Re: [PATCH v3 01/19] xfs: Replace attribute parameters with struct xfs_name

[Brian Foster <bfoster@redhat.com>]

On Wed, Sep 18, 2019 at 11:09:48AM -0700, Allison Collins wrote:
> 
> 
> On 9/18/19 9:43 AM, Brian Foster wrote:
> > On Thu, Sep 05, 2019 at 03:18:19PM -0700, Allison Collins wrote:
> > > This patch replaces the attribute name, length and flags parameters with a
> > > single struct xfs_name parameter.  This helps to clean up the numbers of
> > > parameters being passed around and pre-simplifies the code some.
> > > 
> > > Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> > > ---
> > >   fs/xfs/libxfs/xfs_attr.c | 46 +++++++++++++++++++---------------------------
> > >   fs/xfs/libxfs/xfs_attr.h | 12 +++++-------
> > >   fs/xfs/xfs_acl.c         | 27 +++++++++++++--------------
> > >   fs/xfs/xfs_ioctl.c       | 28 ++++++++++++++++++----------
> > >   fs/xfs/xfs_iops.c        | 12 ++++++++----
> > >   fs/xfs/xfs_xattr.c       | 30 +++++++++++++++++-------------
> > >   6 files changed, 80 insertions(+), 75 deletions(-)
> > > 
> > > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > > index 7589cb7..d0308d6 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.c
> > > +++ b/fs/xfs/libxfs/xfs_attr.c
> > ...
> > > @@ -139,30 +137,28 @@ xfs_attr_get_ilocked(
> > >   int
> > >   xfs_attr_get(
> > >   	struct xfs_inode	*ip,
> > > -	const unsigned char	*name,
> > > -	size_t			namelen,
> > > +	struct xfs_name		*name,
> > >   	unsigned char		**value,
> > > -	int			*valuelenp,
> > > -	int			flags)
> > > +	int			*valuelenp)
> > >   {
> > >   	struct xfs_da_args	args;
> > >   	uint			lock_mode;
> > >   	int			error;
> > > -	ASSERT((flags & (ATTR_ALLOC | ATTR_KERNOVAL)) || *value);
> > > +	ASSERT((name->type & (ATTR_ALLOC | ATTR_KERNOVAL)) || *value);
> > 
> > While this looks like a nice cleanup, I'm not a huge fan of burying the
> > attr flags in the xfs_name like this. To me they are distinct parameters
> > and the interface isn't as clear for new callers. Other than that the
> > patch looks good.
> > 
> > BTW after looking at the next patch, a reasonable compromise might be to
> > leave the flags param for the top level xfs_attr_*() functions and then
> > bury the value in args->name.type for the rest of the lower level code
> > to use. Just a thought..
> > 
> > Brian
> 
> Yes, this was a sort of cleanup suggested in the last review.  While it is
> nice to have less parameters, I ended up having mixed feels about using type
> for flags.  Mostly just because a name of "type" generally implies that the
> field should be handled like an enumeration, and a "flag" implies that is
> should be handled like a bitmask.  So I found myself doing a lot of double
> takes just in looking at it.  I am fine with moving flags back out, but I
> would like folks to weigh in so that we have a consensus on what people are
> comfortable with.
> 

Sure..

> I'm not sure I like the idea of putting "value" in "type" though. Generally
> a "value" implies a sort of payload with a length (of which we have).  But
> but I think separating value and valuelen would look all sorts of weird.  I
> think either value should stay outside with valuelen, or we should probably
> bite the bullet and introduce a new struct for the purpose.  Thoughts?
> 

Note that I was referring to the flags value in a general sense, not the
actual attr value. I.e., leave the xfs_attr_() flags param, then store
flags in args->name.type if you really wanted to save the extra field
from args and remove the rest of the flags passing beneath the top level
functions.

