From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Date: Tue, 20 Apr 2021 13:59:03 +0100 From: Christoph Hellwig Subject: Re: [RFC v2 6/6] fs: add automatic kernel fs freeze / thaw and remove kthread freezing Message-ID: <20210420125903.GC3604224@infradead.org> References: <20210417001026.23858-1-mcgrof@kernel.org> <20210417001026.23858-7-mcgrof@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210417001026.23858-7-mcgrof@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Luis Chamberlain Cc: rafael@kernel.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, jack@suse.cz, bvanassche@acm.org, jeyu@kernel.org, ebiederm@xmission.com, mchehab@kernel.org, keescook@chromium.org, linux-fsdevel@vger.kernel.org, kernel@tuxforce.de, kexec@lists.infradead.org, linux-kernel@vger.kernel.org > This also removes all the superflous freezer calls on all filesystems > as they are no longer needed as the VFS now performs filesystem > freezing/thaw if the filesystem has support for it. The filesystem > therefore is in charge of properly dealing with quiescing of the > filesystem through its callbacks. Can you split that out from the main logic change? Maybe even into one patch per file system? > +#ifdef CONFIG_PM_SLEEP > +static bool super_should_freeze(struct super_block *sb) > +{ > + if (!sb->s_root) > + return false; > + if (!(sb->s_flags & MS_BORN)) > + return false; This is already done in the iterate_supers_excl and iterate_supers_reverse_excl helpers that this helper is always called through. > + /* > + * We don't freeze virtual filesystems, we skip those filesystems with > + * no backing device. > + */ > + if (sb->s_bdi == &noop_backing_dev_info) > + return false; Why? > + /* No need to freeze read-only filesystems */ > + if (sb_rdonly(sb)) > + return false; freeze_super/thaw_super already takes care of read-only file systems, and IMHO in a better way. > + int error = 0; > + > + spin_lock(&sb_lock); > + if (!super_should_freeze(sb)) > + goto out; > + > + pr_info("%s (%s): freezing\n", sb->s_type->name, sb->s_id); > + > + spin_unlock(&sb_lock); I don't see how super_should_freeze needs sb_lock. But if it does the lock should be taken in the function. > + atomic_inc(&sb->s_active); Doesn't this need a atomic_inc_not_zero if we're racing with a delayed unmount? > + error = freeze_locked_super(sb, false); > + if (error) > + atomic_dec(&sb->s_active); And this really needs something like deactivate_locked_super. > + spin_lock(&sb_lock); > + if (error && error != -EBUSY) > + pr_notice("%s (%s): Unable to freeze, error=%d", > + sb->s_type->name, sb->s_id, error); > + > +out: > + spin_unlock(&sb_lock); Huh, what is the point of sb_lock here? > +int fs_suspend_freeze(void) > +{ > + return iterate_supers_reverse_excl(fs_suspend_freeze_sb, NULL); > +} I'd just fold this helper into its only caller. > + error = __thaw_super_locked(sb, false); > + if (!error) > + atomic_dec(&sb->s_active); > + > + spin_lock(&sb_lock); > + if (error && error != -EBUSY) > + pr_notice("%s (%s): Unable to unfreeze, error=%d", > + sb->s_type->name, sb->s_id, error); > + > +out: > + spin_unlock(&sb_lock); > + return error; > +} > + > +int fs_resume_unfreeze(void) > +{ > + return iterate_supers_excl(fs_suspend_thaw_sb, NULL); > +} Same comments as on the freeze side. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec