a configfs update for 4.5, and the configfs tree question

a configfs update for 4.5, and the configfs tree question

[Christoph Hellwig]

Hi all,

I really want the configfs change in this series to go into 4.5.  Originally
both Pantelis and I had changes ontop that would require it in a stable
non-rebased branch, but one or both of those might not make the cut.

As this has been a problem with a increased configfs actitivly lately I'd
like to volunteer to co-maintain configfs and keep a git tree that can
be used as stable baseline for all involved parties instead of the
patch-only -mm tree or occasional merge through the SCSI target tree.

I've started out with just this patch in my tree:

git://git.infradead.org/users/hch/vfs.git configfs-for-4.5

or gitweb:

http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/configfs-for-4.5

I know Krzysztof also had pending changes and I'd be happy to collect them
as well.

[PATCH] configfs: implement binary attributes

[Christoph Hellwig]

From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>

ConfigFS lacked binary attributes up until now. This patch
introduces support for binary attributes in a somewhat similar
manner of sysfs binary attributes albeit with changes that
fit the configfs usage model.

Problems that configfs binary attributes fix are everything that
requires a binary blob as part of the configuration of a resource,
such as bitstream loading for FPGAs, DTBs for dynamically created
devices etc.

Look at Documentation/filesystems/configfs/configfs.txt for internals
and howto use them.

This patch is against linux-next as of today that contains
Christoph's configfs rework.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[hch: folded a fix from Geert Uytterhoeven <geert+renesas@glider.be>]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/filesystems/configfs/configfs.txt |  57 +++++-
 fs/configfs/configfs_internal.h                 |  14 +-
 fs/configfs/dir.c                               |  18 +-
 fs/configfs/file.c                              | 255 +++++++++++++++++++++++-
 fs/configfs/inode.c                             |   2 +-
 include/linux/configfs.h                        |  50 +++++
 6 files changed, 374 insertions(+), 22 deletions(-)

diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt
index af68efd..e5fe521 100644
--- a/Documentation/filesystems/configfs/configfs.txt
+++ b/Documentation/filesystems/configfs/configfs.txt
@@ -51,15 +51,27 @@ configfs tree is always there, whether mounted on /config or not.
 An item is created via mkdir(2).  The item's attributes will also
 appear at this time.  readdir(3) can determine what the attributes are,
 read(2) can query their default values, and write(2) can store new
-values.  Like sysfs, attributes should be ASCII text files, preferably
-with only one value per file.  The same efficiency caveats from sysfs
-apply.  Don't mix more than one attribute in one attribute file.
-
-Like sysfs, configfs expects write(2) to store the entire buffer at
-once.  When writing to configfs attributes, userspace processes should
-first read the entire file, modify the portions they wish to change, and
-then write the entire buffer back.  Attribute files have a maximum size
-of one page (PAGE_SIZE, 4096 on i386).
+values.  Don't mix more than one attribute in one attribute file.
+
+There are two types of configfs attributes:
+
+* Normal attributes, which similar to sysfs attributes, are small ASCII text
+files, with a maximum size of one page (PAGE_SIZE, 4096 on i386).  Preferably
+only one value per file should be used, and the same caveats from sysfs apply.
+Configfs expects write(2) to store the entire buffer at once.  When writing to
+normal configfs attributes, userspace processes should first read the entire
+file, modify the portions they wish to change, and then write the entire
+buffer back.
+
+* Binary attributes, which are somewhat similar to sysfs binary attributes,
+but with a few slight changes to semantics.  The PAGE_SIZE limitation does not
+apply, but the whole binary item must fit in single kernel vmalloc'ed buffer.
+The write(2) calls from user space are buffered, and the attributes'
+write_bin_attribute method will be invoked on the final close, therefore it is
+imperative for user-space to check the return code of close(2) in order to
+verify that the operation finished successfully.
+To avoid a malicious user OOMing the kernel, there's a per-binary attribute
+maximum buffer value.
 
 When an item needs to be destroyed, remove it with rmdir(2).  An
 item cannot be destroyed if any other item has a link to it (via
@@ -171,6 +183,7 @@ among other things.  For that, it needs a type.
 		struct configfs_item_operations         *ct_item_ops;
 		struct configfs_group_operations        *ct_group_ops;
 		struct configfs_attribute               **ct_attrs;
+		struct configfs_bin_attribute		**ct_bin_attrs;
 	};
 
 The most basic function of a config_item_type is to define what
@@ -201,6 +214,32 @@ be called whenever userspace asks for a read(2) on the attribute.  If an
 attribute is writable and provides a ->store  method, that method will be
 be called whenever userspace asks for a write(2) on the attribute.
 
