subversion-1.9.7HEADsubversion-1.9.7master

1 files changed, 1381 insertions, 0 deletions

diff --git a/subversion/libsvn_fs_fs/revprops.c b/subversion/libsvn_fs_fs/revprops.c
new file mode 100644
index 0000000..dbb185b
--- /dev/null
+++ b/subversion/libsvn_fs_fs/revprops.c
@@ -0,0 +1,1381 @@
+/* revprops.c --- everything needed to handle revprops in FSFS
+ *
+ * ====================================================================
+ *    Licensed to the Apache Software Foundation (ASF) under one
+ *    or more contributor license agreements.  See the NOTICE file
+ *    distributed with this work for additional information
+ *    regarding copyright ownership.  The ASF licenses this file
+ *    to you under the Apache License, Version 2.0 (the
+ *    "License"); you may not use this file except in compliance
+ *    with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing,
+ *    software distributed under the License is distributed on an
+ *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *    KIND, either express or implied.  See the License for the
+ *    specific language governing permissions and limitations
+ *    under the License.
+ * ====================================================================
+ */
+
+#include <assert.h>
+
+#include "svn_pools.h"
+#include "svn_hash.h"
+#include "svn_dirent_uri.h"
+
+#include "fs_fs.h"
+#include "revprops.h"
+#include "util.h"
+
+#include "private/svn_subr_private.h"
+#include "private/svn_string_private.h"
+#include "../libsvn_fs/fs-loader.h"
+
+#include "svn_private_config.h"
+
+/* Give writing processes 10 seconds to replace an existing revprop
+   file with a new one. After that time, we assume that the writing
+   process got aborted and that we have re-read revprops. */
+#define REVPROP_CHANGE_TIMEOUT (10 * 1000000)
+
+svn_error_t *
+svn_fs_fs__upgrade_pack_revprops(svn_fs_t *fs,
+                                 svn_fs_upgrade_notify_t notify_func,
+                                 void *notify_baton,
+                                 svn_cancel_func_t cancel_func,
+                                 void *cancel_baton,
+                                 apr_pool_t *scratch_pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  const char *revprops_shard_path;
+  const char *revprops_pack_file_dir;
+  apr_int64_t shard;
+  apr_int64_t first_unpacked_shard
+    =  ffd->min_unpacked_rev / ffd->max_files_per_dir;
+
+  apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+  const char *revsprops_dir = svn_dirent_join(fs->path, PATH_REVPROPS_DIR,
+                                              scratch_pool);
+  int compression_level = ffd->compress_packed_revprops
+                           ? SVN_DELTA_COMPRESSION_LEVEL_DEFAULT
+                           : SVN_DELTA_COMPRESSION_LEVEL_NONE;
+
+  /* first, pack all revprops shards to match the packed revision shards */
+  for (shard = 0; shard < first_unpacked_shard; ++shard)
+    {
+      svn_pool_clear(iterpool);
+
+      revprops_pack_file_dir = svn_dirent_join(revsprops_dir,
+                   apr_psprintf(iterpool,
+                                "%" APR_INT64_T_FMT PATH_EXT_PACKED_SHARD,
+                                shard),
+                   iterpool);
+      revprops_shard_path = svn_dirent_join(revsprops_dir,
+                       apr_psprintf(iterpool, "%" APR_INT64_T_FMT, shard),
+                       iterpool);
+
+      SVN_ERR(svn_fs_fs__pack_revprops_shard(revprops_pack_file_dir,
+                                             revprops_shard_path,
+                                             shard, ffd->max_files_per_dir,
+                                             (int)(0.9 * ffd->revprop_pack_size),
+                                             compression_level,
+                                             cancel_func, cancel_baton,
+                                             iterpool));
+      if (notify_func)
+        SVN_ERR(notify_func(notify_baton, shard,
+                            svn_fs_upgrade_pack_revprops, iterpool));
+    }
+
+  svn_pool_destroy(iterpool);
+
+  return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__upgrade_cleanup_pack_revprops(svn_fs_t *fs,
+                                         svn_fs_upgrade_notify_t notify_func,
+                                         void *notify_baton,
+                                         svn_cancel_func_t cancel_func,
+                                         void *cancel_baton,
+                                         apr_pool_t *scratch_pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  const char *revprops_shard_path;
+  apr_int64_t shard;
+  apr_int64_t first_unpacked_shard
+    =  ffd->min_unpacked_rev / ffd->max_files_per_dir;
+
+  apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+  const char *revsprops_dir = svn_dirent_join(fs->path, PATH_REVPROPS_DIR,
+                                              scratch_pool);
+
+  /* delete the non-packed revprops shards afterwards */
+  for (shard = 0; shard < first_unpacked_shard; ++shard)
+    {
+      svn_pool_clear(iterpool);
+
+      revprops_shard_path = svn_dirent_join(revsprops_dir,
+                       apr_psprintf(iterpool, "%" APR_INT64_T_FMT, shard),
+                       iterpool);
+      SVN_ERR(svn_fs_fs__delete_revprops_shard(revprops_shard_path,
+                                               shard,
+                                               ffd->max_files_per_dir,
+                                               cancel_func, cancel_baton,
+                                               iterpool));
+      if (notify_func)
+        SVN_ERR(notify_func(notify_baton, shard,
+                            svn_fs_upgrade_cleanup_revprops, iterpool));
+    }
+
+  svn_pool_destroy(iterpool);
+
+  return SVN_NO_ERROR;
+}
+
+/* Container for all data required to access the packed revprop file
+ * for a given REVISION.  This structure will be filled incrementally
+ * by read_pack_revprops() its sub-routines.
+ */
+typedef struct packed_revprops_t
+{
+  /* revision number to read (not necessarily the first in the pack) */
+  svn_revnum_t revision;
+
+  /* current revprop generation. Used when populating the revprop cache */
+  apr_int64_t generation;
+
+  /* the actual revision properties */
+  apr_hash_t *properties;
+
+  /* their size when serialized to a single string
+   * (as found in PACKED_REVPROPS) */
+  apr_size_t serialized_size;
+
+
+  /* name of the pack file (without folder path) */
+  const char *filename;
+
+  /* packed shard folder path */
+  const char *folder;
+
+  /* sum of values in SIZES */
+  apr_size_t total_size;
+
+  /* first revision in the pack (>= MANIFEST_START) */
+  svn_revnum_t start_revision;
+
+  /* size of the revprops in PACKED_REVPROPS */
+  apr_array_header_t *sizes;
+
+  /* offset of the revprops in PACKED_REVPROPS */
+  apr_array_header_t *offsets;
+
+
+  /* concatenation of the serialized representation of all revprops
+   * in the pack, i.e. the pack content without header and compression */
+  svn_stringbuf_t *packed_revprops;
+
+  /* First revision covered by MANIFEST.
