--- zzzz-none-000/linux-3.10.107/fs/hpfs/buffer.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/hpfs/buffer.c	2021-02-04 17:41:59.000000000 +0000
@@ -7,8 +7,64 @@
  */
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/blkdev.h>
 #include "hpfs_fn.h"
 
+secno hpfs_search_hotfix_map(struct super_block *s, secno sec)
+{
+	unsigned i;
+	struct hpfs_sb_info *sbi = hpfs_sb(s);
+	for (i = 0; unlikely(i < sbi->n_hotfixes); i++) {
+		if (sbi->hotfix_from[i] == sec) {
+			return sbi->hotfix_to[i];
+		}
+	}
+	return sec;
+}
+
+unsigned hpfs_search_hotfix_map_for_range(struct super_block *s, secno sec, unsigned n)
+{
+	unsigned i;
+	struct hpfs_sb_info *sbi = hpfs_sb(s);
+	for (i = 0; unlikely(i < sbi->n_hotfixes); i++) {
+		if (sbi->hotfix_from[i] >= sec && sbi->hotfix_from[i] < sec + n) {
+			n = sbi->hotfix_from[i] - sec;
+		}
+	}
+	return n;
+}
+
+void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
+{
+	struct buffer_head *bh;
+	struct blk_plug plug;
+
+	if (n <= 0 || unlikely(secno >= hpfs_sb(s)->sb_fs_size))
+		return;
+
+	if (unlikely(hpfs_search_hotfix_map_for_range(s, secno, n) != n))
+		return;
+
+	bh = sb_find_get_block(s, secno);
+	if (bh) {
+		if (buffer_uptodate(bh)) {
+			brelse(bh);
+			return;
+		}
+		brelse(bh);
+	};
+
+	blk_start_plug(&plug);
+	while (n > 0) {
+		if (unlikely(secno >= hpfs_sb(s)->sb_fs_size))
+			break;
+		sb_breadahead(s, secno);
+		secno++;
+		n--;
+	}
+	blk_finish_plug(&plug);
+}
+
 /* Map a sector into a buffer and return pointers to it and to the buffer. */
 
 void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head **bhp,
@@ -18,13 +74,15 @@
 
 	hpfs_lock_assert(s);
 
+	hpfs_prefetch_sectors(s, secno, ahead);
+
 	cond_resched();
 
-	*bhp = bh = sb_bread(s, secno);
+	*bhp = bh = sb_bread(s, hpfs_search_hotfix_map(s, secno));
 	if (bh != NULL)
 		return bh->b_data;
 	else {
-		printk("HPFS: hpfs_map_sector: read error\n");
+		pr_err("%s(): read error\n", __func__);
 		return NULL;
 	}
 }
@@ -40,12 +98,12 @@
 
 	cond_resched();
 
-	if ((*bhp = bh = sb_getblk(s, secno)) != NULL) {
+	if ((*bhp = bh = sb_getblk(s, hpfs_search_hotfix_map(s, secno))) != NULL) {
 		if (!buffer_uptodate(bh)) wait_on_buffer(bh);
 		set_buffer_uptodate(bh);
 		return bh->b_data;
 	} else {
-		printk("HPFS: hpfs_get_sector: getblk failed\n");
+		pr_err("%s(): getblk failed\n", __func__);
 		return NULL;
 	}
 }
@@ -55,7 +113,6 @@
 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);
@@ -63,38 +120,38 @@
 	cond_resched();
 
 	if (secno & 3) {
-		printk("HPFS: hpfs_map_4sectors: unaligned read\n");
+		pr_err("%s(): unaligned read\n", __func__);
 		return NULL;
 	}
 
+	hpfs_prefetch_sectors(s, secno, 4 + ahead);
+
+	if (!hpfs_map_sector(s, secno + 0, &qbh->bh[0], 0)) goto bail0;
+	if (!hpfs_map_sector(s, secno + 1, &qbh->bh[1], 0)) goto bail1;
+	if (!hpfs_map_sector(s, secno + 2, &qbh->bh[2], 0)) goto bail2;
+	if (!hpfs_map_sector(s, secno + 3, &qbh->bh[3], 0)) 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;
+		pr_err("%s(): out of memory\n", __func__);
+		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:
@@ -102,9 +159,6 @@
  bail1:
 	brelse(qbh->bh[0]);
  bail0:
-	kfree(data);
-	printk("HPFS: hpfs_map_4sectors: read error\n");
- bail:
 	return NULL;
 }
 
@@ -118,48 +172,58 @@
 	hpfs_lock_assert(s);
 
 	if (secno & 3) {
-		printk("HPFS: hpfs_get_4sectors: unaligned read\n");
+		pr_err("%s(): unaligned read\n", __func__);
 		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;
+		pr_err("%s(): out of memory\n", __func__);
+		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]);