PXB-3658: Remove redundant fallocate(PUNCH_HOLE) from local_write_sparse

storage/innobase/xtrabackup/src/ds_local.cc

@@ -168,14 +168,12 @@ static int local_write_sparse(ds_file_t *file, const void *buf, size_t len,
                               [[maybe_unused]] bool punch_hole_supported) {
   auto local_file = ((ds_local_file_t *)file->ptr);
   File fd = local_file->fd;
-  [[maybe_unused]] ulonglong seek = 0;
 
   const uchar *ptr = static_cast<const uchar *>(buf);
 
   for (size_t i = 0; i < sparse_map_size; ++i) {
     my_off_t rc;
 
-    seek = my_tell(fd, MYF(MY_WME));
     rc = my_seek(fd, sparse_map[i].skip, MY_SEEK_CUR, MYF(MY_WME));
     if (rc == MY_FILEPOS_ERROR) {
       return 1;
@@ -186,13 +184,6 @@ static int local_write_sparse(ds_file_t *file, const void *buf, size_t len,
       return 1;
     }
 
-#ifdef HAVE_FALLOC_PUNCH_HOLE_AND_KEEP_SIZE
-    if (punch_hole_supported) {
-      fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, seek,
-                sparse_map[i].skip);
-    }
-#endif
-
     ptr += sparse_map[i].len;
   }
   /* to track if last page is sparse */
@@ -201,6 +192,8 @@ static int local_write_sparse(ds_file_t *file, const void *buf, size_t len,
   } else
     local_file->last_seek = 0;
 
