[PATCH 09/10] block: add FALLOC_FL_WRITE_ZEROES support

[Zhang Yi]

From: Zhang Yi <yi.zh...@huawei.com>

Add support for FALLOC_FL_WRITE_ZEROES, if the block device enables the
unmap write zeroes operation, it will issue a write zeroes command.

Signed-off-by: Zhang Yi <yi.zh...@huawei.com>
---
 block/fops.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/block/fops.c b/block/fops.c
index e1c921549d28..050c16f5974a 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -841,7 +841,7 @@ static ssize_t blkdev_read_iter(struct kiocb *iocb, struct 
iov_iter *to)
 
 #define        BLKDEV_FALLOC_FL_SUPPORTED                                      
\
                (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
-                FALLOC_FL_ZERO_RANGE)
+                FALLOC_FL_ZERO_RANGE | FALLOC_FL_WRITE_ZEROES)
 
 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
                             loff_t len)
@@ -856,6 +856,13 @@ static long blkdev_fallocate(struct file *file, int mode, 
loff_t start,
        /* Fail if we don't recognize the flags. */
        if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
                return -EOPNOTSUPP;
+       /*
+        * Don't allow writing zeroes if the device does not enable the
+        * unmap write zeroes operation.
+        */
+       if (!bdev_write_zeroes_unmap(bdev) &&
+           (mode & FALLOC_FL_WRITE_ZEROES))
+               return -EOPNOTSUPP;
 
        /* Don't go off the end of the device. */
        isize = bdev_nr_bytes(bdev);
@@ -886,6 +893,9 @@ static long blkdev_fallocate(struct file *file, int mode, 
loff_t start,
        case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
                flags = BLKDEV_ZERO_NOFALLBACK;
                break;
+       case FALLOC_FL_WRITE_ZEROES:
+               flags = 0;
+               break;
        default:
                error = -EOPNOTSUPP;
                goto fail;
-- 
2.46.1