+[struct configfs_bin_attribute]
+
+	struct configfs_attribute {
+		struct configfs_attribute	cb_attr;
+		void				*cb_private;
+		size_t				cb_max_size;
+	};
+
+The binary attribute is used when the one needs to use binary blob to
+appear as the contents of a file in the item's configfs directory.
+To do so add the binary attribute to the NULL-terminated array
+config_item_type->ct_bin_attrs, and the item appears in configfs, the
+attribute file will appear with the configfs_bin_attribute->cb_attr.ca_name
+filename.  configfs_bin_attribute->cb_attr.ca_mode specifies the file
+permissions.
+The cb_private member is provided for use by the driver, while the
+cb_max_size member specifies the maximum amount of vmalloc buffer
+to be used.
+
+If binary attribute is readable and the config_item provides a
+ct_item_ops->read_bin_attribute() method, that method will be called
+whenever userspace asks for a read(2) on the attribute.  The converse
+will happen for write(2). The reads/writes are bufferred so only a
+single read/write will occur; the attributes' need not concern itself
+with it.
+
 [struct config_group]
 
 A config_item cannot live in a vacuum.  The only way one can be created
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index b65d1ef..ccc31fa 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -53,13 +53,14 @@ struct configfs_dirent {
 #define CONFIGFS_ROOT		0x0001
 #define CONFIGFS_DIR		0x0002
 #define CONFIGFS_ITEM_ATTR	0x0004
+#define CONFIGFS_ITEM_BIN_ATTR	0x0008
 #define CONFIGFS_ITEM_LINK	0x0020
 #define CONFIGFS_USET_DIR	0x0040
 #define CONFIGFS_USET_DEFAULT	0x0080
 #define CONFIGFS_USET_DROPPING	0x0100
 #define CONFIGFS_USET_IN_MKDIR	0x0200
 #define CONFIGFS_USET_CREATING	0x0400
-#define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR)
+#define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)
 
 extern struct mutex configfs_symlink_mutex;
 extern spinlock_t configfs_dirent_lock;
@@ -72,6 +73,8 @@ extern struct inode * configfs_new_inode(umode_t mode, struct configfs_dirent *,
 extern int configfs_create(struct dentry *, umode_t mode, void (*init)(struct inode *));
 
 extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
+extern int configfs_create_bin_file(struct config_item *,
+				    const struct configfs_bin_attribute *);
 extern int configfs_make_dirent(struct configfs_dirent *,
 				struct dentry *, void *, umode_t, int);
 extern int configfs_dirent_is_ready(struct configfs_dirent *);
@@ -88,7 +91,7 @@ extern void configfs_release_fs(void);
 extern struct rw_semaphore configfs_rename_sem;
 extern const struct file_operations configfs_dir_operations;
 extern const struct file_operations configfs_file_operations;
-extern const struct file_operations bin_fops;
+extern const struct file_operations configfs_bin_file_operations;
 extern const struct inode_operations configfs_dir_inode_operations;
 extern const struct inode_operations configfs_root_inode_operations;
 extern const struct inode_operations configfs_symlink_inode_operations;
@@ -119,6 +122,13 @@ static inline struct configfs_attribute * to_attr(struct dentry * dentry)
 	return ((struct configfs_attribute *) sd->s_element);
 }
 
+static inline struct configfs_bin_attribute *to_bin_attr(struct dentry *dentry)
+{
+	struct configfs_attribute *attr = to_attr(dentry);
+
+	return container_of(attr, struct configfs_bin_attribute, cb_attr);
+}
+
 static inline struct config_item *configfs_get_config_item(struct dentry *dentry)
 {
 	struct config_item * item = NULL;
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index a7a1b21..8f6c37a 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -255,6 +255,12 @@ static void configfs_init_file(struct inode * inode)
 	inode->i_fop = &configfs_file_operations;
 }
 
+static void configfs_init_bin_file(struct inode *inode)
+{
+	inode->i_size = 0;
+	inode->i_fop = &configfs_bin_file_operations;
+}
+
 static void init_symlink(struct inode * inode)
 {
 	inode->i_op = &configfs_symlink_inode_operations;
@@ -423,7 +429,9 @@ static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * den
 	spin_unlock(&configfs_dirent_lock);
 
 	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
-				configfs_init_file);
+				(sd->s_type & CONFIGFS_ITEM_ATTR) ?
+					configfs_init_file :
+					configfs_init_bin_file);
 	if (error) {
 		configfs_put(sd);
 		return error;
@@ -583,6 +591,7 @@ static int populate_attrs(struct config_item *item)
 {
 	struct config_item_type *t = item->ci_type;
 	struct configfs_attribute *attr;
+	struct configfs_bin_attribute *bin_attr;
 	int error = 0;
 	int i;
 
@@ -594,6 +603,13 @@ static int populate_attrs(struct config_item *item)
 				break;
 		}
 	}
+	if (t->ct_bin_attrs) {
+		for (i = 0; (bin_attr = t->ct_bin_attrs[i]) != NULL; i++) {
+			error = configfs_create_bin_file(item, bin_attr);
+			if (error)
+				break;
+		}
+	}
 
 	if (error)
 		detach_attrs(item);
diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index d39099e..235f653 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -28,6 +28,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/mutex.h>
+#include <linux/vmalloc.h>
 #include <asm/uaccess.h>
 
 #include <linux/configfs.h>
@@ -48,6 +49,10 @@ struct configfs_buffer {
 	struct configfs_item_operations	* ops;
 	struct mutex		mutex;
 	int			needs_read_fill;
+	int			read_in_progress;
+	int			write_in_progress;
+	char			*bin_buffer;
+	int			bin_buffer_size;
 };
 
