diff options
Diffstat (limited to 'fs/xfs/xfs_log_recover.c')
| -rw-r--r-- | fs/xfs/xfs_log_recover.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c index f05c6c99c4f3..508319039dce 100644 --- a/fs/xfs/xfs_log_recover.c +++ b/fs/xfs/xfs_log_recover.c @@ -5024,16 +5024,27 @@ xlog_recover_process_one_iunlink( } /* - * xlog_iunlink_recover + * Recover AGI unlinked lists * - * This is called during recovery to process any inodes which - * we unlinked but not freed when the system crashed. These - * inodes will be on the lists in the AGI blocks. What we do - * here is scan all the AGIs and fully truncate and free any - * inodes found on the lists. Each inode is removed from the - * lists when it has been fully truncated and is freed. The - * freeing of the inode and its removal from the list must be - * atomic. + * This is called during recovery to process any inodes which we unlinked but + * not freed when the system crashed. These inodes will be on the lists in the + * AGI blocks. What we do here is scan all the AGIs and fully truncate and free + * any inodes found on the lists. Each inode is removed from the lists when it + * has been fully truncated and is freed. The freeing of the inode and its + * removal from the list must be atomic. + * + * If everything we touch in the agi processing loop is already in memory, this + * loop can hold the cpu for a long time. It runs without lock contention, + * memory allocation contention, the need wait for IO, etc, and so will run + * until we either run out of inodes to process, run low on memory or we run out + * of log space. + * + * This behaviour is bad for latency on single CPU and non-preemptible kernels, + * and can prevent other filesytem work (such as CIL pushes) from running. This + * can lead to deadlocks if the recovery process runs out of log reservation + * space. Hence we need to yield the CPU when there is other kernel work + * scheduled on this CPU to ensure other scheduled work can run without undue + * latency. */ STATIC void xlog_recover_process_iunlinks( @@ -5080,6 +5091,7 @@ xlog_recover_process_iunlinks( while (agino != NULLAGINO) { agino = xlog_recover_process_one_iunlink(mp, agno, agino, bucket); + cond_resched(); } } xfs_buf_rele(agibp); |