From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 66E771172A; Sat, 23 Nov 2024 14:01:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732370470; cv=none; b=Iyq1/aywZCvRfKb2Ky391Ab+4p9yj5bioLZk4mHrFhxiZUS6exRbb/dN7opzg4h/nCIeyEJuuSMbeeYjBrD7F17y74hFwk75CFIxQpptfGgNuyFF1C6P/5ZBBmEWdAnS9YBquj8KMrwyy5DGWl24GsjbIvCoAztQLcSh99GhM9Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732370470; c=relaxed/simple; bh=WW3T3lsrLvsiimpxaEbsVwcK4gOxfeY7iZSw0tbUeHU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=UG+5OhQvVM+TX1ED5wddu+24boIirbPgxXmZOhHph9Br0tiFYWTmX5M4cYNLKIE4pVr81wsjQ35Wsxcpm6PBByQ37N5E327uBUkKIa3NbP2qx7Xjf5FqUSQdx/Gdq82ebB37I2WQILK5rJbd9xi4j9yQpEvAPos2WCPFD/gesHU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FnlfKdR/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="FnlfKdR/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 284D4C4CECD; Sat, 23 Nov 2024 14:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732370469; bh=WW3T3lsrLvsiimpxaEbsVwcK4gOxfeY7iZSw0tbUeHU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=FnlfKdR/jv32acPbd1qw0j8VcsJ07iIcNILvT7nfs53QPSs9mrOOxE6+Z4QHdMO6Y Nb/L1hAIvsC9F8OX0YAV8pMJ+mD86AOyIZbBSTW0xjz1TcgVFIgXzauv+9JIfunLxs xPaXA7he8DQfuQdei47kXBbLVPZadPVhXBlYj83Z3hR3T0Hq8XgRW4vohaMmDlzJga d2TYvnJlC/arWCv+apxy7SJGIpsM6ODOiOhuW6u7IJZKhK0KQgfjZL6hh+0eVy0d+I Zml5dDJGnKifGcyNvrxfHiT8UFdGsH7bSiVNe0YWGKu5kbGIRDHRZ65ls/adygJJlt rdxzI0CT9P0Jw== Message-ID: <61292055a11a3f80e3afd2ef6871416e3963b977.camel@kernel.org> Subject: Re: [PATCH v3] fs: Fix data race in inode_set_ctime_to_ts From: Jeff Layton To: Hao-ran Zheng , viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: baijiaju1990@gmail.com, 21371365@buaa.edu.cn Date: Sat, 23 Nov 2024 09:01:08 -0500 In-Reply-To: <20241122130642.460929-1-zhenghaoran@buaa.edu.cn> References: <20241122112228.6him45jdtibue26s@quack3> <20241122130642.460929-1-zhenghaoran@buaa.edu.cn> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV YrOOI5VGLHge0awt7bhMCTM9KAfPc+xL/ZxAMVWd3NCk5SamL2cE99UWgtvNOIYU8m6EjTLhsj8sn VluJH0/RcxEeFbnSaswVChNSGa7mXJrTR22lRL6ZPjdMgS2Km90haWPRc8Wolcz07Y2se0xpGVLEQ cDEsvv5IMmeMe1/qLZ6NaVkNuL3WOXvxaVT9USW1+/SGipO2IpKJjeDZfehlB/kpfF24+RrK+seQf CBYyUE8QJpvTZyfUHNYldXlrjO6n5MdOempLqWpfOmcGkwnyNRBR46g/jf8KnPRwXs509yAqDB6sE LZH+yWr9LQZEwARAQABtCVKZWZmIExheXRvbiA8amxheXRvbkBwb29jaGllcmVkcy5uZXQ+iQI7BB MBAgAlAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUCTpXWPAIZAQAKCRAADmhBGVaCFc65D/4 gBLNMHopQYgG/9RIM3kgFCCQV0pLv0hcg1cjr+bPI5f1PzJoOVi9s0wBDHwp8+vtHgYhM54yt43uI 7Htij0RHFL5eFqoVT4TSfAg2qlvNemJEOY0e4daljjmZM7UtmpGs9NN0r9r50W82eb5Kw5bc/r0km R/arUS2st+ecRsCnwAOj6HiURwIgfDMHGPtSkoPpu3DDp/cjcYUg3HaOJuTjtGHFH963B+f+hyQ2B rQZBBE76ErgTDJ2Db9Ey0kw7VEZ4I2nnVUY9B5dE2pJFVO5HJBMp30fUGKvwaKqYCU2iAKxdmJXRI ONb7dSde8LqZahuunPDMZyMA5+mkQl7kpIpR6kVDIiqmxzRuPeiMP7O2FCUlS2DnJnRVrHmCljLkZ Wf7ZUA22wJpepBligemtSRSbqCyZ3B48zJ8g5B8xLEntPo/NknSJaYRvfEQqGxgk5kkNWMIMDkfQO lDSXZvoxqU9wFH/9jTv1/6p8dHeGM0BsbBLMqQaqnWiVt5mG92E1zkOW69LnoozE6Le+12DsNW7Rj iR5K+27MObjXEYIW7FIvNN/TQ6U1EOsdxwB8o//Yfc3p2QqPr5uS93SDDan5ehH59BnHpguTc27Xi QQZ9EGiieCUx6Zh2ze3X2UW9YNzE15uKwkkuEIj60NvQRmEDfweYfOfPVOueC+iFifbQgSmVmZiBM YXl0b24gPGpsYXl0b25AcmVkaGF0LmNvbT6JAjgEEwECACIFAk6V0q0CGwMGCwkIBwMCBhUIAgkKC wQWAgMBAh4BAheAAAoJEAAOaEEZVoIViKUQALpvsacTMWWOd7SlPFzIYy2/fjvKlfB/Xs4YdNcf9q LqF+lk2RBUHdR/dGwZpvw/OLmnZ8TryDo2zXVJNWEEUFNc7wQpl3i78r6UU/GUY/RQmOgPhs3epQC 3PMJj4xFx+VuVcf/MXgDDdBUHaCTT793hyBeDbQuciARDJAW24Q1RCmjcwWIV/pgrlFa4lAXsmhoa c8UPc82Ijrs6ivlTweFf16VBc4nSLX5FB3ls7S5noRhm5/Zsd4PGPgIHgCZcPgkAnU1S/A/rSqf3F LpU+CbVBDvlVAnOq9gfNF+QiTlOHdZVIe4gEYAU3CUjbleywQqV02BKxPVM0C5/oVjMVx3bri75n1 TkBYGmqAXy9usCkHIsG5CBHmphv9MHmqMZQVsxvCzfnI5IO1+7MoloeeW/lxuyd0pU88dZsV/riHw 87i2GJUJtVlMl5IGBNFpqoNUoqmvRfEMeXhy/kUX4Xc03I1coZIgmwLmCSXwx9MaCPFzV/dOOrju2 xjO+2sYyB5BNtxRqUEyXglpujFZqJxxau7E0eXoYgoY9gtFGsspzFkVNntamVXEWVVgzJJr/EWW0y +jNd54MfPRqH+eCGuqlnNLktSAVz1MvVRY1dxUltSlDZT7P2bUoMorIPu8p7ZCg9dyX1+9T6Muc5d Hxf/BBP/ir+3e8JTFQBFOiLNdFtB9KZWZmIExheXRvbiA8amxheXRvbkBzYW1iYS5vcmc+iQI4BBM BAgAiBQJOldK9AhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAAKCRAADmhBGVaCFWgWD/0ZRi4h N9FK2BdQs9RwNnFZUr7JidAWfCrs37XrA/56olQl3ojn0fQtrP4DbTmCuh0SfMijB24psy1GnkPep naQ6VRf7Dxg/Y8muZELSOtsv2CKt3/02J1BBitrkkqmHyni5fLLYYg6fub0T/8Kwo1qGPdu1hx2BQ RERYtQ/S5d/T0cACdlzi6w8rs5f09hU9Tu4qV1JLKmBTgUWKN969HPRkxiojLQziHVyM/weR5Reu6 FZVNuVBGqBD+sfk/c98VJHjsQhYJijcsmgMb1NohAzwrBKcSGKOWJToGEO/1RkIN8tqGnYNp2G+aR 685D0chgTl1WzPRM6mFG1+n2b2RR95DxumKVpwBwdLPoCkI24JkeDJ7lXSe3uFWISstFGt0HL8Eew P8RuGC8s5h7Ct91HMNQTbjgA+Vi1foWUVXpEintAKgoywaIDlJfTZIl6Ew8ETN/7DLy8bXYgq0Xzh aKg3CnOUuGQV5/nl4OAX/3jocT5Cz/OtAiNYj5mLPeL5z2ZszjoCAH6caqsF2oLyAnLqRgDgR+wTQ T6gMhr2IRsl+cp8gPHBwQ4uZMb+X00c/Amm9VfviT+BI7B66cnC7Zv6Gvmtu2rEjWDGWPqUgccB7h dMKnKDthkA227/82tYoFiFMb/NwtgGrn5n2vwJyKN6SEoygGrNt0SI84y6hEVbQlSmVmZiBMYXl0b 