[PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[Jiri Slaby]

It will be used in suspend code and serves as an easy wrap around
copy_from_user. Similar to simple_read_from_buffer, it takes care
of transfers with proper lengths depending on available and count
parameters and advances ppos appropriately.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Nigel Cunningham <ncunningham@crca.org.au>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
---
 fs/libfs.c         |   35 +++++++++++++++++++++++++++++++++++
 include/linux/fs.h |    2 ++
 2 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index ea9a6cc..cfab42a 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -547,6 +547,40 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
 }
 
 /**
+ * simple_write_to_buffer - copy data from user space to the buffer
+ * @to: the buffer to write to
+ * @available: the size of the buffer
+ * @ppos: the current position in the buffer
+ * @from: the user space buffer to read from
+ * @count: the maximum number of bytes to read
+ *
+ * The simple_write_to_buffer() function reads up to @count bytes from the user
+ * space address starting at @from into the buffer @to at offset @ppos.
+ *
+ * On success, the number of bytes written is returned and the offset @ppos is
+ * advanced by this number, or negative value is returned on error.
+ **/
+ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
+		const void __user *from, size_t count)
+{
+	loff_t pos = *ppos;
+	size_t ret;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= available || !count)
+		return 0;
+	if (count > available - pos)
+		count = available - pos;
+	ret = copy_from_user(to + pos, from, count);
+	if (ret == count)
+		return -EFAULT;
+	count -= ret;
+	*ppos = pos + count;
+	return count;
+}
+
+/**
  * memory_read_from_buffer - copy data from the buffer
  * @to: the kernel space buffer to read to
  * @count: the maximum number of bytes to read
@@ -864,6 +898,7 @@ EXPORT_SYMBOL(simple_statfs);
 EXPORT_SYMBOL(simple_sync_file);
 EXPORT_SYMBOL(simple_unlink);
 EXPORT_SYMBOL(simple_read_from_buffer);
+EXPORT_SYMBOL(simple_write_to_buffer);
 EXPORT_SYMBOL(memory_read_from_buffer);
 EXPORT_SYMBOL(simple_transaction_set);
 EXPORT_SYMBOL(simple_transaction_get);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 66f3caa..e594a8d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2372,6 +2372,8 @@ extern void simple_release_fs(struct vfsmount **mount, int *count);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
 			loff_t *ppos, const void *from, size_t available);
+extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
+		const void __user *from, size_t count);
 
 extern int simple_fsync(struct file *, struct dentry *, int);
 
-- 
1.7.0.3

Re: [PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[Rafael J. Wysocki]

On Tuesday 27 April 2010, Jiri Slaby wrote:
> It will be used in suspend code and serves as an easy wrap around
> copy_from_user. Similar to simple_read_from_buffer, it takes care
> of transfers with proper lengths depending on available and count
> parameters and advances ppos appropriately.
> 
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Nigel Cunningham <ncunningham@crca.org.au>
> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: linux-fsdevel@vger.kernel.org

Thanks for the patches, I'll review them as soon as I can.

Rafael

Re: [PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[Rafael J. Wysocki]

On Tuesday 27 April 2010, Jiri Slaby wrote:
> It will be used in suspend code and serves as an easy wrap around
> copy_from_user. Similar to simple_read_from_buffer, it takes care
> of transfers with proper lengths depending on available and count
> parameters and advances ppos appropriately.

Will anyone object if I take this one into the suspend-2.6 tree?

