hpfs: support hotfixes

When the OS/2 driver hits a disk write error, it writes the sector to
another location and adds the sector mapping to the hotfix map.

This patch makes the hpfs driver understand the hotfix map and remap
accesses accoring to it.

Signed-off-by: Mikulas Patocka <mikulas@twibright.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 6 deletions

diff --git a/fs/hpfs/buffer.c b/fs/hpfs/buffer.c
index 8057fe4e6574..f626114449e4 100644
--- a/fs/hpfs/buffer.c
+++ b/fs/hpfs/buffer.c
@@ -10,6 +10,30 @@
 #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;
@@ -18,6 +42,9 @@ void hpfs_prefetch_sectors(struct super_block *s, unsigned secno, int n)
         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)) {
@@ -51,7 +78,7 @@ void *hpfs_map_sector(struct super_block *s, unsigned secno, struct buffer_head
 
         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 {
@@ -71,7 +98,7 @@ void *hpfs_get_sector(struct super_block *s, unsigned secno, struct buffer_head
 
         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;
@@ -99,10 +126,10 @@ 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 (!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) &&