diff --git a/HISTORY b/HISTORY
index 56804129..e4fb74c9 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,7 +1,7 @@
 SnapRAID HISTORY
 ================
 
-1.8 2011/12
+1.8 2012/1
 ===========
  * Added a new "dup" command to find all the duplicate files.
  * Added a new option "--filter-nohidden" to exclude hidden files.
@@ -9,6 +9,8 @@ SnapRAID HISTORY
  * The example configuration files now put the content files in the data
    disks instead than in the parity disks.
  * Added a checksum at the content file to ensure its integrity.
+ * Using fallocate() instead posix_fallocate() to avoid the very slow
+   posix_fallocate() fallback of writing the whole file.
 
 1.7 2011/11
 ===========
diff --git a/configure.ac b/configure.ac
index 2e120692..19c2485b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,7 +43,7 @@ dnl Checks for library functions.
 AC_SYS_LARGEFILE
 AC_CHECK_FUNCS([memset strchr strerror strrchr mkdir gettimeofday strtoul])
 AC_CHECK_FUNCS([getopt getopt_long snprintf vsnprintf])
-AC_CHECK_FUNCS([ftruncate fsync access posix_fallocate posix_fadvise pread pwrite getc_unlocked ferror_unlocked fnmatch])
+AC_CHECK_FUNCS([ftruncate fallocate fsync access posix_fallocate posix_fadvise pread pwrite getc_unlocked ferror_unlocked fnmatch])
 
 dnl Checks for architecture
 AC_C_BIGENDIAN
diff --git a/parity.c b/parity.c
index 3211f94f..f86bacb4 100644
--- a/parity.c
+++ b/parity.c
@@ -73,9 +73,25 @@ int parity_create(struct snapraid_parity* parity, const char* path, data_off_t s
 	parity->valid_size = parity->st.st_size;
 
 	if (parity->st.st_size < size) {
-#if HAVE_POSIX_FALLOCATE
-		/* allocate real space */
-		ret = posix_fallocate(parity->f, 0, size);
+#if HAVE_FALLOCATE
+		/* allocate real space using the specific Linux fallocate() operation. */
+		/* If the underline filesystem doesn't support it, it's going to fail with the ENOSYS error. */
+		/* Note that posix_fallocate() doesn't fail in such case, and fallbacks to write the whole file. */
+		ret = fallocate(parity->f, 0, 0, size);
+
+		/* fallocate() returns the error number, and it doesn't set errno, just like posix_fallocate() */
+		/* It's not clear if this is correct or a bug, as the official manpage says otherwise */
+		/* http://www.kernel.org/doc/man-pages/online/pages/man2/fallocate.2.html */
+		if (ret > 0) { /* if an error is returned, move it to errno */
+			errno = ret;
+			ret = -1;
+		}
+
+		/* if the operation is not supported, like in ext3 */
+		if (errno == EOPNOTSUPP || errno == ENOSYS) {
+			/* fallback using ftruncate() */
+			ret = ftruncate(parity->f, size);
+		}
 #else
 		/* allocate using a sparse file */
 		ret = ftruncate(parity->f, size);