3 files changed, 78 insertions, 0 deletions

diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index c23177e4623f..1e559fba7bdf 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -788,6 +788,7 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
                 return compat_hdio_getgeo(disk, bdev, compat_ptr(arg));
         case BLKFLSBUF:
         case BLKROSET:
+        case BLKDISCARD:
         /*
          * the ones below are implemented in blkdev_locked_ioctl,
          * but we call blkdev_ioctl, which gets the lock for us
diff --git a/block/ioctl.c b/block/ioctl.c
index 77185e5c026a..342298bb6080 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -111,6 +111,69 @@ static int blkdev_reread_part(struct block_device *bdev)
         return res;
 }
 
+static void blk_ioc_discard_endio(struct bio *bio, int err)
+{
+        if (err) {
+                if (err == -EOPNOTSUPP)
+                        set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
+                clear_bit(BIO_UPTODATE, &bio->bi_flags);
+        }
+        complete(bio->bi_private);
+}
+
+static int blk_ioctl_discard(struct block_device *bdev, uint64_t start,
+                             uint64_t len)
+{
+        struct request_queue *q = bdev_get_queue(bdev);
+        int ret = 0;
+
+        if (start & 511)
+                return -EINVAL;
+        if (len & 511)
+                return -EINVAL;
+        start >>= 9;
+        len >>= 9;
+
+        if (start + len > (bdev->bd_inode->i_size >> 9))
+                return -EINVAL;
+
+        if (!q->prepare_discard_fn)
+                return -EOPNOTSUPP;
+
+        while (len && !ret) {
+                DECLARE_COMPLETION_ONSTACK(wait);
+                struct bio *bio;
+
+                bio = bio_alloc(GFP_KERNEL, 0);
+                if (!bio)
+                        return -ENOMEM;
+
+                bio->bi_end_io = blk_ioc_discard_endio;
+                bio->bi_bdev = bdev;
+                bio->bi_private = &wait;
+                bio->bi_sector = start;
+
+                if (len > q->max_hw_sectors) {
+                        bio->bi_size = q->max_hw_sectors << 9;
+                        len -= q->max_hw_sectors;
+                        start += q->max_hw_sectors;
+                } else {
+                        bio->bi_size = len << 9;
+                        len = 0;
+                }
+                submit_bio(WRITE_DISCARD, bio);
+
+                wait_for_completion(&wait);
+
+                if (bio_flagged(bio, BIO_EOPNOTSUPP))
+                        ret = -EOPNOTSUPP;
+                else if (!bio_flagged(bio, BIO_UPTODATE))
+                        ret = -EIO;
+                bio_put(bio);
+        }
+        return ret;
+}
+
 static int put_ushort(unsigned long arg, unsigned short val)
 {
         return put_user(val, (unsigned short __user *)arg);
@@ -258,6 +321,19 @@ int blkdev_ioctl(struct inode *inode, struct file *file, unsigned cmd,
                 set_device_ro(bdev, n);
                 unlock_kernel();
                 return 0;
+
+        case BLKDISCARD: {
+                uint64_t range[2];
+
+                if (!(file->f_mode & FMODE_WRITE))
+                        return -EBADF;
+
+                if (copy_from_user(range, (void __user *)arg, sizeof(range)))
+                        return -EFAULT;
+
+                return blk_ioctl_discard(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 eb0131319134..88358ca6af25 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -223,6 +223,7 @@ extern int dir_notify_enable;
 #define BLKTRACESTART _IO(0x12,116)
 #define BLKTRACESTOP _IO(0x12,117)
 #define BLKTRACETEARDOWN _IO(0x12,118)
+#define BLKDISCARD _IO(0x12,119)
 
 #define BMAP_IOCTL 1            /* obsolete - kept for compatibility */
 #define FIBMAP     _IO(0x00,1)  /* bmap access */