Merge branch 'fm/file-operations' into dev

* fm/file-operations:
  Update preloaded modules
  Add file:advise/4 - a wrapper to the POSIX syscall posix_fadvise
  Add file:datasync/1 for syncing file contents only
  sys.h: Correct the get_int64() macro

OTP-8637 fm/file-operations

The functions file:advise/4 and file:datasync/1 have been added. (Thanks to
Filipe David Manana.)

22 files changed, 511 insertions, 37 deletions

diff --git a/erts/configure.in b/erts/configure.in
index a14b10adbf..63bf548c89 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -1054,6 +1054,7 @@ fi
 
 AC_SUBST(ERTS_BUILD_SMP_EMU)
 
+AC_CHECK_FUNCS([posix_fadvise])
 
 
 #
@@ -1757,6 +1758,12 @@ fi
 dnl Need by run_erl.
 AC_CHECK_FUNCS([openpty])
 
+dnl fdatasync syscall (Unix only)
+AC_CHECK_FUNCS([fdatasync])
+
+dnl Find which C libraries are required to use fdatasync
+AC_SEARCH_LIBS(fdatasync, [rt])
+
 dnl ----------------------------------------------------------------------
 dnl Checks for features/quirks in the system that affects Erlang.
 dnl ----------------------------------------------------------------------
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index a1955235b7..0f20d36167 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -1173,14 +1173,14 @@ EXTERN_FUNCTION(void*, sys_calloc2, (Uint, Uint));
 
 /* Standard set of integer macros  .. */
 
-#define get_int64(s) ((((unsigned char*) (s))[0] << 56) | \
-                      (((unsigned char*) (s))[1] << 48) | \
-                      (((unsigned char*) (s))[2] << 40) | \
-                      (((unsigned char*) (s))[3] << 32) | \
-                      (((unsigned char*) (s))[4] << 24) | \
-                      (((unsigned char*) (s))[5] << 16) | \
-                      (((unsigned char*) (s))[6] << 8)  | \
-                      (((unsigned char*) (s))[7]))
+#define get_int64(s) (((Uint64)(((unsigned char*) (s))[0]) << 56) | \
+                      (((Uint64)((unsigned char*) (s))[1]) << 48) | \
+                      (((Uint64)((unsigned char*) (s))[2]) << 40) | \
+                      (((Uint64)((unsigned char*) (s))[3]) << 32) | \
+                      (((Uint64)((unsigned char*) (s))[4]) << 24) | \
+                      (((Uint64)((unsigned char*) (s))[5]) << 16) | \
+                      (((Uint64)((unsigned char*) (s))[6]) << 8)  | \
+                      (((Uint64)((unsigned char*) (s))[7])))
 
 #define put_int64(i, s) do {((char*)(s))[0] = (char)((Sint64)(i) >> 56) & 0xff;\
                             ((char*)(s))[1] = (char)((Sint64)(i) >> 48) & 0xff;\
diff --git a/erts/emulator/drivers/common/efile_drv.c b/erts/emulator/drivers/common/efile_drv.c
index d2b916000e..60ae4cb108 100644
--- a/erts/emulator/drivers/common/efile_drv.c
+++ b/erts/emulator/drivers/common/efile_drv.c
@@ -53,6 +53,8 @@
 #define FILE_IPREAD             27
 #define FILE_ALTNAME            28
 #define FILE_READ_LINE          29
+#define FILE_FDATASYNC          30
+#define FILE_FADVISE            31
 
 /* Return codes */
 
@@ -357,6 +359,11 @@ struct t_data
 	    struct t_readdir_buf *first_buf;
 	    struct t_readdir_buf *last_buf;
 	} read_dir;
+	struct {
+	    Sint64 offset;
+	    Sint64 length;
+	    int advise;
+	} fadvise;
     } c;
     char b[1];
 };
@@ -883,6 +890,15 @@ static void invoke_chdir(void *data)
     invoke_name(data, efile_chdir);
 }
 
+static void invoke_fdatasync(void *data)
+{
+    struct t_data *d = (struct t_data *) data;
+    int fd = (int) d->fd;
+
+    d->again = 0;
+    d->result_ok = efile_fdatasync(&d->errInfo, fd);
+}
+
 static void invoke_fsync(void *data)
 {
     struct t_data *d = (struct t_data *) data;
@@ -1637,6 +1653,18 @@ static void invoke_open(void *data)
     d->result_ok = status;
 }
 
+static void invoke_fadvise(void *data)
+{
+    struct t_data *d = (struct t_data *) data;
+    int fd = (int) d->fd;
+    off_t offset = (off_t) d->c.fadvise.offset;
+    off_t length = (off_t) d->c.fadvise.length;
+    int advise = (int) d->c.fadvise.advise;
+
+    d->again = 0;
+    d->result_ok = efile_fadvise(&d->errInfo, fd, offset, length, advise);
+}
+
 static void free_readdir(void *data)
 {
     struct t_data *d = (struct t_data *) data;
@@ -1919,12 +1947,14 @@ file_async_ready(ErlDrvData e, ErlDrvThreadData data)
       case FILE_RMDIR:
       case FILE_CHDIR:
       case FILE_DELETE:
+      case FILE_FDATASYNC:
       case FILE_FSYNC:
       case FILE_TRUNCATE:
       case FILE_LINK:
       case FILE_SYMLINK:
       case FILE_RENAME:
       case FILE_WRITE_INFO:
+      case FILE_FADVISE:
 	reply(desc, d->result_ok, &d->errInfo);
 	free_data(data);
 	break;
@@ -2209,6 +2239,18 @@ file_output(ErlDrvData e, char* buf, int count)
 	    goto done;
 	}
 
