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Subject[PATCH] vfs: Fix vmtruncate() regression
Date

If __block_prepare_write() was failed in block_write_begin(), the
allocated blocks can be outside of ->i_size.

But new truncate_pagecache() in vmtuncate() does nothing if new < old.
It means the above usage is not working anymore.

So, this patch fixes it by removing "new < old" check. It would need
more cleanup/change. But, now -rc and truncate working is in progress,
so, this tried to fix it minimum change.

Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---
mm/truncate.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff -puN mm/truncate.c~truncate_pagecache-fix mm/truncate.c
--- linux-2.6/mm/truncate.c~truncate_pagecache-fix 2010-01-12 05:43:06.000000000 +0900
+++ linux-2.6-hirofumi/mm/truncate.c 2010-01-12 05:43:06.000000000 +0900
@@ -522,22 +522,20 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages
*/
void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
{
- if (new < old) {
- struct address_space *mapping = inode->i_mapping;
+ struct address_space *mapping = inode->i_mapping;

- /*
- * unmap_mapping_range is called twice, first simply for
- * efficiency so that truncate_inode_pages does fewer
- * single-page unmaps. However after this first call, and
- * before truncate_inode_pages finishes, it is possible for
- * private pages to be COWed, which remain after
- * truncate_inode_pages finishes, hence the second
- * unmap_mapping_range call must be made for correctness.
- */
- unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
- truncate_inode_pages(mapping, new);
- unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
- }
+ /*
+ * unmap_mapping_range is called twice, first simply for
+ * efficiency so that truncate_inode_pages does fewer
+ * single-page unmaps. However after this first call, and
+ * before truncate_inode_pages finishes, it is possible for
+ * private pages to be COWed, which remain after
+ * truncate_inode_pages finishes, hence the second
+ * unmap_mapping_range call must be made for correctness.
+ */
+ unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
+ truncate_inode_pages(mapping, new);
+ unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
}
EXPORT_SYMBOL(truncate_pagecache);

_

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