+  posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
+
   return 0;
 }
 

storage/innobase/xtrabackup/test/suites/compression/pxb_3658_sparse_alloc.sh

@@ -0,0 +1,326 @@
+#
+# PXB-3658: Verify that page-compressed tables remain sparse after
+# backup/restore, and that allocated disk size (du) exactly matches
+# the original server files.
+#
+# Strategy: restart the server after inserting data to force a clean
+# shutdown (all dirty pages flushed, checkpoint complete). This gives
+# us a deterministic .ibd state. After backup + prepare (which is a
+# no-op for data pages since redo log is empty) + copy-back, the
+# restored .ibd must have the exact same allocated size.
+#
+# Tests five restore paths:
+#   1. Local backup (no streaming)
+#   2. xbstream extract (no xtrabackup compression) -- SPARSE chunks
+#   3. xbstream extract --decompress (with lz4 compression) -- dense + restore_sparseness via xbstream
+#   4. Local backup with --compress=zstd + xtrabackup --decompress -- restore_sparseness via xtrabackup
+#   5. Streamed backup with --compress=zstd + xbstream extract (no decompress) + xtrabackup --decompress
+#
+
+. inc/common.sh
+. inc/keyring_file.sh
+
+require_lz4
+require_zstd
+
+get_allocated_size() {
+  du --block-size=1 "$1" | awk '{print $1}'
+}
+
+get_apparent_size() {
+  stat --printf "%s" "$1"
+}
+
+check_sparse_exact() {
+  local filepath=$1
+  local label=$2
+  local expected_alloc=$3
+  local tolerance=${4:-0}
+
+  if ! is_sparse_file "$filepath" ; then
+    die "$label: $filepath is NOT sparse"
+  fi
+
+  local apparent=$(get_apparent_size "$filepath")
+  local allocated=$(get_allocated_size "$filepath")
+
+  vlog "$label: apparent=$apparent allocated=$allocated expected=$expected_alloc tolerance=$tolerance"
+
+  local diff=$(( allocated - expected_alloc ))
+  # absolute value
+  if [ "$diff" -lt 0 ] ; then
+    diff=$(( -diff ))
+  fi
+
+  if [ "$diff" -gt "$tolerance" ] ; then
+    die "$label: allocated size mismatch: got $allocated, expected $expected_alloc (diff=$diff, tolerance=$tolerance)"
+  fi
+
+  vlog "$label: PASS (diff=$diff within tolerance=$tolerance)"
+}
+
+setup_and_get_baseline() {
+  run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+CREATE TABLE t_zlib (c1 INT AUTO_INCREMENT PRIMARY KEY, c2 BLOB) COMPRESSION='zlib';
+CREATE TABLE t_plain (c1 INT AUTO_INCREMENT PRIMARY KEY, c2 BLOB);
+EOF
+
+  for tbl in t_zlib t_plain ; do
+    run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+INSERT INTO $tbl (c2) VALUES (REPEAT('x', 5000));
+INSERT INTO $tbl (c2) SELECT c2 FROM $tbl;
+INSERT INTO $tbl (c2) SELECT c2 FROM $tbl;
+INSERT INTO $tbl (c2) SELECT c2 FROM $tbl;
+INSERT INTO $tbl (c2) SELECT c2 FROM $tbl;
+EOF
+  done
+
+  # Graceful shutdown flushes all dirty pages with punch holes,
+  # then restart gives us a clean, deterministic .ibd state.
+  shutdown_server
+  start_server
+
+  if ! is_sparse_file "$mysql_datadir/test/t_zlib.ibd" ; then
+    die "original t_zlib.ibd is NOT sparse after restart"
+  fi
+
+  orig_zlib_alloc=$(get_allocated_size "$mysql_datadir/test/t_zlib.ibd")
+  orig_zlib_apparent=$(get_apparent_size "$mysql_datadir/test/t_zlib.ibd")
+
+  vlog "Baseline t_zlib.ibd: apparent=$orig_zlib_apparent allocated=$orig_zlib_alloc"
+}
+
+#
+# Start server and check punch hole support
+#
+start_server
+
+if grep -q 'PUNCH HOLE support not available' $MYSQLD_ERRFILE ; then
+  skip_test 'punch hole support is not available'
+fi
+
+########################################################################
+# Path 1: Local backup (no streaming)
+########################################################################
+
+vlog "===== Path 1: Local backup ====="
+
+setup_and_get_baseline
+
+record_db_state test
+
+xtrabackup --backup --target-dir=$topdir/backup
+
+xtrabackup --prepare --target-dir=$topdir/backup
+
+check_sparse_exact "$topdir/backup/test/t_zlib.ibd" \
+  "local-backup t_zlib (after prepare)" "$orig_zlib_alloc"
+
+stop_server
+rm -rf $mysql_datadir
+
+xtrabackup --copy-back --target-dir=$topdir/backup
+
+start_server
+
+check_sparse_exact "$mysql_datadir/test/t_zlib.ibd" \
+  "local-backup t_zlib (after copy-back)" "$orig_zlib_alloc"
+
+if is_sparse_file "$mysql_datadir/test/t_plain.ibd" ; then
+  die "t_plain.ibd should NOT be sparse"
+fi
+
+verify_db_state test
+
+run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+DROP TABLE IF EXISTS t_zlib;
+DROP TABLE IF EXISTS t_plain;
+EOF
+
+stop_server
+rm -rf $mysql_datadir
+rm -rf $topdir/backup
+
+########################################################################
+# Path 2: xbstream extract (no xtrabackup compression)
+########################################################################
+
+vlog "===== Path 2: xbstream extract (no xtrabackup compression) ====="
+
+start_server
+setup_and_get_baseline
+
+record_db_state test
+