+    case FILE_FDATASYNC:
+    {
+	    d = EF_SAFE_ALLOC(sizeof(struct t_data));
+
+	    d->fd = fd;
+	    d->command = command;
+	    d->invoke = invoke_fdatasync;
+	    d->free = free_data;
+	    d->level = 2;
+	    goto done;
+    }
+
     case FILE_FSYNC:
     {
 	d = EF_SAFE_ALLOC(sizeof(struct t_data));
@@ -2332,6 +2374,21 @@ file_output(ErlDrvData e, char* buf, int count)
 	    goto done;
 	}
 
+    case FILE_FADVISE:
+    {
+        d = EF_SAFE_ALLOC(sizeof(struct t_data));
+
+        d->fd = fd;
+        d->command = command;
+        d->invoke = invoke_fadvise;
+        d->free = free_data;
+        d->level = 2;
+        d->c.fadvise.offset = get_int64((uchar*) buf);
+        d->c.fadvise.length = get_int64(((uchar*) buf) + sizeof(Sint64));
+        d->c.fadvise.advise = get_int32(((uchar*) buf) + 2 * sizeof(Sint64));
+        goto done;
+    }
+
     }
 
     /*
diff --git a/erts/emulator/drivers/common/erl_efile.h b/erts/emulator/drivers/common/erl_efile.h
index 9aa941e550..bbc973d58b 100644
--- a/erts/emulator/drivers/common/erl_efile.h
+++ b/erts/emulator/drivers/common/erl_efile.h
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 1997-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 1997-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 /*
@@ -126,6 +126,7 @@ int efile_readdir(Efile_error* errInfo, char* name,
 int efile_openfile(Efile_error* errInfo, char* name, int flags,
 		   int* pfd, Sint64* pSize);
 void efile_closefile(int fd);
+int efile_fdatasync(Efile_error* errInfo, int fd);
 int efile_fsync(Efile_error* errInfo, int fd);
 int efile_fileinfo(Efile_error* errInfo, Efile_info* pInfo,
 		   char *name, int info_for_link);
@@ -150,3 +151,5 @@ int efile_altname(Efile_error* errInfo, char *name,
 int efile_link(Efile_error* errInfo, char* old, char* new);
 int efile_symlink(Efile_error* errInfo, char* old, char* new);
 int efile_may_openfile(Efile_error* errInfo, char *name);
+int efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset, Sint64 length,
+		  int advise);
diff --git a/erts/emulator/drivers/common/ram_file_drv.c b/erts/emulator/drivers/common/ram_file_drv.c
index 4a39a156e6..abedcc933a 100644
--- a/erts/emulator/drivers/common/ram_file_drv.c
+++ b/erts/emulator/drivers/common/ram_file_drv.c
@@ -35,6 +35,7 @@
 #define RAM_FILE_TRUNCATE      14
 #define RAM_FILE_PREAD         17
 #define RAM_FILE_PWRITE        18
+#define RAM_FILE_FDATASYNC     19
 
 /* other operations */
 #define RAM_FILE_GET           30
@@ -45,6 +46,8 @@
 #define RAM_FILE_UUENCODE      35  /* uuencode file */
 #define RAM_FILE_UUDECODE      36  /* uudecode file */
 #define RAM_FILE_SIZE          37  /* get file size */
+#define RAM_FILE_ADVISE        38  /* predeclare the access
+                                    * pattern for file data */
 /* possible new operations include:
    DES_ENCRYPT
    DES_DECRYPT
@@ -558,6 +561,13 @@ static void rfile_command(ErlDrvData e, char* buf, int count)
 	    numeric_reply(f, 0); /* 0 is not used */
 	break;
 
+    case RAM_FILE_FDATASYNC:
+	if (f->flags == 0)
+	    error_reply(f, EBADF);
+	else
+	    reply(f, 1, 0);
+	break;
+
     case RAM_FILE_FSYNC:
 	if (f->flags == 0)
 	    error_reply(f, EBADF);
@@ -685,6 +695,13 @@ static void rfile_command(ErlDrvData e, char* buf, int count)
     case RAM_FILE_UUDECODE:   /* uudecode file */
 	ram_file_uudecode(f);
 	break;
+
+    case RAM_FILE_ADVISE:
+	if (f->flags == 0)
+	    error_reply(f, EBADF);
+	else
+	    reply(f, 1, 0);
+	break;
     }
     /*
      * Ignore anything else -- let the caller hang.
diff --git a/erts/emulator/drivers/unix/unix_efile.c b/erts/emulator/drivers/unix/unix_efile.c
index 1d094ee613..ea016526ef 100644
--- a/erts/emulator/drivers/unix/unix_efile.c
+++ b/erts/emulator/drivers/unix/unix_efile.c
@@ -774,6 +774,17 @@ efile_closefile(int fd)
 }
 
