[RFC 6/9] dm-linear: add llseek(SEEK_HOLE/SEEK_DATA) support

Stefan Hajnoczi
2024-03-28T20:40:24Z

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
drivers/md/dm-linear.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 2d3e186ca87e3..9b6cdfa4f951d 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -147,6 +147,30 @@ static int linear_report_zones(struct dm_target *ti,
#define linear_report_zones NULL
#endif

+static loff_t linear_seek_hole_data(struct dm_target *ti, loff_t offset,
+ int whence)
+{
+ struct linear_c *lc = ti->private;
+ loff_t ti_begin = ti->begin << SECTOR_SHIFT;
+ loff_t ti_len = ti->len << SECTOR_SHIFT;
+ loff_t bdev_start = lc->start << SECTOR_SHIFT;
+ loff_t bdev_offset;
+
+ /* TODO underflow/overflow? */
+ bdev_offset = offset - ti_begin + bdev_start;
+
+ bdev_offset = blkdev_seek_hole_data(lc->dev->bdev, bdev_offset,
+ whence);
+ if (bdev_offset < 0)
+ return bdev_offset;
+
+ offset = bdev_offset - bdev_start;
+ if (offset >= ti_len)
+ return whence == SEEK_DATA ? -ENXIO : ti_begin + ti_len;
+
+ return offset + ti_begin;
+}
+
static int linear_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
@@ -212,6 +236,7 @@ static struct target_type linear_target = {
.direct_access = linear_dax_direct_access,
.dax_zero_page_range = linear_dax_zero_page_range,
.dax_recovery_write = linear_dax_recovery_write,
+ .seek_hole_data = linear_seek_hole_data,
};

int __init dm_linear_init(void)
--
2.44.0