configfs currently has a limitation that the kernel can send only
PAGESIZE of data through a attribute.
This patch removes that limitation by using seq_file in the read side of
operations.
Signed-Off-By: Chandra Seetharaman <[email protected]>
--
fs/configfs/file.c | 130 ++++++++++-------------------------------------
include/linux/configfs.h | 3 -
2 files changed, 31 insertions(+), 102 deletions(-)
Index: linux-2.6.18/fs/configfs/file.c
===================================================================
--- linux-2.6.18.orig/fs/configfs/file.c
+++ linux-2.6.18/fs/configfs/file.c
@@ -40,112 +40,33 @@ struct configfs_buffer {
char * page;
struct configfs_item_operations * ops;
struct semaphore sem;
- int needs_read_fill;
+ struct dentry * dentry;
};
/**
- * fill_read_buffer - allocate and fill buffer from item.
- * @dentry: dentry pointer.
- * @buffer: data buffer for file.
- *
- * Allocate @buffer->page, if it hasn't been already, then call the
- * config_item's show() method to fill the buffer with this attribute's
- * data.
- * This is called only once, on the file's first read.
- */
-static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
-{
- struct configfs_attribute * attr = to_attr(dentry);
- struct config_item * item = to_item(dentry->d_parent);
- struct configfs_item_operations * ops = buffer->ops;
- int ret = 0;
- ssize_t count;
-
- if (!buffer->page)
- buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
- if (!buffer->page)
- return -ENOMEM;
-
- count = ops->show_attribute(item,attr,buffer->page);
- buffer->needs_read_fill = 0;
- BUG_ON(count > (ssize_t)PAGE_SIZE);
- if (count >= 0)
- buffer->count = count;
- else
- ret = count;
- return ret;
-}
-
-
-/**
- * flush_read_buffer - push buffer to userspace.
- * @buffer: data buffer for file.
- * @userbuf: user-passed buffer.
- * @count: number of bytes requested.
- * @ppos: file position.
- *
- * Copy the buffer we filled in fill_read_buffer() to userspace.
- * This is done at the reader's leisure, copying and advancing
- * the amount they specify each time.
- * This may be called continuously until the buffer is empty.
- */
-static int flush_read_buffer(struct configfs_buffer * buffer, char __user * buf,
- size_t count, loff_t * ppos)
-{
- int error;
-
- if (*ppos > buffer->count)
- return 0;
-
- if (count > (buffer->count - *ppos))
- count = buffer->count - *ppos;
-
- error = copy_to_user(buf,buffer->page + *ppos,count);
- if (!error)
- *ppos += count;
- return error ? -EFAULT : count;
-}
-
-/**
* configfs_read_file - read an attribute.
- * @file: file pointer.
- * @buf: buffer to fill.
- * @count: number of bytes to read.
- * @ppos: starting offset in file.
+ * @s: seq_file pointer.
+ * @v: unused void pointer
*
* Userspace wants to read an attribute file. The attribute descriptor
- * is in the file's ->d_fsdata. The target item is in the directory's
- * ->d_fsdata.
+ * is available through dentry, which is stored in the seq_file.
+ * The target item is in the dentry's parent.
+ *
+ * We just call the show() method directly.
*
- * We call fill_read_buffer() to allocate and fill the buffer from the
- * item's show() method exactly once (if the read is happening from
- * the beginning of the file). That should fill the entire buffer with
- * all the data the item has to offer for that attribute.
- * We then call flush_read_buffer() to copy the buffer to userspace
- * in the increments specified.
*/
-
-static ssize_t
-configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+static int
+configfs_read_file(struct seq_file *s, void *v)
{
- struct configfs_buffer * buffer = file->private_data;
- ssize_t retval = 0;
+ struct configfs_buffer * buffer = s->private;
+ struct configfs_item_operations * ops = buffer->ops;
+ struct configfs_attribute * attr = to_attr(buffer->dentry);
+ struct config_item * item = to_item(buffer->dentry->d_parent);
- down(&buffer->sem);
- if (buffer->needs_read_fill) {
- if ((retval = fill_read_buffer(file->f_dentry,buffer)))
- goto out;
- }
- pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
- __FUNCTION__,count,*ppos,buffer->page);
- retval = flush_read_buffer(buffer,buf,count,ppos);
-out:
- up(&buffer->sem);
- return retval;
+ return ops->show_attribute(item, attr, s);
}
-
/**
* fill_write_buffer - copy buffer from userspace.
* @buffer: data buffer for file.
@@ -169,7 +90,6 @@ fill_write_buffer(struct configfs_buffer
if (count > PAGE_SIZE)
count = PAGE_SIZE;
error = copy_from_user(buffer->page,buf,count);
- buffer->needs_read_fill = 1;
return error ? -EFAULT : count;
}
@@ -216,7 +136,8 @@ flush_write_buffer(struct dentry * dentr
static ssize_t
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
- struct configfs_buffer * buffer = file->private_data;
+ struct configfs_buffer * buffer =
+ ((struct seq_file *)file->private_data)->private;
ssize_t len;
down(&buffer->sem);
@@ -281,9 +202,14 @@ static int check_perm(struct inode * ino
}
memset(buffer,0,sizeof(struct configfs_buffer));
init_MUTEX(&buffer->sem);
- buffer->needs_read_fill = 1;
buffer->ops = ops;
- file->private_data = buffer;
+ buffer->dentry = file->f_dentry;
+
+ error = single_open(file, configfs_read_file, buffer);
+ if (error) {
+ kfree(buffer);
+ goto Enomem;
+ }
goto Done;
Einval:
@@ -309,7 +235,8 @@ static int configfs_release(struct inode
struct config_item * item = to_item(filp->f_dentry->d_parent);
struct configfs_attribute * attr = to_attr(filp->f_dentry);
struct module * owner = attr->ca_owner;
- struct configfs_buffer * buffer = filp->private_data;
+ struct configfs_buffer * buffer =
+ ((struct seq_file *)filp->private_data)->private;
if (item)
config_item_put(item);
@@ -321,13 +248,14 @@ static int configfs_release(struct inode
free_page((unsigned long)buffer->page);
kfree(buffer);
}
- return 0;
+
+ return single_release(inode, filp);
}
const struct file_operations configfs_file_operations = {
- .read = configfs_read_file,
+ .read = seq_read,
.write = configfs_write_file,
- .llseek = generic_file_llseek,
+ .llseek = seq_lseek,
.open = configfs_open_file,
.release = configfs_release,
};
Index: linux-2.6.18/include/linux/configfs.h
===================================================================
--- linux-2.6.18.orig/include/linux/configfs.h
+++ linux-2.6.18/include/linux/configfs.h
@@ -40,6 +40,7 @@
#include <linux/types.h>
#include <linux/list.h>
#include <linux/kref.h>
+#include <linux/seq_file.h>
#include <asm/atomic.h>
#include <asm/semaphore.h>
@@ -147,7 +148,7 @@ struct configfs_attribute {
*/
struct configfs_item_operations {
void (*release)(struct config_item *);
- ssize_t (*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
+ int (*show_attribute)(struct config_item *, struct configfs_attribute *,struct seq_file *);
ssize_t (*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
int (*allow_link)(struct config_item *src, struct config_item *target);
int (*drop_link)(struct config_item *src, struct config_item *target);
--
----------------------------------------------------------------------
Chandra Seetharaman | Be careful what you choose....
- [email protected] | .......you may get it.
----------------------------------------------------------------------
-
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