 int
+efile_fdatasync(Efile_error *errInfo, /* Where to return error codes. */
+	    int fd)               /* File descriptor for file to sync data. */
+{
+#ifdef HAVE_FDATASYNC
+    return check_error(fdatasync(fd), errInfo);
+#else
+    return efile_fsync(errInfo, fd);
+#endif
+}
+
+int
 efile_fsync(Efile_error *errInfo, /* Where to return error codes. */
 	    int fd)               /* File descriptor for file to sync. */
 {
@@ -1437,3 +1448,14 @@ efile_symlink(Efile_error* errInfo, char* old, char* new)
     return check_error(symlink(old, new), errInfo);
 #endif
 }
+
+int
+efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset,
+		  Sint64 length, int advise)
+{
+#ifdef HAVE_POSIX_FADVISE
+    return check_error(posix_fadvise(fd, offset, length, advise), errInfo);
+#else
+    return check_error(0, errInfo);
+#endif
+}
diff --git a/erts/emulator/drivers/win32/win_efile.c b/erts/emulator/drivers/win32/win_efile.c
index 89aaad31da..d5f2b79706 100644
--- a/erts/emulator/drivers/win32/win_efile.c
+++ b/erts/emulator/drivers/win32/win_efile.c
@@ -1,19 +1,19 @@
 /*
  * %CopyrightBegin%
- * 
- * Copyright Ericsson AB 1997-2009. All Rights Reserved.
- * 
+ *
+ * Copyright Ericsson AB 1997-2010. All Rights Reserved.
+ *
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
  * compliance with the License. You should have received a copy of the
  * Erlang Public License along with this software. If not, it can be
  * retrieved online at http://www.erlang.org/.
- * 
+ *
  * Software distributed under the License is distributed on an "AS IS"
  * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
  * the License for the specific language governing rights and limitations
  * under the License.
- * 
+ *
  * %CopyrightEnd%
  */
 /*
@@ -764,6 +764,15 @@ int fd;				/* File descriptor for file to close. */
 }
 
 int
+efile_fdatasync(errInfo, fd)
+Efile_error* errInfo;		/* Where to return error codes. */
+int fd;				/* File descriptor for file to sync. */
+{
+    /* Not available in Windows, just call regular fsync */
+    return efile_fsync(errInfo, fd);
+}
+
+int
 efile_fsync(errInfo, fd)
 Efile_error* errInfo;		/* Where to return error codes. */
 int fd;				/* File descriptor for file to sync. */
@@ -1424,3 +1433,12 @@ efile_symlink(Efile_error* errInfo, char* old, char* new)
     errno = ENOTSUP;
     return check_error(-1, errInfo);
 }
+
+int
+efile_fadvise(Efile_error* errInfo, int fd, Sint64 offset,
+	    Sint64 length, int advise)
+{
+    /* posix_fadvise is not available on Windows, do nothing */
+    errno = ERROR_SUCCESS;
+    return check_error(0, errInfo);
+}
diff --git a/erts/preloaded/ebin/erl_prim_loader.beam b/erts/preloaded/ebin/erl_prim_loader.beam
index afd8a90b3f..fe3cee1c56 100644
--- a/erts/preloaded/ebin/erl_prim_loader.beam
+++ b/erts/preloaded/ebin/erl_prim_loader.beam
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index 4ec84948d8..5a4c5e9d1e 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/ebin/init.beam b/erts/preloaded/ebin/init.beam
index c3e746f3ee..cfe2c36cee 100644
--- a/erts/preloaded/ebin/init.beam
+++ b/erts/preloaded/ebin/init.beam
diff --git a/erts/preloaded/ebin/otp_ring0.beam b/erts/preloaded/ebin/otp_ring0.beam
index 4b2d8bb2de..74587de26b 100644
--- a/erts/preloaded/ebin/otp_ring0.beam
+++ b/erts/preloaded/ebin/otp_ring0.beam
diff --git a/erts/preloaded/ebin/prim_file.beam b/erts/preloaded/ebin/prim_file.beam
index 2916baaa77..c6610b71e6 100644
--- a/erts/preloaded/ebin/prim_file.beam
+++ b/erts/preloaded/ebin/prim_file.beam
diff --git a/erts/preloaded/ebin/prim_inet.beam b/erts/preloaded/ebin/prim_inet.beam
index 46912e2bea..8d19923281 100644
--- a/erts/preloaded/ebin/prim_inet.beam
+++ b/erts/preloaded/ebin/prim_inet.beam
diff --git a/erts/preloaded/ebin/prim_zip.beam b/erts/preloaded/ebin/prim_zip.beam
index ccf8aff6f6..cd41f36413 100644
--- a/erts/preloaded/ebin/prim_zip.beam
+++ b/erts/preloaded/ebin/prim_zip.beam
diff --git a/erts/preloaded/ebin/zlib.beam b/erts/preloaded/ebin/zlib.beam
index ccd597ba68..ce1163d260 100644
--- a/erts/preloaded/ebin/zlib.beam
+++ b/erts/preloaded/ebin/zlib.beam
diff --git a/erts/preloaded/src/prim_file.erl b/erts/preloaded/src/prim_file.erl
index 43e6f6cd88..2d177bf80e 100644
--- a/erts/preloaded/src/prim_file.erl
+++ b/erts/preloaded/src/prim_file.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 2000-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 2000-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 -module(prim_file).
@@ -25,7 +25,7 @@
 %%% Interface towards a single file's contents. Uses ?FD_DRV.
 
