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Thu, 28 May 2026 07:10:00 -0700 (PDT) Received: from qiwenjie-ThinkCentre-M760t.mioffice.cn ([43.224.245.241]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2bf13d83264sm9398205ad.17.2026.05.28.07.09.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 28 May 2026 07:10:00 -0700 (PDT) From: Wenjie Qi X-Google-Original-From: Wenjie Qi To: jaegeuk@kernel.org, chao@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, qiwenjie@xiaomi.com, qwjhust@gmail.com Subject: [PATCH] f2fs: skip clean inode update during fsync Date: Thu, 28 May 2026 22:09:54 +0800 Message-ID: <20260528140954.3205736-1-qiwenjie@xiaomi.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" f2fs_do_sync_file() calls f2fs_skip_inode_update() before deciding whether it has to write an inode block and continue into the recovery info/flush path. For a full fsync, f2fs_skip_inode_update() currently returns false when FI_AUTO_RECOVER is not set. That makes fsync on an already clean file call f2fs_write_inode(). f2fs_write_inode() then returns immediately if the in-memory timestamps match the inode block and FI_DIRTY_INODE is not set, but f2fs_do_sync_file() still continues through go_write and may end at f2fs_issue_flush(). Avoid that unnecessary path for clean, time-consistent inodes without FI_AUTO_RECOVER. Keep the existing conservative checks for keep-size files and non-block-aligned i_size before allowing the skip, and leave the FI_AUTO_RECOVER path unchanged. On a QEMU/KASAN test VM, repeated fsync() on an existing clean F2FS file improved from about 35.7 us/fsync to about 1.13 us/fsync. The baseline issued one flush per fsync, while the patched kernel kept the F2FS flush count unchanged over 140000 clean fsync calls. Signed-off-by: Wenjie Qi --- fs/f2fs/f2fs.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 9f24287de4c3..ebd485abecb4 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3668,11 +3668,13 @@ static inline bool f2fs_skip_inode_update(struct in= ode *inode, int dsync) spin_unlock(&sbi->inode_lock[DIRTY_META]); return ret; } - if (!is_inode_flag_set(inode, FI_AUTO_RECOVER) || - file_keep_isize(inode) || - i_size_read(inode) & ~PAGE_MASK) + if (file_keep_isize(inode) || i_size_read(inode) & ~PAGE_MASK) return false; =20 + if (!is_inode_flag_set(inode, FI_AUTO_RECOVER)) + return f2fs_is_time_consistent(inode) && + !is_inode_flag_set(inode, FI_DIRTY_INODE); + if (!f2fs_is_time_consistent(inode)) return false; =20 --=20 2.43.0