ext3 corruption fix
PATCH 2/19 ext3 corruption fix
Stephen and Neil Brown recently worked this out. It's a rare situation which only affects data=journal mode.
Fix problem in data=journal mode where writeback could be left pending on a journaled, deleted disk block. If that block then gets reallocated, we can end up with an alias in which the old data can be written back to disk over the new. Thanks to Neil Brown for spotting this and coming up with the initial fix.
fs/jbd/transaction.c renamed from fs/jbd/transaction.c~nb-fix +1 -0
@@ -1861,6 +1861,7 @@ static int journal_unmap_buffer(journal_* running transaction if that is set, but nothing * else. */ JBUFFER_TRACE (jh,"on committing transaction" ); +set_buffer_freed (bh);if (jh->b_next_transaction) {J_ASSERT (jh->b_next_transaction == journal->j_running_transaction);
fs/jbd/commit.c renamed from fs/jbd/commit.c~nb-fix +14 -0
@@ -659,6 +659,20 @@ skip_commit:* there's no point in keeping a checkpoint record for * it. */ bh =jh2bh (jh); + +/* A buffer which has been freed while still being +* journaled by a previous transaction may end up still +* being dirty here, but we want to avoid writing back +* that buffer in the future now that the last use has +* been committed. That's not only a performance gain, +* it also stops aliasing problems if the buffer is left +* behind for writeback and gets reallocated for another +* use in a different page. */ +if (buffer_freed (bh)) { +clear_buffer_freed (bh); +clear_buffer_jbddirty (bh); + } +if (buffer_jdirty (bh)) {JBUFFER_TRACE (jh,"add to new checkpointing trans" );__journal_insert_checkpoint (jh, commit_transaction);
include/linux/jbd.h renamed from include/linux/jbd.h~nb-fix +1 -0
@@ -238,6 +238,7 @@ enum jbd_state_bits { BUFFER_FNS(JBD, jbd) BUFFER_FNS(JBDDirty, jbddirty) TAS_BUFFER_FNS(JBDDirty, jbddirty) +BUFFER_FNS(Freed, freed)static inline struct buffer_head *jh2bh (struct journal_head *jh) {
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