 %% Generic file contents operations
--export([open/2, close/1, sync/1, position/2, truncate/1,
+-export([open/2, close/1, datasync/1, sync/1, advise/4, position/2, truncate/1,
 	 write/2, pwrite/2, pwrite/3, read/2, read_line/1, pread/2, pread/3, copy/3]).
 
 %% Specialized file operations
@@ -96,6 +96,8 @@
 -define(FILE_IPREAD,           27).
 -define(FILE_ALTNAME,          28).
 -define(FILE_READ_LINE,        29).
+-define(FILE_FDATASYNC,        30).
+-define(FILE_ADVISE,           31).
 
 %% Driver responses
 -define(FILE_RESP_OK,          0).
@@ -130,6 +132,13 @@
 %% IPREAD variants
 -define(IPREAD_S32BU_P32BU, 0).
 
+%% POSIX file advises
+-define(POSIX_FADV_NORMAL,     0).
+-define(POSIX_FADV_RANDOM,     1).
+-define(POSIX_FADV_SEQUENTIAL, 2).
+-define(POSIX_FADV_WILLNEED,   3).
+-define(POSIX_FADV_DONTNEED,   4).
+-define(POSIX_FADV_NOREUSE,    5).
 
 
 %%%-----------------------------------------------------------------
@@ -220,7 +229,35 @@ close(#file_descriptor{module = ?MODULE, data = {Port, _}}) ->
 close(Port) when is_port(Port) ->
     drv_close(Port).
 
+-define(ADVISE(Offs, Len, Adv),
+	<<?FILE_ADVISE, Offs:64/signed, Len:64/signed,
+	  Adv:32/signed>>).
 
+%% Returns {error, Reason} | ok.
+advise(#file_descriptor{module = ?MODULE, data = {Port, _}},
+       Offset, Length, Advise) ->
+    case Advise of
+	normal ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_NORMAL),
+	    drv_command(Port, Cmd);
+	random ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_RANDOM),
+	    drv_command(Port, Cmd);
+	sequential ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_SEQUENTIAL),
+	    drv_command(Port, Cmd);
+	will_need ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_WILLNEED),
+	    drv_command(Port, Cmd);
+	dont_need ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_DONTNEED),
+	    drv_command(Port, Cmd);
+	no_reuse ->
+	    Cmd = ?ADVISE(Offset, Length, ?POSIX_FADV_NOREUSE),
+	    drv_command(Port, Cmd);
+	_ ->
+	    {error, einval}
+    end.
 
 %% Returns {error, Reason} | ok.
 write(#file_descriptor{module = ?MODULE, data = {Port, _}}, Bytes) ->
@@ -292,6 +329,9 @@ pwrite(#file_descriptor{module = ?MODULE}, _, _) ->
     {error, badarg}.
 
 
+%% Returns {error, Reason} | ok.
+datasync(#file_descriptor{module = ?MODULE, data = {Port, _}}) ->
+    drv_command(Port, [?FILE_FDATASYNC]).
 
 %% Returns {error, Reason} | ok.
 sync(#file_descriptor{module = ?MODULE, data = {Port, _}}) ->
diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index 50f9722a1c..382262d1ee 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -62,6 +62,25 @@ time() = {{Year, Month, Day}, {Hour, Minute, Second}}
   </section>
   <funcs>
     <func>
+      <name>advise(IoDevice, Offset, Length, Advise) -> ok | {error, Reason}</name>
+      <fsummary>Predeclare an access pattern for file data</fsummary>
+      <type>
+        <v>IoDevice = io_device()</v>
+        <v>Offset = int()</v>
+        <v>Length = int()</v>
+        <v>Advise = posix_file_advise()</v>
+        <v>posix_file_advise() = normal | sequential | random | no_reuse
+          | will_need | dont_need</v>
+        <v>Reason = ext_posix()</v>
+      </type>
+      <desc>
+        <p><c>advise/4</c> can be used to announce an intention to access file
+          data in a specific pattern in the future, thus allowing the
+          operating system to perform appropriate optimizations.</p>
+        <p>On some platforms, this function might have no effect.</p>
+      </desc>
+    </func>
+    <func>
       <name>change_group(Filename, Gid) -> ok | {error, Reason}</name>
       <fsummary>Change group of a file</fsummary>
       <type>
@@ -1641,6 +1660,33 @@ f.txt:  {person, "kalle", 25}.
       </desc>
     </func>
     <func>
+      <name>datasync(IoDevice) -> ok | {error, Reason}</name>
+      <fsummary>Synchronizes the in-memory data of a file, ignoring most of its metadata, with that on the physical medium</fsummary>
+      <type>
+        <v>IoDevice = io_device()</v>
+        <v>Reason = ext_posix() | terminated</v>
+      </type>
+      <desc>
+        <p>Makes sure that any buffers kept by the operating system
+          (not by the Erlang runtime system) are written to disk. In
+          many ways it's resembles fsync but it not requires to update
+          some of file's metadata such as the access time. On
+          some platforms, this function might have no effect.</p>
+        <p>Applications that access databases or log files often write
+          a tiny data fragment (e.g., one line in a log file) and then
+          call fsync() immediately in order to ensure that the written
+          data is physically stored on the harddisk. Unfortunately, fsync()
+          will always initiate two write operations: one for the newly
+          written data and another one in order to update the modification
+          time stored in the inode. If the modification time is not a part
+          of the transaction concept fdatasync() can be used to avoid
+          unnecessary inode disk write operations.</p>
+        <p>Available only in some POSIX systems. This call results in a
+          call to fsync(), or has no effect, in systems not implementing
+          the fdatasync syscall.</p>
+      </desc>
+    </func>
+    <func>
       <name>truncate(IoDevice) -> ok | {error, Reason}</name>
       <fsummary>Truncate a file</fsummary>
       <type>
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 46ffa9d708..a694ed0708 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -36,11 +36,11 @@
 %% Specialized
 -export([ipread_s32bu_p32bu/3]).
 %% Generic file contents.
--export([open/2, close/1, 
+-export([open/2, close/1, advise/4,
 	 read/2, write/2, 
 	 pread/2, pread/3, pwrite/2, pwrite/3,
 	 read_line/1,
-	 position/2, truncate/1, sync/1,
+	 position/2, truncate/1, datasync/1, sync/1,
 	 copy/2, copy/3]).
 %% High level operations
 -export([consult/1, path_consult/2]).
@@ -89,6 +89,8 @@
 -type date()      :: {pos_integer(), pos_integer(), pos_integer()}.
 -type time()      :: {non_neg_integer(), non_neg_integer(), non_neg_integer()}.
 -type date_time() :: {date(), time()}.
+-type posix_file_advise() :: 'normal' | 'sequential' | 'random' | 'no_reuse' |
+                            'will_need' | 'dont_need'.
 
