Re: [PATCH 02/29] xfs: merge xfs_attr_remove into xfs_attr_set

From: Allison Collins <allison.henderson@oracle.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>,
	Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 02/29] xfs: merge xfs_attr_remove into xfs_attr_set
Date: Fri, 24 Jan 2020 21:17:15 -0700	[thread overview]
Message-ID: <52723c8f-1634-424c-e1b6-d3195304fc15@oracle.com> (raw)
In-Reply-To: <20200121172853.GC8247@magnolia>

On 1/21/20 10:28 AM, Darrick J. Wong wrote:
> On Tue, Jan 14, 2020 at 09:10:24AM +0100, Christoph Hellwig wrote:
>> The Linux xattr and acl APIs use a single call for set an remove.  Modify
>> the high-level XFS API to match that and let xfs_attr_set handle removing
>> attributes as well.  With a little bit of reordering this removes a lot
>> of code.
>>
>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>> ---
>>   fs/xfs/libxfs/xfs_attr.c | 174 +++++++++++++--------------------------
>>   fs/xfs/libxfs/xfs_attr.h |   2 -
>>   fs/xfs/xfs_acl.c         |  33 +++-----
>>   fs/xfs/xfs_ioctl.c       |   4 +-
>>   fs/xfs/xfs_xattr.c       |   9 +-
>>   5 files changed, 73 insertions(+), 149 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
>> index e6149720ce02..04431ab9f5f5 100644
>> --- a/fs/xfs/libxfs/xfs_attr.c
>> +++ b/fs/xfs/libxfs/xfs_attr.c
>> @@ -350,149 +350,92 @@ xfs_attr_set(
> 
> xfs_attr_set() ought to gain a comment noting that a NULL @value
> will remove the attribute.
> 
>>   	struct xfs_trans_res	tres;
>>   	int			rsvd = (flags & ATTR_ROOT) != 0;
>>   	int			error, local;
>> -
>> -	XFS_STATS_INC(mp, xs_attr_set);
>> +	unsigned int		total;
>>   
>>   	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
>>   		return -EIO;
>>   
>> -	error = xfs_attr_args_init(&args, dp, name, namelen, flags);
>> -	if (error)
>> -		return error;
>> -
>> -	args.value = value;
>> -	args.valuelen = valuelen;
>> -	args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
>> -	args.total = xfs_attr_calc_size(&args, &local);
>> -
>>   	error = xfs_qm_dqattach(dp);
>>   	if (error)
>>   		return error;
>>   
>> -	/*
>> -	 * If the inode doesn't have an attribute fork, add one.
>> -	 * (inode must not be locked when we call this routine)
>> -	 */
>> -	if (XFS_IFORK_Q(dp) == 0) {
>> -		int sf_size = sizeof(xfs_attr_sf_hdr_t) +
>> -			XFS_ATTR_SF_ENTSIZE_BYNAME(args.namelen, valuelen);
>> -
>> -		error = xfs_bmap_add_attrfork(dp, sf_size, rsvd);
>> -		if (error)
>> -			return error;
>> -	}
>> -
>> -	tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
>> -			 M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
>> -	tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
>> -	tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
>> -
>> -	/*
>> -	 * Root fork attributes can use reserved data blocks for this
>> -	 * operation if necessary
>> -	 */
>> -	error = xfs_trans_alloc(mp, &tres, args.total, 0,
>> -			rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
>> +	error = xfs_attr_args_init(&args, dp, name, namelen, flags);
>>   	if (error)
>>   		return error;
>>   
>> -	xfs_ilock(dp, XFS_ILOCK_EXCL);
>> -	error = xfs_trans_reserve_quota_nblks(args.trans, dp, args.total, 0,
>> -				rsvd ? XFS_QMOPT_RES_REGBLKS | XFS_QMOPT_FORCE_RES :
>> -				       XFS_QMOPT_RES_REGBLKS);
>> -	if (error)
>> -		goto out_trans_cancel;
>> -
>> -	xfs_trans_ijoin(args.trans, dp, 0);
>> -	error = xfs_attr_set_args(&args);
>> -	if (error)
>> -		goto out_trans_cancel;
>> -	if (!args.trans) {
>> -		/* shortform attribute has already been committed */
>> -		goto out_unlock;
>> -	}
>> -
>> -	/*
>> -	 * If this is a synchronous mount, make sure that the
>> -	 * transaction goes to disk before returning to the user.
