[v3] block: create ioctl to discard-or-zeroout a range of blocks
diff mbox

Message ID 20151111062948.GA2214@birch.djwong.org
State New
Headers show

Commit Message

Darrick J. Wong Nov. 11, 2015, 6:29 a.m. UTC
Create a new ioctl to expose the block layer's newfound ability to
issue either a zeroing discard, a WRITE SAME with a zero page, or a
regular write with the zero page.  This BLKZEROOUT2 ioctl takes
{start, length, flags} as parameters.  So far, the only flag available
is to enable the zeroing discard part -- without it, the call invokes
the old BLKZEROOUT behavior.  start and length have the same meaning
as in BLKZEROOUT.

Furthermore, because BLKZEROOUT2 issues commands directly to the
storage device, we must invalidate the page cache (as a regular
O_DIRECT write would do) to avoid returning stale cache contents at a
later time.

v3: Add extra padding for future expansion, and check the padding is zero.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 block/ioctl.c           |   48 ++++++++++++++++++++++++++++++++++++++++-------
 include/uapi/linux/fs.h |    9 +++++++++
 2 files changed, 50 insertions(+), 7 deletions(-)

--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Comments

Jeff Moyer Nov. 13, 2015, 8:23 p.m. UTC | #1
"Darrick J. Wong" <darrick.wong@oracle.com> writes:

> Create a new ioctl to expose the block layer's newfound ability to
> issue either a zeroing discard, a WRITE SAME with a zero page, or a
> regular write with the zero page.  This BLKZEROOUT2 ioctl takes
> {start, length, flags} as parameters.  So far, the only flag available
> is to enable the zeroing discard part -- without it, the call invokes
> the old BLKZEROOUT behavior.  start and length have the same meaning
> as in BLKZEROOUT.
>
> Furthermore, because BLKZEROOUT2 issues commands directly to the
> storage device, we must invalidate the page cache (as a regular
> O_DIRECT write would do) to avoid returning stale cache contents at a
> later time.
>
> v3: Add extra padding for future expansion, and check the padding is zero.

Is there someplace we document ioctls?  This stuff really could use some
good documentation.

Cheers,
Jeff

>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  block/ioctl.c           |   48 ++++++++++++++++++++++++++++++++++++++++-------
>  include/uapi/linux/fs.h |    9 +++++++++
>  2 files changed, 50 insertions(+), 7 deletions(-)
>
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 8061eba..8e67551 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -213,19 +213,39 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
>  }
>  
>  static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
> -			     uint64_t len)
> +			     uint64_t len, uint32_t flags)
>  {
> +	int ret;
> +	struct address_space *mapping;
> +	uint64_t end = start + len - 1;
> +
> +	if (flags & ~BLKZEROOUT2_DISCARD_OK)
> +		return -EINVAL;
>  	if (start & 511)
>  		return -EINVAL;
>  	if (len & 511)
>  		return -EINVAL;
> -	start >>= 9;
> -	len >>= 9;
> -
> -	if (start + len > (i_size_read(bdev->bd_inode) >> 9))
> +	if (end >= i_size_read(bdev->bd_inode))
>  		return -EINVAL;
>  
> -	return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL, false);
> +	/* Invalidate the page cache, including dirty pages */
> +	mapping = bdev->bd_inode->i_mapping;
> +	truncate_inode_pages_range(mapping, start, end);
> +
> +	ret = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
> +				   flags & BLKZEROOUT2_DISCARD_OK);
> +	if (ret)
> +		goto out;
> +
> +	/*
> +	 * Invalidate again; if someone wandered in and dirtied a page,
> +	 * the caller will be given -EBUSY.
> +	 */
> +	ret = invalidate_inode_pages2_range(mapping,
> +					    start >> PAGE_CACHE_SHIFT,
> +					    end >> PAGE_CACHE_SHIFT);
> +out:
> +	return ret;
>  }
>  
>  static int put_ushort(unsigned long arg, unsigned short val)
> @@ -353,7 +373,21 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
>  		if (copy_from_user(range, (void __user *)arg, sizeof(range)))
>  			return -EFAULT;
>  
> -		return blk_ioctl_zeroout(bdev, range[0], range[1]);
> +		return blk_ioctl_zeroout(bdev, range[0], range[1], 0);
> +	}
> +	case BLKZEROOUT2: {
> +		struct blkzeroout2 p;
> +
> +		if (!(mode & FMODE_WRITE))
> +			return -EBADF;
> +
> +		if (copy_from_user(&p, (void __user *)arg, sizeof(p)))
> +			return -EFAULT;
> +
> +		if (p.padding || p.padding2)
> +			return -EINVAL;
> +
> +		return blk_ioctl_zeroout(bdev, p.start, p.length, p.flags);
>  	}
>  
>  	case HDIO_GETGEO: {
> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 9b964a5..b811fa4 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -152,6 +152,15 @@ struct inodes_stat_t {
>  #define BLKSECDISCARD _IO(0x12,125)
>  #define BLKROTATIONAL _IO(0x12,126)
>  #define BLKZEROOUT _IO(0x12,127)
> +struct blkzeroout2 {
> +	__u64 start;
> +	__u64 length;
> +	__u32 flags;
> +	__u32 padding;
> +	__u64 padding2;
> +};
> +#define BLKZEROOUT2_DISCARD_OK	1
> +#define BLKZEROOUT2 _IOR(0x12, 127, struct blkzeroout2)
>  
>  #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
>  #define FIBMAP	   _IO(0x00,1)	/* bmap access */
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Darrick J. Wong Nov. 18, 2015, 4:38 a.m. UTC | #2
On Fri, Nov 13, 2015 at 03:23:25PM -0500, Jeff Moyer wrote:
> "Darrick J. Wong" <darrick.wong@oracle.com> writes:
> 
> > Create a new ioctl to expose the block layer's newfound ability to
> > issue either a zeroing discard, a WRITE SAME with a zero page, or a
> > regular write with the zero page.  This BLKZEROOUT2 ioctl takes
> > {start, length, flags} as parameters.  So far, the only flag available
> > is to enable the zeroing discard part -- without it, the call invokes
> > the old BLKZEROOUT behavior.  start and length have the same meaning
> > as in BLKZEROOUT.
> >
> > Furthermore, because BLKZEROOUT2 issues commands directly to the
> > storage device, we must invalidate the page cache (as a regular
> > O_DIRECT write would do) to avoid returning stale cache contents at a
> > later time.
> >
> > v3: Add extra padding for future expansion, and check the padding is zero.
> 
> Is there someplace we document ioctls?  This stuff really could use some
> good documentation.

