block: add FALLOC_FL_WRITE_ZEROES support

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.zhang@huawei.com>
Link: https://lore.kernel.org/20250619111806.3546162-9-yi.zhang@huaweicloud.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/block/fops.c b/block/fops.c
index e1c921549d28979453880652dd38106a9a767998..474656a0de70a8d4aa8597fb083013436304fcbc 100644 (file)
--- a/block/fops.c
+++ b/block/fops.c
@@ -841,7 +841,7 @@ reexpand:
 
 #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 ((mode & FALLOC_FL_WRITE_ZEROES) &&
+           !bdev_write_zeroes_unmap_sectors(bdev))
+               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;