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Jan Kara de1b794130 jbd2: Fix oops in jbd2_journal_remove_journal_head() ... jbd2_journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 jbd2_journal_commit_transaction() ... processing t_forget list __jbd2_journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); jbd2_journal_try_to_free_buffers() jbd2_journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() jbd2_journal_put_journal_head(jh) jbd2_journal_remove_journal_head(bh); jbd2_journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after jbd2_journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via jbd2_journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]jbd2_journal_refile_buffer(), [__]jbd2_journal_unfile_buffer(), and __jdb2_journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>		14 years ago
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Kconfig	Revert "task_struct: make journal_info conditional"	15 years ago
Makefile	…
checkpoint.c	jbd2: Fix oops in jbd2_journal_remove_journal_head()	14 years ago
commit.c	jbd2: Fix oops in jbd2_journal_remove_journal_head()	14 years ago
journal.c	jbd2: Fix oops in jbd2_journal_remove_journal_head()	14 years ago
recovery.c	jbd2: move debug message into debug #ifdef	14 years ago
revoke.c	Fix common misspellings	14 years ago
transaction.c	jbd2: Fix oops in jbd2_journal_remove_journal_head()	14 years ago