hfsplus: fix "unused node is not erased" error

Zero newly allocated extents in the catalog tree if volume attributes
tell us to.  Not doing so we risk getting the "unused node is not
erased" error.  See kHFSUnusedNodeFix flag in Apple's source code for
reference.

There was a previous commit clearing the node when it is freed: commit
899bed05e9f6 ("hfsplus: fix issue with unzeroed unused b-tree nodes").
But it did not handle newly allocated extents (this patch fixes it).
And it zeroed nodes in all trees unconditionally which is an overkill.

This patch adds a condition and also switches to 'tree->node_size' as a
simpler method of getting the length to zero.

Signed-off-by: Sergei Antonov <saproj@gmail.com>
Cc: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Vyacheslav Dubeyko <slava@dubeyko.com>
Cc: Hin-Tak Leung <htl10@users.sourceforge.net>
Cc: Kyle Laracey <kalaracey@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index a7aafb35b624..a09fcb68c364 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -235,7 +235,7 @@ int hfsplus_get_block(struct inode *inode, sector_t iblock,
                 if (iblock > hip->fs_blocks || !create)
                         return -EIO;
                 if (ablock >= hip->alloc_blocks) {
-                        res = hfsplus_file_extend(inode);
+                        res = hfsplus_file_extend(inode, false);
                         if (res)
                                 return res;
                 }
@@ -425,7 +425,7 @@ int hfsplus_free_fork(struct super_block *sb, u32 cnid,
         return res;
 }
 
-int hfsplus_file_extend(struct inode *inode)
+int hfsplus_file_extend(struct inode *inode, bool zeroout)
 {
         struct super_block *sb = inode->i_sb;
         struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
@@ -463,6 +463,12 @@ int hfsplus_file_extend(struct inode *inode)
                 }
         }
 
+        if (zeroout) {
+                res = sb_issue_zeroout(sb, start, len, GFP_NOFS);
+                if (res)
+                        goto out;
+        }
+
         hfs_dbg(EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len);
 
         if (hip->alloc_blocks <= hip->first_blocks) {