2008-08-02 05:25:12

by Theodore Ts'o

[permalink] [raw]
Subject: [PATCH v2] ext4: Fix lack of credits BUG() when deleting a badly fragmented inode

From: Theodore Ts'o <[email protected]>

The extents codepath for ext4_truncate() requests journal transaction
credits in very small chunks, requesting only what is needed. This
means there may not be enough credits left on the transaction handle
after ext4_truncate() returns and then when ext4_delete_inode() tries
finish up its work, it may not have enough transaction credits,
causing a BUG() oops in the jbd2 core.

Also, reserve an extra 2 blocks when starting an ext4_delete_inode()
since we need to update the inode bitmap, as well as update the
orphaned inode linked list.

Signed-off-by: "Theodore Ts'o" <[email protected]>
This new version of the patch reserves a few extra credits to make sure
we have enough for the inode bitmap and the orphaned inode list. We
keep the call to ext4_ext_journal_restart() because the extents truncate
code doesn't allocate any extra slop.

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 59f3f54..685ed20 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -199,8 +199,9 @@ void ext4_delete_inode (struct inode * inode)
if (is_bad_inode(inode))
goto no_delete;

- handle = start_transaction(inode);
+ handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3);
if (IS_ERR(handle)) {
+ ext4_std_error(inode->i_sb, PTR_ERR(handle));
* If we're going to skip the normal cleanup, we still need to
* make sure that the in-core orphan linked list is properly
@@ -213,8 +214,23 @@ void ext4_delete_inode (struct inode * inode)
if (IS_SYNC(inode))
handle->h_sync = 1;
inode->i_size = 0;
+ if (ext4_mark_inode_dirty(handle, inode))
+ goto stop_handle;
if (inode->i_blocks)
+ /*
+ * ext4_ext_truncate() doesn't reserve any slop when it
+ * restarts journal transactions; therefore there may not be
+ * enough credits left in the handle to remove the inode from
+ * the orphan list and set the dtime field.
+ */
+ if (ext4_ext_journal_restart(handle, 3)) {
+ stop_handle:
+ ext4_journal_stop(handle);
+ goto no_delete;
+ }
* Kill off the orphan record which ext4_truncate created.
* AKPM: I think this can be inside the above `if'.