Rafael


> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> Cc: Nigel Cunningham <ncunningham@crca.org.au>
> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> Cc: linux-fsdevel@vger.kernel.org
> ---
>  fs/libfs.c         |   35 +++++++++++++++++++++++++++++++++++
>  include/linux/fs.h |    2 ++
>  2 files changed, 37 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/libfs.c b/fs/libfs.c
> index ea9a6cc..cfab42a 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -547,6 +547,40 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
>  }
>  
>  /**
> + * simple_write_to_buffer - copy data from user space to the buffer
> + * @to: the buffer to write to
> + * @available: the size of the buffer
> + * @ppos: the current position in the buffer
> + * @from: the user space buffer to read from
> + * @count: the maximum number of bytes to read
> + *
> + * The simple_write_to_buffer() function reads up to @count bytes from the user
> + * space address starting at @from into the buffer @to at offset @ppos.
> + *
> + * On success, the number of bytes written is returned and the offset @ppos is
> + * advanced by this number, or negative value is returned on error.
> + **/
> +ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
> +		const void __user *from, size_t count)
> +{
> +	loff_t pos = *ppos;
> +	size_t ret;
> +
> +	if (pos < 0)
> +		return -EINVAL;
> +	if (pos >= available || !count)
> +		return 0;
> +	if (count > available - pos)
> +		count = available - pos;
> +	ret = copy_from_user(to + pos, from, count);
> +	if (ret == count)
> +		return -EFAULT;
> +	count -= ret;
> +	*ppos = pos + count;
> +	return count;
> +}
> +
> +/**
>   * memory_read_from_buffer - copy data from the buffer
>   * @to: the kernel space buffer to read to
>   * @count: the maximum number of bytes to read
> @@ -864,6 +898,7 @@ EXPORT_SYMBOL(simple_statfs);
>  EXPORT_SYMBOL(simple_sync_file);
>  EXPORT_SYMBOL(simple_unlink);
>  EXPORT_SYMBOL(simple_read_from_buffer);
> +EXPORT_SYMBOL(simple_write_to_buffer);
>  EXPORT_SYMBOL(memory_read_from_buffer);
>  EXPORT_SYMBOL(simple_transaction_set);
>  EXPORT_SYMBOL(simple_transaction_get);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 66f3caa..e594a8d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2372,6 +2372,8 @@ extern void simple_release_fs(struct vfsmount **mount, int *count);
>  
>  extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
>  			loff_t *ppos, const void *from, size_t available);
> +extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
> +		const void __user *from, size_t count);
>  
>  extern int simple_fsync(struct file *, struct dentry *, int);
>  
> 

Re: [PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[Rafael J. Wysocki]

On Tuesday 27 April 2010, Rafael J. Wysocki wrote:
> On Tuesday 27 April 2010, Jiri Slaby wrote:
> > It will be used in suspend code and serves as an easy wrap around
> > copy_from_user. Similar to simple_read_from_buffer, it takes care
> > of transfers with proper lengths depending on available and count
> > parameters and advances ppos appropriately.
> > 
> > Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> > Cc: Nigel Cunningham <ncunningham@crca.org.au>
> > Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> > Cc: linux-fsdevel@vger.kernel.org
> 
> Thanks for the patches, I'll review them as soon as I can.

They look good.  If there are no objections from the other people, I'll add
them to suspend-2.6/linux-next in the next few days.

Rafael

Re: [PATCH 1/5] FS: libfs, implement simple_write_to_buffer

[Rafael J. Wysocki]

On Thursday 29 April 2010, Rafael J. Wysocki wrote:
> On Tuesday 27 April 2010, Rafael J. Wysocki wrote:
> > On Tuesday 27 April 2010, Jiri Slaby wrote:
> > > It will be used in suspend code and serves as an easy wrap around
> > > copy_from_user. Similar to simple_read_from_buffer, it takes care
> > > of transfers with proper lengths depending on available and count
> > > parameters and advances ppos appropriately.
> > > 
> > > Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> > > Cc: Nigel Cunningham <ncunningham@crca.org.au>
> > > Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
> > > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> > > Cc: linux-fsdevel@vger.kernel.org
> > 
> > Thanks for the patches, I'll review them as soon as I can.
> 
> They look good.  If there are no objections from the other people, I'll add
> them to suspend-2.6/linux-next in the next few days.

All patches in this series applied to suspend-2.6/linux-next.

I fixed up the Pavel's address in the copyright notice in kernel/power/block_io.c.

Thanks,
Rafael