This allows splicing zeroed pages into a pipe, and allows discarding
pages from a pipe by splicing them to /dev/zero. Writing to /dev/zero
should have the same effect as writing to /dev/null, and a
"splice_write" implementation exists only for /dev/null.
To: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Max Kellermann <max.kellermann@xxxxxxxxx>
---
drivers/char/mem.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index cc296f0823bd..6c504f92c986 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -642,6 +642,7 @@ static int open_port(struct inode *inode, struct file *filp)
#define full_lseek null_lseek
#define write_zero write_null
#define write_iter_zero write_iter_null
+#define splice_write_zero splice_write_null
#define open_mem open_port
static const struct file_operations __maybe_unused mem_fops = {
@@ -678,6 +679,8 @@ static const struct file_operations zero_fops = {
.read_iter = read_iter_zero,
.read = read_zero,
.write_iter = write_iter_zero,
+ .splice_read = generic_file_splice_read,
+ .splice_write = splice_write_zero,
.mmap = mmap_zero,
.get_unmapped_area = get_unmapped_area_zero,
#ifndef CONFIG_MMU
@@ -689,6 +692,7 @@ static const struct file_operations full_fops = {
.llseek = full_lseek,
.read_iter = read_iter_zero,
.write = write_full,
+ .splice_read = generic_file_splice_read,
};
static const struct memdev {
--
2.34.0