+xtrabackup --backup --stream=xbstream --target-dir=$topdir/tmp \
+  > $topdir/backup.xbs
+
+rm -rf $topdir/backup && mkdir $topdir/backup
+xbstream -x -v -C $topdir/backup < $topdir/backup.xbs
+
+xtrabackup --prepare --target-dir=$topdir/backup
+
+check_sparse_exact "$topdir/backup/test/t_zlib.ibd" \
+  "xbstream t_zlib (after prepare)" "$orig_zlib_alloc"
+
+stop_server
+rm -rf $mysql_datadir
+
+xtrabackup --copy-back --target-dir=$topdir/backup
+
+start_server
+
+check_sparse_exact "$mysql_datadir/test/t_zlib.ibd" \
+  "xbstream t_zlib (after copy-back)" "$orig_zlib_alloc"
+
+if is_sparse_file "$mysql_datadir/test/t_plain.ibd" ; then
+  die "t_plain.ibd should NOT be sparse (xbstream path)"
+fi
+
+verify_db_state test
+
+run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+DROP TABLE IF EXISTS t_zlib;
+DROP TABLE IF EXISTS t_plain;
+EOF
+
+stop_server
+rm -rf $mysql_datadir
+rm -rf $topdir/backup $topdir/backup.xbs
+
+########################################################################
+# Path 3: xbstream extract --decompress (with lz4 compression)
+########################################################################
+
+vlog "===== Path 3: xbstream --decompress (lz4) ====="
+
+start_server
+setup_and_get_baseline
+
+record_db_state test
+
+xtrabackup --backup --compress=lz4 --stream=xbstream --target-dir=$topdir/tmp \
+  > $topdir/backup.xbs
+
+rm -rf $topdir/backup && mkdir $topdir/backup
+xbstream -x -v -C $topdir/backup --decompress < $topdir/backup.xbs
+
+xtrabackup --prepare --target-dir=$topdir/backup
+
+check_sparse_exact "$topdir/backup/test/t_zlib.ibd" \
+  "xbstream-decompress t_zlib (after prepare)" "$orig_zlib_alloc"
+
+stop_server
+rm -rf $mysql_datadir
+
+xtrabackup --copy-back --target-dir=$topdir/backup
+
+start_server
+
+check_sparse_exact "$mysql_datadir/test/t_zlib.ibd" \
+  "xbstream-decompress t_zlib (after copy-back)" "$orig_zlib_alloc"
+
+if is_sparse_file "$mysql_datadir/test/t_plain.ibd" ; then
+  die "t_plain.ibd should NOT be sparse (decompress path)"
+fi
+
+verify_db_state test
+
+run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+DROP TABLE IF EXISTS t_zlib;
+DROP TABLE IF EXISTS t_plain;
+EOF
+
+stop_server
+rm -rf $mysql_datadir
+rm -rf $topdir/backup $topdir/backup.xbs
+
+########################################################################
+# Path 4: Local backup with --compress=zstd + xtrabackup --decompress
+########################################################################
+
+vlog "===== Path 4: Local backup + compress=zstd + xtrabackup --decompress ====="
+
+start_server
+setup_and_get_baseline
+
+record_db_state test
+
+xtrabackup --backup --compress=zstd --target-dir=$topdir/backup
+
+xtrabackup --decompress --target-dir=$topdir/backup
+
+xtrabackup --prepare --target-dir=$topdir/backup
+
+check_sparse_exact "$topdir/backup/test/t_zlib.ibd" \
+  "local-zstd-decompress t_zlib (after prepare)" "$orig_zlib_alloc"
+
+stop_server
+rm -rf $mysql_datadir
+
+xtrabackup --copy-back --target-dir=$topdir/backup
+
+start_server
+
+check_sparse_exact "$mysql_datadir/test/t_zlib.ibd" \
+  "local-zstd-decompress t_zlib (after copy-back)" "$orig_zlib_alloc"
+
+if is_sparse_file "$mysql_datadir/test/t_plain.ibd" ; then
+  die "t_plain.ibd should NOT be sparse (local zstd decompress path)"
+fi
+
+verify_db_state test
+
+run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+DROP TABLE IF EXISTS t_zlib;
+DROP TABLE IF EXISTS t_plain;
+EOF
+
+stop_server
+rm -rf $mysql_datadir
+rm -rf $topdir/backup
+
+########################################################################
+# Path 5: Stream + compress=zstd + xbstream extract + xtrabackup --decompress
+########################################################################
+
+vlog "===== Path 5: xbstream extract (no decompress) + xtrabackup --decompress (zstd) ====="
+
+start_server
+setup_and_get_baseline
+
+record_db_state test
+
+xtrabackup --backup --compress=zstd --stream=xbstream --target-dir=$topdir/tmp \
+  > $topdir/backup.xbs
+
+rm -rf $topdir/backup && mkdir $topdir/backup
+xbstream -x -v -C $topdir/backup < $topdir/backup.xbs
+
+xtrabackup --decompress --target-dir=$topdir/backup
+
+xtrabackup --prepare --target-dir=$topdir/backup
+
+check_sparse_exact "$topdir/backup/test/t_zlib.ibd" \
+  "stream-zstd-xb-decompress t_zlib (after prepare)" "$orig_zlib_alloc"
+
+stop_server
+rm -rf $mysql_datadir
+
+xtrabackup --copy-back --target-dir=$topdir/backup
+
+start_server
+
+check_sparse_exact "$mysql_datadir/test/t_zlib.ibd" \
+  "stream-zstd-xb-decompress t_zlib (after copy-back)" "$orig_zlib_alloc"
+
+if is_sparse_file "$mysql_datadir/test/t_plain.ibd" ; then
+  die "t_plain.ibd should NOT be sparse (stream zstd xb-decompress path)"
+fi
+
+verify_db_state test
+
+run_cmd $MYSQL $MYSQL_ARGS test <<EOF
+DROP TABLE IF EXISTS t_zlib;
+DROP TABLE IF EXISTS t_plain;
+EOF