vm.block_dump is nasty in that it dumps IO traces directly to printk. It isn't scalable and can easily lead to looping behavior - IO generating kernel message which in turn genreates log IO, ad infinitum.
Now that proper tracepoints are in place, vm.block_dump isn't necessary. Generate a warning if used so that it can be removed down the road. Signed-off-by: Tejun Heo <[email protected]> --- include/linux/writeback.h | 3 +++ kernel/sysctl.c | 2 +- mm/page-writeback.c | 14 ++++++++++++++ 3 files changed, 18 insertions(+), 1 deletion(-) diff --git a/include/linux/writeback.h b/include/linux/writeback.h index b82a83a..678ee6d 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -143,6 +143,9 @@ extern int dirty_ratio_handler(struct ctl_table *table, int write, extern int dirty_bytes_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +extern int block_dump_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); struct ctl_table; int dirty_writeback_centisecs_handler(struct ctl_table *, int, diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c88878d..9e7f7b5 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1288,7 +1288,7 @@ static struct ctl_table vm_table[] = { .data = &block_dump, .maxlen = sizeof(block_dump), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = block_dump_handler, .extra1 = &zero, }, { diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 6f42712..5548bef 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -390,6 +390,20 @@ int dirty_bytes_handler(struct ctl_table *table, int write, return ret; } +int block_dump_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + static bool warned = false; + int ret; + + ret = proc_dointvec(table, write, buffer, lenp, ppos); + if (!warned && block_dump) { + pr_warning("sysctl: vm.block_dump is scheduled for removal. Please use tracepoints instead.\n"); + warned = true; + } + return ret; +} + static unsigned long wp_next_time(unsigned long cur_time) { cur_time += VM_COMPLETIONS_PERIOD_LEN; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
