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Tue, 30 Jun 2026 03:08:33 -0700 From: Yun Zhou To: , , , , , , , , CC: , , , Subject: [PATCH v12 1/4] fs: add iput_if_not_last() helper Date: Tue, 30 Jun 2026 18:08:26 +0800 Message-ID: <20260630100829.1257618-2-yun.zhou@windriver.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260630100829.1257618-1-yun.zhou@windriver.com> References: <20260630100829.1257618-1-yun.zhou@windriver.com> Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-GUID: 847kMgzQmbSQnyPpFQOLfeoZUEUUQ1Wm X-Authority-Analysis: v=2.4 cv=HsJG3UTS c=1 sm=1 tr=0 ts=6a4395a5 cx=c_pps a=AbJuCvi4Y3V6hpbCNWx0WA==:117 a=AbJuCvi4Y3V6hpbCNWx0WA==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=bi6dqmuHe4P4UrxVR6um:22 a=HK-ge7EqtdluswH-FwHe:22 a=t7CeM3EgAAAA:8 a=VwQbUJbxAAAA:8 a=vCr0if_IiwaKUNF-nsEA:9 a=FdTzh2GWekK77mhwV6Dw:22 X-Proofpoint-ORIG-GUID: 847kMgzQmbSQnyPpFQOLfeoZUEUUQ1Wm X-Proofpoint-Spam-Info: AW1haW4tMjYwNjMwMDA5MSBTYWx0ZWRfX1ob3c2rfqd2+ UxcKJhTDuhbJO/VImJqCH52qL9QeUitV+O+IReNnbsJ1bkbZG0POxbevN4F0kCWA8/Q2JVIBrep aXV9E+qtSCN59aQD1xvC7NPNdz6BwDWYiN54cJnT+BNEHRkSI4EM X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjMwMDA5MSBTYWx0ZWRfX+ogSmW6rdTxK rZEKBizk91oRAAjhCaJ3X6Is8aoqXnN8a/i9Hdn9QG/ntzYR3xfwFxyLa9UzWuudOs+gAdxOJIn zCYZ96JzpDwWUByb9SzMwo18a6WAE72XEsOjoUC4ddQ2MT/CSgUzxqhHsqQhGULF+BdKzIJoqK/ X+nn5vHizx8aezhahgV+MKWe9Uy6y0ghiSlCbSgvu3yfjfu4OtA6XnfKAeWjwCg3uGI/w7wQeRn zos25lAU+7xJmaOy6h6V5gBLbgxYUm1Wwy+4X8V6DFNETtDy6UNCGKlTCF+Sr577gamjLggMCor 6zpJKHlJNGxYV/fC+J9my7ln4w2klEucjlgigvnFR1bpkjTkyNsB/IYF40myvnYh61KBe/VQ8IS h4NdmQgs8jt/0GARgyJplHJxLOlDeBRHyUuMY8JzTYkz5pv4ZSU10ff+3S0oEFyLA4vFrlRGVCY Q2KxZ2tMElsrTCyyDiw== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-30_03,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 clxscore=1015 impostorscore=0 adultscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2606300091 Add a helper that drops an inode reference only if the caller does not hold the last one. Returns true if the reference was dropped, false otherwise. This is useful for filesystems that need to release inode references in contexts where triggering final iput (and thus eviction) would be unsafe due to lock ordering constraints. The caller can check the return value and defer the final iput to a safe context. Unlike iput_not_last() which BUG_ON's if called with the last ref, this variant is designed to be called speculatively. Signed-off-by: Yun Zhou Suggested-by: Jan Kara Reviewed-by: Jan Kara Reviewed-by: Christian Brauner (Amutable) --- include/linux/fs.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index d10897b3a1e3..04f0de78fa7a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2413,6 +2413,19 @@ static inline void super_set_sysfs_name_generic(struct super_block *sb, const ch extern void ihold(struct inode * inode); extern void iput(struct inode *); void iput_not_last(struct inode *); + +/** + * iput_if_not_last - drop an inode reference only if it is not the last one + * @inode: inode to put + * + * Returns true if the reference was dropped, false if this was the last + * reference and the caller must arrange for final iput() in a safe context. + */ +static inline bool __must_check iput_if_not_last(struct inode *inode) +{ + return atomic_add_unless(&inode->i_count, -1, 1); +} + int inode_update_time(struct inode *inode, enum fs_update_time type, unsigned int flags); int generic_update_time(struct inode *inode, enum fs_update_time type, -- 2.43.0