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

Jaegeuk Kim
2021-05-24T17:07:16Z

On 05/24, Chao Yu wrote:
> 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?

Hmm, overlayfs?

>
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> > ---
> > 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))?

Oh, updated.

>
> 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;
> >