Messages in this thread Patch in this message | | | Date | Tue, 25 Mar 2003 17:39:40 GMT | From | Stephen Tweedie <> | Subject | [Patch 2/8] 2.4: Fix for enormous numbers of buffers on BUF_LOCKED |
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Buffer_head syncing places BUF_DIRTY buffers on the BUF_LOCKED, but buffers can stay there indefinitely, upsetting buffer accounting. The symptoms are benign, mostly just nonsensical numbers in alt-sysrq-m output, but it's pretty cheap to clean these up in kupdated nonetheless, just by refiling any unlocked buffers which happen to be at the head of the BUF_LOCKED list. (We stop at the first locked buffer rather than walking the whole list, avoiding walking any buffers more than once.)
--- linux-2.4-ext3push/fs/buffer.c.=K0001=.orig 2003-03-25 10:59:15.000000000 +0000 +++ linux-2.4-ext3push/fs/buffer.c 2003-03-25 10:59:15.000000000 +0000 @@ -2958,6 +2958,30 @@ int bdflush(void *startup) } } + +/* + * Do some IO post-processing here!!! + */ +void do_io_postprocessing(void) +{ + int i; + struct buffer_head *bh, *next; + + spin_lock(&lru_list_lock); + bh = lru_list[BUF_LOCKED]; + if (bh) { + for (i = nr_buffers_type[BUF_LOCKED]; i-- > 0; bh = next) { + next = bh->b_next_free; + + if (!buffer_locked(bh)) + __refile_buffer(bh); + else + break; + } + } + spin_unlock(&lru_list_lock); +} + /* * This is the kernel update daemon. It was used to live in userspace * but since it's need to run safely we want it unkillable by mistake. @@ -3009,6 +3033,7 @@ int kupdate(void *startup) #ifdef DEBUG printk(KERN_DEBUG "kupdate() activated...\n"); #endif + do_io_postprocessing(); sync_old_buffers(); run_task_queue(&tq_disk); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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