>> -	 */
>> -	if (mp->m_flags & XFS_MOUNT_WSYNC)
>> -		xfs_trans_set_sync(args.trans);
>> -
>> -	if ((flags & ATTR_KERNOTIME) == 0)
>> -		xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);
>> +	args.value = value;
>> +	args.valuelen = valuelen;
>>   
>>   	/*
>> -	 * Commit the last in the sequence of transactions.
>> +	 * We have no control over the attribute names that userspace passes us
>> +	 * to remove, so we have to allow the name lookup prior to attribute
>> +	 * removal to fail as well.
>>   	 */
>> -	xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
>> -	error = xfs_trans_commit(args.trans);
>> -out_unlock:
>> -	xfs_iunlock(dp, XFS_ILOCK_EXCL);
>> -	return error;
>> -
>> -out_trans_cancel:
>> -	if (args.trans)
>> -		xfs_trans_cancel(args.trans);
>> -	goto out_unlock;
>> -}
>> +	args.op_flags = XFS_DA_OP_OKNOENT;
>>   
>> -/*
>> - * Generic handler routine to remove a name from an attribute list.
>> - * Transitions attribute list from Btree to shortform as necessary.
>> - */
>> -int
>> -xfs_attr_remove(
>> -	struct xfs_inode	*dp,
>> -	const unsigned char	*name,
>> -	size_t			namelen,
>> -	int			flags)
>> -{
>> -	struct xfs_mount	*mp = dp->i_mount;
>> -	struct xfs_da_args	args;
>> -	int			error;
>> +	if (value) {
>> +		XFS_STATS_INC(mp, xs_attr_set);
>>   
>> -	XFS_STATS_INC(mp, xs_attr_remove);
>> +		args.op_flags |= XFS_DA_OP_ADDNAME;
>> +		args.total = xfs_attr_calc_size(&args, &local);
>>   
>> -	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
>> -		return -EIO;
>> +		/*
>> +		 * If the inode doesn't have an attribute fork, add one.
>> +		 * (inode must not be locked when we call this routine)
>> +		 */
>> +		if (XFS_IFORK_Q(dp) == 0) {
>> +			int sf_size = sizeof(struct xfs_attr_sf_hdr) +
>> +				XFS_ATTR_SF_ENTSIZE_BYNAME(args.namelen,
>> +						valuelen);
>>   
>> -	error = xfs_attr_args_init(&args, dp, name, namelen, flags);
>> -	if (error)
>> -		return error;
>> +			error = xfs_bmap_add_attrfork(dp, sf_size, rsvd);
>> +			if (error)
>> +				return error;
>> +		}
>>   
>> -	/*
>> -	 * we have no control over the attribute names that userspace passes us
>> -	 * to remove, so we have to allow the name lookup prior to attribute
>> -	 * removal to fail.
>> -	 */
>> -	args.op_flags = XFS_DA_OP_OKNOENT;
>> +		tres.tr_logres = M_RES(mp)->tr_attrsetm.tr_logres +
>> +				 M_RES(mp)->tr_attrsetrt.tr_logres * args.total;
>> +		tres.tr_logcount = XFS_ATTRSET_LOG_COUNT;
>> +		tres.tr_logflags = XFS_TRANS_PERM_LOG_RES;
>> +		total = args.total;
>> +	} else {
>> +		XFS_STATS_INC(mp, xs_attr_remove);
>>   
>> -	error = xfs_qm_dqattach(dp);
>> -	if (error)
>> -		return error;
>> +		tres = M_RES(mp)->tr_attrrm;
>> +		total = XFS_ATTRRM_SPACE_RES(mp);
>> +	}
>>   
>>   	/*
>>   	 * Root fork attributes can use reserved data blocks for this
>>   	 * operation if necessary
>>   	 */
>> -	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_attrrm,
>> -			XFS_ATTRRM_SPACE_RES(mp), 0,
>> -			(flags & ATTR_ROOT) ? XFS_TRANS_RESERVE : 0,
>> -			&args.trans);
>> +	error = xfs_trans_alloc(mp, &tres, total, 0,
>> +			rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
>>   	if (error)
>>   		return error;
>>   
>>   	xfs_ilock(dp, XFS_ILOCK_EXCL);
>> -	/*
>> -	 * No need to make quota reservations here. We expect to release some
>> -	 * blocks not allocate in the common case.
