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ext3: Avoid filesystem corruption after a crash under heavy delete load

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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. <amir73il@users.sourceforge.net>

Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2010-07-12 21:04:31 +02:00
parent 4c4d390122
commit f25f624263
1 changed files with 25 additions and 21 deletions
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46
fs/ext3/inode.c
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@ -2269,27 +2269,6 @@ static void ext3_free_branches(handle_t *handle, struct inode *inode,
(__le32*)bh->b_data + addr_per_block, (__le32*)bh->b_data + addr_per_block,
depth); 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 * Everything below this this pointer has been
* released. Now let this top-of-subtree go. * 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); 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); ext3_free_blocks(handle, inode, nr, 1);
if (parent_bh) { if (parent_bh) {