A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-29 19:21:31 -04:00
Code Issues Projects Releases Packages Wiki Activity

ext4: fix deadlock in journal_unmap_buffer()

Browse source 
We cannot wait for transaction commit in journal_unmap_buffer()
because we hold page lock which ranks below transaction start.  We
solve the issue by bailing out of journal_unmap_buffer() and
jbd2_journal_invalidatepage() with -EBUSY.  Caller is then responsible
for waiting for transaction commit to finish and try invalidation
again. Since the issue can happen only for page stradding i_size, it
is simple enough to manually call jbd2_journal_invalidatepage() for
such page from ext4_setattr(), check the return value and wait if
necessary.

Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
This commit is contained in:
Jan Kara 2012-12-25 13:29:52 -05:00 • committed by Theodore Ts'o
commit 53e872681f
3 changed files with 86 additions and 25 deletions
Download patch file Download diff file Expand all files Collapse all files

27
fs/jbd2/transaction.c
View file

@ -1840,7 +1840,6 @@ static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
BUFFER_TRACE(bh, "entry");
retry:
/*
* It is safe to proceed here without the j_list_lock because the
* buffers cannot be stolen by try_to_free_buffers as long as we are
@ -1935,14 +1934,11 @@ retry:
* for commit and try again.
*/
if (partial_page) {
tid_t tid = journal->j_committing_transaction->t_tid;
jbd2_journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
write_unlock(&journal->j_state_lock);
jbd2_log_wait_commit(journal, tid);
goto retry;
return -EBUSY;
}
/*
* OK, buffer won't be reachable after truncate. We just set
@ -2003,21 +1999,23 @@ zap_buffer_unlocked:
* @page: page to flush
* @offset: length of page to invalidate.
*
* Reap page buffers containing data after offset in page.
*
* Reap page buffers containing data after offset in page. Can return -EBUSY
* if buffers are part of the committing transaction and the page is straddling
* i_size. Caller then has to wait for current commit and try again.
*/
void jbd2_journal_invalidatepage(journal_t *journal,
struct page *page,
unsigned long offset)
int jbd2_journal_invalidatepage(journal_t *journal,
struct page *page,
unsigned long offset)
{
struct buffer_head *head, *bh, *next;
unsigned int curr_off = 0;
int may_free = 1;
int ret = 0;
if (!PageLocked(page))
BUG();
if (!page_has_buffers(page))
return;
return 0;
/* We will potentially be playing with lists other than just the
* data lists (especially for journaled data mode), so be
@ -2031,9 +2029,11 @@ void jbd2_journal_invalidatepage(journal_t *journal,
if (offset <= curr_off) {
/* This block is wholly outside the truncation point */
lock_buffer(bh);
may_free &= journal_unmap_buffer(journal, bh,
offset > 0);
ret = journal_unmap_buffer(journal, bh, offset > 0);
unlock_buffer(bh);
if (ret < 0)
return ret;
may_free &= ret;
}
curr_off = next_off;
bh = next;
@ -2044,6 +2044,7 @@ void jbd2_journal_invalidatepage(journal_t *journal,
if (may_free && try_to_free_buffers(page))
J_ASSERT(!page_has_buffers(page));
}
return 0;
}
/*