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SubjectRe: [PATCH v3] f2fs: checkpoint disabling
Hi Daniel,

Can we add WANR_ON() in f2fs_write_checkpoint() to detect any bug when it
is disabled?
Please check some comments below.

On 08/07, Daniel Rosenberg wrote:
> This adds a lightweight non-persistent snapshotting scheme to f2fs.
>
> To use, mount with the option checkpoint=disable, and to return to
> normal operation, remount with checkpoint=enable. If the filesystem
> is shut down before remounting with checkpoint=enable, it will revert
> back to its apparent state when it was first mounted with
> checkpoint=disable. This is useful for situations where you wish to be
> able to roll back the state of the disk in case of some critical
> failure.
>
> Signed-off-by: Daniel Rosenberg <drosen@google.com>
> ---
> v3: Rebased, and fixed issue in inc_valid_block_count from kbuild-all.
> It turns out there was a separate issue in that code anyways, with
> log_blocks_per_seg vs blocks_per_seg.
>
> v2: Included changes suggested by Jaegeuk and Chao.
> it now holds the gc lock around setting up free space tracking in
> f2fs_disable_checkpoint. I wasn't quite sure what was mean by
> the comment on should_update_outplace, but I've changed it to return
> true for NEW_ADDR as well. It may be better to instead skip over the
> reset of that block if old_blkaddr is NEW_ADDR, because I think that
> means the data has not yet been committed, and thus wouldn't be
> overwriting data from the previous checkpoint.
>
> We're currently using this during updates to extend the period of time
> that we can safely roll back a faulty update. After performing an update
> and reboot, we'd mount in this mode. If there ends up being some sort of
> fatal error, data changes are automatically reverted, allowing us to
> revert to the state before the update without worrying about any incompatible
> changes that may've been made to data while running under the faulty system.
> It increases our ability to revert a faulty update from up to mounting user
> data partitions to a bit farther along.
> Documentation/filesystems/f2fs.txt | 5 ++
> fs/f2fs/data.c | 23 ++++++
> fs/f2fs/f2fs.h | 56 ++++++++++++++
> fs/f2fs/file.c | 18 +++++
> fs/f2fs/gc.c | 4 +
> fs/f2fs/segment.c | 58 ++++++++++++---
> fs/f2fs/segment.h | 26 +++++++
> fs/f2fs/super.c | 116 +++++++++++++++++++++++++++--
> 8 files changed, 290 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
> index 69f8de9957397..a026b353a99d4 100644
> --- a/Documentation/filesystems/f2fs.txt
> +++ b/Documentation/filesystems/f2fs.txt
> @@ -193,6 +193,11 @@ fsync_mode=%s Control the policy of fsync. Currently supports "posix",
> non-atomic files likewise "nobarrier" mount option.
> test_dummy_encryption Enable dummy encryption, which provides a fake fscrypt
> context. The fake fscrypt context is used by xfstests.
> +checkpoint=%s Set to "disable" to turn off checkpointing. Set to "enable"
> + to reenable checkpointing. Is enabled by default. While
> + disabled, any unmounting or unexpected shutdowns will cause
> + the filesystem contents to appear as they did when the
> + filesystem was mounted with that option.
>
> ================================================================================
> DEBUGFS ENTRIES
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 45f043ee48bdb..c43c198b373cc 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1692,6 +1692,19 @@ bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
>
> if (test_opt(sbi, LFS))
> return true;
> + if (test_opt(sbi, DISABLE_CHECKPOINT)) {
> + struct seg_entry *se;
> + unsigned int segno, offset;
> +
> + if (!fio || fio->old_blkaddr == NULL_ADDR ||
> + fio->old_blkaddr == NEW_ADDR)
> + return true;
> + segno = GET_SEGNO(sbi, fio->old_blkaddr);
> + se = get_seg_entry(sbi, segno);
> + offset = GET_BLKOFF_FROM_SEG0(sbi, fio->old_blkaddr);
> + if (f2fs_test_bit(offset, se->ckpt_valid_map))
> + return true;
> + }
> if (S_ISDIR(inode->i_mode))
> return true;
> if (f2fs_is_atomic_file(inode))
> @@ -1719,10 +1732,13 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
> {
> struct page *page = fio->page;
> struct inode *inode = page->mapping->host;
> + struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> struct dnode_of_data dn;
> struct extent_info ei = {0,0,0};
> struct node_info ni;
> bool ipu_force = false;
> + bool need_tmp_grab = test_opt(sbi, DISABLE_CHECKPOINT);
> + blkcnt_t tmp_block = 1;
> int err = 0;
>
> set_new_dnode(&dn, inode, NULL, NULL, 0);
> @@ -1800,6 +1816,11 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
> if (err)
> goto out_writepage;
>
> + if (need_tmp_grab) {
> + err = inc_valid_block_count(sbi, dn.inode, &tmp_block);
> + if (err)
> + goto out_writepage;