24gPGpsYXl0b25AcHJpbWFyeWRhdGEuY29tPokCOQQTAQIAIwUCU4xmKQIbAwcLCQgHAwIBBhUIAg kKCwQWAgMBAh4BAheAAAoJEAAOaEEZVoIV1H0P/j4OUTwFd7BBbpoSp695qb6HqCzWMuExsp8nZjr uymMaeZbGr3OWMNEXRI1FWNHMtcMHWLP/RaDqCJil28proO+PQ/yPhsr2QqJcW4nr91tBrv/MqItu AXLYlsgXqp4BxLP67bzRJ1Bd2x0bWXurpEXY//VBOLnODqThGEcL7jouwjmnRh9FTKZfBDpFRaEfD FOXIfAkMKBa/c9TQwRpx2DPsl3eFWVCNuNGKeGsirLqCxUg5kWTxEorROppz9oU4HPicL6rRH22Ce 6nOAON2vHvhkUuO3GbffhrcsPD4DaYup4ic+DxWm+DaSSRJ+e1yJvwi6NmQ9P9UAuLG93S2MdNNbo sZ9P8k2mTOVKMc+GooI9Ve/vH8unwitwo7ORMVXhJeU6Q0X7zf3SjwDq2lBhn1DSuTsn2DbsNTiDv qrAaCvbsTsw+SZRwF85eG67eAwouYk+dnKmp1q57LDKMyzysij2oDKbcBlwB/TeX16p8+LxECv51a sjS9TInnipssssUDrHIvoTTXWcz7Y5wIngxDFwT8rPY3EggzLGfK5Zx2Q5S/N0FfmADmKknG/D8qG IcJE574D956tiUDKN4I+/g125ORR1v7bP+OIaayAvq17RP+qcAqkxc0x8iCYVCYDouDyNvWPGRhbL UO7mlBpjW9jK9e2fvZY9iw3QzIPGKtClKZWZmIExheXRvbiA8amVmZi5sYXl0b25AcHJpbWFyeWRh dGEuY29tPokCOQQTAQIAIwUCU4xmUAIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEAAOa EEZVoIVzJoQALFCS6n/FHQS+hIzHIb56JbokhK0AFqoLVzLKzrnaeXhE5isWcVg0eoV2oTScIwUSU apy94if69tnUo4Q7YNt8/6yFM6hwZAxFjOXR0ciGE3Q+Z1zi49Ox51yjGMQGxlakV9ep4sV/d5a50 M+LFTmYSAFp6HY23JN9PkjVJC4PUv5DYRbOZ6Y1+TfXKBAewMVqtwT1Y+LPlfmI8dbbbuUX/kKZ5d dhV2736fgyfpslvJKYl0YifUOVy4D1G/oSycyHkJG78OvX4JKcf2kKzVvg7/Rnv+AueCfFQ6nGwPn 0P91I7TEOC4XfZ6a1K3uTp4fPPs1Wn75X7K8lzJP/p8lme40uqwAyBjk+IA5VGd+CVRiyJTpGZwA0 jwSYLyXboX+Dqm9pSYzmC9+/AE7lIgpWj+3iNisp1SWtHc4pdtQ5EU2SEz8yKvDbD0lNDbv4ljI7e flPsvN6vOrxz24mCliEco5DwhpaaSnzWnbAPXhQDWb/lUgs/JNk8dtwmvWnqCwRqElMLVisAbJmC0 BhZ/Ab4sph3EaiZfdXKhiQqSGdK4La3OTJOJYZphPdGgnkvDV9Pl1QZ0ijXQrVIy3zd6VCNaKYq7B AKidn5g/2Q8oio9Tf4XfdZ9dtwcB+bwDJFgvvDYaZ5bI3ln4V3EyW5i2NfXazz/GA/I/ZtbsigCFc 8ftCBKZWZmIExheXRvbiA8amxheXRvbkBrZXJuZWwub3JnPokCOAQTAQIAIgUCWe8u6AIbAwYLCQg HAwIGFQgCCQoLBBYCAwECHgECF4AACgkQAA5oQRlWghUuCg/+Lb/xGxZD2Q1oJVAE37uW308UpVSD 2tAMJUvFTdDbfe3zKlPDTuVsyNsALBGclPLagJ5ZTP+Vp2irAN9uwBuacBOTtmOdz4ZN2tdvNgozz uxp4CHBDVzAslUi2idy+xpsp47DWPxYFIRP3M8QG/aNW052LaPc0cedYxp8+9eiVUNpxF4SiU4i9J DfX/sn9XcfoVZIxMpCRE750zvJvcCUz9HojsrMQ1NFc7MFT1z3MOW2/RlzPcog7xvR5ENPH19ojRD CHqumUHRry+RF0lH00clzX/W8OrQJZtoBPXv9ahka/Vp7kEulcBJr1cH5Wz/WprhsIM7U9pse1f1g Yy9YbXtWctUz8uvDR7shsQxAhX3qO7DilMtuGo1v97I/Kx4gXQ52syh/w6EBny71CZrOgD6kJwPVV AaM1LRC28muq91WCFhs/nzHozpbzcheyGtMUI2Ao4K6mnY+3zIuXPygZMFr9KXE6fF7HzKxKuZMJO aEZCiDOq0anx6FmOzs5E6Jqdpo/mtI8beK+BE7Va6ni7YrQlnT0i3vaTVMTiCThbqsB20VrbMjlhp