Re: [f2fs-dev] [PATCH 2/2] f2fs: support RO feature

From: Chao Yu
Date: Mon May 24 2021 - 07:53:33 EST

On 2021/5/22 3:02, Jaegeuk Kim wrote:
Given RO feature in superblock, we don't need to check provisioning/reserve
spaces and SSA area.

Cool, any solution to update files of ro f2fs image if there is such
scenario?


Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/f2fs.h | 2 ++
fs/f2fs/segment.c | 3 +++
fs/f2fs/super.c | 35 +++++++++++++++++++++++++++++++----
3 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c0bead0df66a..2c6913261586 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -168,6 +168,7 @@ struct f2fs_mount_info {
#define F2FS_FEATURE_SB_CHKSUM 0x0800
#define F2FS_FEATURE_CASEFOLD 0x1000
#define F2FS_FEATURE_COMPRESSION 0x2000
+#define F2FS_FEATURE_RO 0x4000
#define __F2FS_HAS_FEATURE(raw_super, mask) \
((raw_super->feature & cpu_to_le32(mask)) != 0)
@@ -939,6 +940,7 @@ static inline void set_new_dnode(struct dnode_of_data *dn, struct inode *inode,
#define NR_CURSEG_DATA_TYPE (3)
#define NR_CURSEG_NODE_TYPE (3)
#define NR_CURSEG_INMEM_TYPE (2)
+#define NR_CURSEG_RO_TYPE (2)
#define NR_CURSEG_PERSIST_TYPE (NR_CURSEG_DATA_TYPE + NR_CURSEG_NODE_TYPE)
#define NR_CURSEG_TYPE (NR_CURSEG_INMEM_TYPE + NR_CURSEG_PERSIST_TYPE)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8668df7870d0..67cec8f858a2 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4674,6 +4674,9 @@ static int sanity_check_curseg(struct f2fs_sb_info *sbi)
{
int i;
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO))

Why not using F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO))?

Ditto for all below __F2FS_HAS_FEATURE().

Thanks,

+ return 0;
+
/*
* In LFS/SSR curseg, .next_blkoff should point to an unused blkaddr;
* In LFS curseg, all blkaddr after .next_blkoff should be unused.
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index b29de80ab60e..312bfab54693 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1819,7 +1819,11 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
static void default_options(struct f2fs_sb_info *sbi)
{
/* init some FS parameters */
- F2FS_OPTION(sbi).active_logs = NR_CURSEG_PERSIST_TYPE;
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO))
+ F2FS_OPTION(sbi).active_logs = NR_CURSEG_RO_TYPE;
+ else
+ F2FS_OPTION(sbi).active_logs = NR_CURSEG_PERSIST_TYPE;
+
F2FS_OPTION(sbi).inline_xattr_size = DEFAULT_INLINE_XATTR_ADDRS;
F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
F2FS_OPTION(sbi).alloc_mode = ALLOC_MODE_DEFAULT;
@@ -1994,6 +1998,11 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
err = parse_options(sb, data, true);
if (err)
goto restore_opts;
+
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO) &&
+ !(*flags & SB_RDONLY))
+ goto restore_opts;
+
checkpoint_changed =
disable_checkpoint != test_opt(sbi, DISABLE_CHECKPOINT);
@@ -3137,16 +3146,18 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
reserved_segments = le32_to_cpu(ckpt->rsvd_segment_count);
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO))
+ goto no_reserved;
if (unlikely(fsmeta < F2FS_MIN_META_SEGMENTS ||
ovp_segments == 0 || reserved_segments == 0)) {
f2fs_err(sbi, "Wrong layout: check mkfs.f2fs version");
return 1;
}
-
+no_reserved:
user_block_count = le64_to_cpu(ckpt->user_block_count);
segment_count_main = le32_to_cpu(raw_super->segment_count_main);
log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
- if (!user_block_count || user_block_count >=
+ if (!user_block_count || user_block_count >
segment_count_main << log_blocks_per_seg) {
f2fs_err(sbi, "Wrong user_block_count: %u",
user_block_count);
@@ -3175,6 +3186,10 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
if (le32_to_cpu(ckpt->cur_node_segno[i]) >= main_segs ||
le16_to_cpu(ckpt->cur_node_blkoff[i]) >= blocks_per_seg)
return 1;
+
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO))
+ goto check_data;
+
for (j = i + 1; j < NR_CURSEG_NODE_TYPE; j++) {
if (le32_to_cpu(ckpt->cur_node_segno[i]) ==
le32_to_cpu(ckpt->cur_node_segno[j])) {
@@ -3185,10 +3200,15 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
}
}
}
+check_data:
for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
return 1;
+
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO))
+ goto skip_cross;
+
for (j = i + 1; j < NR_CURSEG_DATA_TYPE; j++) {
if (le32_to_cpu(ckpt->cur_data_segno[i]) ==
le32_to_cpu(ckpt->cur_data_segno[j])) {
@@ -3210,7 +3230,7 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
}
}
}
-
+skip_cross:
sit_bitmap_size = le32_to_cpu(ckpt->sit_ver_bitmap_bytesize);
nat_bitmap_size = le32_to_cpu(ckpt->nat_ver_bitmap_bytesize);
@@ -3703,6 +3723,13 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
if (err)
goto free_options;
+ if (__F2FS_HAS_FEATURE(sbi->raw_super, F2FS_FEATURE_RO) &&
+ !f2fs_readonly(sbi->sb)) {
+ f2fs_info(sbi, "Allow to mount readonly mode only");
+ err = -EINVAL;
+ goto free_options;
+ }
+
sb->s_maxbytes = max_file_blocks(NULL) <<
le32_to_cpu(raw_super->log_blocksize);
sb->s_max_links = F2FS_LINK_MAX;