+   * Will equal the shard start revision or 1, for the 1st shard. */
+  svn_revnum_t manifest_start;
+
+  /* content of the manifest.
+   * Maps long(rev - MANIFEST_START) to const char* pack file name */
+  apr_array_header_t *manifest;
+} packed_revprops_t;
+
+/* Parse the serialized revprops in CONTENT and return them in *PROPERTIES.
+ * Also, put them into the revprop cache, if activated, for future use.
+ * Three more parameters are being used to update the revprop cache: FS is
+ * our file system, the revprops belong to REVISION and the global revprop
+ * GENERATION is used as well.
+ *
+ * The returned hash will be allocated in POOL, SCRATCH_POOL is being used
+ * for temporary allocations.
+ */
+static svn_error_t *
+parse_revprop(apr_hash_t **properties,
+              svn_fs_t *fs,
+              svn_revnum_t revision,
+              apr_int64_t generation,
+              svn_string_t *content,
+              apr_pool_t *pool,
+              apr_pool_t *scratch_pool)
+{
+  svn_stream_t *stream = svn_stream_from_string(content, scratch_pool);
+  *properties = apr_hash_make(pool);
+
+  SVN_ERR_W(svn_hash_read2(*properties, stream, SVN_HASH_TERMINATOR, pool),
+            apr_psprintf(scratch_pool, "Failed to parse revprops for r%ld.",
+                         revision));
+
+  return SVN_NO_ERROR;
+}
+
+/* Read the non-packed revprops for revision REV in FS, put them into the
+ * revprop cache if activated and return them in *PROPERTIES.  GENERATION
+ * is the current revprop generation.
+ *
+ * If the data could not be read due to an otherwise recoverable error,
+ * leave *PROPERTIES unchanged. No error will be returned in that case.
+ *
+ * Allocations will be done in POOL.
+ */
+static svn_error_t *
+read_non_packed_revprop(apr_hash_t **properties,
+                        svn_fs_t *fs,
+                        svn_revnum_t rev,
+                        apr_int64_t generation,
+                        apr_pool_t *pool)
+{
+  svn_stringbuf_t *content = NULL;
+  apr_pool_t *iterpool = svn_pool_create(pool);
+  svn_boolean_t missing = FALSE;
+  int i;
+
+  for (i = 0;
+       i < SVN_FS_FS__RECOVERABLE_RETRY_COUNT && !missing && !content;
+       ++i)
+    {
+      svn_pool_clear(iterpool);
+      SVN_ERR(svn_fs_fs__try_stringbuf_from_file(&content,
+                              &missing,
+                              svn_fs_fs__path_revprops(fs, rev, iterpool),
+                              i + 1 < SVN_FS_FS__RECOVERABLE_RETRY_COUNT ,
+                              iterpool));
+    }
+
+  if (content)
+    SVN_ERR(parse_revprop(properties, fs, rev, generation,
+                          svn_stringbuf__morph_into_string(content),
+                          pool, iterpool));
+
+  svn_pool_clear(iterpool);
+
+  return SVN_NO_ERROR;
+}
+
+/* Return the minimum length of any packed revprop file name in REVPROPS. */
+static apr_size_t
+get_min_filename_len(packed_revprops_t *revprops)
+{
+  char number_buffer[SVN_INT64_BUFFER_SIZE];
+
+  /* The revprop filenames have the format <REV>.<COUNT> - with <REV> being
+   * at least the first rev in the shard and <COUNT> having at least one
+   * digit.  Thus, the minimum is 2 + #decimal places in the start rev.
+   */
+  return svn__i64toa(number_buffer, revprops->manifest_start) + 2;
+}
+
+/* Given FS and REVPROPS->REVISION, fill the FILENAME, FOLDER and MANIFEST
+ * members. Use POOL for allocating results and SCRATCH_POOL for temporaries.
+ */
+static svn_error_t *
+get_revprop_packname(svn_fs_t *fs,
+                     packed_revprops_t *revprops,
+                     apr_pool_t *pool,
+                     apr_pool_t *scratch_pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  svn_stringbuf_t *content = NULL;
+  const char *manifest_file_path;
+  int idx, rev_count;
+  char *buffer, *buffer_end;
+  const char **filenames, **filenames_end;
+  apr_size_t min_filename_len;
+
+  /* Determine the dimensions. Rev 0 is excluded from the first shard. */
+  rev_count = ffd->max_files_per_dir;
+  revprops->manifest_start
+    = revprops->revision - (revprops->revision % rev_count);
+  if (revprops->manifest_start == 0)
+    {
+      ++revprops->manifest_start;
+      --rev_count;
+    }
+
+  revprops->manifest = apr_array_make(pool, rev_count, sizeof(const char*));
+
+  /* No line in the file can be less than this number of chars long. */
+  min_filename_len = get_min_filename_len(revprops);
+
+  /* Read the content of the manifest file */
+  revprops->folder
+    = svn_fs_fs__path_revprops_pack_shard(fs, revprops->revision, pool);
+  manifest_file_path
+    = svn_dirent_join(revprops->folder, PATH_MANIFEST, pool);
+
+  SVN_ERR(svn_fs_fs__read_content(&content, manifest_file_path, pool));
+
+  /* There CONTENT must have a certain minimal size and there no
+   * unterminated lines at the end of the file.  Both guarantees also
+   * simplify the parser loop below.
+   */
+  if (   content->len < rev_count * (min_filename_len + 1)
+      || content->data[content->len - 1] != '\n')
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Packed revprop manifest for r%ld not "
+                               "properly terminated"), revprops->revision);
+
+  /* Chop (parse) the manifest CONTENT into filenames, one per line.
+   * We only have to replace all newlines with NUL and add all line
+   * starts to REVPROPS->MANIFEST.
+   *
+   * There must be exactly REV_COUNT lines and that is the number of
+   * lines we parse from BUFFER to FILENAMES.  Set the end pointer for
+   * the source BUFFER such that BUFFER+MIN_FILENAME_LEN is still valid
+   * BUFFER_END is always valid due to CONTENT->LEN > MIN_FILENAME_LEN.
+   *
+   * Please note that this loop is performance critical for e.g. 'svn log'.
+   * It is run 1000x per revprop access, i.e. per revision and about
+   * 50 million times per sec (and CPU core).
