[PATCH] ufs: reallocation fix

In blocks reallocation function sometimes does not update some of
buffer_head::b_blocknr, which may and cause data damage.

Signed-off-by: Evgeniy Dushistov <dushistov@mail.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ufs/balloc.c b/fs/ufs/balloc.c
index 96ca845..638f4c5 100644 (file)
--- a/fs/ufs/balloc.c
+++ b/fs/ufs/balloc.c
@@ -227,14 +227,14 @@ failed:
  * We can come here from ufs_writepage or ufs_prepare_write,
  * locked_page is argument of these functions, so we already lock it.
  */
-static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk,
+static void ufs_change_blocknr(struct inode *inode, unsigned int beg,
                               unsigned int count, unsigned int oldb,
                               unsigned int newb, struct page *locked_page)
 {
-       unsigned int blk_per_page = 1 << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-       struct address_space *mapping = inode->i_mapping;
+       const unsigned mask = (1 << (PAGE_CACHE_SHIFT - inode->i_blkbits)) - 1;
+       struct address_space * const mapping = inode->i_mapping;
        pgoff_t index, cur_index;
-       unsigned int i, j;
+       unsigned end, pos, j;
        struct page *page;
        struct buffer_head *head, *bh;
 
@@ -246,8 +246,8 @@ static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk,
 
        cur_index = locked_page->index;
 
-       for (i = 0; i < count; i += blk_per_page) {
-               index = (baseblk+i) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
+       for (end = count + beg; beg < end; beg = (beg | mask) + 1) {
+               index = beg >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
 
                if (likely(cur_index != index)) {
                        page = ufs_get_locked_page(mapping, index);
@@ -256,21 +256,32 @@ static void ufs_change_blocknr(struct inode *inode, unsigned int baseblk,
                } else
                        page = locked_page;
 
-               j = i;
                head = page_buffers(page);
                bh = head;
+               pos = beg & mask;
+               for (j = 0; j < pos; ++j)
+                       bh = bh->b_this_page;
+               j = 0;
                do {
-                       if (likely(bh->b_blocknr == j + oldb && j < count)) {
-                               unmap_underlying_metadata(bh->b_bdev,
-                                                         bh->b_blocknr);
-                               bh->b_blocknr = newb + j++;
-                               mark_buffer_dirty(bh);
+                       if (buffer_mapped(bh)) {
+                               pos = bh->b_blocknr - oldb;
+                               if (pos < count) {
+                                       UFSD(" change from %llu to %llu\n",
+                                            (unsigned long long)pos + oldb,
+                                            (unsigned long long)pos + newb);
+                                       bh->b_blocknr = newb + pos;
+                                       unmap_underlying_metadata(bh->b_bdev,
+                                                                 bh->b_blocknr);
+                                       mark_buffer_dirty(bh);
+                                       ++j;
+                               }
                        }
 
                        bh = bh->b_this_page;
                } while (bh != head);
 
-               set_page_dirty(page);
+               if (j)
+                       set_page_dirty(page);
 
                if (likely(cur_index != index))
                        ufs_put_locked_page(page);
@@ -418,14 +429,14 @@ unsigned ufs_new_fragments(struct inode * inode, __fs32 * p, unsigned fragment,
        }
        result = ufs_alloc_fragments (inode, cgno, goal, request, err);
        if (result) {
+               ufs_clear_frags(inode, result + oldcount, newcount - oldcount,
+                               locked_page != NULL);
                ufs_change_blocknr(inode, fragment - oldcount, oldcount, tmp,
                                   result, locked_page);
 
                *p = cpu_to_fs32(sb, result);
                *err = 0;
                UFS_I(inode)->i_lastfrag = max_t(u32, UFS_I(inode)->i_lastfrag, fragment + count);
-               ufs_clear_frags(inode, result + oldcount, newcount - oldcount,
-                               locked_page != NULL);
                unlock_super(sb);
                if (newcount < request)
                        ufs_free_fragments (inode, result + newcount, request - newcount);