tools/xenstore/xenstored_core.c @@ -16,6 +16,7 @@ along with this program; If not, see <http://www.gnu.org/licenses/>. */ +#include <inttypes.h> #include <sys/types.h> #include <sys/stat.h> #include <poll.h> @@ -147,6 +148,7 @@ static char *sockmsg_string(enum xsd_sockmsg_type type) case XS_RESUME: return "RESUME"; case XS_SET_TARGET: return "SET_TARGET"; case XS_RESET_WATCHES: return "RESET_WATCHES"; + case XS_DIRECTORY_PART: return "DIRECTORY_PART"; default: return "**UNKNOWN**"; } @@ -812,6 +814,67 @@ static void send_directory(struct connection *conn, struct buffered_data *in) send_reply(conn, XS_DIRECTORY, node->children, node->childlen); } +static void send_directory_part(struct connection *conn, + struct buffered_data *in) +{ + unsigned int off, len, maxlen, genlen; + char *name, *child, *data; + struct node *node; + char gen[24]; + + if (xs_count_strings(in->buffer, in->used) != 2) { + send_error(conn, EINVAL); + return; + } + + /* First arg is node name. */ + name = canonicalize(conn, in->buffer); + + /* Second arg is childlist offset. */ + off = atoi(in->buffer + strlen(in->buffer) + 1); + + node = get_node(conn, in, name, XS_PERM_READ); + if (!node) { + send_error(conn, errno); + return; + } + + genlen = snprintf(gen, sizeof(gen), "%"PRIu64, node->generation) + 1; + + /* Offset behind list: just return a list with an empty string. */ + if (off >= node->childlen) { + gen[genlen] = 0; + send_reply(conn, XS_DIRECTORY_PART, gen, genlen + 1); + return; + } + + len = 0; + maxlen = XENSTORE_PAYLOAD_MAX - genlen - 1; + child = node->children + off; + + while (len + strlen(child) < maxlen) { + len += strlen(child) + 1; + child += strlen(child) + 1; + if (off + len == node->childlen) + break; + } + + data = talloc_array(in, char, genlen + len + 1); + if (!data) { + send_error(conn, ENOMEM); + return; + } + + memcpy(data, gen, genlen); + memcpy(data + genlen, node->children + off, len); + if (off + len == node->childlen) { + data[genlen + len] = 0; + len++; + } + + send_reply(conn, XS_DIRECTORY_PART, data, genlen + len); +} + static void do_read(struct connection *conn, struct buffered_data *in) { struct node *node; @@ -1334,6 +1397,10 @@ static void process_message(struct connection *conn, struct buffered_data *in) do_reset_watches(conn, in); break; + case XS_DIRECTORY_PART: + send_directory_part(conn, in); + break; + default: eprintf("Client unknown operation %i", in->hdr.msg.type); send_error(conn, ENOSYS); diff --git a/xen/include/public/io/xs_wire.h b/xen/include/public/io/xs_wire.h index 0a0cdbc..9a6f8eb 100644 --- a/xen/include/public/io/xs_wire.h +++ b/xen/include/public/io/xs_wire.h @@ -50,6 +50,9 @@ enum xsd_sockmsg_type XS_SET_TARGET, XS_RESTRICT, XS_RESET_WATCHES, + XS_DIRECTORY_PART, + + XS_NEXT_ENTRY, /* First unused type. */ XS_INVALID = 0xffff /* Guaranteed to remain an invalid type */ };