+   */
+  for (filenames = (const char **)revprops->manifest->elts,
+       filenames_end = filenames + rev_count,
+       buffer = content->data,
+       buffer_end = buffer + content->len - min_filename_len;
+       (filenames < filenames_end) && (buffer < buffer_end);
+       ++filenames)
+    {
+      /* BUFFER always points to the start of the next line / filename. */
+      *filenames = buffer;
+
+      /* Find the next EOL.  This is guaranteed to stay within the CONTENT
+       * buffer because we left enough room after BUFFER_END and we know
+       * we will always see a newline as the last non-NUL char. */
+      buffer += min_filename_len;
+      while (*buffer != '\n')
+        ++buffer;
+
+      /* Found EOL.  Turn it into the filename terminator and move BUFFER
+       * to the start of the next line or CONTENT buffer end. */
+      *buffer = '\0';
+      ++buffer;
+    }
+
+  /* We must have reached the end of both buffers. */
+  if (buffer < content->data + content->len)
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Packed revprop manifest for r%ld "
+                               "has too many entries"), revprops->revision);
+
+  if (filenames < filenames_end)
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Packed revprop manifest for r%ld "
+                               "has too few entries"), revprops->revision);
+
+  /* The target array has now exactly one entry per revision. */
+  revprops->manifest->nelts = rev_count;
+
+  /* Now get the file name */
+  idx = (int)(revprops->revision - revprops->manifest_start);
+  revprops->filename = APR_ARRAY_IDX(revprops->manifest, idx, const char*);
+
+  return SVN_NO_ERROR;
+}
+
+/* Return TRUE, if revision R1 and R2 refer to the same shard in FS.
+ */
+static svn_boolean_t
+same_shard(svn_fs_t *fs,
+           svn_revnum_t r1,
+           svn_revnum_t r2)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  return (r1 / ffd->max_files_per_dir) == (r2 / ffd->max_files_per_dir);
+}
+
+/* Given FS and the full packed file content in REVPROPS->PACKED_REVPROPS,
+ * fill the START_REVISION member, and make PACKED_REVPROPS point to the
+ * first serialized revprop.  If READ_ALL is set, initialize the SIZES
+ * and OFFSETS members as well.
+ *
+ * Parse the revprops for REVPROPS->REVISION and set the PROPERTIES as
+ * well as the SERIALIZED_SIZE member.  If revprop caching has been
+ * enabled, parse all revprops in the pack and cache them.
+ */
+static svn_error_t *
+parse_packed_revprops(svn_fs_t *fs,
+                      packed_revprops_t *revprops,
+                      svn_boolean_t read_all,
+                      apr_pool_t *pool,
+                      apr_pool_t *scratch_pool)
+{
+  svn_stream_t *stream;
+  apr_int64_t first_rev, count, i;
+  apr_off_t offset;
+  const char *header_end;
+  apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+
+  /* decompress (even if the data is only "stored", there is still a
+   * length header to remove) */
+  svn_stringbuf_t *compressed = revprops->packed_revprops;
+  svn_stringbuf_t *uncompressed = svn_stringbuf_create_empty(pool);
+  SVN_ERR(svn__decompress(compressed, uncompressed, APR_SIZE_MAX));
+
+  /* read first revision number and number of revisions in the pack */
+  stream = svn_stream_from_stringbuf(uncompressed, scratch_pool);
+  SVN_ERR(svn_fs_fs__read_number_from_stream(&first_rev, NULL, stream,
+                                             iterpool));
+  SVN_ERR(svn_fs_fs__read_number_from_stream(&count, NULL, stream,
+                                             iterpool));
+
+  /* Check revision range for validity. */
+  if (   !same_shard(fs, revprops->revision, first_rev)
+      || !same_shard(fs, revprops->revision, first_rev + count - 1)
+      || count < 1)
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Revprop pack for revision r%ld"
+                               " contains revprops for r%ld .. r%ld"),
+                             revprops->revision,
+                             (svn_revnum_t)first_rev,
+                             (svn_revnum_t)(first_rev + count -1));
+
+  /* Since start & end are in the same shard, it is enough to just test
+   * the FIRST_REV for being actually packed.  That will also cover the
+   * special case of rev 0 never being packed. */
+  if (!svn_fs_fs__is_packed_revprop(fs, first_rev))
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Revprop pack for revision r%ld"
+                               " starts at non-packed revisions r%ld"),
+                             revprops->revision, (svn_revnum_t)first_rev);
+
+  /* make PACKED_REVPROPS point to the first char after the header.
+   * This is where the serialized revprops are. */
+  header_end = strstr(uncompressed->data, "\n\n");
+  if (header_end == NULL)
+    return svn_error_create(SVN_ERR_FS_CORRUPT, NULL,
+                            _("Header end not found"));
+
+  offset = header_end - uncompressed->data + 2;
+
+  revprops->packed_revprops = svn_stringbuf_create_empty(pool);
+  revprops->packed_revprops->data = uncompressed->data + offset;
+  revprops->packed_revprops->len = (apr_size_t)(uncompressed->len - offset);
+  revprops->packed_revprops->blocksize = (apr_size_t)(uncompressed->blocksize - offset);
+
+  /* STREAM still points to the first entry in the sizes list. */
+  revprops->start_revision = (svn_revnum_t)first_rev;
+  if (read_all)
+    {
+      /* Init / construct REVPROPS members. */
+      revprops->sizes = apr_array_make(pool, (int)count, sizeof(offset));
+      revprops->offsets = apr_array_make(pool, (int)count, sizeof(offset));
+    }
+
+  /* Now parse, revision by revision, the size and content of each
+   * revisions' revprops. */
+  for (i = 0, offset = 0, revprops->total_size = 0; i < count; ++i)
+    {
+      apr_int64_t size;
+      svn_string_t serialized;
+      svn_revnum_t revision = (svn_revnum_t)(first_rev + i);
+      svn_pool_clear(iterpool);
+
+      /* read & check the serialized size */
+      SVN_ERR(svn_fs_fs__read_number_from_stream(&size, NULL, stream,
+                                                 iterpool));
+      if (size + offset > (apr_int64_t)revprops->packed_revprops->len)
+        return svn_error_create(SVN_ERR_FS_CORRUPT, NULL,
+                        _("Packed revprop size exceeds pack file size"));
+
+      /* Parse this revprops list, if necessary */
+      serialized.data = revprops->packed_revprops->data + offset;
+      serialized.len = (apr_size_t)size;
+
+      if (revision == revprops->revision)
+        {
+          SVN_ERR(parse_revprop(&revprops->properties, fs, revision,
+                                revprops->generation, &serialized,
+                                pool, iterpool));
+          revprops->serialized_size = serialized.len;
+
+          /* If we only wanted the revprops for REVISION then we are done. */
+          if (!read_all)
+            break;
+        }
+
+      if (read_all)
+        {
+          /* fill REVPROPS data structures */
+          APR_ARRAY_PUSH(revprops->sizes, apr_off_t) = serialized.len;
+          APR_ARRAY_PUSH(revprops->offsets, apr_off_t) = offset;
+        }
+      revprops->total_size += serialized.len;
+
+      offset += serialized.len;
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/* In filesystem FS, read the packed revprops for revision REV into
+ * *REVPROPS.  Use GENERATION to populate the revprop cache, if enabled.