> + }
> set_page_writeback(page);
> ClearPageError(page);
>
> @@ -1809,6 +1830,8 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
> set_inode_flag(inode, FI_APPEND_WRITE);
> if (page->index == 0)
> set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
> + if (need_tmp_grab)
> + dec_valid_block_count(sbi, dn.inode, tmp_block);
> out_writepage:
> f2fs_put_dnode(&dn);
> out:
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4525f4f82af0c..654b355f9654c 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -97,6 +97,7 @@ extern char *f2fs_fault_name[FAULT_MAX];
> #define F2FS_MOUNT_QUOTA 0x00400000
> #define F2FS_MOUNT_INLINE_XATTR_SIZE 0x00800000
> #define F2FS_MOUNT_RESERVE_ROOT 0x01000000
> +#define F2FS_MOUNT_DISABLE_CHECKPOINT 0x02000000
>
> #define F2FS_OPTION(sbi) ((sbi)->mount_opt)
> #define clear_opt(sbi, option) (F2FS_OPTION(sbi).opt &= ~F2FS_MOUNT_##option)
> @@ -175,6 +176,7 @@ enum {
> #define CP_RECOVERY 0x00000008
> #define CP_DISCARD 0x00000010
> #define CP_TRIMMED 0x00000020
> +#define CP_PAUSE 0x00000040
>
> #define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi)
> #define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per round */
> @@ -1081,6 +1083,7 @@ enum {
> SBI_NEED_SB_WRITE, /* need to recover superblock */
> SBI_NEED_CP, /* need to checkpoint */
> SBI_IS_SHUTDOWN, /* shutdown by ioctl */
> + SBI_CP_DISABLED, /* CP was disabled last mount */
> };
>
> enum {
> @@ -1211,6 +1214,12 @@ struct f2fs_sb_info {
> block_t reserved_blocks; /* configurable reserved blocks */
> block_t current_reserved_blocks; /* current reserved blocks */
>
> + /* Additional tracking for no checkpoint mode */
> + block_t unusable_block_count; /* # of blocks saved by last cp */
> + block_t free_ssr_data_block;
> + block_t free_ssr_node_block;
> + block_t free_segments;
> +
> unsigned int nquota_files; /* # of quota sysfile */
>
> u32 s_next_generation; /* for NFS support */
> @@ -1691,6 +1700,8 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
>
> if (!__allow_reserved_blocks(sbi, inode, true))
> avail_user_block_count -= F2FS_OPTION(sbi).root_reserved_blocks;
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + avail_user_block_count -= sbi->unusable_block_count;
>
> if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
> diff = sbi->total_valid_block_count - avail_user_block_count;
> @@ -1704,6 +1715,38 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
> goto enospc;
> }
> }
> + if (likely(!test_opt(sbi, DISABLE_CHECKPOINT)))
> + goto normal;
> + if (unlikely(*count > sbi->free_ssr_data_block)) {
> + /* We'll need to pull from free. */
> + blkcnt_t needed = *count - sbi->free_ssr_data_block;
> + blkcnt_t new_segs = ((needed - 1) >>
> + sbi->log_blocks_per_seg) + 1;
> +
> + /* Check if we have enough free */
> + if (unlikely(new_segs > sbi->free_segments)) {
> + blkcnt_t seg_rel, seg_diff, mask;
> +
> + seg_diff = new_segs - sbi->free_segments;
> + mask = sbi->blocks_per_seg - 1;
> + seg_rel = ((needed - 1) & mask) + 1;
> + seg_rel += (seg_diff - 1) << sbi->log_blocks_per_seg;
> +
> + new_segs -= seg_diff;
> + *count -= seg_rel;
> + release += seg_rel;
> + if (!*count) {
> + spin_unlock(&sbi->stat_lock);
> + goto enospc;
> + }
> + }
> +
> + sbi->free_segments -= new_segs;
> + sbi->free_ssr_data_block += new_segs << sbi->log_blocks_per_seg;
> +
> + }
> + sbi->free_ssr_data_block -= *count;
> +normal:
> spin_unlock(&sbi->stat_lock);
>
> if (unlikely(release)) {
> @@ -1900,6 +1943,8 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
>
> if (!__allow_reserved_blocks(sbi, inode, false))
> valid_block_count += F2FS_OPTION(sbi).root_reserved_blocks;
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + valid_block_count += sbi->unusable_block_count;
>
> if (unlikely(valid_block_count > sbi->user_block_count)) {
> spin_unlock(&sbi->stat_lock);
> @@ -1912,6 +1957,17 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
> goto enospc;
> }
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT)) {
> + if (unlikely(!sbi->free_ssr_node_block)) {
> + if (unlikely(!sbi->free_segments)) {
> + spin_unlock(&sbi->stat_lock);
> + goto enospc;
> + }
> + sbi->free_segments--;
> + }
> + sbi->free_ssr_node_block--;
> + }
> +
> sbi->total_valid_node_count++;
> sbi->total_valid_block_count++;
> spin_unlock(&sbi->stat_lock);
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 560751adba01c..6fc36296000cf 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -150,6 +150,9 @@ static inline enum cp_reason_type need_do_checkpoint(struct inode *inode)
> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> enum cp_reason_type cp_reason = CP_NO_NEEDED;
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return CP_NO_NEEDED;
> +
> if (!S_ISREG(inode->i_mode))
