Implement a read-only file for DAMON debugfs interface deprecation
notice, to let users who manually read/write the DAMON debugfs files
from their shell command line easily notice the fact.
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
mm/damon/dbgfs.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 7dac24e69e3b..fc6ece5a9f37 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -805,6 +805,18 @@ static void dbgfs_destroy_ctx(struct damon_ctx *ctx)
damon_destroy_ctx(ctx);
}
+static ssize_t damon_dbgfs_deprecated_read(struct file *file,
+ char __user *buf, size_t count, loff_t *ppos)
+{
+ char kbuf[512] = "DAMON debugfs interface is deprecated, "
+ "so users should move to DAMON_SYSFS. If you cannot, "
+ "please report your usecase to damon@xxxxxxxxxxxxxxx and "
+ "linux-mm@xxxxxxxxx.\n";
+ int len = strnlen(kbuf, 1024);
+
+ return simple_read_from_buffer(buf, count, ppos, kbuf, len);
+}
+
/*
* Make a context of @name and create a debugfs directory for it.
*
@@ -1056,6 +1068,10 @@ static int damon_dbgfs_static_file_open(struct inode *inode, struct file *file)
return nonseekable_open(inode, file);
}
+static const struct file_operations deprecated_fops = {
+ .read = damon_dbgfs_deprecated_read,
+};
+
static const struct file_operations mk_contexts_fops = {
.open = damon_dbgfs_static_file_open,
.write = dbgfs_mk_context_write,
@@ -1076,9 +1092,9 @@ static int __init __damon_dbgfs_init(void)
{
struct dentry *dbgfs_root;
const char * const file_names[] = {"mk_contexts", "rm_contexts",
- "monitor_on"};
+ "monitor_on", "DEPRECATED"};
const struct file_operations *fops[] = {&mk_contexts_fops,
- &rm_contexts_fops, &monitor_on_fops};
+ &rm_contexts_fops, &monitor_on_fops, &deprecated_fops};
int i;
dbgfs_root = debugfs_create_dir("damon", NULL);
--
2.39.2
