block: ioctl to zero block ranges

Introduce a BLKZEROOUT ioctl which can be used to clear block ranges by
way of blkdev_issue_zeroout().

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 28 insertions, 0 deletions

diff --git a/block/ioctl.c b/block/ioctl.c
index 4476e0e85d16..769d2960c0a6 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -185,6 +185,22 @@ static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
         return blkdev_issue_discard(bdev, start, len, GFP_KERNEL, flags);
 }
 
+static int blk_ioctl_zeroout(struct block_device *bdev, uint64_t start,
+                             uint64_t len)
+{
+        if (start & 511)
+                return -EINVAL;
+        if (len & 511)
+                return -EINVAL;
+        start >>= 9;
+        len >>= 9;
+
+        if (start + len > (i_size_read(bdev->bd_inode) >> 9))
+                return -EINVAL;
+
+        return blkdev_issue_zeroout(bdev, start, len, GFP_KERNEL);
+}
+
 static int put_ushort(unsigned long arg, unsigned short val)
 {
         return put_user(val, (unsigned short __user *)arg);
@@ -300,6 +316,17 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
                 return blk_ioctl_discard(bdev, range[0], range[1],
                                          cmd == BLKSECDISCARD);
         }
+        case BLKZEROOUT: {
+                uint64_t range[2];
+
+                if (!(mode & FMODE_WRITE))
+                        return -EBADF;
+
+                if (copy_from_user(range, (void __user *)arg, sizeof(range)))
+                        return -EFAULT;
+
+                return blk_ioctl_zeroout(bdev, range[0], range[1]);
+        }
 
         case HDIO_GETGEO: {
                 struct hd_geometry geo;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index aa110476a95b..bd6f6e7ca48e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -335,6 +335,7 @@ struct inodes_stat_t {
 #define BLKDISCARDZEROES _IO(0x12,124)
 #define BLKSECDISCARD _IO(0x12,125)
 #define BLKROTATIONAL _IO(0x12,126)
+#define BLKZEROOUT _IO(0x12,127)
 
 #define BMAP_IOCTL 1            /* obsolete - kept for compatibility */
 #define FIBMAP     _IO(0x00,1)  /* bmap access */