+ * If you want to modify revprop contents / update REVPROPS, READ_ALL
+ * must be set.  Otherwise, only the properties of REV are being provided.
+ * Allocate data in POOL.
+ */
+static svn_error_t *
+read_pack_revprop(packed_revprops_t **revprops,
+                  svn_fs_t *fs,
+                  svn_revnum_t rev,
+                  apr_int64_t generation,
+                  svn_boolean_t read_all,
+                  apr_pool_t *pool)
+{
+  apr_pool_t *iterpool = svn_pool_create(pool);
+  svn_boolean_t missing = FALSE;
+  svn_error_t *err;
+  packed_revprops_t *result;
+  int i;
+
+  /* someone insisted that REV is packed. Double-check if necessary */
+  if (!svn_fs_fs__is_packed_revprop(fs, rev))
+     SVN_ERR(svn_fs_fs__update_min_unpacked_rev(fs, iterpool));
+
+  if (!svn_fs_fs__is_packed_revprop(fs, rev))
+    return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
+                              _("No such packed revision %ld"), rev);
+
+  /* initialize the result data structure */
+  result = apr_pcalloc(pool, sizeof(*result));
+  result->revision = rev;
+  result->generation = generation;
+
+  /* try to read the packed revprops. This may require retries if we have
+   * concurrent writers. */
+  for (i = 0;
+       i < SVN_FS_FS__RECOVERABLE_RETRY_COUNT && !result->packed_revprops;
+       ++i)
+    {
+      const char *file_path;
+      svn_pool_clear(iterpool);
+
+      /* there might have been concurrent writes.
+       * Re-read the manifest and the pack file.
+       */
+      SVN_ERR(get_revprop_packname(fs, result, pool, iterpool));
+      file_path  = svn_dirent_join(result->folder,
+                                   result->filename,
+                                   iterpool);
+      SVN_ERR(svn_fs_fs__try_stringbuf_from_file(&result->packed_revprops,
+                                &missing,
+                                file_path,
+                                i + 1 < SVN_FS_FS__RECOVERABLE_RETRY_COUNT,
+                                pool));
+    }
+
+  /* the file content should be available now */
+  if (!result->packed_revprops)
+    return svn_error_createf(SVN_ERR_FS_PACKED_REVPROP_READ_FAILURE, NULL,
+                  _("Failed to read revprop pack file for r%ld"), rev);
+
+  /* parse it. RESULT will be complete afterwards. */
+  err = parse_packed_revprops(fs, result, read_all, pool, iterpool);
+  svn_pool_destroy(iterpool);
+  if (err)
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, err,
+                  _("Revprop pack file for r%ld is corrupt"), rev);
+
+  *revprops = result;
+
+  return SVN_NO_ERROR;
+}
+
+/* Read the revprops for revision REV in FS and return them in *PROPERTIES_P.
+ *
+ * Allocations will be done in POOL.
+ */
+svn_error_t *
+svn_fs_fs__get_revision_proplist(apr_hash_t **proplist_p,
+                                 svn_fs_t *fs,
+                                 svn_revnum_t rev,
+                                 apr_pool_t *pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  apr_int64_t generation = 0;
+
+  /* not found, yet */
+  *proplist_p = NULL;
+
+  /* should they be available at all? */
+  SVN_ERR(svn_fs_fs__ensure_revision_exists(rev, fs, pool));
+
+  /* if REV had not been packed when we began, try reading it from the
+   * non-packed shard.  If that fails, we will fall through to packed
+   * shard reads. */
+  if (!svn_fs_fs__is_packed_revprop(fs, rev))
+    {
+      svn_error_t *err = read_non_packed_revprop(proplist_p, fs, rev,
+                                                 generation, pool);
+      if (err)
+        {
+          if (!APR_STATUS_IS_ENOENT(err->apr_err)
+              || ffd->format < SVN_FS_FS__MIN_PACKED_REVPROP_FORMAT)
+            return svn_error_trace(err);
+
+          svn_error_clear(err);
+          *proplist_p = NULL; /* in case read_non_packed_revprop changed it */
+        }
+    }
+
+  /* if revprop packing is available and we have not read the revprops, yet,
+   * try reading them from a packed shard.  If that fails, REV is most
+   * likely invalid (or its revprops highly contested). */
+  if (ffd->format >= SVN_FS_FS__MIN_PACKED_REVPROP_FORMAT && !*proplist_p)
+    {
+      packed_revprops_t *revprops;
+      SVN_ERR(read_pack_revprop(&revprops, fs, rev, generation, FALSE, pool));
+      *proplist_p = revprops->properties;
+    }
+
+  /* The revprops should have been there. Did we get them? */
+  if (!*proplist_p)
+    return svn_error_createf(SVN_ERR_FS_NO_SUCH_REVISION, NULL,
+                             _("Could not read revprops for revision %ld"),
+                             rev);
+
+  return SVN_NO_ERROR;
+}
+
+/* Serialize the revision property list PROPLIST of revision REV in
+ * filesystem FS to a non-packed file.  Return the name of that temporary
+ * file in *TMP_PATH and the file path that it must be moved to in
+ * *FINAL_PATH.
+ *
+ * Use POOL for allocations.
+ */
+static svn_error_t *
+write_non_packed_revprop(const char **final_path,
+                         const char **tmp_path,
+                         svn_fs_t *fs,
+                         svn_revnum_t rev,
+                         apr_hash_t *proplist,
+                         apr_pool_t *pool)
+{
+  apr_file_t *file;
+  svn_stream_t *stream;
+  *final_path = svn_fs_fs__path_revprops(fs, rev, pool);
+
+  /* ### do we have a directory sitting around already? we really shouldn't
+     ### have to get the dirname here. */
+  SVN_ERR(svn_io_open_unique_file3(&file, tmp_path,
+                                   svn_dirent_dirname(*final_path, pool),
+                                   svn_io_file_del_none, pool, pool));
+  stream = svn_stream_from_aprfile2(file, TRUE, pool);
+  SVN_ERR(svn_hash_write2(proplist, stream, SVN_HASH_TERMINATOR, pool));
+  SVN_ERR(svn_stream_close(stream));
+
+  /* Flush temporary file to disk and close it. */
+  SVN_ERR(svn_io_file_flush_to_disk(file, pool));
+  SVN_ERR(svn_io_file_close(file, pool));
+
+  return SVN_NO_ERROR;
+}
+
+/* After writing the new revprop file(s), call this function to move the
+ * file at TMP_PATH to FINAL_PATH and give it the permissions from
+ * PERMS_REFERENCE.
+ *
+ * Finally, delete all the temporary files given in FILES_TO_DELETE.
+ * The latter may be NULL.
