On Fri, Jul 19, 2013 at 05:31:38PM -0500, Chandra Seetharaman wrote:
>
> 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 <sekharan@xxxxxxxxxx>
Looks fine.
Reviewed-by: Ben Myers <bpm@xxxxxxx>
Applied.
|