From: Chandra Seetharaman Date: Fri, 19 Jul 2013 22:31:38 +0000 (-0500) Subject: xfs: Fix a deadlock in xfs_log_commit_cil() code path X-Git-Tag: v3.12-rc1~22^2~123 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=297aa63769e6ae06b7db97eb76c9211beeb32c69;p=linux-2.6-block.git xfs: Fix a deadlock in xfs_log_commit_cil() code path While testing and rearranging pquota/gquota code, I stumbled on a xfs_shutdown() during a mount. But the mount just hung. Debugged and found that there is a deadlock involving &log->l_cilp->xc_ctx_lock. It is in a code path where &log->l_cilp->xc_ctx_lock is first acquired in read mode and some levels down the same semaphore is being acquired in write mode causing a deadlock. This is the stack: xfs_log_commit_cil -> acquires &log->l_cilp->xc_ctx_lock in read mode xlog_print_tic_res xfs_force_shutdown xfs_log_force_umount xlog_cil_force xlog_cil_force_lsn xlog_cil_push_foreground xlog_cil_push - tries to acquire same semaphore in write mode This patch fixes the deadlock by changing the reason code for xfs_force_shutdown in xlog_print_tic_res() to SHUTDOWN_LOG_IO_ERROR. SHUTDOWN_LOG_IO_ERROR is the right reason code to be set since we are in the log path. Thanks to Dave for suggesting this solution. Signed-off-by: Chandra Seetharaman Reviewed-by: Ben Myers Signed-off-by: Ben Myers --- diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c index d852a2b3e1fd..bf89eb97fefd 100644 --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -1941,7 +1941,7 @@ xlog_print_tic_res( xfs_alert_tag(mp, XFS_PTAG_LOGRES, "xlog_write: reservation ran out. Need to up reservation"); - xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); + xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR); } /*