f8lfK1XVNbRq/R7GZ9zHESlsa35ha60yd/j3pu5hT2xyy8krV8vGhHvnJ1XRMJBAB/UYb6FyC7S+m QZIQXVeAA+smfTT0tDrisj1U5x6ZB9b3nBg65kc= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.1 (3.54.1-1.fc41app1) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Fri, 2024-11-22 at 21:06 +0800, Hao-ran Zheng wrote: > A data race may occur when the function `inode_set_ctime_to_ts()` and > the function `inode_get_ctime_sec()` are executed concurrently. When > two threads call `aio_read` and `aio_write` respectively, they will > be distributed to the read and write functions of the corresponding > file system respectively. Taking the btrfs file system as an example, > the `btrfs_file_read_iter` and `btrfs_file_write_iter` functions are > finally called. These two functions created a data race when they > finally called `inode_get_ctime_sec()` and `inode_set_ctime_to_ns()`. > The specific call stack that appears during testing is as follows: >=20 > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3DDATA_RACE=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D > btrfs_delayed_update_inode+0x1f61/0x7ce0 [btrfs] > btrfs_update_inode+0x45e/0xbb0 [btrfs] > btrfs_dirty_inode+0x2b8/0x530 [btrfs] > btrfs_update_time+0x1ad/0x230 [btrfs] > touch_atime+0x211/0x440 > filemap_read+0x90f/0xa20 > btrfs_file_read_iter+0xeb/0x580 [btrfs] > aio_read+0x275/0x3a0 > io_submit_one+0xd22/0x1ce0 > __se_sys_io_submit+0xb3/0x250 > do_syscall_64+0xc1/0x190 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3DOTHER_INFO=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D > btrfs_write_check+0xa15/0x1390 [btrfs] > btrfs_buffered_write+0x52f/0x29d0 [btrfs] > btrfs_do_write_iter+0x53d/0x1590 [btrfs] > btrfs_file_write_iter+0x41/0x60 [btrfs] > aio_write+0x41e/0x5f0 > io_submit_one+0xd42/0x1ce0 > __se_sys_io_submit+0xb3/0x250 > do_syscall_64+0xc1/0x190 > entry_SYSCALL_64_after_hwframe+0x77/0x7f >=20 > To address this issue, it is recommended to add WRITE_ONCE > when writing the `inode->i_ctime_sec` variable.and add > READ_ONCE when reading in function `inode_get_ctime_sec()` > and `inode_get_ctime_nsec()`. >=20 > Signed-off-by: Hao-ran Zheng > --- > V2 -> V3: Added READ_ONCE in inode_get_ctime_nsec() and addressed review = comments > V1 -> V2: Added READ_ONCE in inode_get_ctime_sec() > --- > include/linux/fs.