From 0ea221d236e7e4cb2e685c51b336ea305ae448f4 Mon Sep 17 00:00:00 2001 From: Daniel Lee Date: Sat, 2 Aug 2025 12:17:22 -0700 Subject: [PATCH] BACKPORT: FROMGIT: f2fs: add sysfs entry for effective lookup mode This commit introduces a new read-only sysfs entry at /sys/fs/f2fs//effective_lookup_mode. This entry displays the actual directory lookup mode F2FS is currently using. This is needed for debugging and verification, as the behavior is determined by both on-disk flags and mount options. Bug: 432807936 (cherry picked from commit 1bd119da0b93d6d61891edf2b9d036800aba687f https: //git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git dev) Link: https://lore.kernel.org/linux-f2fs-devel/20250805065228.1473089-1-chullee@google.com/ Change-Id: Iabb9548bb9f73ef42d46ed0506a0372ec37e75d8 [chullee: resolved merge conflicts in the document] Signed-off-by: Daniel Lee Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- Documentation/ABI/testing/sysfs-fs-f2fs | 15 +++++++++++++++ fs/f2fs/sysfs.c | 18 ++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs index 837f0690f856..ddb367f130a6 100644 --- a/Documentation/ABI/testing/sysfs-fs-f2fs +++ b/Documentation/ABI/testing/sysfs-fs-f2fs @@ -868,3 +868,18 @@ Description: This threshold is used to control triggering garbage collection whi reserved section before preallocating on pinned file. By default, the value is ovp_sections, especially, for zoned ufs, the value is 1. + +What: /sys/fs/f2fs//effective_lookup_mode +Date: August 2025 +Contact: "Daniel Lee" +Description: + This is a read-only entry to show the effective directory lookup mode + F2FS is currently using for casefolded directories. + This considers both the "lookup_mode" mount option and the on-disk + encoding flag, SB_ENC_NO_COMPAT_FALLBACK_FL. + + Possible values are: + - "perf": Hash-only lookup. + - "compat": Hash-based lookup with a linear search fallback enabled + - "auto:perf": lookup_mode is auto and fallback is disabled on-disk + - "auto:compat": lookup_mode is auto and fallback is enabled on-disk diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 46216f0a203a..493aef63cf0a 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -281,6 +281,22 @@ static ssize_t encoding_flags_show(struct f2fs_attr *a, le16_to_cpu(F2FS_RAW_SUPER(sbi)->s_encoding_flags)); } +static ssize_t effective_lookup_mode_show(struct f2fs_attr *a, + struct f2fs_sb_info *sbi, char *buf) +{ + switch (f2fs_get_lookup_mode(sbi)) { + case LOOKUP_PERF: + return sysfs_emit(buf, "perf\n"); + case LOOKUP_COMPAT: + return sysfs_emit(buf, "compat\n"); + case LOOKUP_AUTO: + if (sb_no_casefold_compat_fallback(sbi->sb)) + return sysfs_emit(buf, "auto:perf\n"); + return sysfs_emit(buf, "auto:compat\n"); + } + return 0; +} + static ssize_t mounted_time_sec_show(struct f2fs_attr *a, struct f2fs_sb_info *sbi, char *buf) { @@ -1174,6 +1190,7 @@ F2FS_GENERAL_RO_ATTR(current_reserved_blocks); F2FS_GENERAL_RO_ATTR(unusable); F2FS_GENERAL_RO_ATTR(encoding); F2FS_GENERAL_RO_ATTR(encoding_flags); +F2FS_GENERAL_RO_ATTR(effective_lookup_mode); F2FS_GENERAL_RO_ATTR(mounted_time_sec); F2FS_GENERAL_RO_ATTR(main_blkaddr); F2FS_GENERAL_RO_ATTR(pending_discard); @@ -1290,6 +1307,7 @@ static struct attribute *f2fs_attrs[] = { ATTR_LIST(current_reserved_blocks), ATTR_LIST(encoding), ATTR_LIST(encoding_flags), + ATTR_LIST(effective_lookup_mode), ATTR_LIST(mounted_time_sec), #ifdef CONFIG_F2FS_STAT_FS ATTR_LIST(cp_foreground_calls),