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]);