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) >=20 > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 3559446279c1..c18f9a9ee5e7 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -1655,12 +1655,12 @@ static inline struct timespec64 inode_set_mtime(s= truct inode *inode, > =20 > static inline time64_t inode_get_ctime_sec(const struct inode *inode) > { > - return inode->i_ctime_sec; > + return READ_ONCE(inode->i_ctime_sec); > } > =20 > static inline long inode_get_ctime_nsec(const struct inode *inode) > { > - return inode->i_ctime_nsec; > + return READ_ONCE(inode->i_ctime_nsec); > } > =20 > static inline struct timespec64 inode_get_ctime(const struct inode *inod= e) > @@ -1674,8 +1674,8 @@ static inline struct timespec64 inode_get_ctime(con= st struct inode *inode) > static inline struct timespec64 inode_set_ctime_to_ts(struct inode *inod= e, > struct timespec64 ts) > { > - inode->i_ctime_sec =3D ts.tv_sec; > - inode->i_ctime_nsec =3D ts.tv_nsec; > + WRITE_ONCE(inode->i_ctime_sec, ts.tv_sec); > + WRITE_ONCE(inode->i_ctime_nsec, ts.tv_nsec); > return ts; > } > =20 Looks reasonable. There are also bare fetches and stores of the i_ctime_sec field in inode_set_ctime_current(). Do we need something like this in addition to the above? diff --git a/fs/inode.c b/fs/inode.c index b13b778257ae..d869ee6f1c6b 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2788,7 +2788,7 @@ struct timespec64 inode_set_ctime_current(struct inod= e *inode) */ cns =3D smp_load_acquire(&inode->i_ctime_nsec); if (cns & I_CTIME_QUERIED) { - struct timespec64 ctime =3D { .tv_sec =3D inode->i_ctime_sec, + struct timespec64 ctime =3D { .tv_sec =3D READ_ONCE(inode->i_ctime_sec), .tv_nsec =3D cns & ~I_CTIME_QUERIED }; =20 if (timespec64_compare(&now, &ctime) <=3D 0) { @@ -2809,7 +2809,7 @@ struct timespec64 inode_set_ctime_current(struct inod= e *inode) /* Try to swap the nsec value into place. */ if (try_cmpxchg(&inode->i_ctime_nsec, &cur, now.tv_nsec)) { /* If swap occurred, then we're (mostly) done */ - inode->i_ctime_sec =3D now.tv_sec; + WRITE_ONCE(inode->i_ctime_sec, now.tv_sec); trace_ctime_ns_xchg(inode, cns, now.tv_nsec, cur); mgtime_counter_inc(mg_ctime_swaps); } else { @@ -2824,7 +2824,7 @@ struct timespec64 inode_set_ctime_current(struct inod= e *inode) goto retry; } /* Otherwise, keep the existing ctime */ - now.tv_sec =3D inode->i_ctime_sec; + now.tv_sec =3D READ_ONCE(inode->i_ctime_sec); now.tv_nsec =3D cur & ~I_CTIME_QUERIED; } out: