Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753175Ab2FFDBS (ORCPT ); Tue, 5 Jun 2012 23:01:18 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:50457 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752040Ab2FFDBQ (ORCPT ); Tue, 5 Jun 2012 23:01:16 -0400 Date: Wed, 6 Jun 2012 11:00:55 +0800 From: Wanpeng Li To: Gavin Shan Cc: Andrew Morton , Fengguang Wu , Rob Landley , Alexander Viro , "Eric W. Biederman" , Lucas De Marchi , "David S. Miller" , Jan Kara , Mel Gorman , Minchan Kim , DavidHowells , James Morris , Ingo Molnar , "MichelLespinasse@kernel" , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Wanpeng Li Subject: Re: [PATCH v2] remove no longer use of pdflush interface Message-ID: <20120606030028.GA10953@kernel> Reply-To: Wanpeng Li References: <1338888372-3555-1-git-send-email-liwp.linux@gmail.com> <20120605144519.GA4054@shangw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120605144519.GA4054@shangw> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7834 Lines: 212 On Tue, Jun 05, 2012 at 10:45:20PM +0800, Gavin Shan wrote: Hi Gavin, > >- Why not just remove the proc entry since we needn't it anymore? Some user applications maybe still use this interface, so we should take attention to back-compatibility issues. >- If we really want to keep the entry and just output warning message, we *only* > can see the message out of system console. It's reasonable to put the message > into the buffer directly so that any users from system console/telnet/ssh can > see the warning message? Maybe this is a good idea. > >>From: Wanpeng Li >> >>------------------ >> >>Change in v2: >> >>* add printk warning >>* add description in Documentation >> >>------------------ >> >>Signed-off-by: Wanpeng Li >>--- >> .../ABI/obsolete/proc-sys-vm-nr_pdflush_threads | 5 +++++ >> Documentation/feature-removal-schedule.txt | 8 ++++++++ >> Documentation/sysctl/vm.txt | 11 ----------- >> fs/fs-writeback.c | 5 ----- >> include/linux/sysctl.h | 3 +++ >> include/linux/writeback.h | 5 ----- >> kernel/sysctl.c | 18 +++++++++++++----- >> kernel/sysctl_binary.c | 2 +- >> 8 files changed, 30 insertions(+), 27 deletions(-) >> create mode 100644 Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads >> >>diff --git a/Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads b/Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads >>new file mode 100644 >>index 0000000..edbe548 >>--- /dev/null >>+++ b/Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads >>@@ -0,0 +1,5 @@ >>+What: /proc/sys/vm/nr_pdflush_threads >>+Date: June 2012 >>+Contact: Wanpeng Li >>+Description: Since pdflush is replaced by per-BDI flusher, the interface of old pdflush >>+ exported in /proc/sys/vm/ should be removed. >>diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt >>index e4b5775..7eea1ee 100644 >>--- a/Documentation/feature-removal-schedule.txt >>+++ b/Documentation/feature-removal-schedule.txt >>@@ -6,6 +6,14 @@ be removed from this file. >> >> --------------------------- >> >>+What: /proc/sys/vm/nr_pdflush_threads >>+When: 2012 >>+Why: Since pdflush is deprecated, the interface exported in /proc/sys/vm/ >>+ should be removed. >>+Who: Wanpeng Li >>+ >>+--------------------------- >>+ >> What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle >> When: 2012 >> Why: This optional sub-feature of APM is of dubious reliability, >>diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt >>index 96f0ee8..71c17d2 100644 >>--- a/Documentation/sysctl/vm.txt >>+++ b/Documentation/sysctl/vm.txt >>@@ -42,7 +42,6 @@ Currently, these files are in /proc/sys/vm: >> - mmap_min_addr >> - nr_hugepages >> - nr_overcommit_hugepages >>-- nr_pdflush_threads >> - nr_trim_pages (only if CONFIG_MMU=n) >> - numa_zonelist_order >> - oom_dump_tasks >>@@ -426,16 +425,6 @@ See Documentation/vm/hugetlbpage.txt >> >> ============================================================== >> >>-nr_pdflush_threads >>- >>-The current number of pdflush threads. This