Brian

> Allison
> 
> > 
> > >   	XFS_STATS_INC(ip->i_mount, xs_attr_get);
> > >   	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
> > >   		return -EIO;
> > > -	error = xfs_attr_args_init(&args, ip, name, namelen, flags);
> > > +	error = xfs_attr_args_init(&args, ip, name);
> > >   	if (error)
> > >   		return error;
> > >   	/* Entirely possible to look up a name which doesn't exist */
> > >   	args.op_flags = XFS_DA_OP_OKNOENT;
> > > -	if (flags & ATTR_ALLOC)
> > > +	if (name->type & ATTR_ALLOC)
> > >   		args.op_flags |= XFS_DA_OP_ALLOCVAL;
> > >   	else
> > >   		args.value = *value;
> > > @@ -175,7 +171,7 @@ xfs_attr_get(
> > >   	/* on error, we have to clean up allocated value buffers */
> > >   	if (error) {
> > > -		if (flags & ATTR_ALLOC) {
> > > +		if (name->type & ATTR_ALLOC) {
> > >   			kmem_free(args.value);
> > >   			*value = NULL;
> > >   		}
> > > @@ -339,16 +335,14 @@ xfs_attr_remove_args(
> > >   int
> > >   xfs_attr_set(
> > >   	struct xfs_inode	*dp,
> > > -	const unsigned char	*name,
> > > -	size_t			namelen,
> > > +	struct xfs_name		*name,
> > >   	unsigned char		*value,
> > > -	int			valuelen,
> > > -	int			flags)
> > > +	int			valuelen)
> > >   {
> > >   	struct xfs_mount	*mp = dp->i_mount;
> > >   	struct xfs_da_args	args;
> > >   	struct xfs_trans_res	tres;
> > > -	int			rsvd = (flags & ATTR_ROOT) != 0;
> > > +	int			rsvd = (name->type & ATTR_ROOT) != 0;
> > >   	int			error, local;
> > >   	XFS_STATS_INC(mp, xs_attr_set);
> > > @@ -356,7 +350,7 @@ xfs_attr_set(
> > >   	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
> > >   		return -EIO;
> > > -	error = xfs_attr_args_init(&args, dp, name, namelen, flags);
> > > +	error = xfs_attr_args_init(&args, dp, name);
> > >   	if (error)
> > >   		return error;
> > > @@ -419,7 +413,7 @@ xfs_attr_set(
> > >   	if (mp->m_flags & XFS_MOUNT_WSYNC)
> > >   		xfs_trans_set_sync(args.trans);
> > > -	if ((flags & ATTR_KERNOTIME) == 0)
> > > +	if ((name->type & ATTR_KERNOTIME) == 0)
> > >   		xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);
> > >   	/*
> > > @@ -444,9 +438,7 @@ xfs_attr_set(
> > >   int
> > >   xfs_attr_remove(
> > >   	struct xfs_inode	*dp,
> > > -	const unsigned char	*name,
> > > -	size_t			namelen,
> > > -	int			flags)
> > > +	struct xfs_name		*name)
> > >   {
> > >   	struct xfs_mount	*mp = dp->i_mount;
> > >   	struct xfs_da_args	args;
> > > @@ -457,7 +449,7 @@ xfs_attr_remove(
> > >   	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
> > >   		return -EIO;
> > > -	error = xfs_attr_args_init(&args, dp, name, namelen, flags);
> > > +	error = xfs_attr_args_init(&args, dp, name);
> > >   	if (error)
> > >   		return error;
> > > @@ -478,7 +470,7 @@ xfs_attr_remove(
> > >   	 */
> > >   	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_attrrm,
> > >   			XFS_ATTRRM_SPACE_RES(mp), 0,
> > > -			(flags & ATTR_ROOT) ? XFS_TRANS_RESERVE : 0,
> > > +			(name->type & ATTR_ROOT) ? XFS_TRANS_RESERVE : 0,
> > >   			&args.trans);
> > >   	if (error)
> > >   		return error;
> > > @@ -501,7 +493,7 @@ xfs_attr_remove(
> > >   	if (mp->m_flags & XFS_MOUNT_WSYNC)
> > >   		xfs_trans_set_sync(args.trans);
> > > -	if ((flags & ATTR_KERNOTIME) == 0)
> > > +	if ((name->type & ATTR_KERNOTIME) == 0)
> > >   		xfs_trans_ichgtime(args.trans, dp, XFS_ICHGTIME_CHG);
> > >   	/*
> > > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h
> > > index 106a2f2..cedb4e2 100644
> > > --- a/fs/xfs/libxfs/xfs_attr.h
> > > +++ b/fs/xfs/libxfs/xfs_attr.h
> > > @@ -144,14 +144,12 @@ int xfs_attr_list_int_ilocked(struct xfs_attr_list_context *);
> > >   int xfs_attr_list_int(struct xfs_attr_list_context *);
> > >   int xfs_inode_hasattr(struct xfs_inode *ip);
> > >   int xfs_attr_get_ilocked(struct xfs_inode *ip, struct xfs_da_args *args);
> > > -int xfs_attr_get(struct xfs_inode *ip, const unsigned char *name,
> > > -		 size_t namelen, unsigned char **value, int *valuelenp,