 %%%-----------------------------------------------------------------
 %%% General functions
@@ -352,6 +354,18 @@ close(#file_descriptor{module = Module} = Handle) ->
 close(_) ->
     {error, badarg}.
 
+-spec advise(File :: io_device(), Offset :: integer(),
+        Length :: integer(), Advise :: posix_file_advise()) ->
+	'ok' | {'error', posix()}.
+
+advise(File, Offset, Length, Advise) when is_pid(File) ->
+    R = file_request(File, {advise, Offset, Length, Advise}),
+    wait_file_reply(File, R);
+advise(#file_descriptor{module = Module} = Handle, Offset, Length, Advise) ->
+    Module:advise(Handle, Offset, Length, Advise);
+advise(_, _, _, _) ->
+    {error, badarg}.
+
 -spec read(File :: io_device(), Size :: non_neg_integer()) ->
 	'eof' | {'ok', [char()] | binary()} | {'error', posix()}.
 
@@ -472,6 +486,16 @@ pwrite(#file_descriptor{module = Module} = Handle, Offs, Bytes) ->
 pwrite(_, _, _) ->
     {error, badarg}.
 
+-spec datasync(File :: io_device()) -> 'ok' | {'error', posix()}.
+
+datasync(File) when is_pid(File) ->
+    R = file_request(File, datasync),
+    wait_file_reply(File, R);
+datasync(#file_descriptor{module = Module} = Handle) ->
+    Module:datasync(Handle);
+datasync(_) ->
+    {error, badarg}.
+
 -spec sync(File :: io_device()) -> 'ok' | {'error', posix()}.
 
 sync(File) when is_pid(File) ->
diff --git a/lib/kernel/src/file_io_server.erl b/lib/kernel/src/file_io_server.erl
index 3ac35a209d..39dc32bb79 100644
--- a/lib/kernel/src/file_io_server.erl
+++ b/lib/kernel/src/file_io_server.erl
@@ -198,6 +198,14 @@ io_reply(From, ReplyAs, Reply) ->
 %%%-----------------------------------------------------------------
 %%% file requests
 
+file_request({advise,Offset,Length,Advise},
+         #state{handle=Handle}=State) ->
+    case ?PRIM_FILE:advise(Handle, Offset, Length, Advise) of
+    {error,_}=Reply ->
+        {stop,normal,Reply,State};
+    Reply ->
+        {reply,Reply,State}
+    end;
 file_request({pread,At,Sz}, 
 	     #state{handle=Handle,buf=Buf,read_mode=ReadMode}=State) ->
     case position(Handle, At, Buf) of
@@ -219,6 +227,14 @@ file_request({pwrite,At,Data},
 	Reply ->
 	    std_reply(Reply, State)
     end;
+file_request(datasync,
+	     #state{handle=Handle}=State) ->
+    case ?PRIM_FILE:datasync(Handle) of
+	{error,_}=Reply ->
+	    {stop,normal,Reply,State};
+	Reply ->
+	    {reply,Reply,State}
+    end;
 file_request(sync, 
 	     #state{handle=Handle}=State) ->
     case ?PRIM_FILE:sync(Handle) of
diff --git a/lib/kernel/src/ram_file.erl b/lib/kernel/src/ram_file.erl
index d996650948..48ea871433 100644
--- a/lib/kernel/src/ram_file.erl
+++ b/lib/kernel/src/ram_file.erl
@@ -1,19 +1,19 @@
 %%
 %% %CopyrightBegin%
-%% 
-%% Copyright Ericsson AB 1997-2009. All Rights Reserved.
-%% 
+%%
+%% Copyright Ericsson AB 1997-2010. All Rights Reserved.
+%%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
 %% compliance with the License. You should have received a copy of the
 %% Erlang Public License along with this software. If not, it can be
 %% retrieved online at http://www.erlang.org/.
-%% 
+%%
 %% Software distributed under the License is distributed on an "AS IS"
 %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 %% the License for the specific language governing rights and limitations
 %% under the License.
-%% 
+%%
 %% %CopyrightEnd%
 %%
 -module(ram_file).
@@ -24,11 +24,11 @@
 -export([open/2, close/1]).
 -export([write/2, read/2, copy/3,
 	 pread/2, pread/3, pwrite/2, pwrite/3, 
-	 position/2, truncate/1, sync/1]).
+	 position/2, truncate/1, datasync/1, sync/1]).
 
