Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751774Ab2FEOqd (ORCPT ); Tue, 5 Jun 2012 10:46:33 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:38712 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751176Ab2FEOqb (ORCPT ); Tue, 5 Jun 2012 10:46:31 -0400 Date: Tue, 5 Jun 2012 22:45:20 +0800 From: Gavin Shan To: Wanpeng Li Cc: Fengguang Wu , Rob Landley , Alexander Viro , "Eric W. Biederman" , Lucas De Marchi , Andrew Morton , "David S. Miller" , Jan Kara , Mel Gorman , Minchan Kim , David Howells , James Morris , Ingo Molnar , Michel Lespinasse , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v2] remove no longer use of pdflush interface Message-ID: <20120605144519.GA4054@shangw> Reply-To: Gavin Shan References: <1338888372-3555-1-git-send-email-liwp.linux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1338888372-3555-1-git-send-email-liwp.linux@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12060514-5518-0000-0000-000004EDC5D0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7230 Lines: 202 Hi WanPeng, I have 2 questions here. - Why not just remove the proc entry since we needn't it anymore? - 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? Thanks, Gavin >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/