>> -	 */
>>   	xfs_trans_ijoin(args.trans, dp, 0);
>> +	if (value) {
>> +		unsigned int	quota_flags = XFS_QMOPT_RES_REGBLKS;
>>   
>> -	error = xfs_attr_remove_args(&args);
>> -	if (error)
>> -		goto out;
>> +		if (rsvd)
>> +			quota_flags |= XFS_QMOPT_FORCE_RES;
>> +		error = xfs_trans_reserve_quota_nblks(args.trans, dp,
>> +				args.total, 0, quota_flags);
>> +		if (error)
>> +			goto out_trans_cancel;
>> +		error = xfs_attr_set_args(&args);
>> +		if (error)
>> +			goto out_trans_cancel;
>> +		/* shortform attribute has already been committed */
>> +		if (!args.trans)
>> +			goto out_unlock;
>> +	} else {
>> +		error = xfs_attr_remove_args(&args);
>> +		if (error)
>> +			goto out_trans_cancel;
>> +	}
>>   
>>   	/*
>>   	 * If this is a synchronous mount, make sure that the
>> @@ -509,15 +452,14 @@ xfs_attr_remove(
>>   	 */
>>   	xfs_trans_log_inode(args.trans, dp, XFS_ILOG_CORE);
>>   	error = xfs_trans_commit(args.trans);
>> +out_unlock:
>>   	xfs_iunlock(dp, XFS_ILOCK_EXCL);
>> -
>>   	return error;
>>   
>> -out:
>> +out_trans_cancel:
>>   	if (args.trans)
>>   		xfs_trans_cancel(args.trans);
>> -	xfs_iunlock(dp, XFS_ILOCK_EXCL);
>> -	return error;
>> +	goto out_unlock;
>>   }
>>   
>>   /*========================================================================
>> diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
>> index 71bcf1298e4c..db58a6c7dea5 100644
>> --- a/fs/xfs/libxfs/xfs_attr.h
>> +++ b/fs/xfs/libxfs/xfs_attr.h
>> @@ -152,8 +152,6 @@ int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
>>   int xfs_attr_set(struct xfs_inode *dp, const unsigned char *name,
>>   		 size_t namelen, unsigned char *value, int valuelen, int flags);
>>   int xfs_attr_set_args(struct xfs_da_args *args);
>> -int xfs_attr_remove(struct xfs_inode *dp, const unsigned char *name,
>> -		    size_t namelen, int flags);
>>   int xfs_attr_remove_args(struct xfs_da_args *args);
>>   int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize,
>>   		  int flags, struct attrlist_cursor_kern *cursor);
>> diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
>> index cd743fad8478..2628f8530bf0 100644
>> --- a/fs/xfs/xfs_acl.c
>> +++ b/fs/xfs/xfs_acl.c
>> @@ -168,6 +168,8 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>>   {
>>   	struct xfs_inode *ip = XFS_I(inode);
>>   	unsigned char *ea_name;
>> +	struct xfs_acl *xfs_acl = NULL;
>> +	int len = 0;
>>   	int error;
>>   
>>   	switch (type) {
>> @@ -184,9 +186,7 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>>   	}
>>   
>>   	if (acl) {
>> -		struct xfs_acl *xfs_acl;
>> -		int len = XFS_ACL_MAX_SIZE(ip->i_mount);
>> -
>> +		len = XFS_ACL_MAX_SIZE(ip->i_mount);
>>   		xfs_acl = kmem_zalloc_large(len, 0);
>>   		if (!xfs_acl)
>>   			return -ENOMEM;
>> @@ -196,26 +196,17 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>>   		/* subtract away the unused acl entries */
>>   		len -= sizeof(struct xfs_acl_entry) *
>>   			 (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
>> -
>> -		error = xfs_attr_set(ip, ea_name, strlen(ea_name),
>> -				     (unsigned char *)xfs_acl, len, ATTR_ROOT);
>> -
>> -		kmem_free(xfs_acl);
>> -	} else {
>> -		/*
>> -		 * A NULL ACL argument means we want to remove the ACL.
