NTFS: Fix page_has_buffers()/page_buffers() handling in fs/ntfs/aops.c.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

2 files changed, 22 insertions, 17 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index c3b510210743..029f856c56c0 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -85,6 +85,7 @@ ToDo/Notes:
           removal of the get_bh()/put_bh() pairs for each buffer.
         - Fix fs/ntfs/aops.c::ntfs_{read,write}_block() to handle the case
           where a concurrent truncate has truncated the runlist under our feet.
+        - Fix page_has_buffers()/page_buffers() handling in fs/ntfs/aops.c.
 
 2.1.23 - Implement extension of resident files and make writing safe as well as
          many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 2482b677a82a..52e1aff98b00 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -185,13 +185,15 @@ static int ntfs_read_block(struct page *page)
         blocksize_bits = VFS_I(ni)->i_blkbits;
         blocksize = 1 << blocksize_bits;
 
-        if (!page_has_buffers(page))
+        if (!page_has_buffers(page)) {
                 create_empty_buffers(page, blocksize, 0);
-        bh = head = page_buffers(page);
-        if (unlikely(!bh)) {
-                unlock_page(page);
-                return -ENOMEM;
+                if (unlikely(!page_has_buffers(page))) {
+                        unlock_page(page);
+                        return -ENOMEM;
+                }
         }
+        bh = head = page_buffers(page);
+        BUG_ON(!bh);
 
         iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
         read_lock_irqsave(&ni->size_lock, flags);
@@ -530,19 +532,21 @@ static int ntfs_write_block(struct page *page, struct writeback_control *wbc)
                 BUG_ON(!PageUptodate(page));
                 create_empty_buffers(page, blocksize,
                                 (1 << BH_Uptodate) | (1 << BH_Dirty));
+                if (unlikely(!page_has_buffers(page))) {
+                        ntfs_warning(vol->sb, "Error allocating page "
+                                        "buffers.  Redirtying page so we try "
+                                        "again later.");
+                        /*
+                         * Put the page back on mapping->dirty_pages, but leave
+                         * its buffers' dirty state as-is.
+                         */
+                        redirty_page_for_writepage(wbc, page);
+                        unlock_page(page);
+                        return 0;
+                }
         }
         bh = head = page_buffers(page);
-        if (unlikely(!bh)) {
-                ntfs_warning(vol->sb, "Error allocating page buffers. "
-                                "Redirtying page so we try again later.");
-                /*
-                 * Put the page back on mapping->dirty_pages, but leave its
-                 * buffer's dirty state as-is.
-                 */
-                redirty_page_for_writepage(wbc, page);
-                unlock_page(page);
-                return 0;
-        }
+        BUG_ON(!bh);
 
         /* NOTE: Different naming scheme to ntfs_read_block()! */
 
@@ -910,7 +914,6 @@ static int ntfs_write_mst_block(struct page *page,
         sync = (wbc->sync_mode == WB_SYNC_ALL);
 
         /* Make sure we have mapped buffers. */
-        BUG_ON(!page_has_buffers(page));
         bh = head = page_buffers(page);
         BUG_ON(!bh);
 
@@ -2397,6 +2400,7 @@ void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) {
                         buffers_to_free = bh;
         }
         bh = head = page_buffers(page);
+        BUG_ON(!bh);
         do {
                 bh_ofs = bh_offset(bh);
                 if (bh_ofs + bh_size <= ofs)