Re: [f2fs-dev] [PATCH 2/2 v3] f2fs: support RO feature

From: Jaegeuk Kim
Date: Wed May 26 2021 - 21:40:16 EST

On 05/27, Chao Yu wrote:
> 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.
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> > 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;
> > + }
>
> remount() -> parse_options() will fail due to below check, so it doesn't need
> to check again? Am I missing something?

We haven't changed sb->ro at this point yet.

>
> @@ -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;
> }
>
> Thanks,
>
> > +
> > #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);
> >