[Xen-devel] [PATCH v3 00/12] xenstore: support reading directory with many children

[Juergen Gross <jgross@xxxxxxxx>]

Reading the children list of a xenstore node with the length of that
list exceeding 4096 bytes is currently not possible. This can be a
problem for a large host with a huge number of domains as Xen tools
will no longer by capable to scan some directories of xenstore (e.g.
/local/domain).

This patch series adds a new xs wire command to read a directory
in multiple chunks. libxenstore is modified in a compatible way to
show an unmodified result in case xenstored doesn't support the new
command.

As there have been questions regarding handling of memory allocation
failures I've decided to add proper handling of those, requiring some
more rework.

The patch set has been verified to work by using the following shell script:

xenstore-write /test "test"

for i in `seq 100 500`
do
    xenstore-write /test/entry_with_very_long_name_$i $i
done

xenstore-ls
xenstore-rm /test

Xenstore has been verified to work by starting multiple domain types.
Especially HVM with qemu-stubdom has been tested as this configuration
seems to be rather sensible to concurrent transactions.

Changes in V3:
- remove patch 1, as it has been applied already
- new patches 7-12
- some minor modifications in patch 5 (was 6) as suggested by Jan Beulich

Changes in V2:
- complete rework as suggested by Jan Beulich: don't use transactions
  for consistency, but a per-node generation count
- fix a (minor?) problem in transaction code regarding watches (patch 1)

Juergen Gross (12):
  xenstore: modify add_change_node() parameter types
  xenstore: call add_change_node() directly when writing node
  xenstore: use common tdb record header in xenstore
  xenstore: add per-node generation counter
  xenstore: add support for reading directory with many children
  xenstore: support XS_DIRECTORY_PART in libxenstore
  xenstore: use array for xenstore wire command handling
  xenstore: let command functions return error or success
  xenstore: make functions static
  xenstore: add helper functions for wire argument parsing
  xenstore: add small default data buffer to internal struct
  xenstore: handle memory allocation failures in xenstored

 tools/xenstore/include/xenstore_lib.h  |  24 +-
 tools/xenstore/xenstore_client.c       | 117 +++++
 tools/xenstore/xenstored_core.c        | 799 ++++++++++++++++++---------------
 tools/xenstore/xenstored_core.h        |  23 +-
 tools/xenstore/xenstored_domain.c      | 218 ++++-----
 tools/xenstore/xenstored_domain.h      |  14 +-
 tools/xenstore/xenstored_transaction.c | 100 +++--
 tools/xenstore/xenstored_transaction.h |   8 +-
 tools/xenstore/xenstored_watch.c       |  89 ++--
 tools/xenstore/xenstored_watch.h       |   6 +-
 tools/xenstore/xs.c                    |  80 +++-
 tools/xenstore/xs_lib.c                | 112 -----
 tools/xenstore/xs_tdb_dump.c           |  11 +-
 xen/include/public/io/xs_wire.h        |   3 +
 14 files changed, 872 insertions(+), 732 deletions(-)

-- 
2.6.6


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