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Wed, 9 Apr 2025 18:30:28 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id c1thBsS89mf4HAAAD6G6ig (envelope-from ); Wed, 09 Apr 2025 18:30:28 +0000 Date: Wed, 9 Apr 2025 20:30:22 +0200 From: David Sterba To: Yangtao Li Cc: clm@fb.com, josef@toxicpanda.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] btrfs: convert to spinlock guards in btrfs_update_ioctl_balance_args() Message-ID: <20250409183022.GG13292@suse.cz> Reply-To: dsterba@suse.cz References: <20250409125724.145597-1-frank.li@vivo.com> Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250409125724.145597-1-frank.li@vivo.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) X-Rspamd-Queue-Id: 3C14C1F38D X-Spam-Score: -4.21 X-Rspamd-Action: no action X-Spamd-Result: default: False [-4.21 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; HAS_REPLYTO(0.30)[dsterba@suse.cz]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCVD_TLS_ALL(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCPT_COUNT_FIVE(0.00)[6]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; REPLYTO_ADDR_EQ_FROM(0.00)[]; DKIM_TRACE(0.00)[suse.cz:+]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; REPLYTO_DOM_NEQ_TO_DOM(0.00)[] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Flag: NO X-Spam-Level: On Wed, Apr 09, 2025 at 06:57:22AM -0600, Yangtao Li wrote: > To simplify handling, use the guard helper to let the compiler care for > unlocking. > > Signed-off-by: Yangtao Li > --- > fs/btrfs/ioctl.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index 63aeacc54945..7cec105a4cb0 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -3438,9 +3438,8 @@ void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info, > memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta)); > memcpy(&bargs->sys, &bctl->sys, sizeof(bargs->sys)); > > - spin_lock(&fs_info->balance_lock); > + guard(spinlock)(&fs_info->balance_lock); Please don't do the guard() conversions in fs/btrfs/, the explicit locking is the preferred style. If other subsystems use the scoped locking guards then let them do it. I personally hate it as it totally disrupts the perception of visibly demarcated critical sections. I don't see the benefit comparing saved lines of code vs clear and understandable code. We rarely have a clear case for the guards, I found a few where it could be used but then this means we have 2 styles of locking, yet another code pattern to learn.