From: SeongJae Park Date: Tue, 30 Jan 2024 01:35:42 +0000 (-0800) Subject: mm/damon/dbgfs: implement deprecation notice file X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f921003b40d107e805b29358fd1035eadae3806c;p=linux.git mm/damon/dbgfs: implement deprecation notice file 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. [arnd@arndb.de: fix bogus string length] Link: https://lkml.kernel.org/r/20240202124339.892862-1-arnd@kernel.org Link: https://lkml.kernel.org/r/20240130013549.89538-4-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Arnd Bergmann Cc: Alex Shi Cc: Hu Haowen <2023002089@link.tyut.edu.cn> Cc: Jonathan Corbet Cc: Shuah Khan Cc: Yanteng Si Cc: Arnd Bergmann Signed-off-by: Andrew Morton --- diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 7dac24e69e3b9..f66865acb523d 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -805,6 +805,17 @@ 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) +{ + static const char kbuf[512] = "DAMON debugfs interface is deprecated, " + "so users should move to DAMON_SYSFS. If you cannot, " + "please report your usecase to damon@lists.linux.dev and " + "linux-mm@kvack.org.\n"; + + return simple_read_from_buffer(buf, count, ppos, kbuf, strlen(kbuf)); +} + /* * Make a context of @name and create a debugfs directory for it. * @@ -1056,6 +1067,10 @@ 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 +1091,9 @@ 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);