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Thu, 09 May 2024 02:21:50 +0200 Message-ID: Date: Thu, 9 May 2024 09:51:46 +0930 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/8] btrfs: preallocate inodes xarray entry to avoid transaction abort To: fdmanana@kernel.org, linux-btrfs@vger.kernel.org References: Content-Language: en-US From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00iVQUJDToH pgAKCRDCPZHzoSX+qNKACACkjDLzCvcFuDlgqCiS4ajHAo6twGra3uGgY2klo3S4JespWifr BLPPak74oOShqNZ8yWzB1Bkz1u93Ifx3c3H0r2vLWrImoP5eQdymVqMWmDAq+sV1Koyt8gXQ XPD2jQCrfR9nUuV1F3Z4Lgo+6I5LjuXBVEayFdz/VYK63+YLEAlSowCF72Lkz06TmaI0XMyj jgRNGM2MRgfxbprCcsgUypaDfmhY2nrhIzPUICURfp9t/65+/PLlV4nYs+DtSwPyNjkPX72+ LdyIdY+BqS8cZbPG5spCyJIlZonADojLDYQq4QnufARU51zyVjzTXMg5gAttDZwTH+8LbNI4 mm2YzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00ibgUJDToHvwAK CRDCPZHzoSX+qK6vB/9yyZlsS+ijtsvwYDjGA2WhVhN07Xa5SBBvGCAycyGGzSMkOJcOtUUf tD+ADyrLbLuVSfRN1ke738UojphwkSFj4t9scG5A+U8GgOZtrlYOsY2+cG3R5vjoXUgXMP37 INfWh0KbJodf0G48xouesn08cbfUdlphSMXujCA8y5TcNyRuNv2q5Nizl8sKhUZzh4BascoK DChBuznBsucCTAGrwPgG4/ul6HnWE8DipMKvkV9ob1xJS2W4WJRPp6QdVrBWJ9cCdtpR6GbL iQi22uZXoSPv/0oUrGU+U5X4IvdnvT+8viPzszL5wXswJZfqfy8tmHM85yjObVdIG6AlnrrD In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:B2cSA3eJ5XJ/Aj4MQxZ0DqUcvfdJReCvqhTg0J1W3rS1pZkjIqr cAVDj2Wlny/wn9bIYiO85tCsdrkELD8bppW9VZHHY5X+esCexq0xCz1wGfnJ/tqzZbfTLCZ z23RvVNm5ymQfJhPHrFGXCBoTKthH0xKLh+ZzCgq5nyHMDYgyas10K9m8yRI7VvAaV5trOq ep/rpVKFZS1Pzz5TvW2AQ== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:U3yim41m8vY=;meeVD8F/jBR8k8HXKz8tOT234Wz Z90znkTOxrxByDYG1TlIicO+yUNrRhpBuzwS/fQgYnwNEFXsPe59xP7QTYj0lPiesnSV6ahB/ C4DoEEwg3VeiZTQjV3UyNU3D1e8pwj/mS4GStJeIj8nHg9RTsGvE9rjW6Obemr75bWUSwqIM+ nGpxCR54zSiUbTuRRaH2jjBTPfpz4V7I4WcRc8wjD3XeMik9VLCg8V3czC8znZPQUkaKdYJ28 8knNTnghuOJd8SvwD8MSDSg5na0nStB9QXWBnyb4HRmRRXhiA369FBqVLKnSadrWOgNNWtX5C g59leendNfHbSNqmUV00J15Zpp9kNChYuxSkJJu/YSjG9+Ki9OfZZzFPGc8bwhZ18RCaHK2Tt N1jn2H/ucfcDs7b2lfEuYMJjFWaOG321LZ1Mro6i+yIghO56pXXzfEO6lozb/ymAKx++x9/9w dPbfAMx5j0tMncIqmzPrfKjkCKDDfCvXKsNpDCsxYZWcZLoHPetdyqSiZpsRO5CEnEEX2FAvi J9L+0uP7QtGqBEHMpG8+pTqMWXHkAlIEhHwUhIiq8dcOQJmIpHrkqkLuZnIslf8A/GJJPJFQc gwWLwhvTl5oJ8gZS8BtB9BVR4tnGBsR4n8/euW50lFiv60tIOXz5llsVMS7Vv2sjvNDo9S+Q0 yJwpgpuhErwZgDhbJ82wBioUKu9THpUbqmQWMwRa/WhtJ6ytuyjFKIbLLmKEdPK1fah8YYjgs Hd7jDpDX2uR4g/F4oyVCsVfg+6q5omg89zua5Xk1hrnqIqB0lgsv7boeZ/KNeYS+f3HYkxExd M29T9VmUKm0nftgTjkNaaW7DIvRtyFxwMsrNjjiutLp4k= =E5=9C=A8 2024/5/8 21:47, fdmanana@kernel.org =E5=86=99=E9=81=93: > From: Filipe Manana > > When creating a new inode, at btrfs_create_new_inode(), one of the very > last steps is to add the inode to the root's inodes xarray. This often > requires allocating memory which may fail (even though xarrays have a > dedicated kmem_cache which make it less likely to fail), and at that poi= nt > we are forced to abort the current transaction (as some, but not all, of > the inode metadata was added to its subvolume btree). > > To avoid a transaction abort, preallocate memory for the xarray early at > btrfs_create_new_inode(), so that if we fail we don't need to abort the > transaction and the insertion into the xarray is guaranteed to succeed. > > Signed-off-by: Filipe Manana Reviewed-by: Qu Wenruo Thanks, Qu > --- > fs/btrfs/inode.c | 26 +++++++++++++++++++------- > 1 file changed, 19 insertions(+), 7 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 450fe1582f1d..85dbc19c2f6f 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -5493,7 +5493,7 @@ static int fixup_tree_root_location(struct btrfs_f= s_info *fs_info, > return err; > } > > -static int btrfs_add_inode_to_root(struct btrfs_inode *inode) > +static int btrfs_add_inode_to_root(struct btrfs_inode *inode, bool prea= lloc) > { > struct btrfs_root *root =3D inode->root; > struct btrfs_inode *existing; > @@ -5503,9 +5503,11 @@ static int btrfs_add_inode_to_root(struct btrfs_i= node *inode) > if (inode_unhashed(&inode->vfs_inode)) > return 0; > > - ret =3D xa_reserve(&root->inodes, ino, GFP_NOFS); > - if (ret) > - return ret; > + if (prealloc) { > + ret =3D xa_reserve(&root->inodes, ino, GFP_NOFS); > + if (ret) > + return ret; > + } > > spin_lock(&root->inode_lock); > existing =3D xa_store(&root->inodes, ino, inode, GFP_ATOMIC); > @@ -5606,7 +5608,7 @@ struct inode *btrfs_iget_path(struct super_block *= s, u64 ino, > > ret =3D btrfs_read_locked_inode(inode, path); > if (!ret) { > - ret =3D btrfs_add_inode_to_root(BTRFS_I(inode)); > + ret =3D btrfs_add_inode_to_root(BTRFS_I(inode), true); > if (ret) { > iget_failed(inode); > inode =3D ERR_PTR(ret); > @@ -6237,6 +6239,7 @@ int btrfs_create_new_inode(struct btrfs_trans_hand= le *trans, > struct btrfs_item_batch batch; > unsigned long ptr; > int ret; > + bool xa_reserved =3D false; > > path =3D btrfs_alloc_path(); > if (!path) > @@ -6251,6 +6254,11 @@ int btrfs_create_new_inode(struct btrfs_trans_han= dle *trans, > goto out; > inode->i_ino =3D objectid; > > + ret =3D xa_reserve(&root->inodes, objectid, GFP_NOFS); > + if (ret) > + goto out; > + xa_reserved =3D true; > + > if (args->orphan) { > /* > * O_TMPFILE, set link count to 0, so that after this point, we > @@ -6424,8 +6432,9 @@ int btrfs_create_new_inode(struct btrfs_trans_hand= le *trans, > } > } > > - ret =3D btrfs_add_inode_to_root(BTRFS_I(inode)); > - if (ret) { > + ret =3D btrfs_add_inode_to_root(BTRFS_I(inode), false); > + if (WARN_ON(ret)) { > + /* Shouldn't happen, we used xa_reserve() before. */ > btrfs_abort_transaction(trans, ret); > goto discard; > } > @@ -6456,6 +6465,9 @@ int btrfs_create_new_inode(struct btrfs_trans_hand= le *trans, > ihold(inode); > discard_new_inode(inode); > out: > + if (xa_reserved) > + xa_release(&root->inodes, objectid); > + > btrfs_free_path(path); > return ret; > }