Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754756Ab2FFHmH (ORCPT ); Wed, 6 Jun 2012 03:42:07 -0400 Received: from natasha.panasas.com ([67.152.220.90]:45815 "EHLO natasha.panasas.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751640Ab2FFHmE (ORCPT ); Wed, 6 Jun 2012 03:42:04 -0400 Message-ID: <4FCF082B.2080305@panasas.com> Date: Wed, 6 Jun 2012 10:35:07 +0300 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:8.0) Gecko/20111113 Thunderbird/8.0 MIME-Version: 1.0 To: Wanpeng Li CC: Andrew Morton , Fengguang Wu , Rob Landley , Alexander Viro , "Eric W.Biederman" , Lucas De Marchi , "David S. Miller" , Jan Kara , Mel Gorman , Minchan Kim , James Morris , Ingo Molnar , Michel Lespinasse , , , , Gavin Shan , Wanpeng Li Subject: Re: [PATCH v3] remove no longer use of pdflush interface References: <1338960385-14127-1-git-send-email-liwp.linux@gmail.com> In-Reply-To: <1338960385-14127-1-git-send-email-liwp.linux@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7841 Lines: 212 On 06/06/2012 08:26 AM, Wanpeng Li wrote: > From: Wanpeng Li > > Since per-BDI flusher introduced to linux 2.6, pdflush mechanism is not > used any more. But the old interface of pdflush exported in /proc/sys/vm/ > is still there. In order to take attention to back-compatibility issues, > printk warning information and return -ENOSYS to notice the users the > interface is removed. > > Signed-off-by: Wanpeng Li > > ------------------ > > v3: > > * rename proc_deprecated() to proc_obsolete() > * replace printk in proc_obsolete by prink_once and change warning information > > v2: > > * add printk warning > * add description in Documentation > > v1: > > * remove nr_pdflush_threads associated codes > > ------------------ > --- > .../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 56000b3..8e4a60c 100644 > --- a/Documentation/feature-removal-schedule.txt > +++ b/Documentation/feature-removal-schedule.txt > @@ -13,6 +13,14 @@ Who: Jim Cromie , Jason Baron > > --------------------------- > > +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 8d2fb8c..f2d0109 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..5fa7bfa 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_obsolete(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 6d0a0fc..c66fe33 100644 > --- a/include/linux/writeback.h > +++ b/include/linux/writeback.h > @@ -189,9 +189,4 @@ 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..8d95a54 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_obsolete, > }, > { > .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 obsoleted */ > +int proc_obsolete(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, loff_t *ppos) > +{ > + printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n", > + table->procname); What Andrew meant is that if you use printk_once here than it means you will no longer be able to also use this generic functions for other obsolete entries. Since only the very first one will print. Boaz > + 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_obsolete); > 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 */ -- 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/