 %% Specialized file operations
 -export([get_size/1, get_file/1, set_file/2, get_file_close/1]).
--export([compress/1, uncompress/1, uuencode/1, uudecode/1]).
+-export([compress/1, uncompress/1, uuencode/1, uudecode/1, advise/4]).
 
 -export([open_mode/1]).  %% used by ftp-file
 
@@ -60,6 +60,7 @@
 -define(RAM_FILE_TRUNCATE,       14).
 -define(RAM_FILE_PREAD,          17).
 -define(RAM_FILE_PWRITE,         18).
+-define(RAM_FILE_FDATASYNC,      19).
 
 %% Other operations
 -define(RAM_FILE_GET,            30).
@@ -70,6 +71,7 @@
 -define(RAM_FILE_UUENCODE,       35).
 -define(RAM_FILE_UUDECODE,       36).
 -define(RAM_FILE_SIZE,           37).
+-define(RAM_FILE_ADVISE,         38).
 
 %% Open modes for RAM_FILE_OPEN
 -define(RAM_FILE_MODE_READ,       1).
@@ -90,6 +92,14 @@
 -define(RAM_FILE_RESP_NUMBER,     3).
 -define(RAM_FILE_RESP_INFO,       4).
 
+%% POSIX file advises
+-define(POSIX_FADV_NORMAL,     0).
+-define(POSIX_FADV_RANDOM,     1).
+-define(POSIX_FADV_SEQUENTIAL, 2).
+-define(POSIX_FADV_WILLNEED,   3).
+-define(POSIX_FADV_DONTNEED,   4).
+-define(POSIX_FADV_NOREUSE,    5).
+
 %% --------------------------------------------------------------------------
 %% Generic file contents operations.
 %%
@@ -167,6 +177,8 @@ copy(#file_descriptor{module = ?MODULE} = Source,
     %% XXX Should be moved down to the driver for optimization.
     file:copy_opened(Source, Dest, Length).
 
+datasync(#file_descriptor{module = ?MODULE, data = Port}) ->
+    call_port(Port, <<?RAM_FILE_FDATASYNC>>).
 
 sync(#file_descriptor{module = ?MODULE, data = Port}) -> 
     call_port(Port, <<?RAM_FILE_FSYNC>>).
@@ -349,6 +361,28 @@ uudecode(#file_descriptor{module = ?MODULE, data = Port}) ->
 uudecode(#file_descriptor{}) ->
     {error, enotsup}.
 
+advise(#file_descriptor{module = ?MODULE, data = Port}, Offset,
+        Length, Advise) ->
+    Cmd0 = <<?RAM_FILE_ADVISE, Offset:64/signed, Length:64/signed>>,
+    case Advise of
+    normal ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_NORMAL:32/signed>>);
+    random ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_RANDOM:32/signed>>);
+    sequential ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_SEQUENTIAL:32/signed>>);
+    will_need ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_WILLNEED:32/signed>>);
+    dont_need ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_DONTNEED:32/signed>>);
+    no_reuse ->
+        call_port(Port, <<Cmd0/binary, ?POSIX_FADV_NOREUSE:32/signed>>);
+    _ ->
+        {error, einval}
+    end;
+advise(#file_descriptor{}, _Offset, _Length, _Advise) ->
+    {error, enotsup}.
+
 
 
 %%%-----------------------------------------------------------------
diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl
index 1d170790a3..1d652679b0 100644
--- a/lib/kernel/test/file_SUITE.erl
+++ b/lib/kernel/test/file_SUITE.erl
@@ -52,7 +52,7 @@
 	 old_modes/1, new_modes/1, path_open/1, open_errors/1]).
 -export([file_info/1, file_info_basic_file/1, file_info_basic_directory/1,
 	 file_info_bad/1, file_info_times/1, file_write_file_info/1]).
--export([rename/1, access/1, truncate/1, sync/1,
+-export([rename/1, access/1, truncate/1, datasync/1, sync/1,
 	 read_write/1, pread_write/1, append/1]).
 -export([errors/1, e_delete/1, e_rename/1, e_make_dir/1, e_del_dir/1]).
 -export([otp_5814/1]).
@@ -82,6 +82,8 @@
 
 -export([read_line_1/1, read_line_2/1, read_line_3/1,read_line_4/1]).
 