 
@@ -123,6 +128,87 @@ out:
 	return retval;
 }
 
+/**
+ *	configfs_read_bin_file - read a binary attribute.
+ *	@file:	file pointer.
+ *	@buf:	buffer to fill.
+ *	@count:	number of bytes to read.
+ *	@ppos:	starting offset in file.
+ *
+ *	Userspace wants to read a binary attribute file. The attribute
+ *	descriptor is in the file's ->d_fsdata. The target item is in the
+ *	directory's ->d_fsdata.
+ *
+ *	We check whether we need to refill the buffer. If so we will
+ *	call the attributes' attr->read() twice. The first time we
+ *	will pass a NULL as a buffer pointer, which the attributes' method
+ *	will use to return the size of the buffer required. If no error
+ *	occurs we will allocate the buffer using vmalloc and call
+ *	attr->read() again passing that buffer as an argument.
+ *	Then we just copy to user-space using simple_read_from_buffer.
+ */
+
+static ssize_t
+configfs_read_bin_file(struct file *file, char __user *buf,
+		       size_t count, loff_t *ppos)
+{
+	struct configfs_buffer *buffer = file->private_data;
+	struct dentry *dentry = file->f_path.dentry;
+	struct config_item *item = to_item(dentry->d_parent);
+	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
+	ssize_t retval = 0;
+	ssize_t len = min_t(size_t, count, PAGE_SIZE);
+
+	mutex_lock(&buffer->mutex);
+
+	/* we don't support switching read/write modes */
+	if (buffer->write_in_progress) {
+		retval = -EINVAL;
+		goto out;
+	}
+	buffer->read_in_progress = 1;
+
+	if (buffer->needs_read_fill) {
+		/* perform first read with buf == NULL to get extent */
+		len = bin_attr->read(item, NULL, 0);
+		if (len <= 0) {
+			retval = len;
+			goto out;
+		}
+
+		/* do not exceed the maximum value */
+		if (bin_attr->cb_max_size && len > bin_attr->cb_max_size) {
+			retval = -EFBIG;
+			goto out;
+		}
+
+		buffer->bin_buffer = vmalloc(len);
+		if (buffer->bin_buffer == NULL) {
+			retval = -ENOMEM;
+			goto out;
+		}
+		buffer->bin_buffer_size = len;
+
+		/* perform second read to fill buffer */
+		len = bin_attr->read(item, buffer->bin_buffer, len);
+		if (len < 0) {
+			retval = len;
+			vfree(buffer->bin_buffer);
+			buffer->bin_buffer_size = 0;
+			buffer->bin_buffer = NULL;
+			goto out;
+		}
+
+		buffer->needs_read_fill = 0;
+	}
+
+	retval = simple_read_from_buffer(buf, count, ppos, buffer->bin_buffer,
+					buffer->bin_buffer_size);
+out:
+	mutex_unlock(&buffer->mutex);
+	return retval;
+}
+
 
 /**
  *	fill_write_buffer - copy buffer from userspace.
@@ -209,10 +295,80 @@ configfs_write_file(struct file *file, const char __user *buf, size_t count, lof
 	return len;
 }
 
-static int check_perm(struct inode * inode, struct file * file)
+/**
+ *	configfs_write_bin_file - write a binary attribute.
+ *	@file:	file pointer
+ *	@buf:	data to write
+ *	@count:	number of bytes
+ *	@ppos:	starting offset
+ *
+ *	Writing to a binary attribute file is similar to a normal read.
+ *	We buffer the consecutive writes (binary attribute files do not
+ *	support lseek) in a continuously growing buffer, but we don't
+ *	commit until the close of the file.
+ */
+
+static ssize_t
+configfs_write_bin_file(struct file *file, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	struct configfs_buffer *buffer = file->private_data;
+	struct dentry *dentry = file->f_path.dentry;
+	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
+	void *tbuf = NULL;
+	ssize_t len;
+
+	mutex_lock(&buffer->mutex);
+
+	/* we don't support switching read/write modes */
+	if (buffer->read_in_progress) {
+		len = -EINVAL;
+		goto out;
+	}
+	buffer->write_in_progress = 1;
+
+	/* buffer grows? */
+	if (*ppos + count > buffer->bin_buffer_size) {
+
+		if (bin_attr->cb_max_size &&
+			*ppos + count > bin_attr->cb_max_size) {
+			len = -EFBIG;
+		}
+
+		tbuf = vmalloc(*ppos + count);
+		if (tbuf == NULL) {
+			len = -ENOMEM;
+			goto out;
+		}
+
+		/* copy old contents */
+		if (buffer->bin_buffer) {
+			memcpy(tbuf, buffer->bin_buffer,
+				buffer->bin_buffer_size);
+			vfree(buffer->bin_buffer);
+		}
+
+		/* clear the new area */
+		memset(tbuf + buffer->bin_buffer_size, 0,
+			*ppos + count - buffer->bin_buffer_size);
+		buffer->bin_buffer = tbuf;
+		buffer->bin_buffer_size = *ppos + count;
+	}
+
+	len = simple_write_to_buffer(buffer->bin_buffer,
+			buffer->bin_buffer_size, ppos, buf, count);
+	if (len > 0)
+		*ppos += len;
+out:
+	mutex_unlock(&buffer->mutex);
+	return len;
+}
+
+static int check_perm(struct inode * inode, struct file * file, int type)
 {
 	struct config_item *item = configfs_get_config_item(file->f_path.dentry->d_parent);
 	struct configfs_attribute * attr = to_attr(file->f_path.dentry);
+	struct configfs_bin_attribute *bin_attr = NULL;
 	struct configfs_buffer * buffer;
 	struct configfs_item_operations * ops = NULL;
 	int error = 0;
@@ -220,6 +376,9 @@ static int check_perm(struct inode * inode, struct file * file)
 	if (!item || !attr)
 		goto Einval;
 