> > > -		 int flags);
> > > -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_get(struct xfs_inode *ip, struct xfs_name *name,
> > > +		 unsigned char **value, int *valuelenp);
> > > +int xfs_attr_set(struct xfs_inode *dp, struct xfs_name *name,
> > > +		 unsigned char *value, int valuelen);
> > >   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(struct xfs_inode *dp, struct xfs_name *name);
> > >   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 12be708..f8fb6e10 100644
> > > --- a/fs/xfs/xfs_acl.c
> > > +++ b/fs/xfs/xfs_acl.c
> > > @@ -113,7 +113,7 @@ xfs_get_acl(struct inode *inode, int type)
> > >   	struct xfs_inode *ip = XFS_I(inode);
> > >   	struct posix_acl *acl = NULL;
> > >   	struct xfs_acl *xfs_acl = NULL;
> > > -	unsigned char *ea_name;
> > > +	struct xfs_name name;
> > >   	int error;
> > >   	int len;
> > > @@ -121,10 +121,10 @@ xfs_get_acl(struct inode *inode, int type)
> > >   	switch (type) {
> > >   	case ACL_TYPE_ACCESS:
> > > -		ea_name = SGI_ACL_FILE;
> > > +		name.name = SGI_ACL_FILE;
> > >   		break;
> > >   	case ACL_TYPE_DEFAULT:
> > > -		ea_name = SGI_ACL_DEFAULT;
> > > +		name.name = SGI_ACL_DEFAULT;
> > >   		break;
> > >   	default:
> > >   		BUG();
> > > @@ -135,9 +135,9 @@ xfs_get_acl(struct inode *inode, int type)
> > >   	 * go out to the disk.
> > >   	 */
> > >   	len = XFS_ACL_MAX_SIZE(ip->i_mount);
> > > -	error = xfs_attr_get(ip, ea_name, strlen(ea_name),
> > > -				(unsigned char **)&xfs_acl, &len,
> > > -				ATTR_ALLOC | ATTR_ROOT);
> > > +	name.len = strlen(name.name);
> > > +	name.type = ATTR_ALLOC | ATTR_ROOT;
> > > +	error = xfs_attr_get(ip, &name, (unsigned char **)&xfs_acl, &len);
> > >   	if (error) {
> > >   		/*
> > >   		 * If the attribute doesn't exist make sure we have a negative
> > > @@ -157,17 +157,17 @@ int
> > >   __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_name name;
> > >   	int error;
> > >   	switch (type) {
> > >   	case ACL_TYPE_ACCESS:
> > > -		ea_name = SGI_ACL_FILE;
> > > +		name.name = SGI_ACL_FILE;
> > >   		break;
> > >   	case ACL_TYPE_DEFAULT:
> > >   		if (!S_ISDIR(inode->i_mode))
> > >   			return acl ? -EACCES : 0;
> > > -		ea_name = SGI_ACL_DEFAULT;
> > > +		name.name = SGI_ACL_DEFAULT;
> > >   		break;
> > >   	default:
> > >   		return -EINVAL;
> > > @@ -187,17 +187,16 @@ __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
> > >   		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);
> > > +		name.len = strlen(name.name);
> > > +		name.type = ATTR_ROOT;
> > > +		error = xfs_attr_set(ip, &name, (unsigned char *)xfs_acl, len);
> > >   		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);
> > > +		error = xfs_attr_remove(ip, &name);
> > >   		/*
> > >   		 * If the attribute didn't exist to start with that's fine.
> > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > > index d440426..626420d 100644
> > > --- a/fs/xfs/xfs_ioctl.c
> > > +++ b/fs/xfs/xfs_ioctl.c
> > > @@ -431,7 +431,11 @@ xfs_attrmulti_attr_get(
> > >   {
> > >   	unsigned char		*kbuf;
> > >   	int			error = -EFAULT;
> > > -	size_t			namelen;
> > > +	struct xfs_name		xname = {
> > > +		.name		= name,
> > > +		.len		= strlen(name),
> > > +		.type		= flags,
> > > +	};
> > >   	if (*len > XFS_XATTR_SIZE_MAX)
> > >   		return -EINVAL;
> > > @@ -439,9 +443,7 @@ xfs_attrmulti_attr_get(
> > >   	if (!kbuf)
> > >   		return -ENOMEM;
> > > -	namelen = strlen(name);
> > > -	error = xfs_attr_get(XFS_I(inode), name, namelen, &kbuf, (int *)len,
> > > -			     flags);
> > > +	error = xfs_attr_get(XFS_I(inode), &xname, &kbuf, (int *)len);
> > >   	if (error)
> > >   		goto out_kfree;
> > > @@ -463,7 +465,7 @@ xfs_attrmulti_attr_set(
> > >   {
> > >   	unsigned char		*kbuf;
> > >   	int			error;
> > > -	size_t			namelen;
> > > +	struct xfs_name		xname;
> > >   	if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> > >   		return -EPERM;