+ *
+ * Use POOL for temporary allocations.
+ */
+static svn_error_t *
+switch_to_new_revprop(svn_fs_t *fs,
+                      const char *final_path,
+                      const char *tmp_path,
+                      const char *perms_reference,
+                      apr_array_header_t *files_to_delete,
+                      apr_pool_t *pool)
+{
+  SVN_ERR(svn_fs_fs__move_into_place(tmp_path, final_path, perms_reference,
+                                     pool));
+
+  /* Clean up temporary files, if necessary. */
+  if (files_to_delete)
+    {
+      apr_pool_t *iterpool = svn_pool_create(pool);
+      int i;
+
+      for (i = 0; i < files_to_delete->nelts; ++i)
+        {
+          const char *path = APR_ARRAY_IDX(files_to_delete, i, const char*);
+
+          svn_pool_clear(iterpool);
+          SVN_ERR(svn_io_remove_file2(path, TRUE, iterpool));
+        }
+
+      svn_pool_destroy(iterpool);
+    }
+  return SVN_NO_ERROR;
+}
+
+/* Write a pack file header to STREAM that starts at revision START_REVISION
+ * and contains the indexes [START,END) of SIZES.
+ */
+static svn_error_t *
+serialize_revprops_header(svn_stream_t *stream,
+                          svn_revnum_t start_revision,
+                          apr_array_header_t *sizes,
+                          int start,
+                          int end,
+                          apr_pool_t *pool)
+{
+  apr_pool_t *iterpool = svn_pool_create(pool);
+  int i;
+
+  SVN_ERR_ASSERT(start < end);
+
+  /* start revision and entry count */
+  SVN_ERR(svn_stream_printf(stream, pool, "%ld\n", start_revision));
+  SVN_ERR(svn_stream_printf(stream, pool, "%d\n", end - start));
+
+  /* the sizes array */
+  for (i = start; i < end; ++i)
+    {
+      /* Non-standard pool usage.
+       *
+       * We only allocate a few bytes each iteration -- even with a
+       * million iterations we would still be in good shape memory-wise.
+       */
+      apr_off_t size = APR_ARRAY_IDX(sizes, i, apr_off_t);
+      SVN_ERR(svn_stream_printf(stream, iterpool, "%" APR_OFF_T_FMT "\n",
+                                size));
+    }
+
+  /* the double newline char indicates the end of the header */
+  SVN_ERR(svn_stream_printf(stream, iterpool, "\n"));
+
+  svn_pool_destroy(iterpool);
+  return SVN_NO_ERROR;
+}
+
+/* Writes the a pack file to FILE.  It copies the serialized data
+ * from REVPROPS for the indexes [START,END) except for index CHANGED_INDEX.
+ *
+ * The data for the latter is taken from NEW_SERIALIZED.  Note, that
+ * CHANGED_INDEX may be outside the [START,END) range, i.e. no new data is
+ * taken in that case but only a subset of the old data will be copied.
+ *
+ * NEW_TOTAL_SIZE is a hint for pre-allocating buffers of appropriate size.
+ * POOL is used for temporary allocations.
+ */
+static svn_error_t *
+repack_revprops(svn_fs_t *fs,
+                packed_revprops_t *revprops,
+                int start,
+                int end,
+                int changed_index,
+                svn_stringbuf_t *new_serialized,
+                apr_off_t new_total_size,
+                apr_file_t *file,
+                apr_pool_t *pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  svn_stream_t *stream;
+  int i;
+
+  /* create data empty buffers and the stream object */
+  svn_stringbuf_t *uncompressed
+    = svn_stringbuf_create_ensure((apr_size_t)new_total_size, pool);
+  svn_stringbuf_t *compressed
+    = svn_stringbuf_create_empty(pool);
+  stream = svn_stream_from_stringbuf(uncompressed, pool);
+
+  /* write the header*/
+  SVN_ERR(serialize_revprops_header(stream, revprops->start_revision + start,
+                                    revprops->sizes, start, end, pool));
+
+  /* append the serialized revprops */
+  for (i = start; i < end; ++i)
+    if (i == changed_index)
+      {
+        SVN_ERR(svn_stream_write(stream,
+                                 new_serialized->data,
+                                 &new_serialized->len));
+      }
+    else
+      {
+        apr_size_t size
+            = (apr_size_t)APR_ARRAY_IDX(revprops->sizes, i, apr_off_t);
+        apr_size_t offset
+            = (apr_size_t)APR_ARRAY_IDX(revprops->offsets, i, apr_off_t);
+
+        SVN_ERR(svn_stream_write(stream,
+                                 revprops->packed_revprops->data + offset,
+                                 &size));
+      }
+
+  /* flush the stream buffer (if any) to our underlying data buffer */
+  SVN_ERR(svn_stream_close(stream));
+
+  /* compress / store the data */
+  SVN_ERR(svn__compress(uncompressed,
+                        compressed,
+                        ffd->compress_packed_revprops
+                          ? SVN_DELTA_COMPRESSION_LEVEL_DEFAULT
+                          : SVN_DELTA_COMPRESSION_LEVEL_NONE));
+
+  /* finally, write the content to the target file, flush and close it */
+  SVN_ERR(svn_io_file_write_full(file, compressed->data, compressed->len,
+                                 NULL, pool));
+  SVN_ERR(svn_io_file_flush_to_disk(file, pool));
+  SVN_ERR(svn_io_file_close(file, pool));
+
+  return SVN_NO_ERROR;
+}
+
+/* Allocate a new pack file name for revisions
+ *     [REVPROPS->START_REVISION + START, REVPROPS->START_REVISION + END - 1]
+ * of REVPROPS->MANIFEST.  Add the name of old file to FILES_TO_DELETE,
+ * auto-create that array if necessary.  Return an open file *FILE that is
+ * allocated in POOL.