+	if (type & CONFIGFS_ITEM_BIN_ATTR)
+		bin_attr = to_bin_attr(file->f_path.dentry);
+
 	/* Grab the module reference for this attribute if we have one */
 	if (!try_module_get(attr->ca_owner)) {
 		error = -ENODEV;
@@ -236,9 +395,14 @@ static int check_perm(struct inode * inode, struct file * file)
 	 * and we must have a store method.
 	 */
 	if (file->f_mode & FMODE_WRITE) {
-		if (!(inode->i_mode & S_IWUGO) || !attr->store)
+		if (!(inode->i_mode & S_IWUGO))
+			goto Eaccess;
+
+		if ((type & CONFIGFS_ITEM_ATTR) && !attr->store)
 			goto Eaccess;
 
+		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->write)
+			goto Eaccess;
 	}
 
 	/* File needs read support.
@@ -246,7 +410,13 @@ static int check_perm(struct inode * inode, struct file * file)
 	 * must be a show method for it.
 	 */
 	if (file->f_mode & FMODE_READ) {
-		if (!(inode->i_mode & S_IRUGO) || !attr->show)
+		if (!(inode->i_mode & S_IRUGO))
+			goto Eaccess;
+
+		if ((type & CONFIGFS_ITEM_ATTR) && !attr->show)
+			goto Eaccess;
+
+		if ((type & CONFIGFS_ITEM_BIN_ATTR) && !bin_attr->read)
 			goto Eaccess;
 	}
 
@@ -260,6 +430,8 @@ static int check_perm(struct inode * inode, struct file * file)
 	}
 	mutex_init(&buffer->mutex);
 	buffer->needs_read_fill = 1;
+	buffer->read_in_progress = 0;
+	buffer->write_in_progress = 0;
 	buffer->ops = ops;
 	file->private_data = buffer;
 	goto Done;
@@ -277,12 +449,7 @@ static int check_perm(struct inode * inode, struct file * file)
 	return error;
 }
 
-static int configfs_open_file(struct inode * inode, struct file * filp)
-{
-	return check_perm(inode,filp);
-}
-
-static int configfs_release(struct inode * inode, struct file * filp)
+static int configfs_release(struct inode *inode, struct file *filp)
 {
 	struct config_item * item = to_item(filp->f_path.dentry->d_parent);
 	struct configfs_attribute * attr = to_attr(filp->f_path.dentry);
@@ -303,6 +470,47 @@ static int configfs_release(struct inode * inode, struct file * filp)
 	return 0;
 }
 
+static int configfs_open_file(struct inode *inode, struct file *filp)
+{
+	return check_perm(inode, filp, CONFIGFS_ITEM_ATTR);
+}
+
+static int configfs_open_bin_file(struct inode *inode, struct file *filp)
+{
+	return check_perm(inode, filp, CONFIGFS_ITEM_BIN_ATTR);
+}
+
+static int configfs_release_bin_file(struct inode *inode, struct file *filp)
+{
+	struct configfs_buffer *buffer = filp->private_data;
+	struct dentry *dentry = filp->f_path.dentry;
+	struct config_item *item = to_item(dentry->d_parent);
+	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
+	ssize_t len = 0;
+	int ret;
+
+	buffer->read_in_progress = 0;
+
+	if (buffer->write_in_progress) {
+		buffer->write_in_progress = 0;
+
+		len = bin_attr->write(item, buffer->bin_buffer,
+				buffer->bin_buffer_size);
+
+		/* vfree on NULL is safe */
+		vfree(buffer->bin_buffer);
+		buffer->bin_buffer = NULL;
+		buffer->bin_buffer_size = 0;
+		buffer->needs_read_fill = 1;
+	}
+
+	ret = configfs_release(inode, filp);
+	if (len < 0)
+		return len;
+	return ret;
+}
+
+
 const struct file_operations configfs_file_operations = {
 	.read		= configfs_read_file,
 	.write		= configfs_write_file,
@@ -311,6 +519,14 @@ const struct file_operations configfs_file_operations = {
 	.release	= configfs_release,
 };
 
