From f25f624263445785b94f39739a6339ba9ed3275d Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 12 Jul 2010 21:04:31 +0200 Subject: [PATCH] ext3: Avoid filesystem corruption after a crash under heavy delete load It can happen that ext3_free_branches calls ext3_forget() for an indirect block in an earlier transaction than a transaction in which we clear pointer to this indirect block. Thus if we crash before a transaction clearing the block pointer is committed, we will see indirect block pointing to already freed blocks and complain during orphan list cleanup. The fix is simple: Make sure ext3_forget() is called in the transaction doing block pointer clearing. This is a backport of an ext4 fix by Amir G. Signed-off-by: Jan Kara --- fs/ext3/inode.c | 46 +++++++++++++++++++++++++--------------------- 1 file changed, 25 insertions(+), 21 deletions(-) diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c index a786db403efc..436e5bbccbc2 100644 --- a/fs/ext3/inode.c +++ b/fs/ext3/inode.c @@ -2269,27 +2269,6 @@ static void ext3_free_branches(handle_t *handle, struct inode *inode, (__le32*)bh->b_data + addr_per_block, depth); - /* - * We've probably journalled the indirect block several - * times during the truncate. But it's no longer - * needed and we now drop it from the transaction via - * journal_revoke(). - * - * That's easy if it's exclusively part of this - * transaction. But if it's part of the committing - * transaction then journal_forget() will simply - * brelse() it. That means that if the underlying - * block is reallocated in ext3_get_block(), - * unmap_underlying_metadata() will find this block - * and will try to get rid of it. damn, damn. - * - * If this block has already been committed to the - * journal, a revoke record will be written. And - * revoke records must be emitted *before* clearing - * this block's bit in the bitmaps. - */ - ext3_forget(handle, 1, inode, bh, bh->b_blocknr); - /* * Everything below this this pointer has been * released. Now let this top-of-subtree go. @@ -2313,6 +2292,31 @@ static void ext3_free_branches(handle_t *handle, struct inode *inode, truncate_restart_transaction(handle, inode); } + /* + * We've probably journalled the indirect block several + * times during the truncate. But it's no longer + * needed and we now drop it from the transaction via + * journal_revoke(). + * + * That's easy if it's exclusively part of this + * transaction. But if it's part of the committing + * transaction then journal_forget() will simply + * brelse() it. That means that if the underlying + * block is reallocated in ext3_get_block(), + * unmap_underlying_metadata() will find this block + * and will try to get rid of it. damn, damn. Thus + * we don't allow a block to be reallocated until + * a transaction freeing it has fully committed. + * + * We also have to make sure journal replay after a + * crash does not overwrite non-journaled data blocks + * with old metadata when the block got reallocated for + * data. Thus we have to store a revoke record for a + * block in the same transaction in which we free the + * block. + */ + ext3_forget(handle, 1, inode, bh, bh->b_blocknr); + ext3_free_blocks(handle, inode, nr, 1); if (parent_bh) {