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 14999176ADB for ; Mon, 28 Apr 2025 21:35:44 +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=1745876145; cv=none; b=pVNaZEN3mbPhMFrSZrOGFmQMenYEmwWcPyHtXSz58wbVkhYLtPamJL7tRdcDrw/ABqHQy49g5wq2GEgEwnEyQnZc1fYXUxSyV4tdYKU+DW0yqESPEeYf0bSsY8PXgPCKM+gEPLSfcR1NnrbswLmAKCXiSLsHL+KUT6eOJ77dTCk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745876145; c=relaxed/simple; bh=YX34DpVGTC31bL7bOAy5Aam24RGUoWGG/vjoJWG7Kig=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=BWRUngH1gu71Cmc5s1knWNbhEc7vnVYy0prgrzjRx5xNpPl9epj+uyU3XPM5Q9oAfkOE9QPPorg4xwOjClYLCFKncTz12tO+l1R3+lsPSxMTXG6agGRCVYdUtJiH7B+jzlryr+6oTwmsZsdz1rpKiUS4PJ5pg7h9RIgV7dv2xUk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qdRaFld3; 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="qdRaFld3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BB36C4CEE4; Mon, 28 Apr 2025 21:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745876144; bh=YX34DpVGTC31bL7bOAy5Aam24RGUoWGG/vjoJWG7Kig=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=qdRaFld3xgXeZiisXSoPZ/dxGntOmKuWv1lmA+96SzoTQv16KN8vgOao0pbxMLDMs +emeizWrv8ZqBkST19qVKQSOC7kFaRFV0buH1yJlEyjS7cXB9CxdLLZXNCTHxuBmSK Tn617+LkhGzWUb1mhfYmG+jaLpA8zODp65egMiuF4v+J1j2FykOBMluPwx/KeCZuTw adNawSGlVnYaLIjlIGlzfVvxa1hiGgnz1TrOLRjtEvnKsxpQJ9tb6gkCU6pPJLaAez Oi2XyTrk7vO3Hd1H18WE81plW+b1lNfTXHGBtuq730bHU1MAjDVOp1Ku+rGtbS7QTs LGV6fGE2WzLGA== Message-ID: <683b78ce40c6aa209aef7f9e79ead74aaeb1440a.camel@kernel.org> Subject: Re: [PATCH v2] NFS: Avoid flushing data while holding directory locks in nfs_rename() From: Jeff Layton To: trondmy@kernel.org, Anna Schumaker Cc: linux-nfs@vger.kernel.org Date: Mon, 28 Apr 2025 14:35:43 -0700 In-Reply-To: <5cd8fe68532655c0d4482ad712799d2fe1ab4ed2.1745858923.git.trond.myklebust@hammerspace.com> References: <5cd8fe68532655c0d4482ad712799d2fe1ab4ed2.1745858923.git.trond.myklebust@hammerspace.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Mon, 2025-04-28 at 09:49 -0700, trondmy@kernel.org wrote: > From: Trond Myklebust >=20 > The Linux client assumes that all filehandles are non-volatile for > renames within the same directory (otherwise sillyrename cannot work). > However, the existence of the Linux 'subtree_check' export option has > meant that nfs_rename() has always assumed it needs to flush writes > before attempting to rename. >=20 > Since NFSv4 does allow the client to query whether or not the server > exhibits this behaviour, and since knfsd does actually set the > appropriate flag when 'subtree_check' is enabled on an export, it > should be OK to optimise away the write flushing behaviour in the cases > where it is clearly not needed. >=20 > Signed-off-by: Trond Myklebust > --- > fs/nfs/client.c | 2 ++ > fs/nfs/dir.c | 15 ++++++++++++++- > include/linux/nfs_fs_sb.h | 12 +++++++++--- > 3 files changed, 25 insertions(+), 4 deletions(-) >=20 > diff --git a/fs/nfs/client.c b/fs/nfs/client.c > index 2115c1189c2d..6d63b958c4bb 100644 > --- a/fs/nfs/client.c > +++ b/fs/nfs/client.c > @@ -1105,6 +1105,8 @@ struct nfs_server *nfs_create_server(struct fs_cont= ext *fc) > if (server->namelen =3D=3D 0 || server->namelen > NFS2_MAXNAMLEN) > server->namelen =3D NFS2_MAXNAMLEN; > } > + /* Linux 'subtree_check' borkenness mandates this setting */ > + server->fh_expire_type =3D NFS_FH_VOL_RENAME; > =20 > if (!(fattr->valid & NFS_ATTR_FATTR)) { > error =3D ctx->nfs_mod->rpc_ops->getattr(server, ctx->mntfh, > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index bd23fc736b39..d0e0b435a843 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -2676,6 +2676,18 @@ nfs_unblock_rename(struct rpc_task *task, struct n= fs_renamedata *data) > unblock_revalidate(new_dentry); > } > =20 > +static bool nfs_rename_is_unsafe_cross_dir(struct dentry *old_dentry, > + struct dentry *new_dentry) > +{ > + struct nfs_server *server =3D NFS_SB(old_dentry->d_sb); > + > + if (old_dentry->d_parent !=3D new_dentry->d_parent) > + return false; > + if (server->fh_expire_type & NFS_FH_RENAME_UNSAFE) > + return !(server->fh_expire_type & NFS_FH_NOEXPIRE_WITH_OPEN); > + return true; > +} > + > /* > * RENAME > * FIXME: Some nfsds, like the Linux user space nfsd, may generate a > @@ -2763,7 +2775,8 @@ int nfs_rename(struct mnt_idmap *idmap, struct inod= e *old_dir, > =20 > } > =20 > - if (S_ISREG(old_inode->i_mode)) > + if (S_ISREG(old_inode->i_mode) && > + nfs_rename_is_unsafe_cross_dir(old_dentry, new_dentry)) > nfs_sync_inode(old_inode); > task =3D nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, > must_unblock ? nfs_unblock_rename : NULL); > diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h > index 71319637a84e..ee03f3cef30c 100644 > --- a/include/linux/nfs_fs_sb.h > +++ b/include/linux/nfs_fs_sb.h > @@ -213,6 +213,15 @@ struct nfs_server { > char *fscache_uniq; /* Uniquifier (or NULL) */ > #endif > =20 > + /* The following #defines numerically match the NFSv4 equivalents */ > +#define NFS_FH_NOEXPIRE_WITH_OPEN (0x1) > +#define NFS_FH_VOLATILE_ANY (0x2) > +#define NFS_FH_VOL_MIGRATION (0x4) > +#define NFS_FH_VOL_RENAME (0x8) > +#define NFS_FH_RENAME_UNSAFE (NFS_FH_VOLATILE_ANY | NFS_FH_VOL_RENAME) > + u32 fh_expire_type; /* V4 bitmask representing file > + handle volatility type for > + this filesystem */ > u32 pnfs_blksize; /* layout_blksize attr */ > #if IS_ENABLED(CONFIG_NFS_V4) > u32 attr_bitmask[3];/* V4 bitmask representing the set > @@ -236,9 +245,6 @@ struct nfs_server { > u32 acl_bitmask; /* V4 bitmask representing the ACEs > that are supported on this > filesystem */ > - u32 fh_expire_type; /* V4 bitmask representing file > - handle volatility type for > - this filesystem */ > struct pnfs_layoutdriver_type *pnfs_curr_ld; /* Active layout driver *= / > struct rpc_wait_queue roc_rpcwaitq; > void *pnfs_ld_data; /* per mount point data */ Reviewed-by: Jeff Layton