+ */
+static svn_error_t *
+repack_file_open(apr_file_t **file,
+                 svn_fs_t *fs,
+                 packed_revprops_t *revprops,
+                 int start,
+                 int end,
+                 apr_array_header_t **files_to_delete,
+                 apr_pool_t *pool)
+{
+  apr_int64_t tag;
+  const char *tag_string;
+  svn_string_t *new_filename;
+  int i;
+  int manifest_offset
+    = (int)(revprops->start_revision - revprops->manifest_start);
+
+  /* get the old (= current) file name and enlist it for later deletion */
+  const char *old_filename = APR_ARRAY_IDX(revprops->manifest,
+                                           start + manifest_offset,
+                                           const char*);
+
+  if (*files_to_delete == NULL)
+    *files_to_delete = apr_array_make(pool, 3, sizeof(const char*));
+
+  APR_ARRAY_PUSH(*files_to_delete, const char*)
+    = svn_dirent_join(revprops->folder, old_filename, pool);
+
+  /* increase the tag part, i.e. the counter after the dot */
+  tag_string = strchr(old_filename, '.');
+  if (tag_string == NULL)
+    return svn_error_createf(SVN_ERR_FS_CORRUPT, NULL,
+                             _("Packed file '%s' misses a tag"),
+                             old_filename);
+
+  SVN_ERR(svn_cstring_atoi64(&tag, tag_string + 1));
+  new_filename = svn_string_createf(pool, "%ld.%" APR_INT64_T_FMT,
+                                    revprops->start_revision + start,
+                                    ++tag);
+
+  /* update the manifest to point to the new file */
+  for (i = start; i < end; ++i)
+    APR_ARRAY_IDX(revprops->manifest, i + manifest_offset, const char*)
+      = new_filename->data;
+
+  /* open the file */
+  SVN_ERR(svn_io_file_open(file, svn_dirent_join(revprops->folder,
+                                                 new_filename->data,
+                                                 pool),
+                           APR_WRITE | APR_CREATE, APR_OS_DEFAULT, pool));
+
+  return SVN_NO_ERROR;
+}
+
+/* For revision REV in filesystem FS, set the revision properties to
+ * PROPLIST.  Return a new file in *TMP_PATH that the caller shall move
+ * to *FINAL_PATH to make the change visible.  Files to be deleted will
+ * be listed in *FILES_TO_DELETE which may remain unchanged / unallocated.
+ * Use POOL for allocations.
+ */
+static svn_error_t *
+write_packed_revprop(const char **final_path,
+                     const char **tmp_path,
+                     apr_array_header_t **files_to_delete,
+                     svn_fs_t *fs,
+                     svn_revnum_t rev,
+                     apr_hash_t *proplist,
+                     apr_pool_t *pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  packed_revprops_t *revprops;
+  apr_int64_t generation = 0;
+  svn_stream_t *stream;
+  apr_file_t *file;
+  svn_stringbuf_t *serialized;
+  apr_off_t new_total_size;
+  int changed_index;
+
+  /* read contents of the current pack file */
+  SVN_ERR(read_pack_revprop(&revprops, fs, rev, generation, TRUE, pool));
+
+  /* serialize the new revprops */
+  serialized = svn_stringbuf_create_empty(pool);
+  stream = svn_stream_from_stringbuf(serialized, pool);
+  SVN_ERR(svn_hash_write2(proplist, stream, SVN_HASH_TERMINATOR, pool));
+  SVN_ERR(svn_stream_close(stream));
+
+  /* calculate the size of the new data */
+  changed_index = (int)(rev - revprops->start_revision);
+  new_total_size = revprops->total_size - revprops->serialized_size
+                 + serialized->len
+                 + (revprops->offsets->nelts + 2) * SVN_INT64_BUFFER_SIZE;
+
+  APR_ARRAY_IDX(revprops->sizes, changed_index, apr_off_t) = serialized->len;
+
+  /* can we put the new data into the same pack as the before? */
+  if (   new_total_size < ffd->revprop_pack_size
+      || revprops->sizes->nelts == 1)
+    {
+      /* simply replace the old pack file with new content as we do it
+       * in the non-packed case */
+
+      *final_path = svn_dirent_join(revprops->folder, revprops->filename,
+                                    pool);
+      SVN_ERR(svn_io_open_unique_file3(&file, tmp_path, revprops->folder,
+                                       svn_io_file_del_none, pool, pool));
+      SVN_ERR(repack_revprops(fs, revprops, 0, revprops->sizes->nelts,
+                              changed_index, serialized, new_total_size,
+                              file, pool));
+    }
+  else
+    {
+      /* split the pack file into two of roughly equal size */
+      int right_count, left_count, i;
+
+      int left = 0;
+      int right = revprops->sizes->nelts - 1;
+      apr_off_t left_size = 2 * SVN_INT64_BUFFER_SIZE;
+      apr_off_t right_size = 2 * SVN_INT64_BUFFER_SIZE;
+
+      /* let left and right side grow such that their size difference
+       * is minimal after each step. */
+      while (left <= right)
+        if (  left_size + APR_ARRAY_IDX(revprops->sizes, left, apr_off_t)
+            < right_size + APR_ARRAY_IDX(revprops->sizes, right, apr_off_t))
+          {
+            left_size += APR_ARRAY_IDX(revprops->sizes, left, apr_off_t)
+                      + SVN_INT64_BUFFER_SIZE;
+            ++left;
+          }
+        else
+          {
+            right_size += APR_ARRAY_IDX(revprops->sizes, right, apr_off_t)
+                        + SVN_INT64_BUFFER_SIZE;
+            --right;
+          }
+
+       /* since the items need much less than SVN_INT64_BUFFER_SIZE
+        * bytes to represent their length, the split may not be optimal */
+      left_count = left;
+      right_count = revprops->sizes->nelts - left;
+
+      /* if new_size is large, one side may exceed the pack size limit.
+       * In that case, split before and after the modified revprop.*/
+      if (   left_size > ffd->revprop_pack_size
+          || right_size > ffd->revprop_pack_size)
+        {
+          left_count = changed_index;
+          right_count = revprops->sizes->nelts - left_count - 1;
+        }
+
+      /* write the new, split files */
+      if (left_count)
+        {
+          SVN_ERR(repack_file_open(&file, fs, revprops, 0,
+                                   left_count, files_to_delete, pool));
+          SVN_ERR(repack_revprops(fs, revprops, 0, left_count,
+                                  changed_index, serialized, new_total_size,
+                                  file, pool));
+        }
+
+      if (left_count + right_count < revprops->sizes->nelts)
+        {
+          SVN_ERR(repack_file_open(&file, fs, revprops, changed_index,
+                                   changed_index + 1, files_to_delete,
+                                   pool));
+          SVN_ERR(repack_revprops(fs, revprops, changed_index,
+                                  changed_index + 1,
+                                  changed_index, serialized, new_total_size,
+                                  file, pool));
+        }
+
+      if (right_count)
+        {
+          SVN_ERR(repack_file_open(&file, fs, revprops,
+                                   revprops->sizes->nelts - right_count,
+                                   revprops->sizes->nelts,
+                                   files_to_delete, pool));
+          SVN_ERR(repack_revprops(fs, revprops,
+                                  revprops->sizes->nelts - right_count,
+                                  revprops->sizes->nelts, changed_index,
+                                  serialized, new_total_size, file,
+                                  pool));
+        }
+
+      /* write the new manifest */
+      *final_path = svn_dirent_join(revprops->folder, PATH_MANIFEST, pool);
+      SVN_ERR(svn_io_open_unique_file3(&file, tmp_path, revprops->folder,
+                                       svn_io_file_del_none, pool, pool));
+
+      for (i = 0; i < revprops->manifest->nelts; ++i)
+        {
+          const char *filename = APR_ARRAY_IDX(revprops->manifest, i,
+                                               const char*);
+          SVN_ERR(svn_io_file_write_full(file, filename, strlen(filename),
+                                         NULL, pool));
+          SVN_ERR(svn_io_file_putc('\n', file, pool));
+        }
+
+      SVN_ERR(svn_io_file_flush_to_disk(file, pool));
+      SVN_ERR(svn_io_file_close(file, pool));
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/* Set the revision property list of revision REV in filesystem FS to
+   PROPLIST.  Use POOL for temporary allocations. */
+svn_error_t *
+svn_fs_fs__set_revision_proplist(svn_fs_t *fs,
+                                 svn_revnum_t rev,
+                                 apr_hash_t *proplist,
+                                 apr_pool_t *pool)
+{
+  svn_boolean_t is_packed;
+  const char *final_path;
+  const char *tmp_path;
+  const char *perms_reference;
+  apr_array_header_t *files_to_delete = NULL;
+
+  SVN_ERR(svn_fs_fs__ensure_revision_exists(rev, fs, pool));
+
+  /* this info will not change while we hold the global FS write lock */
+  is_packed = svn_fs_fs__is_packed_revprop(fs, rev);
+
+  /* Serialize the new revprop data */
+  if (is_packed)
+    SVN_ERR(write_packed_revprop(&final_path, &tmp_path, &files_to_delete,
+                                 fs, rev, proplist, pool));
+  else
+    SVN_ERR(write_non_packed_revprop(&final_path, &tmp_path,
+                                     fs, rev, proplist, pool));
+
+  /* We use the rev file of this revision as the perms reference,
+   * because when setting revprops for the first time, the revprop
+   * file won't exist and therefore can't serve as its own reference.
