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BACKPORT: FROMGIT: f2fs: add sysfs entry for effective lookup mode

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This commit introduces a new read-only sysfs entry at
/sys/fs/f2fs/<device>/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 <chullee@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Daniel Lee
2025-08-02 12:17:22 -07:00
committed by Paul Lawrence
parent 34d1a222d4
commit f75a674cd8
2 changed files with 33 additions and 0 deletions
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15
Documentation/ABI/testing/sysfs-fs-f2fs
View File

@@ -554,3 +554,18 @@ Description: This is a read-only entry to show the value of sb.s_encoding_flags,
SB_ENC_STRICT_MODE_FL 0x00000001
SB_ENC_NO_COMPAT_FALLBACK_FL 0x00000002
============================ ==========
What: /sys/fs/f2fs/<disk>/effective_lookup_mode
Date: August 2025
Contact: "Daniel Lee" <chullee@google.com>
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

18
fs/f2fs/sysfs.c
View File

@@ -220,6 +220,22 @@ 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)
{
@@ -764,6 +780,7 @@ 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);
@@ -882,6 +899,7 @@ 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),