> > > @@ -474,8 +476,10 @@ xfs_attrmulti_attr_set(
> > >   	if (IS_ERR(kbuf))
> > >   		return PTR_ERR(kbuf);
> > > -	namelen = strlen(name);
> > > -	error = xfs_attr_set(XFS_I(inode), name, namelen, kbuf, len, flags);
> > > +	xname.name = name;
> > > +	xname.len = strlen(name);
> > > +	xname.type = flags;
> > > +	error = xfs_attr_set(XFS_I(inode), &xname, kbuf, len);
> > >   	if (!error)
> > >   		xfs_forget_acl(inode, name, flags);
> > >   	kfree(kbuf);
> > > @@ -489,12 +493,16 @@ xfs_attrmulti_attr_remove(
> > >   	uint32_t		flags)
> > >   {
> > >   	int			error;
> > > -	size_t			namelen;
> > > +	struct xfs_name		xname = {
> > > +		.name		= name,
> > > +		.len		= strlen(name),
> > > +		.type		= flags,
> > > +	};
> > >   	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_remove(XFS_I(inode), &xname);
> > >   	if (!error)
> > >   		xfs_forget_acl(inode, name, flags);
> > >   	return error;
> > > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
> > > index 92de0a7..469e8e2 100644
> > > --- a/fs/xfs/xfs_iops.c
> > > +++ b/fs/xfs/xfs_iops.c
> > > @@ -49,10 +49,14 @@ xfs_initxattrs(
> > >   	int			error = 0;
> > >   	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> > > -		error = xfs_attr_set(ip, xattr->name,
> > > -				     strlen(xattr->name),
> > > -				     xattr->value, xattr->value_len,
> > > -				     ATTR_SECURE);
> > > +		struct xfs_name	name = {
> > > +			.name	= xattr->name,
> > > +			.len	= strlen(xattr->name),
> > > +			.type	= ATTR_SECURE,
> > > +		};
> > > +
> > > +		error = xfs_attr_set(ip, &name,
> > > +				     xattr->value, xattr->value_len);
> > >   		if (error < 0)
> > >   			break;
> > >   	}
> > > diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c
> > > index 59ffe6c..6309da4 100644
> > > --- a/fs/xfs/xfs_xattr.c
> > > +++ b/fs/xfs/xfs_xattr.c
> > > @@ -20,19 +20,21 @@ static int
> > >   xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
> > >   		struct inode *inode, const char *name, void *value, size_t size)
> > >   {
> > > -	int xflags = handler->flags;
> > >   	struct xfs_inode *ip = XFS_I(inode);
> > >   	int error, asize = size;
> > > -	size_t namelen = strlen(name);
> > > +	struct xfs_name xname = {
> > > +		.name	= name,
> > > +		.len	= strlen(name),
> > > +		.type	= handler->flags
> > > +	};
> > >   	/* Convert Linux syscall to XFS internal ATTR flags */
> > >   	if (!size) {
> > > -		xflags |= ATTR_KERNOVAL;
> > > +		xname.type |= ATTR_KERNOVAL;
> > >   		value = NULL;
> > >   	}
> > > -	error = xfs_attr_get(ip, name, namelen, (unsigned char **)&value,
> > > -			     &asize, xflags);
> > > +	error = xfs_attr_get(ip, &xname, (unsigned char **)&value, &asize);
> > >   	if (error)
> > >   		return error;
> > >   	return asize;
> > > @@ -65,23 +67,25 @@ xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
> > >   		struct inode *inode, const char *name, const void *value,
> > >   		size_t size, int flags)
> > >   {
> > > -	int			xflags = handler->flags;
> > >   	struct xfs_inode	*ip = XFS_I(inode);
> > >   	int			error;
> > > -	size_t			namelen = strlen(name);
> > > +	struct xfs_name		xname = {
> > > +		.name		= name,
> > > +		.len		= strlen(name),
> > > +		.type		= handler->flags,
> > > +	};
> > >   	/* Convert Linux syscall to XFS internal ATTR flags */
> > >   	if (flags & XATTR_CREATE)
> > > -		xflags |= ATTR_CREATE;
> > > +		xname.type |= ATTR_CREATE;
> > >   	if (flags & XATTR_REPLACE)
> > > -		xflags |= ATTR_REPLACE;
> > > +		xname.type |= ATTR_REPLACE;
> > >   	if (!value)
> > > -		return xfs_attr_remove(ip, name,
> > > -				       namelen, xflags);
> > > -	error = xfs_attr_set(ip, name, namelen, (void *)value, size, xflags);
> > > +		return xfs_attr_remove(ip, &xname);
> > > +	error = xfs_attr_set(ip, &xname, (void *)value, size);
> > >   	if (!error)
> > > -		xfs_forget_acl(inode, name, xflags);
> > > +		xfs_forget_acl(inode, name, xname.type);
> > >   	return error;
> > >   }
> > > -- 
> > > 2.7.4
> > >