+   * (Whereas the rev file should already exist at this point.)
+   */
+  perms_reference = svn_fs_fs__path_rev_absolute(fs, rev, pool);
+
+  /* Now, switch to the new revprop data. */
+  SVN_ERR(switch_to_new_revprop(fs, final_path, tmp_path, perms_reference,
+                                files_to_delete, pool));
+
+  return SVN_NO_ERROR;
+}
+
+/* Return TRUE, if for REVISION in FS, we can find the revprop pack file.
+ * Use POOL for temporary allocations.
+ * Set *MISSING, if the reason is a missing manifest or pack file.
+ */
+svn_boolean_t
+svn_fs_fs__packed_revprop_available(svn_boolean_t *missing,
+                                    svn_fs_t *fs,
+                                    svn_revnum_t revision,
+                                    apr_pool_t *pool)
+{
+  fs_fs_data_t *ffd = fs->fsap_data;
+  svn_stringbuf_t *content = NULL;
+
+  /* try to read the manifest file */
+  const char *folder
+    = svn_fs_fs__path_revprops_pack_shard(fs, revision, pool);
+  const char *manifest_path = svn_dirent_join(folder, PATH_MANIFEST, pool);
+
+  svn_error_t *err = svn_fs_fs__try_stringbuf_from_file(&content,
+                                                        missing,
+                                                        manifest_path,
+                                                        FALSE,
+                                                        pool);
+
+  /* if the manifest cannot be read, consider the pack files inaccessible
+   * even if the file itself exists. */
+  if (err)
+    {
+      svn_error_clear(err);
+      return FALSE;
+    }
+
+  if (*missing)
+    return FALSE;
+
+  /* parse manifest content until we find the entry for REVISION.
+   * Revision 0 is never packed. */
+  revision = revision < ffd->max_files_per_dir
+           ? revision - 1
+           : revision % ffd->max_files_per_dir;
+  while (content->data)
+    {
+      char *next = strchr(content->data, '\n');
+      if (next)
+        {
+          *next = 0;
+          ++next;
+        }
+
+      if (revision-- == 0)
+        {
+          /* the respective pack file must exist (and be a file) */
+          svn_node_kind_t kind;
+          err = svn_io_check_path(svn_dirent_join(folder, content->data,
+                                                  pool),
+                                  &kind, pool);
+          if (err)
+            {
+              svn_error_clear(err);
+              return FALSE;
+            }
+
+          *missing = kind == svn_node_none;
+          return kind == svn_node_file;
+        }
+
+      content->data = next;
+    }
+
+  return FALSE;
+}
+
+
+/****** Packing FSFS shards *********/
+
+svn_error_t *
+svn_fs_fs__copy_revprops(const char *pack_file_dir,
+                         const char *pack_filename,
+                         const char *shard_path,
+                         svn_revnum_t start_rev,
+                         svn_revnum_t end_rev,
+                         apr_array_header_t *sizes,
+                         apr_size_t total_size,
+                         int compression_level,
+                         svn_cancel_func_t cancel_func,
+                         void *cancel_baton,
+                         apr_pool_t *scratch_pool)
+{
+  svn_stream_t *pack_stream;
+  apr_file_t *pack_file;
+  svn_revnum_t rev;
+  apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+
+  /* create empty data buffer and a write stream on top of it */
+  svn_stringbuf_t *uncompressed
+    = svn_stringbuf_create_ensure(total_size, scratch_pool);
+  svn_stringbuf_t *compressed
+    = svn_stringbuf_create_empty(scratch_pool);
+  pack_stream = svn_stream_from_stringbuf(uncompressed, scratch_pool);
+
+  /* write the pack file header */
+  SVN_ERR(serialize_revprops_header(pack_stream, start_rev, sizes, 0,
+                                    sizes->nelts, iterpool));
+
+  /* Some useful paths. */
+  SVN_ERR(svn_io_file_open(&pack_file, svn_dirent_join(pack_file_dir,
+                                                       pack_filename,
+                                                       scratch_pool),
+                           APR_WRITE | APR_CREATE, APR_OS_DEFAULT,
+                           scratch_pool));
+
+  /* Iterate over the revisions in this shard, squashing them together. */
+  for (rev = start_rev; rev <= end_rev; rev++)
+    {
+      const char *path;
+      svn_stream_t *stream;
+
+      svn_pool_clear(iterpool);
+
+      /* Construct the file name. */
+      path = svn_dirent_join(shard_path, apr_psprintf(iterpool, "%ld", rev),
+                             iterpool);
+
+      /* Copy all the bits from the non-packed revprop file to the end of
+       * the pack file. */
+      SVN_ERR(svn_stream_open_readonly(&stream, path, iterpool, iterpool));
+      SVN_ERR(svn_stream_copy3(stream, pack_stream,
+                               cancel_func, cancel_baton, iterpool));
+    }
+
+  /* flush stream buffers to content buffer */
+  SVN_ERR(svn_stream_close(pack_stream));
+
+  /* compress the content (or just store it for COMPRESSION_LEVEL 0) */
+  SVN_ERR(svn__compress(uncompressed, compressed, compression_level));
+
+  /* write the pack file content to disk */
+  SVN_ERR(svn_io_file_write_full(pack_file, compressed->data, compressed->len,
+                                 NULL, scratch_pool));
+  SVN_ERR(svn_io_file_flush_to_disk(pack_file, scratch_pool));
+  SVN_ERR(svn_io_file_close(pack_file, scratch_pool));
+
+  svn_pool_destroy(iterpool);
+
+  return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__pack_revprops_shard(const char *pack_file_dir,
+                               const char *shard_path,
+                               apr_int64_t shard,
