1 files changed, 50 insertions, 46 deletions

diff --git a/fs/hpfs/buffer.c b/fs/hpfs/buffer.c
index 4d0a1afa058c..139ef1684d07 100644
--- a/fs/hpfs/buffer.c
+++ b/fs/hpfs/buffer.c
@@ -86,7 +86,6 @@ void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head
 void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffer_head *qbh,
 		   int ahead)
 {
-	struct buffer_head *bh;
 	char *data;
 
 	hpfs_lock_assert(s);
@@ -100,34 +99,32 @@ void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffe
 
 	hpfs_prefetch_sectors(s, secno, 4 + ahead);
 
+	if (!(qbh->bh[0] = sb_bread(s, secno + 0))) goto bail0;
+	if (!(qbh->bh[1] = sb_bread(s, secno + 1))) goto bail1;
+	if (!(qbh->bh[2] = sb_bread(s, secno + 2))) goto bail2;
+	if (!(qbh->bh[3] = sb_bread(s, secno + 3))) goto bail3;
+
+	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
+	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
+	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
+		return qbh->data = qbh->bh[0]->b_data;
+	}
+
 	qbh->data = data = kmalloc(2048, GFP_NOFS);
 	if (!data) {
 		printk("HPFS: hpfs_map_4sectors: out of memory\n");
-		goto bail;
+		goto bail4;
 	}
 
-	qbh->bh[0] = bh = sb_bread(s, secno);
-	if (!bh)
-		goto bail0;
-	memcpy(data, bh->b_data, 512);
-
-	qbh->bh[1] = bh = sb_bread(s, secno + 1);
-	if (!bh)
-		goto bail1;
-	memcpy(data + 512, bh->b_data, 512);
-
-	qbh->bh[2] = bh = sb_bread(s, secno + 2);
-	if (!bh)
-		goto bail2;
-	memcpy(data + 2 * 512, bh->b_data, 512);
-
-	qbh->bh[3] = bh = sb_bread(s, secno + 3);
-	if (!bh)
-		goto bail3;
-	memcpy(data + 3 * 512, bh->b_data, 512);
+	memcpy(data + 0 * 512, qbh->bh[0]->b_data, 512);
+	memcpy(data + 1 * 512, qbh->bh[1]->b_data, 512);
+	memcpy(data + 2 * 512, qbh->bh[2]->b_data, 512);
+	memcpy(data + 3 * 512, qbh->bh[3]->b_data, 512);
 
 	return data;
 
+ bail4:
+	brelse(qbh->bh[3]);
  bail3:
 	brelse(qbh->bh[2]);
  bail2:
@@ -135,9 +132,6 @@ void *hpfs_map_4sectors(struct super_block *s, unsigned secno, struct quad_buffe
  bail1:
 	brelse(qbh->bh[0]);
  bail0:
-	kfree(data);
-	printk("HPFS: hpfs_map_4sectors: read error\n");
- bail:
 	return NULL;
 }
 
@@ -155,44 +149,54 @@ void *hpfs_get_4sectors(struct super_block *s, unsigned secno,
 		return NULL;
 	}
 
-	/*return hpfs_map_4sectors(s, secno, qbh, 0);*/
+	if (!hpfs_get_sector(s, secno + 0, &qbh->bh[0])) goto bail0;
+	if (!hpfs_get_sector(s, secno + 1, &qbh->bh[1])) goto bail1;
+	if (!hpfs_get_sector(s, secno + 2, &qbh->bh[2])) goto bail2;
+	if (!hpfs_get_sector(s, secno + 3, &qbh->bh[3])) goto bail3;
+
+	if (likely(qbh->bh[1]->b_data == qbh->bh[0]->b_data + 1 * 512) &&
+	    likely(qbh->bh[2]->b_data == qbh->bh[0]->b_data + 2 * 512) &&
+	    likely(qbh->bh[3]->b_data == qbh->bh[0]->b_data + 3 * 512)) {
+		return qbh->data = qbh->bh[0]->b_data;
+	}
+
 	if (!(qbh->data = kmalloc(2048, GFP_NOFS))) {
 		printk("HPFS: hpfs_get_4sectors: out of memory\n");
-		return NULL;
+		goto bail4;
 	}
-	if (!(hpfs_get_sector(s, secno, &qbh->bh[0]))) goto bail0;
-	if (!(hpfs_get_sector(s, secno + 1, &qbh->bh[1]))) goto bail1;
-	if (!(hpfs_get_sector(s, secno + 2, &qbh->bh[2]))) goto bail2;
-	if (!(hpfs_get_sector(s, secno + 3, &qbh->bh[3]))) goto bail3;
-	memcpy(qbh->data, qbh->bh[0]->b_data, 512);
-	memcpy(qbh->data + 512, qbh->bh[1]->b_data, 512);
-	memcpy(qbh->data + 2*512, qbh->bh[2]->b_data, 512);
-	memcpy(qbh->data + 3*512, qbh->bh[3]->b_data, 512);
 	return qbh->data;
 
-	bail3:	brelse(qbh->bh[2]);
-	bail2:	brelse(qbh->bh[1]);
-	bail1:	brelse(qbh->bh[0]);
-	bail0:
+bail4:
+	brelse(qbh->bh[3]);
+bail3:
+	brelse(qbh->bh[2]);
+bail2:
+	brelse(qbh->bh[1]);
+bail1:
+	brelse(qbh->bh[0]);
+bail0:
 	return NULL;
 }
 	
 
 void hpfs_brelse4(struct quad_buffer_head *qbh)
 {
-	brelse(qbh->bh[3]);
-	brelse(qbh->bh[2]);
-	brelse(qbh->bh[1]);
+	if (unlikely(qbh->data != qbh->bh[0]->b_data))
+		kfree(qbh->data);
 	brelse(qbh->bh[0]);
-	kfree(qbh->data);
+	brelse(qbh->bh[1]);
+	brelse(qbh->bh[2]);
+	brelse(qbh->bh[3]);
 }	
 
 void hpfs_mark_4buffers_dirty(struct quad_buffer_head *qbh)
 {
-	memcpy(qbh->bh[0]->b_data, qbh->data, 512);
-	memcpy(qbh->bh[1]->b_data, qbh->data + 512, 512);
-	memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
-	memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
+	if (unlikely(qbh->data != qbh->bh[0]->b_data)) {
+		memcpy(qbh->bh[0]->b_data, qbh->data + 0 * 512, 512);
+		memcpy(qbh->bh[1]->b_data, qbh->data + 1 * 512, 512);
+		memcpy(qbh->bh[2]->b_data, qbh->data + 2 * 512, 512);
+		memcpy(qbh->bh[3]->b_data, qbh->data + 3 * 512, 512);
+	}
 	mark_buffer_dirty(qbh->bh[0]);
 	mark_buffer_dirty(qbh->bh[1]);
 	mark_buffer_dirty(qbh->bh[2]);