[RFC 2/2] JBD: blocks reservation fix for large block support

[Mingming Cao <cmm@us.ibm.com>]

The blocks per page could be less or quals to 1 with the large block support in VM.
The patch fixed the way to calculate the number of blocks to reserve in journal in the
case blocksize > pagesize.



Signed-off-by: Mingming Cao <cmm@us.ibm.com>

Index: my2.6/fs/jbd/journal.c
===================================================================
--- my2.6.orig/fs/jbd/journal.c	2007-08-31 13:27:16.000000000 -0700
+++ my2.6/fs/jbd/journal.c	2007-08-31 13:28:18.000000000 -0700
@@ -1611,7 +1611,12 @@ void journal_ack_err(journal_t *journal)
 
 int journal_blocks_per_page(struct inode *inode)
 {
-	return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
+	int bits = PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits;
+
+	if (bits > 0)
+		return 1 << bits;
+	else
+		return 1;
 }
 
 /*
Index: my2.6/fs/jbd2/journal.c
===================================================================
--- my2.6.orig/fs/jbd2/journal.c	2007-08-31 13:32:21.000000000 -0700
+++ my2.6/fs/jbd2/journal.c	2007-08-31 13:32:30.000000000 -0700
@@ -1612,7 +1612,12 @@ void jbd2_journal_ack_err(journal_t *jou
 
 int jbd2_journal_blocks_per_page(struct inode *inode)
 {
-	return 1 << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
+	int bits = PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits;
+
+	if (bits > 0)
+		return 1 << bits;
+	else
+		return 1;
 }
 
 /*