+                               int max_files_per_dir,
+                               apr_off_t max_pack_size,
+                               int compression_level,
+                               svn_cancel_func_t cancel_func,
+                               void *cancel_baton,
+                               apr_pool_t *scratch_pool)
+{
+  const char *manifest_file_path, *pack_filename = NULL;
+  apr_file_t *manifest_file;
+  svn_stream_t *manifest_stream;
+  svn_revnum_t start_rev, end_rev, rev;
+  apr_off_t total_size;
+  apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+  apr_array_header_t *sizes;
+
+  /* Some useful paths. */
+  manifest_file_path = svn_dirent_join(pack_file_dir, PATH_MANIFEST,
+                                       scratch_pool);
+
+  /* Remove any existing pack file for this shard, since it is incomplete. */
+  SVN_ERR(svn_io_remove_dir2(pack_file_dir, TRUE, cancel_func, cancel_baton,
+                             scratch_pool));
+
+  /* Create the new directory and manifest file stream. */
+  SVN_ERR(svn_io_dir_make(pack_file_dir, APR_OS_DEFAULT, scratch_pool));
+
+  SVN_ERR(svn_io_file_open(&manifest_file, manifest_file_path,
+                           APR_WRITE | APR_BUFFERED | APR_CREATE | APR_EXCL,
+                           APR_OS_DEFAULT, scratch_pool));
+  manifest_stream = svn_stream_from_aprfile2(manifest_file, TRUE,
+                                             scratch_pool);
+
+  /* revisions to handle. Special case: revision 0 */
+  start_rev = (svn_revnum_t) (shard * max_files_per_dir);
+  end_rev = (svn_revnum_t) ((shard + 1) * (max_files_per_dir) - 1);
+  if (start_rev == 0)
+    ++start_rev;
+    /* Special special case: if max_files_per_dir is 1, then at this point
+       start_rev == 1 and end_rev == 0 (!).  Fortunately, everything just
+       works. */
+
+  /* initialize the revprop size info */
+  sizes = apr_array_make(scratch_pool, max_files_per_dir, sizeof(apr_off_t));
+  total_size = 2 * SVN_INT64_BUFFER_SIZE;
+
+  /* Iterate over the revisions in this shard, determine their size and
+   * squashing them together into pack files. */
+  for (rev = start_rev; rev <= end_rev; rev++)
+    {
+      apr_finfo_t finfo;
+      const char *path;
+
+      svn_pool_clear(iterpool);
+
+      /* Get the size of the file. */
+      path = svn_dirent_join(shard_path, apr_psprintf(iterpool, "%ld", rev),
+                             iterpool);
+      SVN_ERR(svn_io_stat(&finfo, path, APR_FINFO_SIZE, iterpool));
+
+      /* if we already have started a pack file and this revprop cannot be
+       * appended to it, write the previous pack file. */
+      if (sizes->nelts != 0 &&
+          total_size + SVN_INT64_BUFFER_SIZE + finfo.size > max_pack_size)
+        {
+          SVN_ERR(svn_fs_fs__copy_revprops(pack_file_dir, pack_filename,
+                                           shard_path, start_rev, rev-1,
+                                           sizes, (apr_size_t)total_size,
+                                           compression_level, cancel_func,
+                                           cancel_baton, iterpool));
+
+          /* next pack file starts empty again */
+          apr_array_clear(sizes);
+          total_size = 2 * SVN_INT64_BUFFER_SIZE;
+          start_rev = rev;
+        }
+
+      /* Update the manifest. Allocate a file name for the current pack
+       * file if it is a new one */
+      if (sizes->nelts == 0)
+        pack_filename = apr_psprintf(scratch_pool, "%ld.0", rev);
+
+      SVN_ERR(svn_stream_printf(manifest_stream, iterpool, "%s\n",
+                                pack_filename));
+
+      /* add to list of files to put into the current pack file */
+      APR_ARRAY_PUSH(sizes, apr_off_t) = finfo.size;
+      total_size += SVN_INT64_BUFFER_SIZE + finfo.size;
+    }
+
+  /* write the last pack file */
+  if (sizes->nelts != 0)
+    SVN_ERR(svn_fs_fs__copy_revprops(pack_file_dir, pack_filename,
+                                     shard_path, start_rev, rev-1,
+                                     sizes, (apr_size_t)total_size,
+                                     compression_level, cancel_func,
+                                     cancel_baton, iterpool));
+
+  /* flush the manifest file to disk and update permissions */
+  SVN_ERR(svn_stream_close(manifest_stream));
+  SVN_ERR(svn_io_file_flush_to_disk(manifest_file, iterpool));
+  SVN_ERR(svn_io_file_close(manifest_file, iterpool));
+  SVN_ERR(svn_io_copy_perms(shard_path, pack_file_dir, iterpool));
+
+  svn_pool_destroy(iterpool);
+
+  return SVN_NO_ERROR;
+}
+
+svn_error_t *
+svn_fs_fs__delete_revprops_shard(const char *shard_path,
+                                 apr_int64_t shard,
+                                 int max_files_per_dir,
+                                 svn_cancel_func_t cancel_func,
+                                 void *cancel_baton,
+                                 apr_pool_t *scratch_pool)
+{
+  if (shard == 0)
+    {
+      apr_pool_t *iterpool = svn_pool_create(scratch_pool);
+      int i;
+
+      /* delete all files except the one for revision 0 */
+      for (i = 1; i < max_files_per_dir; ++i)
+        {
+          const char *path;
+          svn_pool_clear(iterpool);
+
+          path = svn_dirent_join(shard_path,
+                                 apr_psprintf(iterpool, "%d", i),
+                                 iterpool);
+          if (cancel_func)
+            SVN_ERR((*cancel_func)(cancel_baton));
+
+          SVN_ERR(svn_io_remove_file2(path, TRUE, iterpool));
+        }
+
+      svn_pool_destroy(iterpool);
+    }
+  else
+    SVN_ERR(svn_io_remove_dir2(shard_path, TRUE,
+                               cancel_func, cancel_baton, scratch_pool));
+
+  return SVN_NO_ERROR;
+}
+