On 7/24/2025 11:06 PM, Jaegeuk Kim wrote:
Can we disable linear lookup by default, but add an option to enable it?
Sure.
On 07/24, Chao Yu wrote:
It provides a way to disable linear lookup fallback during mkfs.
Usage:
1. Disable linear lookup:
mkfs.f2fs -f -O casefold -C utf8:hashonly /dev/vdb
dump.f2fs -d3 /dev/vdb |grep s_encoding_flags
s_encoding_flags [0x 2 : 2]
2. Enable linear lookup:
mkfs.f2fs -f -O casefold -C utf8:nohashonly /dev/vdb
dump.f2fs -d3 /dev/vdb |grep s_encoding_flags
s_encoding_flags [0x 0 : 0]
mkfs.f2fs -f -O casefold -C utf8 /dev/vdb
dump.f2fs -d3 /dev/vdb |grep s_encoding_flags
s_encoding_flags [0x 0 : 0]
Let me update the logic to disable linear lookup by default for case 2.2).
1) mkfs.f2fs -f -O casefold -C utf8:hashonly /dev/vdb
2.1) mkfs.f2fs -f -O casefold -C utf8:nohashonly /dev/vdb
2.2) mkfs.f2fs -f -O casefold -C utf8 /dev/vdb
Thanks,
Signed-off-by: Chao Yu <c...@kernel.org>
---
lib/libf2fs.c | 1 +
man/mkfs.f2fs.8 | 8 +++++++-
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/lib/libf2fs.c b/lib/libf2fs.c
index 2f012c8..0e3e62a 100644
--- a/lib/libf2fs.c
+++ b/lib/libf2fs.c
@@ -1424,6 +1424,7 @@ static const struct enc_flags {
char *param;
} encoding_flags[] = {
{ F2FS_ENC_STRICT_MODE_FL, "strict" },
+ { F2FS_ENC_NO_COMPAT_FALLBACK_FL, "hashonly"}
};
/* Return a positive number < 0xff indicating the encoding magic number
diff --git a/man/mkfs.f2fs.8 b/man/mkfs.f2fs.8
index 8b3b0cc..b57f033 100644
--- a/man/mkfs.f2fs.8
+++ b/man/mkfs.f2fs.8
@@ -232,10 +232,16 @@ Use UTF-8 for casefolding.
.I flags:
.RS 1.2i
.TP 1.2i
-.B strict
+.B [no]strict
This flag specifies that invalid strings should be rejected by the filesystem.
Default is disabled.
.RE
+.RS 1.2i
+.TP 1.2i
+.B [no]hashonly
+This flag specifies that there is no linear lookup fallback during lookup.
+By default, linear lookup fallback is enabled.
+.RE
.RE
.TP
.BI \-q
--
2.49.0
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