This patch adds a "readahead" method to the io_manager interface

Signed-off-by: Vladimir V. Saveliev vs@clusterfs.com

Index: e2fsprogs-1.40.2/lib/ext2fs/ext2_io.h
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/ext2_io.h
+++ e2fsprogs-1.40.2/lib/ext2fs/ext2_io.h
@@ -68,6 +68,8 @@ struct struct_io_manager {
 	errcode_t (*set_blksize)(io_channel channel, int blksize);
 	errcode_t (*read_blk)(io_channel channel, unsigned long block,
 			      int count, void *data);
+	errcode_t (*readahead)(io_channel channel, unsigned long block,
+			       int count);
 	errcode_t (*write_blk)(io_channel channel, unsigned long block,
 			       int count, const void *data);
 	errcode_t (*flush)(io_channel channel);
@@ -89,6 +91,7 @@ struct struct_io_manager {
 #define io_channel_close(c) 		((c)->manager->close((c)))
 #define io_channel_set_blksize(c,s)	((c)->manager->set_blksize((c),s))
 #define io_channel_read_blk(c,b,n,d)	((c)->manager->read_blk((c),b,n,d))
+#define io_channel_readahead(c,b,n)	((c)->manager->readahead((c),b,n))
 #define io_channel_write_blk(c,b,n,d)	((c)->manager->write_blk((c),b,n,d))
 #define io_channel_flush(c) 		((c)->manager->flush((c)))
 #define io_channel_bumpcount(c)		((c)->refcount++)
@@ -99,6 +102,8 @@ extern errcode_t io_channel_set_options(
 extern errcode_t io_channel_write_byte(io_channel channel, 
 				       unsigned long offset,
 				       int count, const void *data);
+extern errcode_t readahead_noop(io_channel channel, unsigned long block,
+				int count);
 
 /* unix_io.c */
 extern io_manager unix_io_manager;
Index: e2fsprogs-1.40.2/lib/ext2fs/unix_io.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/unix_io.c
+++ e2fsprogs-1.40.2/lib/ext2fs/unix_io.c
@@ -15,6 +15,8 @@
  * %End-Header%
  */
 
+#define _XOPEN_SOURCE 600
+#define _FILE_OFFSET_BITS 64
 #define _LARGEFILE_SOURCE
 #define _LARGEFILE64_SOURCE
 
@@ -78,6 +80,8 @@ static errcode_t unix_close(io_channel c
 static errcode_t unix_set_blksize(io_channel channel, int blksize);
 static errcode_t unix_read_blk(io_channel channel, unsigned long block,
 			       int count, void *data);
+static errcode_t unix_readahead(io_channel channel, unsigned long block,
+				int count);
 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 				int count, const void *data);
 static errcode_t unix_flush(io_channel channel);
@@ -106,6 +110,7 @@ static struct struct_io_manager struct_u
 	unix_close,
 	unix_set_blksize,
 	unix_read_blk,
+	unix_readahead,
 	unix_write_blk,
 	unix_flush,
 #ifdef NEED_BOUNCE_BUFFER
@@ -611,6 +616,18 @@ static errcode_t unix_read_blk(io_channe
 #endif /* NO_IO_CACHE */
 }
 
+static errcode_t unix_readahead(io_channel channel, unsigned long block,
+				int count)
+{
+	struct unix_private_data *data;
+
+	data = (struct unix_private_data *)channel->private_data;
+	posix_fadvise(data->dev, (ext2_loff_t)block * channel->block_size,
+		      (ext2_loff_t)count * channel->block_size,
+		      POSIX_FADV_WILLNEED);
+	return 0;
+}
+
 static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 				int count, const void *buf)
 {
Index: e2fsprogs-1.40.2/lib/ext2fs/inode_io.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/inode_io.c
+++ e2fsprogs-1.40.2/lib/ext2fs/inode_io.c
@@ -64,6 +64,7 @@ static struct struct_io_manager struct_i
 	inode_close,
 	inode_set_blksize,
 	inode_read_blk,
+	readahead_noop,
 	inode_write_blk,
 	inode_flush,
 	inode_write_byte
Index: e2fsprogs-1.40.2/lib/ext2fs/dosio.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/dosio.c
+++ e2fsprogs-1.40.2/lib/ext2fs/dosio.c
@@ -64,6 +64,7 @@ static struct struct_io_manager struct_d
         dos_close,
         dos_set_blksize,
         dos_read_blk,
+        readahead_noop,
         dos_write_blk,
         dos_flush
 };
Index: e2fsprogs-1.40.2/lib/ext2fs/nt_io.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/nt_io.c
+++ e2fsprogs-1.40.2/lib/ext2fs/nt_io.c
@@ -236,6 +236,7 @@ static struct struct_io_manager struct_n
 	nt_close,
 	nt_set_blksize,
 	nt_read_blk,
+	readahead_noop,
 	nt_write_blk,
 	nt_flush
 };
Index: e2fsprogs-1.40.2/lib/ext2fs/test_io.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/test_io.c
+++ e2fsprogs-1.40.2/lib/ext2fs/test_io.c
@@ -74,6 +74,7 @@ static struct struct_io_manager struct_t
 	test_close,
 	test_set_blksize,
 	test_read_blk,
+	readahead_noop,
 	test_write_blk,
 	test_flush,
 	test_write_byte,
Index: e2fsprogs-1.40.2/lib/ext2fs/io_manager.c
===================================================================
--- e2fsprogs-1.40.2.orig/lib/ext2fs/io_manager.c
+++ e2fsprogs-1.40.2/lib/ext2fs/io_manager.c
@@ -67,3 +67,9 @@ errcode_t io_channel_write_byte(io_chann
 
 	return EXT2_ET_UNIMPLEMENTED;
 }
+
+errcode_t readahead_noop(io_channel channel, unsigned long block,
+			 int count)
+{
+	return 0;
+}