+const struct file_operations configfs_bin_file_operations = {
+	.read		= configfs_read_bin_file,
+	.write		= configfs_write_bin_file,
+	.llseek		= NULL,		/* bin file is not seekable */
+	.open		= configfs_open_bin_file,
+	.release	= configfs_release_bin_file,
+};
+
 /**
  *	configfs_create_file - create an attribute file for an item.
  *	@item:	item we're creating for.
@@ -332,3 +548,24 @@ int configfs_create_file(struct config_item * item, const struct configfs_attrib
 	return error;
 }
 
+/**
+ *	configfs_create_bin_file - create a binary attribute file for an item.
+ *	@item:	item we're creating for.
+ *	@attr:	atrribute descriptor.
+ */
+
+int configfs_create_bin_file(struct config_item *item,
+		const struct configfs_bin_attribute *bin_attr)
+{
+	struct dentry *dir = item->ci_dentry;
+	struct configfs_dirent *parent_sd = dir->d_fsdata;
+	umode_t mode = (bin_attr->cb_attr.ca_mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
+
+	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_NORMAL);
+	error = configfs_make_dirent(parent_sd, NULL, (void *) bin_attr, mode,
+				     CONFIGFS_ITEM_BIN_ATTR);
+	mutex_unlock(&dir->d_inode->i_mutex);
+
+	return error;
+}
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index eae8757..0cc810e 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -218,7 +218,7 @@ const unsigned char * configfs_get_name(struct configfs_dirent *sd)
 	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
 		return sd->s_dentry->d_name.name;
 
-	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
+	if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
 		attr = sd->s_element;
 		return attr->ca_name;
 	}
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 758a029..f7300d0 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -51,6 +51,7 @@ struct module;
 struct configfs_item_operations;
 struct configfs_group_operations;
 struct configfs_attribute;
+struct configfs_bin_attribute;
 struct configfs_subsystem;
 
 struct config_item {
@@ -84,6 +85,7 @@ struct config_item_type {
 	struct configfs_item_operations		*ct_item_ops;
 	struct configfs_group_operations	*ct_group_ops;
 	struct configfs_attribute		**ct_attrs;
+	struct configfs_bin_attribute		**ct_bin_attrs;
 };
 
 /**
@@ -154,6 +156,54 @@ static struct configfs_attribute _pfx##attr_##_name = {	\
 	.store		= _pfx##_name##_store,		\
 }
 
+struct file;
+struct vm_area_struct;
+
+struct configfs_bin_attribute {
+	struct configfs_attribute cb_attr;	/* std. attribute */
+	void *cb_private;			/* for user       */
+	size_t cb_max_size;			/* max core size  */
+	ssize_t (*read)(struct config_item *, void *, size_t);
+	ssize_t (*write)(struct config_item *, const void *, size_t);
+};
+
+#define CONFIGFS_BIN_ATTR(_pfx, _name, _priv, _maxsz)		\
+static struct configfs_bin_attribute _pfx##attr_##_name = {	\
+	.cb_attr = {						\
+		.ca_name	= __stringify(_name),		\
+		.ca_mode	= S_IRUGO | S_IWUSR,		\
+		.ca_owner	= THIS_MODULE,			\
+	},							\
+	.cb_private	= _priv,				\
+	.cb_max_size	= _maxsz,				\
+	.read		= _pfx##_name##_read,			\
+	.write		= _pfx##_name##_write,			\
+}
+
+#define CONFIGFS_BIN_ATTR_RO(_pfx, _name, _priv, _maxsz)	\
+static struct configfs_attribute _pfx##attr_##_name = {		\
+	.cb_attr = {						\
+		.ca_name	= __stringify(_name),		\
+		.ca_mode	= S_IRUGO,			\
+		.ca_owner	= THIS_MODULE,			\
+	},							\
+	.cb_private	= _priv,				\
+	.cb_max_size	= _maxsz,				\
+	.read		= _pfx##_name##_read,			\
+}
+
+#define CONFIGFS_BIN_ATTR_WO(_pfx, _name, _priv, _maxsz)	\
+static struct configfs_attribute _pfx##attr_##_name = {		\
+	.cb_attr = {						\
+		.ca_name	= __stringify(_name),		\
+		.ca_mode	= S_IWUSR,			\
+		.ca_owner	= THIS_MODULE,			\
+	},							\
+	.cb_private	= _priv,				\
+	.cb_max_size	= _maxsz,				\
+	.write		= _pfx##_name##_write,			\
+}
+
 /*
  * If allow_link() exists, the item can symlink(2) out to other
  * items.  If the item is a group, it may support mkdir(2).
-- 
1.9.1

Re: [PATCH] configfs: implement binary attributes

[Joel Becker]

On Thu, Dec 24, 2015 at 03:51:10PM +0100, Christoph Hellwig wrote:
> From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> 
> ConfigFS lacked binary attributes up until now. This patch
> introduces support for binary attributes in a somewhat similar
> manner of sysfs binary attributes albeit with changes that
> fit the configfs usage model.
> 
> Problems that configfs binary attributes fix are everything that
> requires a binary blob as part of the configuration of a resource,
> such as bitstream loading for FPGAs, DTBs for dynamically created
> devices etc.

Overall, I really like this addition.

