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mm/damon/dbgfs: implement deprecation notice file

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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 <sj@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park 2024-01-29 17:35:42 -08:00 committed by Andrew Morton
parent f4cba4bf67
commit f921003b40
1 changed files with 17 additions and 2 deletions
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19
mm/damon/dbgfs.c
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@ -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);