>> -		 */
>> -		error = xfs_attr_remove(ip, ea_name,
>> -					strlen(ea_name),
>> -					ATTR_ROOT);
>> -
>> -		/*
>> -		 * If the attribute didn't exist to start with that's fine.
>> -		 */
>> -		if (error == -ENOATTR)
>> -			error = 0;
>>   	}
>>   
>> +	error = xfs_attr_set(ip, ea_name, strlen(ea_name),
>> +			(unsigned char *)xfs_acl, len, ATTR_ROOT);
>> +	kmem_free(xfs_acl);
>> +
>> +	/*
>> +	 * If the attribute didn't exist to start with that's fine.
>> +	 */
>> +	if (error == -ENOATTR)
> 
> if (!acl && error == -ENOATTR)
> 
> ...because that's a behavior change w.r.t. error codes.  I didn't see
> anywhere in the attr code where setting a value would actually return
> this, but let's not leave a logic bomb in case we ever do.
> 
> (The first thing my brain thought was, "ENOATTR on a set operation
> suggests to me that something's seriously broken in the attr code; why
> would you mask it?")
> 
> --D

Would either of you mind if I were to pick up this patch and make a mini 
set that resolves some of the overlap between our sets?  I'll fix the 
nits here.  Let me know, thanks!

Allison

> 
>> +		error = 0;
>>   	if (!error)
>>   		set_cached_acl(inode, type, acl);
>>   	return error;
>> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
>> index d42de92cb283..8e35887f62fa 100644
>> --- a/fs/xfs/xfs_ioctl.c
>> +++ b/fs/xfs/xfs_ioctl.c
>> @@ -415,12 +415,10 @@ xfs_attrmulti_attr_remove(
>>   	uint32_t		flags)
>>   {
>>   	int			error;
>> -	size_t			namelen;
>>   
>>   	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
>>   		return -EPERM;
>> -	namelen = strlen(name);
>> -	error = xfs_attr_remove(XFS_I(inode), name, namelen, flags);
>> +	error = xfs_attr_set(XFS_I(inode), name, strlen(name), NULL, 0, flags);
>>   	if (!error)
>>   		xfs_forget_acl(inode, name, flags);
>>   	return error;
>> diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
>> index b0fedb543f97..1670bfbc9ad2 100644
>> --- a/fs/xfs/xfs_xattr.c
>> +++ b/fs/xfs/xfs_xattr.c
>> @@ -69,7 +69,6 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
>>   	int			xflags = handler->flags;
>>   	struct xfs_inode	*ip = XFS_I(inode);
>>   	int			error;
>> -	size_t			namelen = strlen(name);
>>   
>>   	/* Convert Linux syscall to XFS internal ATTR flags */
>>   	if (flags & XATTR_CREATE)
>> @@ -77,14 +76,10 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
>>   	if (flags & XATTR_REPLACE)
>>   		xflags |= ATTR_REPLACE;
>>   
>> -	if (value)
>> -		error = xfs_attr_set(ip, name, namelen, (void *)value, size,
>> -				xflags);
>> -	else
>> -		error = xfs_attr_remove(ip, name, namelen, xflags);
>> +	error = xfs_attr_set(ip, (unsigned char *)name, strlen(name),
>> +				(void *)value, size, xflags);
>>   	if (!error)
>>   		xfs_forget_acl(inode, name, xflags);
>> -
>>   	return error;
>>   }
>>   
>> -- 
>> 2.24.1
>>