> @@ -423,7 +429,9 @@ static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * den
>  	spin_unlock(&configfs_dirent_lock);
>  
>  	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
> -				configfs_init_file);
> +				(sd->s_type & CONFIGFS_ITEM_ATTR) ?
> +					configfs_init_file :
> +					configfs_init_bin_file);

BIN_ATTRs are the more uncommon type, at least for now.  I would think
this code should check for special cases and fall back to ITEM_ATTR.  So
reverse it.

	(sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
  		configfs_init_bin_file :
		configfs_init_file

> +static ssize_t
> +configfs_read_bin_file(struct file *file, char __user *buf,
> +		       size_t count, loff_t *ppos)
> +{
> +	struct configfs_buffer *buffer = file->private_data;
> +	struct dentry *dentry = file->f_path.dentry;
> +	struct config_item *item = to_item(dentry->d_parent);
> +	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
> +	ssize_t retval = 0;
> +	ssize_t len = min_t(size_t, count, PAGE_SIZE);
> +
> +	mutex_lock(&buffer->mutex);
> +
> +	/* we don't support switching read/write modes */
> +	if (buffer->write_in_progress) {
> +		retval = -EINVAL;
> +		goto out;
> +	}

These are valid arguments, it's just competing with another operation.
Wouldn't something like EINPROGRESS or ETXTBSY make more sense and be
more informative?  The same for configfs_write_bin_file().

Joel 

-- 

"Soap and education are not as sudden as a massacre, but they are more
 deadly in the long run."
	- Mark Twain


			http://www.jlbec.org/
			jlbec@evilplan.org

Re: [PATCH] configfs: implement binary attributes

[Krzysztof Opasiak]

W dniu 2015-12-30 o 00:00, Joel Becker pisze:
 > On Thu, Dec 24, 2015 at 03:51:10PM +0100, Christoph Hellwig wrote:
 >> From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
 >>
 >> ConfigFS lacked binary attributes up until now. This patch
 >> introduces support for binary attributes in a somewhat similar
 >> manner of sysfs binary attributes albeit with changes that
 >> fit the configfs usage model.
 >>
 >> Problems that configfs binary attributes fix are everything that
 >> requires a binary blob as part of the configuration of a resource,
 >> such as bitstream loading for FPGAs, DTBs for dynamically created
 >> devices etc.
 >
 > Overall, I really like this addition.
 >
 >> @@ -423,7 +429,9 @@ static int configfs_attach_attr(struct 
configfs_dirent * sd, struct dentry * den
 >>   	spin_unlock(&configfs_dirent_lock);
 >>
 >>   	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | 
S_IFREG,
 >> -				configfs_init_file);
 >> +				(sd->s_type & CONFIGFS_ITEM_ATTR) ?
 >> +					configfs_init_file :
 >> +					configfs_init_bin_file);
 >
 > BIN_ATTRs are the more uncommon type, at least for now.  I would think
 > this code should check for special cases and fall back to ITEM_ATTR.  So
 > reverse it.
 >
 > 	(sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
 >    		configfs_init_bin_file :
 > 		configfs_init_file
 >

I think that static inline helper can be usefull here to improve readability

 >> +static ssize_t
 >> +configfs_read_bin_file(struct file *file, char __user *buf,
 >> +		       size_t count, loff_t *ppos)
 >> +{
 >> +	struct configfs_buffer *buffer = file->private_data;
 >> +	struct dentry *dentry = file->f_path.dentry;
 >> +	struct config_item *item = to_item(dentry->d_parent);
 >> +	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
 >> +	ssize_t retval = 0;
 >> +	ssize_t len = min_t(size_t, count, PAGE_SIZE);
 >> +
 >> +	mutex_lock(&buffer->mutex);
 >> +
 >> +	/* we don't support switching read/write modes */
 >> +	if (buffer->write_in_progress) {
 >> +		retval = -EINVAL;
 >> +		goto out;
 >> +	}
 >
 > These are valid arguments, it's just competing with another operation.
 > Wouldn't something like EINPROGRESS or ETXTBSY make more sense and be
 > more informative?  The same for configfs_write_bin_file().
 >
 > Joel
 >

-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics

Re: [PATCH] configfs: implement binary attributes

[Pantelis Antoniou]

Hi Joel,

> On Dec 30, 2015, at 01:00 , Joel Becker <jlbec@evilplan.org> wrote:
> 
> On Thu, Dec 24, 2015 at 03:51:10PM +0100, Christoph Hellwig wrote:
>> From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>> 
>> ConfigFS lacked binary attributes up until now. This patch
>> introduces support for binary attributes in a somewhat similar
>> manner of sysfs binary attributes albeit with changes that
>> fit the configfs usage model.
>> 
>> Problems that configfs binary attributes fix are everything that
>> requires a binary blob as part of the configuration of a resource,
>> such as bitstream loading for FPGAs, DTBs for dynamically created
>> devices etc.
> 
> Overall, I really like this addition.
> 

That’s good :)

>> @@ -423,7 +429,9 @@ static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * den
>> 	spin_unlock(&configfs_dirent_lock);
>> 
>> 	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
>> -				configfs_init_file);
>> +				(sd->s_type & CONFIGFS_ITEM_ATTR) ?
>> +					configfs_init_file :
>> +					configfs_init_bin_file);
> 
> BIN_ATTRs are the more uncommon type, at least for now.  I would think
> this code should check for special cases and fall back to ITEM_ATTR.  So
> reverse it.
> 
> 	(sd->s_type & CONFIGFS_ITEM_BIN_ATTR) ?
>  		configfs_init_bin_file :
> 		configfs_init_file
> 

OK.

