test: improve the cp fiemap tests

* tests/cp/fiemap-2: Enable the fiemap check for files, which
will enable the test for files on ext3.
* tests/cp/fiemap-perf: Comment why we're not enabling for ext3.
* tests/cp/sparse-fiemap: Ditto.  Also sync the files before
doing a fiemap which was needed for ext4 loop back at least.
Add a comment that FIEMAP_FLAG_SYNC is ineffective, thus
requiring the explicit syncs.
* tests/fiemap-capable: A new python script to determine
if a specified path supports fiemap.
* tests/init.cfg (fiemap_capable_): Use the new python script.
* tests/Makefile.am (EXTRA_DIST): Include the new python script.

tests/Makefile.am

@@ -11,6 +11,7 @@ EXTRA_DIST =		\
   check.mk		\
   envvar-check		\
   filefrag-extent-compare \
+  fiemap-capable	\
   init.cfg		\
   init.sh		\
   lang-default		\

tests/cp/fiemap-2

@@ -20,7 +20,8 @@
 print_ver_ cp
 
 # Require a fiemap-enabled FS.
-fiemap_capable_ . \
+touch fiemap_chk # check a file rather than current dir for best coverage
+fiemap_capable_ fiemap_chk \
   || skip_ "this file system lacks FIEMAP support"
 
 # Exercise the code that handles a file ending in a hole.

tests/cp/fiemap-perf

@@ -20,6 +20,8 @@
 print_ver_ cp
 
 # Require a fiemap-enabled FS.
+# Note we don't check a file here as that could enable
+# the test on ext3 where emulated extent scanning can be slow.
 fiemap_capable_ . \
   || skip_ "this file system lacks FIEMAP support"
 

tests/cp/sparse-fiemap

@@ -19,6 +19,8 @@
 . "${srcdir=.}/init.sh"; path_prepend_ ../src
 print_ver_ cp
 
+# Note we don't check a file here as that could enable
+# the test on ext3 where this test is seen to fail.
 if fiemap_capable_ . ; then
   : # Current dir is on a partition with working extents.  Good!
 else
@@ -66,11 +68,13 @@ for i in $(seq 1 2 21); do
     $PERL -e 'BEGIN { $n = '$i' * 1024; *F = *STDOUT }' \
           -e 'for (1..'$j') { sysseek (*F, $n, 1)' \
           -e '&& syswrite (*F, chr($_)x$n) or die "$!"}' > j1 || fail=1
-    # sync
+
+    # Note the explicit fdatasync is used here as
+    # it was seen that `filefrag -s` (FIEMAP_FLAG_SYNC) was
+    # ineffective on ext4 loopback on Linux 2.6.35.10-72.fc14.i686
+    dd if=/dev/null of=j1 conv=notrunc,fdatasync
     cp --sparse=always j1 j2 || fail=1
-    # sync
-    # Technically we may need the 'sync' uses above, but
-    # uncommenting them makes this test take much longer.
+    dd if=/dev/null of=j2 conv=notrunc,fdatasync
 
     cmp j1 j2 || fail=1
     filefrag -v j1 | grep extent \

tests/fiemap-capable

@@ -0,0 +1,16 @@
+import struct, fcntl, sys, os
+
+def sizeof(t): return struct.calcsize(t)
+IOCPARM_MASK = 0x7f
+IOC_OUT = 0x40000000
+IOC_IN = 0x80000000
+IOC_INOUT = (IOC_IN|IOC_OUT)
+def _IOWR(x,y,t): return (IOC_INOUT|((sizeof(t)&IOCPARM_MASK)<<16)|((x)<<8)|y)
+
+try:
+    fd = os.open (len (sys.argv) == 2 and sys.argv[1] or '.', os.O_RDONLY)
+    struct_fiemap = '=qqllll'
+    FS_IOC_FIEMAP = _IOWR (ord ('f'), 11, struct_fiemap)
+    fcntl.ioctl (fd, FS_IOC_FIEMAP, struct.pack(struct_fiemap, 0,~0,0,0,0,0))
+except:
+    sys.exit (1)

tests/init.cfg

@@ -295,13 +295,16 @@ require_proc_pid_status_()
     kill $pid
 }
 
-# Return nonzero if the specified directory is on a file system for
-# which FIEMAP support exists, and the file system type is new enough
-# (unlike ext2 and ext3) that it is hard to find an instance *without*
-# FIEMAP support.
+# Return nonzero if the specified path is on a file system for
+# which FIEMAP support exists.  Note some file systems (like ext3)
+# only support FIEMAP for files, not directories.
 fiemap_capable_()
 {
-  df -T -t btrfs -t xfs -t ext4 -t ocfs2 -t gfs2 "$@"
+  if ! python < /dev/null; then
+    echo 'fiemap_capable_: python missing: assuming not fiemap capable' 1>&2
+    return 1
+  fi
+  python $abs_srcdir/fiemap-capable "$@"
 }
 
 # Does the current (working-dir) file system support sparse files?