diff options
| -rw-r--r-- | fs/xfs/xfs_log.c | 53 |
1 files changed, 44 insertions, 9 deletions
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index 8497a00e399d..08624dc67317 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1181,11 +1181,14 @@ xlog_iodone(xfs_buf_t *bp) /* log I/O is always issued ASYNC */ ASSERT(XFS_BUF_ISASYNC(bp)); xlog_state_done_syncing(iclog, aborted); + /* - * do not reference the buffer (bp) here as we could race - * with it being freed after writing the unmount record to the - * log. + * drop the buffer lock now that we are done. Nothing references + * the buffer after this, so an unmount waiting on this lock can now + * tear it down safely. As such, it is unsafe to reference the buffer + * (bp) after the unlock as we could race with it being freed. */ + xfs_buf_unlock(bp); } /* @@ -1368,8 +1371,16 @@ xlog_alloc_log( bp = xfs_buf_alloc(mp->m_logdev_targp, 0, BTOBB(log->l_iclog_size), 0); if (!bp) goto out_free_log; - bp->b_iodone = xlog_iodone; + + /* + * The iclogbuf buffer locks are held over IO but we are not going to do + * IO yet. Hence unlock the buffer so that the log IO path can grab it + * when appropriately. + */ ASSERT(xfs_buf_islocked(bp)); + xfs_buf_unlock(bp); + + bp->b_iodone = xlog_iodone; log->l_xbuf = bp; spin_lock_init(&log->l_icloglock); @@ -1398,6 +1409,9 @@ xlog_alloc_log( if (!bp) goto out_free_iclog; + ASSERT(xfs_buf_islocked(bp)); + xfs_buf_unlock(bp); + bp->b_iodone = xlog_iodone; iclog->ic_bp = bp; iclog->ic_data = bp->b_addr; @@ -1422,7 +1436,6 @@ xlog_alloc_log( iclog->ic_callback_tail = &(iclog->ic_callback); iclog->ic_datap = (char *)iclog->ic_data + log->l_iclog_hsize; - ASSERT(xfs_buf_islocked(iclog->ic_bp)); init_waitqueue_head(&iclog->ic_force_wait); init_waitqueue_head(&iclog->ic_write_wait); @@ -1631,6 +1644,12 @@ xlog_cksum( * we transition the iclogs to IOERROR state *after* flushing all existing * iclogs to disk. This is because we don't want anymore new transactions to be * started or completed afterwards. + * + * We lock the iclogbufs here so that we can serialise against IO completion + * during unmount. We might be processing a shutdown triggered during unmount, + * and that can occur asynchronously to the unmount thread, and hence we need to + * ensure that completes before tearing down the iclogbufs. Hence we need to + * hold the buffer lock across the log IO to acheive that. */ STATIC int xlog_bdstrat( @@ -1638,6 +1657,7 @@ xlog_bdstrat( { struct xlog_in_core *iclog = bp->b_fspriv; + xfs_buf_lock(bp); if (iclog->ic_state & XLOG_STATE_IOERROR) { xfs_buf_ioerror(bp, EIO); xfs_buf_stale(bp); @@ -1645,7 +1665,8 @@ xlog_bdstrat( /* * It would seem logical to return EIO here, but we rely on * the log state machine to propagate I/O errors instead of - * doing it here. + * doing it here. Similarly, IO completion will unlock the + * buffer, so we don't do it here. */ return 0; } @@ -1847,14 +1868,28 @@ xlog_dealloc_log( xlog_cil_destroy(log); /* - * always need to ensure that the extra buffer does not point to memory - * owned by another log buffer before we free it. + * Cycle all the iclogbuf locks to make sure all log IO completion + * is done before we tear down these buffers. */ + iclog = log->l_iclog; + for (i = 0; i < log->l_iclog_bufs; i++) { + xfs_buf_lock(iclog->ic_bp); + xfs_buf_unlock(iclog->ic_bp); + iclog = iclog->ic_next; + } + + /* + * Always need to ensure that the extra buffer does not point to memory + * owned by another log buffer before we free it. Also, cycle the lock + * first to ensure we've completed IO on it. + */ + xfs_buf_lock(log->l_xbuf); + xfs_buf_unlock(log->l_xbuf); xfs_buf_set_empty(log->l_xbuf, BTOBB(log->l_iclog_size)); xfs_buf_free(log->l_xbuf); iclog = log->l_iclog; - for (i=0; i<log->l_iclog_bufs; i++) { + for (i = 0; i < log->l_iclog_bufs; i++) { xfs_buf_free(iclog->ic_bp); next_iclog = iclog->ic_next; kmem_free(iclog); |