value is read-only. >>-The value changes according to the number of dirty pages in the system. >>- >>-When necessary, additional pdflush threads are created, one per second, up to >>-nr_pdflush_threads_max. >>- >>-============================================================== >>- >> nr_trim_pages >> >> This is available only on NOMMU kernels. >>diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c >>index 539f36c..30ddb8a 100644 >>--- a/fs/fs-writeback.c >>+++ b/fs/fs-writeback.c >>@@ -52,11 +52,6 @@ struct wb_writeback_work { >> struct completion *done; /* set if the caller waits */ >> }; >> >>-/* >>- * We don't actually have pdflush, but this one is exported though /proc... >>- */ >>-int nr_pdflush_threads; >>- >> /** >> * writeback_in_progress - determine whether there is writeback in progress >> * @bdi: the device's backing_dev_info structure. >>diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h >>index c34b4c8..f25be74 100644 >>--- a/include/linux/sysctl.h >>+++ b/include/linux/sysctl.h >>@@ -964,6 +964,9 @@ extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int, >> void __user *, size_t *, loff_t *); >> extern int proc_do_large_bitmap(struct ctl_table *, int, >> void __user *, size_t *, loff_t *); >>+extern int proc_deprecated(struct ctl_table *, int, >>+ void __user *, size_t *, loff_t *); >>+ >> >> /* >> * Register a set of sysctl names by calling register_sysctl_table >>diff --git a/include/linux/writeback.h b/include/linux/writeback.h >>index a2b84f5..13b5df7 100644 >>--- a/include/linux/writeback.h >>+++ b/include/linux/writeback.h >>@@ -193,9 +193,4 @@ void tag_pages_for_writeback(struct address_space *mapping, >> >> void account_page_redirty(struct page *page); >> >>-/* pdflush.c */ >>-extern int nr_pdflush_threads; /* Global so it can be exported to sysctl >>- read-only. */ >>- >>- >> #endif /* WRITEBACK_H */ >>diff --git a/kernel/sysctl.c b/kernel/sysctl.c >>index 4ab1187..1ab53cb 100644 >>--- a/kernel/sysctl.c >>+++ b/kernel/sysctl.c >>@@ -1095,11 +1095,9 @@ static struct ctl_table vm_table[] = { >> .extra1 = &zero, >> }, >> { >>- .procname = "nr_pdflush_threads", >>- .data = &nr_pdflush_threads, >>- .maxlen = sizeof nr_pdflush_threads, >>- .mode = 0444 /* read-only*/, >>- .proc_handler = proc_dointvec, >>+ .procname = "nr_pdflush_threads", >>+ .mode = 0444 /* read-only */, >>+ .proc_handler = proc_deprecated, >> }, >> { >> .procname = "swappiness", >>@@ -2505,6 +2503,15 @@ int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int write, >> >> #endif /* CONFIG_PROC_SYSCTL */ >> >>+/* notice associated proc deprecated */ >>+int proc_deprecated(struct ctl_table *table, int write, >>+ void __user *buffer, size_t *lenp, loff_t *ppos) >>+{ >>+ printk(KERN_WARNING "%s exported in /proc is deprecated\n", >>+ table->procname); >>+ return -ENOSYS; >>+} >>+ >> /* >> * No sense putting this after each symbol definition, twice, >> * exception granted :-) >>@@ -2517,3 +2524,4 @@ EXPORT_SYMBOL(proc_dointvec_ms_jiffies); >> EXPORT_SYMBOL(proc_dostring); >> EXPORT_SYMBOL(proc_doulongvec_minmax); >> EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax); >>+EXPORT_SYMBOL(proc_deprecated); >>diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c >>index a650694..65bdcf1 100644 >>--- a/kernel/sysctl_binary.c >>+++ b/kernel/sysctl_binary.c >>@@ -147,7 +147,7 @@ static const struct bin_table bin_vm_table[] = { >> { CTL_INT, VM_DIRTY_RATIO, "dirty_ratio" }, >> /* VM_DIRTY_WB_CS "dirty_writeback_centisecs" no longer used */ >> /* VM_DIRTY_EXPIRE_CS "dirty_expire_centisecs" no longer used */ >>- { CTL_INT, VM_NR_PDFLUSH_THREADS, "nr_pdflush_threads" }, >>+ /* VM_NR_PDFLUSH_THREADS "nr_pdflush_threads" no longer used */ >> { CTL_INT, VM_OVERCOMMIT_RATIO, "overcommit_ratio" }, >> /* VM_PAGEBUF unused */ >> /* VM_HUGETLB_PAGES "nr_hugepages" no longer used */ >>-- >>1.7.9.5 >> > >-- >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/ -- 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/