+-export([advise/1]).
+
 %% Debug exports
 -export([create_file_slow/2, create_file/2, create_bin/2]).
 -export([verify_file/2, verify_bin/3]).
@@ -377,7 +379,9 @@ win_cur_dir_1(_Config) ->
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-files(suite) -> [open,pos,file_info,consult,eval,script,truncate,sync].
+files(suite) ->
+    [open,pos,file_info,consult,eval,script,truncate,
+     sync,datasync,advise].
 
 open(suite) -> [open1,old_modes,new_modes,path_open,close,access,read_write,
 	       pread_write,append,open_errors].
@@ -1355,6 +1359,30 @@ truncate(Config) when is_list(Config) ->
     ok.
 
 
+datasync(suite) -> [];
+datasync(doc) -> "Tests that ?FILE_MODULE:datasync/1 at least doesn't crash.";
+datasync(Config) when is_list(Config) ->
+    ?line Dog = test_server:timetrap(test_server:seconds(5)),
+    ?line PrivDir = ?config(priv_dir, Config),
+    ?line Sync = filename:join(PrivDir,
+			       atom_to_list(?MODULE)
+			       ++"_sync.fil"),
+
+    %% Raw open.
+    ?line {ok, Fd} = ?FILE_MODULE:open(Sync, [write, raw]),
+    ?line ok = ?FILE_MODULE:datasync(Fd),
+    ?line ok = ?FILE_MODULE:close(Fd),
+
+    %% Ordinary open.
+    ?line {ok, Fd2} = ?FILE_MODULE:open(Sync, [write]),
+    ?line ok = ?FILE_MODULE:datasync(Fd2),
+    ?line ok = ?FILE_MODULE:close(Fd2),
+
+    ?line [] = flush(),
+    ?line test_server:timetrap_cancel(Dog),
+    ok.
+
+
 sync(suite) -> [];
 sync(doc) -> "Tests that ?FILE_MODULE:sync/1 at least doesn't crash.";
 sync(Config) when is_list(Config) ->
@@ -1378,6 +1406,77 @@ sync(Config) when is_list(Config) ->
     ?line test_server:timetrap_cancel(Dog),
     ok.
 
+advise(suite) -> [];
+advise(doc) -> "Tests that ?FILE_MODULE:advise/4 at least doesn't crash.";
+advise(Config) when is_list(Config) ->
+    ?line Dog = test_server:timetrap(test_server:seconds(5)),
+    ?line PrivDir = ?config(priv_dir, Config),
+    ?line Advise = filename:join(PrivDir,
+			       atom_to_list(?MODULE)
+			       ++"_advise.fil"),
+
+    Line1 = "Hello\n",
+    Line2 = "World!\n",
+
+    ?line {ok, Fd} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd, 0, 0, normal),
+    ?line ok = io:format(Fd, "~s", [Line1]),
+    ?line ok = io:format(Fd, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd),
+
+    ?line {ok, Fd2} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd2, 0, 0, random),
+    ?line ok = io:format(Fd2, "~s", [Line1]),
+    ?line ok = io:format(Fd2, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd2),
+
+    ?line {ok, Fd3} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd3, 0, 0, sequential),
+    ?line ok = io:format(Fd3, "~s", [Line1]),
+    ?line ok = io:format(Fd3, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd3),
+
+    ?line {ok, Fd4} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd4, 0, 0, will_need),
+    ?line ok = io:format(Fd4, "~s", [Line1]),
+    ?line ok = io:format(Fd4, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd4),
+
+    ?line {ok, Fd5} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd5, 0, 0, dont_need),
+    ?line ok = io:format(Fd5, "~s", [Line1]),
+    ?line ok = io:format(Fd5, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd5),
+
+    ?line {ok, Fd6} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = ?FILE_MODULE:advise(Fd6, 0, 0, no_reuse),
+    ?line ok = io:format(Fd6, "~s", [Line1]),
+    ?line ok = io:format(Fd6, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd6),
+
+    ?line {ok, Fd7} = ?FILE_MODULE:open(Advise, [write]),
+    ?line {error, einval} = ?FILE_MODULE:advise(Fd7, 0, 0, bad_advise),
+    ?line ok = ?FILE_MODULE:close(Fd7),
+
+    %% test write without advise, then a read after an advise
+    ?line {ok, Fd8} = ?FILE_MODULE:open(Advise, [write]),
+    ?line ok = io:format(Fd8, "~s", [Line1]),
+    ?line ok = io:format(Fd8, "~s", [Line2]),
+    ?line ok = ?FILE_MODULE:close(Fd8),
+    ?line {ok, Fd9} = ?FILE_MODULE:open(Advise, [read]),
+    Offset = 0,
+    %% same as a 0 length in some implementations
+    Length = length(Line1) + length(Line2),
+    ?line ok = ?FILE_MODULE:advise(Fd9, Offset, Length, sequential),
+    ?line {ok, Line1} = ?FILE_MODULE:read_line(Fd9),
+    ?line {ok, Line2} = ?FILE_MODULE:read_line(Fd9),
+    ?line eof = ?FILE_MODULE:read_line(Fd9),
+    ?line ok = ?FILE_MODULE:close(Fd9),
+
+    ?line [] = flush(),
+    ?line test_server:timetrap_cancel(Dog),
+    ok.
+
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
diff --git a/lib/kernel/test/prim_file_SUITE.erl b/lib/kernel/test/prim_file_SUITE.erl
index 6badbb5090..21bdc06fdc 100644
--- a/lib/kernel/test/prim_file_SUITE.erl
+++ b/lib/kernel/test/prim_file_SUITE.erl
@@ -34,7 +34,7 @@
 	 file_info_times_a/1, file_info_times_b/1, 
 	 file_write_file_info_a/1, file_write_file_info_b/1]).
 -export([rename_a/1, rename_b/1, 
-	 access/1, truncate/1, sync/1,
+	 access/1, truncate/1, datasync/1, sync/1,
 	 read_write/1, pread_write/1, append/1]).
 -export([errors/1, e_delete/1, e_rename/1, e_make_dir/1, e_del_dir/1]).
 
