[PATCH] [2.4] beyond_eof check in generic_direct_IO

[Chris Mason <mason@suse.com>]

Hello all,

reiserfs has to do a few odd tail conversion steps during direct io. 
Picture a file whose size is currently 3500 bytes, and a direct io write
extending it to 4096 bytes.

reiserfs will have those 3500 bytes packed into a tail, and when it gets
a get_block call with create == 1, it will convert the tail into a full
block and return the newly created block.

The new generic_direct_IO code doesn't send create == 1 to get_block
unless the new block is entirely past eof.  I think it should instead
allow any part of the block to be past eof, which allows reiserfs to
properly convert the tail:

-chris

--- 1.89/fs/buffer.c	Tue Jun 24 17:11:29 2003
+++ edited/fs/buffer.c	Fri Jul 18 13:24:57 2003
@@ -2147,7 +2148,7 @@
 		bh.b_size = blocksize;
 		bh.b_page = NULL;
 
-		if (((loff_t) blocknr) * blocksize >= inode->i_size)
+		if (((loff_t) (blocknr + 1)) * blocksize > inode->i_size)
 			beyond_eof = 1;
 
 		/* Only allow get_block to create new blocks if we are safely