| Message ID | 1365456754-29373-11-git-send-email-jack@suse.cz |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Mon, Apr 08, 2013 at 11:32:15PM +0200, Jan Kara wrote: > jbd2_journal_extend() first checked whether transaction can accept extending > handle with more credits and then added credits to t_outstanding_credits. > This can race with start_this_handle() adding another handle to a transaction > and thus overbooking a transaction. Make jbd2_journal_extend() use > atomic_add_return() to close the race. > > Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Zheng Liu <wenqing.lz@taobao.com> Regards, - Zheng > --- > fs/jbd2/transaction.c | 6 ++++-- > 1 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c > index aee40c9..9639e47 100644 > --- a/fs/jbd2/transaction.c > +++ b/fs/jbd2/transaction.c > @@ -434,11 +434,13 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) > } > > spin_lock(&transaction->t_handle_lock); > - wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks; > + wanted = atomic_add_return(nblocks, > + &transaction->t_outstanding_credits); > > if (wanted > journal->j_max_transaction_buffers) { > jbd_debug(3, "denied handle %p %d blocks: " > "transaction too large\n", handle, nblocks); > + atomic_sub(nblocks, &transaction->t_outstanding_credits); > goto unlock; > } > > @@ -446,6 +448,7 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) > jbd2_log_space_left(journal)) { > jbd_debug(3, "denied handle %p %d blocks: " > "insufficient log space\n", handle, nblocks); > + atomic_sub(nblocks, &transaction->t_outstanding_credits); > goto unlock; > } > > @@ -457,7 +460,6 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) > > handle->h_buffer_credits += nblocks; > handle->h_requested_credits += nblocks; > - atomic_add(nblocks, &transaction->t_outstanding_credits); > result = 0; > > jbd_debug(3, "extended handle %p by %d\n", handle, nblocks); > -- > 1.7.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index aee40c9..9639e47 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -434,11 +434,13 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) } spin_lock(&transaction->t_handle_lock); - wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks; + wanted = atomic_add_return(nblocks, + &transaction->t_outstanding_credits); if (wanted > journal->j_max_transaction_buffers) { jbd_debug(3, "denied handle %p %d blocks: " "transaction too large\n", handle, nblocks); + atomic_sub(nblocks, &transaction->t_outstanding_credits); goto unlock; } @@ -446,6 +448,7 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) jbd2_log_space_left(journal)) { jbd_debug(3, "denied handle %p %d blocks: " "insufficient log space\n", handle, nblocks); + atomic_sub(nblocks, &transaction->t_outstanding_credits); goto unlock; } @@ -457,7 +460,6 @@ int jbd2_journal_extend(handle_t *handle, int nblocks) handle->h_buffer_credits += nblocks; handle->h_requested_credits += nblocks; - atomic_add(nblocks, &transaction->t_outstanding_credits); result = 0; jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
jbd2_journal_extend() first checked whether transaction can accept extending handle with more credits and then added credits to t_outstanding_credits. This can race with start_this_handle() adding another handle to a transaction and thus overbooking a transaction. Make jbd2_journal_extend() use atomic_add_return() to close the race. Signed-off-by: Jan Kara <jack@suse.cz> --- fs/jbd2/transaction.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-)