@@ -48,6 +48,8 @@
 	 symlinks_a/1, symlinks_b/1,
 	 list_dir_limit/1]).
 
+-export([advise/1]).
+
 -include("test_server.hrl").
 -include_lib("kernel/include/file.hrl").
 
@@ -380,7 +382,7 @@ win_cur_dir_1(_Config, Handle) ->
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-files(suite) -> [open,pos,file_info,truncate,sync].
+files(suite) -> [open,pos,file_info,truncate,sync,datasync,advise].
 
 open(suite) -> [open1,modes,close,access,read_write,
 	       pread_write,append].
@@ -1064,6 +1066,24 @@ truncate(Config) when is_list(Config) ->
     ok.
 
 
+datasync(suite) -> [];
+datasync(doc) -> "Tests that ?PRIM_FILE:datasync/1 at least doesn't crash.";
+datasync(Config) when is_list(Config) ->
+    ?line Dog = test_server:timetrap(test_server:seconds(5)),
+    ?line PrivDir = ?config(priv_dir, Config),
+    ?line Sync = filename:join(PrivDir,
+			       atom_to_list(?MODULE)
+			       ++"_sync.fil"),
+
+    %% Raw open.
+    ?line {ok, Fd} = ?PRIM_FILE:open(Sync, [write]),
+    ?line ok = ?PRIM_FILE:datasync(Fd),
+    ?line ok = ?PRIM_FILE:close(Fd),
+
+    ?line test_server:timetrap_cancel(Dog),
+    ok.
+
+
 sync(suite) -> [];
 sync(doc) -> "Tests that ?PRIM_FILE:sync/1 at least doesn't crash.";
 sync(Config) when is_list(Config) ->
@@ -1082,6 +1102,77 @@ sync(Config) when is_list(Config) ->
     ok.
 
 
+advise(suite) -> [];
+advise(doc) -> "Tests that ?PRIM_FILE:advise/4 at least doesn't crash.";
+advise(Config) when is_list(Config) ->
+    ?line Dog = test_server:timetrap(test_server:seconds(5)),
+    ?line PrivDir = ?config(priv_dir, Config),
+    ?line Advise = filename:join(PrivDir,
+			       atom_to_list(?MODULE)
+			       ++"_advise.fil"),
+
+    Line1 = "Hello\n",
+    Line2 = "World!\n",
+
+    ?line {ok, Fd} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd, 0, 0, normal),
+    ?line ok = ?PRIM_FILE:write(Fd, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd),
+
+    ?line {ok, Fd2} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd2, 0, 0, random),
+    ?line ok = ?PRIM_FILE:write(Fd2, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd2, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd2),
+
+    ?line {ok, Fd3} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd3, 0, 0, sequential),
+    ?line ok = ?PRIM_FILE:write(Fd3, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd3, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd3),
+
+    ?line {ok, Fd4} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd4, 0, 0, will_need),
+    ?line ok = ?PRIM_FILE:write(Fd4, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd4, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd4),
+
+    ?line {ok, Fd5} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd5, 0, 0, dont_need),
+    ?line ok = ?PRIM_FILE:write(Fd5, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd5, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd5),
+
+    ?line {ok, Fd6} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:advise(Fd6, 0, 0, no_reuse),
+    ?line ok = ?PRIM_FILE:write(Fd6, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd6, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd6),
+
+    ?line {ok, Fd7} = ?PRIM_FILE:open(Advise, [write]),
+    ?line {error, einval} = ?PRIM_FILE:advise(Fd7, 0, 0, bad_advise),
+    ?line ok = ?PRIM_FILE:close(Fd7),
+
+    %% test write without advise, then a read after an advise
+    ?line {ok, Fd8} = ?PRIM_FILE:open(Advise, [write]),
+    ?line ok = ?PRIM_FILE:write(Fd8, Line1),
+    ?line ok = ?PRIM_FILE:write(Fd8, Line2),
+    ?line ok = ?PRIM_FILE:close(Fd8),
+    ?line {ok, Fd9} = ?PRIM_FILE:open(Advise, [read]),
+    Offset = 0,
+    %% same as a 0 length in some implementations
+    Length = length(Line1) + length(Line2),
+    ?line ok = ?PRIM_FILE:advise(Fd9, Offset, Length, sequential),
+    ?line {ok, Line1} = ?PRIM_FILE:read_line(Fd9),
+    ?line {ok, Line2} = ?PRIM_FILE:read_line(Fd9),
+    ?line eof = ?PRIM_FILE:read_line(Fd9),
+    ?line ok = ?PRIM_FILE:close(Fd9),
+
+    ?line test_server:timetrap_cancel(Dog),
+    ok.
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 delete_a(suite) -> [];