There's no place that I know of.  I looked in man-pages.git but didn't see
anything promising.  There's what, like ~2000 ioctls?

--D

> 
> Cheers,
> Jeff
> 
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  block/ioctl.c           |   48 ++++++++++++++++++++++++++++++++++++++++-------
> >  include/uapi/linux/fs.h |    9 +++++++++
> >  2 files changed, 50 insertions(+), 7 deletions(-)
> >
> > diff --git a/block/ioctl.c b/block/ioctl.c
> > index 8061eba..8e67551 100644
> > --- a/block/ioctl.c
> > +++ b/block/ioctl.c
> > @@ -213,19 +213,39 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
> >  }
> >  
> >  static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
> > -			     uint64_t len)
> > +			     uint64_t len, uint32_t flags)
> >  {
> > +	int ret;
> > +	struct address_space *mapping;
> > +	uint64_t end = start + len - 1;
> > +
> > +	if (flags & ~BLKZEROOUT2_DISCARD_OK)
> > +		return -EINVAL;
> >  	if (start & 511)
> >  		return -EINVAL;
> >  	if (len & 511)
> >  		return -EINVAL;
> > -	start >>= 9;
> > -	len >>= 9;
> > -
> > -	if (start + len > (i_size_read(bdev->bd_inode) >> 9))
> > +	if (end >= i_size_read(bdev->bd_inode))
> >  		return -EINVAL;
> >  
> > -	return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL, false);
> > +	/* Invalidate the page cache, including dirty pages */
> > +	mapping = bdev->bd_inode->i_mapping;
> > +	truncate_inode_pages_range(mapping, start, end);
> > +
> > +	ret = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
> > +				   flags & BLKZEROOUT2_DISCARD_OK);
> > +	if (ret)
> > +		goto out;
> > +
> > +	/*
> > +	 * Invalidate again; if someone wandered in and dirtied a page,
> > +	 * the caller will be given -EBUSY.
> > +	 */
> > +	ret = invalidate_inode_pages2_range(mapping,
> > +					    start >> PAGE_CACHE_SHIFT,
> > +					    end >> PAGE_CACHE_SHIFT);
> > +out:
> > +	return ret;
> >  }
> >  
> >  static int put_ushort(unsigned long arg, unsigned short val)
> > @@ -353,7 +373,21 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
> >  		if (copy_from_user(range, (void __user *)arg, sizeof(range)))
> >  			return -EFAULT;
> >  
> > -		return blk_ioctl_zeroout(bdev, range[0], range[1]);
> > +		return blk_ioctl_zeroout(bdev, range[0], range[1], 0);
> > +	}
> > +	case BLKZEROOUT2: {
> > +		struct blkzeroout2 p;
> > +
> > +		if (!(mode & FMODE_WRITE))
> > +			return -EBADF;
> > +
> > +		if (copy_from_user(&p, (void __user *)arg, sizeof(p)))
> > +			return -EFAULT;
> > +
> > +		if (p.padding || p.padding2)
> > +			return -EINVAL;
> > +
> > +		return blk_ioctl_zeroout(bdev, p.start, p.length, p.flags);
> >  	}
> >  
> >  	case HDIO_GETGEO: {
> > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> > index 9b964a5..b811fa4 100644
> > --- a/include/uapi/linux/fs.h
> > +++ b/include/uapi/linux/fs.h
> > @@ -152,6 +152,15 @@ struct inodes_stat_t {
> >  #define BLKSECDISCARD _IO(0x12,125)
> >  #define BLKROTATIONAL _IO(0x12,126)
> >  #define BLKZEROOUT _IO(0x12,127)
> > +struct blkzeroout2 {
> > +	__u64 start;
> > +	__u64 length;
> > +	__u32 flags;
> > +	__u32 padding;
> > +	__u64 padding2;
> > +};
> > +#define BLKZEROOUT2_DISCARD_OK	1
> > +#define BLKZEROOUT2 _IOR(0x12, 127, struct blkzeroout2)
> >  
> >  #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
> >  #define FIBMAP	   _IO(0x00,1)	/* bmap access */
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox

diff --git a/block/ioctl.c b/block/ioctl.c
index 8061eba..8e67551 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -213,19 +213,39 @@  static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
 }
 
 static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
-			     uint64_t len)
+			     uint64_t len, uint32_t flags)
 {
+	int ret;
+	struct address_space *mapping;
+	uint64_t end = start + len - 1;
+
+	if (flags & ~BLKZEROOUT2_DISCARD_OK)
+		return -EINVAL;
 	if (start & 511)
 		return -EINVAL;
 	if (len & 511)
 		return -EINVAL;
-	start >>= 9;
-	len >>= 9;
-
-	if (start + len > (i_size_read(bdev->bd_inode) >> 9))
+	if (end >= i_size_read(bdev->bd_inode))
 		return -EINVAL;
 
-	return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL, false);
+	/* Invalidate the page cache, including dirty pages */
+	mapping = bdev->bd_inode->i_mapping;
+	truncate_inode_pages_range(mapping, start, end);
+
+	ret = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, GFP_KERNEL,
+				   flags & BLKZEROOUT2_DISCARD_OK);
+	if (ret)
+		goto out;
+
+	/*
+	 * Invalidate again; if someone wandered in and dirtied a page,
+	 * the caller will be given -EBUSY.
+	 */
+	ret = invalidate_inode_pages2_range(mapping,
+					    start >> PAGE_CACHE_SHIFT,
+					    end >> PAGE_CACHE_SHIFT);
+out:
+	return ret;
 }
 
 static int put_ushort(unsigned long arg, unsigned short val)
@@ -353,7 +373,21 @@  int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 		if (copy_from_user(range, (void __user *)arg, sizeof(range)))
 			return -EFAULT;
 
-		return blk_ioctl_zeroout(bdev, range[0], range[1]);
+		return blk_ioctl_zeroout(bdev, range[0], range[1], 0);
+	}
+	case BLKZEROOUT2: {
+		struct blkzeroout2 p;
+
+		if (!(mode & FMODE_WRITE))
+			return -EBADF;
+
+		if (copy_from_user(&p, (void __user *)arg, sizeof(p)))
+			return -EFAULT;
+
+		if (p.padding || p.padding2)
+			return -EINVAL;
+
+		return blk_ioctl_zeroout(bdev, p.start, p.length, p.flags);
 	}
 
 	case HDIO_GETGEO: {
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 9b964a5..b811fa4 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -152,6 +152,15 @@  struct inodes_stat_t {
 #define BLKSECDISCARD _IO(0x12,125)
 #define BLKROTATIONAL _IO(0x12,126)
 #define BLKZEROOUT _IO(0x12,127)
+struct blkzeroout2 {
+	__u64 start;
+	__u64 length;
+	__u32 flags;
+	__u32 padding;
+	__u64 padding2;
+};
+#define BLKZEROOUT2_DISCARD_OK	1
+#define BLKZEROOUT2 _IOR(0x12, 127, struct blkzeroout2)
 
 #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
 #define FIBMAP	   _IO(0x00,1)	/* bmap access */