>> +static ssize_t
>> +configfs_read_bin_file(struct file *file, char __user *buf,
>> +		       size_t count, loff_t *ppos)
>> +{
>> +	struct configfs_buffer *buffer = file->private_data;
>> +	struct dentry *dentry = file->f_path.dentry;
>> +	struct config_item *item = to_item(dentry->d_parent);
>> +	struct configfs_bin_attribute *bin_attr = to_bin_attr(dentry);
>> +	ssize_t retval = 0;
>> +	ssize_t len = min_t(size_t, count, PAGE_SIZE);
>> +
>> +	mutex_lock(&buffer->mutex);
>> +
>> +	/* we don't support switching read/write modes */
>> +	if (buffer->write_in_progress) {
>> +		retval = -EINVAL;
>> +		goto out;
>> +	}
> 
> These are valid arguments, it's just competing with another operation.
> Wouldn't something like EINPROGRESS or ETXTBSY make more sense and be
> more informative?  The same for configfs_write_bin_file().
> 

Yep, will be done.

> Joel 
> 

Regards

— Pantelis

PS. A big thanks to Christoph for keeping this going. I will shortly post a new version with the
requested changes incorporated.


> -- 
> 
> "Soap and education are not as sudden as a massacre, but they are more
> deadly in the long run."
> 	- Mark Twain
> 
> 
> 			http://www.jlbec.org/
> 			jlbec@evilplan.org

Re: [PATCH] configfs: implement binary attributes

[Krzysztof Opasiak]

W dniu 2015-12-24 o 15:51, Christoph Hellwig pisze:
> From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
>
> ConfigFS lacked binary attributes up until now. This patch
> introduces support for binary attributes in a somewhat similar
> manner of sysfs binary attributes albeit with changes that
> fit the configfs usage model.
>
> Problems that configfs binary attributes fix are everything that
> requires a binary blob as part of the configuration of a resource,
> such as bitstream loading for FPGAs, DTBs for dynamically created
> devices etc.
>
> Look at Documentation/filesystems/configfs/configfs.txt for internals
> and howto use them.
>
> This patch is against linux-next as of today that contains
> Christoph's configfs rework.
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> [hch: folded a fix from Geert Uytterhoeven <geert+renesas@glider.be>]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

(...)

>
>   #include <linux/configfs.h>
> @@ -48,6 +49,10 @@ struct configfs_buffer {
>   	struct configfs_item_operations	* ops;
>   	struct mutex		mutex;
>   	int			needs_read_fill;
> +	int			read_in_progress;
> +	int			write_in_progress;

Those 2 should be probably bool instead of int.

> +	char			*bin_buffer;
> +	int			bin_buffer_size;
>   };

(...)

> diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
> index eae8757..0cc810e 100644
> --- a/fs/configfs/inode.c
> +++ b/fs/configfs/inode.c
> @@ -218,7 +218,7 @@ const unsigned char * configfs_get_name(struct configfs_dirent *sd)
>   	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
>   		return sd->s_dentry->d_name.name;
>
> -	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
> +	if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {

I would also recomend a static inline helper here instead of adding this 
or as this may simplify the code in a few places.


Best regards,
-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics

Re: a configfs update for 4.5, and the configfs tree question

[Joel Becker]

On Thu, Dec 24, 2015 at 03:51:09PM +0100, Christoph Hellwig wrote:
> Hi all,
> 
> I really want the configfs change in this series to go into 4.5.  Originally
> both Pantelis and I had changes ontop that would require it in a stable
> non-rebased branch, but one or both of those might not make the cut.
> 
> As this has been a problem with a increased configfs actitivly lately I'd
> like to volunteer to co-maintain configfs and keep a git tree that can
> be used as stable baseline for all involved parties instead of the
> patch-only -mm tree or occasional merge through the SCSI target tree.
> 
> I've started out with just this patch in my tree:
> 
> git://git.infradead.org/users/hch/vfs.git configfs-for-4.5
> 
> or gitweb:
> 
> http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/configfs-for-4.5
> 
> I know Krzysztof also had pending changes and I'd be happy to collect them
> as well.
> 

Hoi,

I'm well aware that I've caught some reviews and missed some others.  I
support funneling through hch's tree here.

Joel

-- 

"A narcissist is someone better looking than you are."  
         - Gore Vidal

			http://www.jlbec.org/
			jlbec@evilplan.org

Re: a configfs update for 4.5, and the configfs tree question

[Christoph Hellwig]

On Tue, Dec 29, 2015 at 03:05:30PM -0800, Joel Becker wrote:
> 
> Hoi,
> 
> I'm well aware that I've caught some reviews and missed some others.  I
> support funneling through hch's tree here.

