From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: [PATCH 2/4] vfs: Move autoclose of BSD accounting into a work queue Date: Mon, 14 Apr 2014 00:40:44 -0700 Message-ID: <87mwfouznn.fsf_-_@x220.int.ebiederm.org> References: <87sipmbe8x.fsf@x220.int.ebiederm.org> <20140409175322.GZ18016@ZenIV.linux.org.uk> <20140409182830.GA18016@ZenIV.linux.org.uk> <87txa286fu.fsf@x220.int.ebiederm.org> <87fvlm860e.fsf_-_@x220.int.ebiederm.org> <20140409232423.GB18016@ZenIV.linux.org.uk> <87lhva5h4k.fsf@x220.int.ebiederm.org> <20140413053956.GM18016@ZenIV.linux.org.uk> <87zjjp3e7w.fsf@x220.int.ebiederm.org> <87ppkl1xb7.fsf@x220.int.ebiederm.org> <20140413215242.GP18016@ZenIV.linux.org.uk> <87y4z8uzqw.fsf_-_@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain Cc: Linus Torvalds , "Serge E. Hallyn" , Linux-Fsdevel , Kernel Mailing List , Andy Lutomirski , Rob Landley , Miklos Szeredi , Christoph Hellwig , Karel Zak , "J. Bruce Fields" , Fengguang Wu , tytso@mit.edu To: Al Viro Return-path: In-Reply-To: <87y4z8uzqw.fsf_-_@x220.int.ebiederm.org> (Eric W. Biederman's message of "Mon, 14 Apr 2014 00:38:47 -0700") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org The autoclose of BSD accounting writes a record to the BSD accounting file. When mntput is called from moderaly deep within the stack the (3KiB or so) generating I/O can be problemenatic as some I/O paths require nearly 5KiB of stack on their own. Avoid the possibility of stack overflow by moving the close of the BSD accounting file into a work queue. Signed-off-by: "Eric W. Biederman" --- kernel/acct.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/kernel/acct.c b/kernel/acct.c index 8d6e145138bb..1853dd4a1d01 100644 --- a/kernel/acct.c +++ b/kernel/acct.c @@ -93,6 +93,7 @@ struct bsd_acct_struct { static DEFINE_SPINLOCK(acct_lock); static LIST_HEAD(acct_list); +static LIST_HEAD(acct_close_list); /* * Check the amount of free space and suspend/resume accordingly. @@ -280,6 +281,20 @@ SYSCALL_DEFINE1(acct, const char __user *, name) return error; } +static void acct_close_mnts(struct work_struct *unused) +{ + struct bsd_acct_struct *acct; + + spin_lock(&acct_lock); +restart: + list_for_each_entry(acct, &acct_close_list, list) { + acct_file_reopen(acct, NULL, NULL); + goto restart; + } + spin_unlock(&acct_lock); +} +static DECLARE_WORK(acct_close_work, acct_close_mnts); + /** * acct_auto_close - turn off a filesystem's accounting if it is on * @m: vfsmount being shut down @@ -289,15 +304,15 @@ SYSCALL_DEFINE1(acct, const char __user *, name) */ void acct_auto_close_mnt(struct vfsmount *m) { - struct bsd_acct_struct *acct; + struct bsd_acct_struct *acct, *tmp; spin_lock(&acct_lock); -restart: - list_for_each_entry(acct, &acct_list, list) + list_for_each_entry_safe(acct, tmp, &acct_list, list) { if (acct->file && acct->file->f_path.mnt == m) { - acct_file_reopen(acct, NULL, NULL); - goto restart; + list_move_tail(&acct->list, &acct_close_list); + schedule_work(&acct_close_work); } + } spin_unlock(&acct_lock); } -- 1.9.1