On 2021/5/26 22:43, Jaegeuk Kim wrote:
Given RO feature in superblock, we don't need to check provisioning/reserve
spaces and SSA area.

It needs to update below two sysfs entries for RO feature?
/sys/fs/f2fs/<device>/features
/sys/fs/f2fs/features/..

Thanks,


Signed-off-by: Jaegeuk Kim <[email protected]>
---
Change log from v2:
  - allow curseg updates
  - fix some bugs

  fs/f2fs/f2fs.h    |  2 ++
  fs/f2fs/segment.c |  4 ++++
  fs/f2fs/super.c   | 37 +++++++++++++++++++++++++++++++------
  3 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index eaf57b5f3c4b..9ad502f92529 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)
@@ -940,6 +941,7 @@ 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..02e0c38be7eb 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4683,6 +4683,10 @@ static int sanity_check_curseg(struct f2fs_sb_info *sbi)
                struct seg_entry *se = get_seg_entry(sbi, curseg->segno);
                unsigned int blkofs = curseg->next_blkoff;
+ if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) &&
+                       i != CURSEG_HOT_DATA && i != CURSEG_HOT_NODE)
+                       continue;
+
                sanity_check_seg_type(sbi, curseg->seg_type);
if (f2fs_test_bit(blkofs, se->cur_valid_map))
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index e70aca8f97bd..6788e7b71e27 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -555,7 +555,7 @@ static int parse_options(struct super_block *sb, char 
*options, bool is_remount)
        int ret;
if (!options)
-               return 0;
+               goto default_check;
while ((p = strsep(&options, ",")) != NULL) {
                int token;
@@ -1090,6 +1090,7 @@ static int parse_options(struct super_block *sb, char 
*options, bool is_remount)
                        return -EINVAL;
                }
        }
+default_check:
  #ifdef CONFIG_QUOTA
        if (f2fs_check_quota_options(sbi))
                return -EINVAL;
@@ -1162,6 +1163,11 @@ static int parse_options(struct super_block *sb, char 
*options, bool is_remount)
         */
        if (F2FS_OPTION(sbi).active_logs != NR_CURSEG_TYPE)
                F2FS_OPTION(sbi).whint_mode = WHINT_MODE_OFF;
+
+       if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !f2fs_readonly(sbi->sb)) {
+               f2fs_err(sbi, "Allow to mount readonly mode only");
+               return -EROFS;
+       }
        return 0;
  }
@@ -1819,7 +1825,11 @@ 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, 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;
@@ -2001,6 +2011,11 @@ static int f2fs_remount(struct super_block *sb, int 
*flags, char *data)
        if (f2fs_readonly(sb) && (*flags & SB_RDONLY))
                goto skip;
+ if (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) && !(*flags & SB_RDONLY)) {
+               err = -EROFS;
+               goto restore_opts;
+       }
+
  #ifdef CONFIG_QUOTA
        if (!f2fs_readonly(sb) && (*flags & SB_RDONLY)) {
                err = dquot_suspend(sb, -1);
@@ -3134,14 +3149,15 @@ 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 (unlikely(fsmeta < F2FS_MIN_META_SEGMENTS ||
+       if (!F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) &&
+                       unlikely(fsmeta < F2FS_MIN_META_SEGMENTS ||
                        ovp_segments == 0 || reserved_segments == 0)) {
                f2fs_err(sbi, "Wrong layout: check mkfs.f2fs version");
                return 1;
        }
-
        user_block_count = le64_to_cpu(ckpt->user_block_count);
-       segment_count_main = le32_to_cpu(raw_super->segment_count_main);
+       segment_count_main = le32_to_cpu(raw_super->segment_count_main) +
+                       (F2FS_HAS_FEATURE(sbi, F2FS_FEATURE_RO) ? 1 : 0);
        log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
        if (!user_block_count || user_block_count >=
                        segment_count_main << log_blocks_per_seg) {
@@ -3172,6 +3188,10 @@ 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, 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])) {
@@ -3182,10 +3202,15 @@ 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, 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])) {
@@ -3207,7 +3232,7 @@ 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);


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