Thanks.  I've created a separate repo for configfs:

	git://git.infradead.org/users/hch/configfs.git

gitweb:

	http://git.infradead.org/users/hch/configfs.git

this has the binary attribute patch with the most important
review fixes, and the patch attached below to add myself as co-maintainer
and update the git repo in MAINTAINERS.  I'd like a signoff from you
for that second one and then move it to for-next.

Fengguang, can you give this tree the full buildbot treatment?

Stephen, can you add

	git://git.infradead.org/users/hch/configfs.git for-next

to for-next?  It's currently emptry but will contain the two commits
from the pending branch as soon as I get the signoff from Joel.

Re: a configfs update for 4.5, and the configfs tree question

[Fengguang Wu]

On Mon, Jan 04, 2016 at 12:51:01PM +0100, Christoph Hellwig wrote:
> On Tue, Dec 29, 2015 at 03:05:30PM -0800, Joel Becker wrote:
> > 
> > Hoi,
> > 
> > I'm well aware that I've caught some reviews and missed some others.  I
> > support funneling through hch's tree here.
> 
> Thanks.  I've created a separate repo for configfs:
> 
> 	git://git.infradead.org/users/hch/configfs.git

[snip]

> Fengguang, can you give this tree the full buildbot treatment?

OK, done.

Thanks,
Fengguang

Re: a configfs update for 4.5, and the configfs tree question

[Stephen Rothwell]

Hi Christoph,

On Mon, 4 Jan 2016 12:51:01 +0100 Christoph Hellwig <hch@lst.de> wrote:
>
> Stephen, can you add
> 
> 	git://git.infradead.org/users/hch/configfs.git for-next
> 
> to for-next?  It's currently emptry but will contain the two commits
> from the pending branch as soon as I get the signoff from Joel.

Added from today.

Thanks for adding your subsystem tree as a participant of linux-next.  As
you may know, this is not a judgment of your code.  The purpose of
linux-next is for integration testing and to lower the impact of
conflicts between subsystems in the next merge window. 

You will need to ensure that the patches/commits in your tree/series have
been:
     * submitted under GPL v2 (or later) and include the Contributor's
        Signed-off-by,
     * posted to the relevant mailing list,
     * reviewed by you (or another maintainer of your subsystem tree),
     * successfully unit tested, and 
     * destined for the current or next Linux merge window.

Basically, this should be just what you would send to Linus (or ask him
to fetch).  It is allowed to be rebased if you deem it necessary.

-- 
Cheers,
Stephen Rothwell 
sfr@canb.auug.org.au

Re: a configfs update for 4.5, and the configfs tree question

[Joel Becker]

On Mon, Jan 04, 2016 at 12:51:01PM +0100, Christoph Hellwig wrote:
> On Tue, Dec 29, 2015 at 03:05:30PM -0800, Joel Becker wrote:
> > 
> > Hoi,
> > 
> > I'm well aware that I've caught some reviews and missed some others.  I
> > support funneling through hch's tree here.
> 
> Thanks.  I've created a separate repo for configfs:
> 
> 	git://git.infradead.org/users/hch/configfs.git
> 
> gitweb:
> 
> 	http://git.infradead.org/users/hch/configfs.git
> 
> this has the binary attribute patch with the most important
> review fixes, and the patch attached below to add myself as co-maintainer
> and update the git repo in MAINTAINERS.  I'd like a signoff from you
> for that second one and then move it to for-next.

commit 4170b875784c85790388952200ee1432cdb70793
Signed-off-by: Joel Becker <jlbec@evilplan.org>

-- 

"What no boss of a programmer can ever understand is that a programmer
 is working when he's staring out of the window"
	- With apologies to Burton Rascoe

			http://www.jlbec.org/
			jlbec@evilplan.org

Re: a configfs update for 4.5, and the configfs tree question

[Nicholas A. Bellinger]

On Thu, 2015-12-24 at 15:51 +0100, Christoph Hellwig wrote:
> Hi all,
> 
> I really want the configfs change in this series to go into 4.5.  Originally
> both Pantelis and I had changes ontop that would require it in a stable
> non-rebased branch, but one or both of those might not make the cut.
> 
> As this has been a problem with a increased configfs actitivly lately I'd
> like to volunteer to co-maintain configfs and keep a git tree that can
> be used as stable baseline for all involved parties instead of the
> patch-only -mm tree or occasional merge through the SCSI target tree.
> 
> I've started out with just this patch in my tree:
> 
> git://git.infradead.org/users/hch/vfs.git configfs-for-4.5
> 
> or gitweb:
> 
> http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/configfs-for-4.5
> 
> I know Krzysztof also had pending changes and I'd be happy to collect them
> as well.

Wrt to Krzysztof's set of aforementioned configfs patches, they have
been in target-pending/for-next for the last few weeks now..

Since the larger set of Andrzej's usb-gadget target changes depend upon
these configfs changes, it makes sense to keep them together in the
target tree.

Beyond that, I'm glad to see a dedicated configfs tree.

Thanks HCH.