[PATCH] hfsplus: avoid crash on failed block map free

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

From: Alan Cox <alan@linux.intel.com>

If the read fails we kmap an error code. This doesn't end well. Instead
print a critical error and pray. This mirrors the rest of the fs behaviour
with critical error cases.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---

 fs/hfsplus/bitmap.c |    8 ++++++++
 1 file changed, 8 insertions(+)


diff --git a/fs/hfsplus/bitmap.c b/fs/hfsplus/bitmap.c
index 4cfbe2e..5eeefee 100644
--- a/fs/hfsplus/bitmap.c
+++ b/fs/hfsplus/bitmap.c
@@ -182,6 +182,8 @@ int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
 	mapping = sbi->alloc_file->i_mapping;
 	pnr = offset / PAGE_CACHE_BITS;
 	page = read_mapping_page(mapping, pnr, NULL);
+	if (IS_ERR(page))
+		goto kaboom;
 	pptr = kmap(page);
 	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
 	end = pptr + PAGE_CACHE_BITS / 32;
@@ -214,6 +216,8 @@ int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
 		set_page_dirty(page);
 		kunmap(page);
 		page = read_mapping_page(mapping, ++pnr, NULL);
+		if (IS_ERR(page))
+			goto kaboom;
 		pptr = kmap(page);
 		curr = pptr;
 		end = pptr + PAGE_CACHE_BITS / 32;
@@ -231,5 +235,9 @@ out:
 	hfsplus_mark_mdb_dirty(sb);
 	mutex_unlock(&sbi->alloc_mutex);
 
+kaboom:
+	printk(KERN_CRIT "hfsplus: unable to mark blocks free: error %ld\n",
+			PTR_ERR(page));
+	mutex_unlock(&sbi->alloc_mutex);
 	return 0;
 }