[PATCH 1/5] f2fs: cache: introduce metadata_cache sysfs node

[Chao Yu]

From: Chao Yu <chao@xxxxxxxxxx>

This patch exposes a new sysfs node 'metadata_cache' under
/sys/fs/f2fs/features/ to indicate runtime support for the in-kernel
metadata cache infrastructure.

Userspace can check this feature entry to determine support before
configuring metadata cache knobs (e.g., cache_wb_interval) or parsing
per-cache memory statistics in debugfs.

Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-fs-f2fs | 2 +-
 fs/f2fs/sysfs.c                         | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index c4746c416ac2..5b196806b3bc 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -271,7 +271,7 @@ Description:	Shows all enabled kernel features.
 		inode_crtime, lost_found, verity, sb_checksum,
 		casefold, readonly, compression, test_dummy_encryption_v2,
 		atomic_write, pin_file, encrypted_casefold, linear_lookup,
-		fserror.
+		fserror, metadata_cache.
 
 What:		/sys/fs/f2fs/<disk>/inject_rate
 Date:		May 2016
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 9749da70089a..afce74744d4d 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -1421,6 +1421,7 @@ F2FS_FEATURE_RO_ATTR(linear_lookup);
 #endif
 F2FS_FEATURE_RO_ATTR(packed_ssa);
 F2FS_FEATURE_RO_ATTR(fserror);
+F2FS_FEATURE_RO_ATTR(metadata_cache);
 
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
 static struct attribute *f2fs_attrs[] = {
@@ -1592,6 +1593,7 @@ static struct attribute *f2fs_feat_attrs[] = {
 #endif
 	BASE_ATTR_LIST(packed_ssa),
 	BASE_ATTR_LIST(fserror),
+	BASE_ATTR_LIST(metadata_cache),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_feat);
-- 
2.49.0