> cp_reason = CP_NON_REGULAR;
> else if (inode->i_nlink != 1)
> @@ -2083,6 +2086,9 @@ static int f2fs_ioc_gc(struct file *filp, unsigned long arg)
> if (f2fs_readonly(sbi->sb))
> return -EROFS;
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return -EINVAL;
> +
> ret = mnt_want_write_file(filp);
> if (ret)
> return ret;
> @@ -2125,6 +2131,9 @@ static int f2fs_ioc_gc_range(struct file *filp, unsigned long arg)
> return -EINVAL;
> }
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return -EINVAL;
> +
> ret = mnt_want_write_file(filp);
> if (ret)
> return ret;
> @@ -2160,6 +2169,12 @@ static int f2fs_ioc_write_checkpoint(struct file *filp, unsigned long arg)
> if (f2fs_readonly(sbi->sb))
> return -EROFS;
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT)) {
> + f2fs_msg(sbi->sb, KERN_INFO,
> + "Skipping Checkpoint. Checkpoints currently disabled.");
> + return -EINVAL;
> + }
> +
> ret = mnt_want_write_file(filp);
> if (ret)
> return ret;
> @@ -2531,6 +2546,9 @@ static int f2fs_ioc_flush_device(struct file *filp, unsigned long arg)
> if (f2fs_readonly(sbi->sb))
> return -EROFS;
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return -EINVAL;
> +
> if (copy_from_user(&range, (struct f2fs_flush_device __user *)arg,
> sizeof(range)))
> return -EFAULT;
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index d816c328f02b4..339debc0dadef 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -60,6 +60,9 @@ static int gc_thread_func(void *data)
> }
> #endif
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + goto do_balance;
> +
> if (!sb_start_write_trylock(sbi->sb))
> continue;
>
> @@ -105,6 +108,7 @@ static int gc_thread_func(void *data)
> trace_f2fs_background_gc(sbi->sb, wait_ms,
> prefree_segments(sbi), free_segments(sbi));
>
> +do_balance:
> /* balancing f2fs's metadata periodically */
> f2fs_balance_fs_bg(sbi);
> next:
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 73f24de28bf46..3b29d335b7fca 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -179,6 +179,10 @@ bool f2fs_need_SSR(struct f2fs_sb_info *sbi)
> return false;
> if (sbi->gc_mode == GC_URGENT)
> return true;
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return true;
> + if (sbi->gc_mode == GC_URGENT)
> + return true;
>
> return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs +
> SM_I(sbi)->min_ssr_sections + reserved_sections(sbi));
> @@ -489,6 +493,8 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
> * We should do GC or end up with checkpoint, if there are so many dirty
> * dir/node pages without enough free segments.
> */
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return;
> if (has_not_enough_free_secs(sbi, 0, 0)) {
> mutex_lock(&sbi->gc_mutex);
> f2fs_gc(sbi, false, false, NULL_SEGNO);
> @@ -531,8 +537,10 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
> f2fs_sync_dirty_inodes(sbi, FILE_INODE);
> blk_finish_plug(&plug);
> }
> - f2fs_sync_fs(sbi->sb, true);
> - stat_inc_bg_cp_count(sbi->stat_info);
> + if (!test_opt(sbi, DISABLE_CHECKPOINT)) {
> + f2fs_sync_fs(sbi->sb, true);
> + stat_inc_bg_cp_count(sbi->stat_info);
> + }
> }
> }
>
> @@ -747,8 +755,8 @@ int f2fs_flush_device_cache(struct f2fs_sb_info *sbi)
> return ret;
> }
>
> -static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
> - enum dirty_type dirty_type)
> +void __locate_dirty_segment(struct f2fs_sb_info *sbi,
> + unsigned int segno, enum dirty_type dirty_type)
> {
> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>
> @@ -772,8 +780,8 @@ static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
> }
> }
>
> -static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
> - enum dirty_type dirty_type)
> +void __remove_dirty_segment(struct f2fs_sb_info *sbi,
> + unsigned int segno, enum dirty_type dirty_type)
> {
> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
>
> @@ -793,6 +801,7 @@ static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
> }
> }
>
> +
> /*
> * Should not occur error such as -ENOMEM.
> * Adding dirty entry into seglist is not critical operation.
> @@ -801,7 +810,7 @@ static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
> static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
> {
> struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> - unsigned short valid_blocks;
> + unsigned short valid_blocks, ckpt_valid_blocks;
>
> if (segno == NULL_SEGNO || IS_CURSEG(sbi, segno))
> return;
> @@ -809,8 +818,10 @@ static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
> mutex_lock(&dirty_i->seglist_lock);
>
> valid_blocks = get_valid_blocks(sbi, segno, false);
> + ckpt_valid_blocks = get_ckpt_valid_blocks(sbi, segno);
>
> - if (valid_blocks == 0) {
> + if (valid_blocks == 0 && (ckpt_valid_blocks == sbi->blocks_per_seg ||
> + !test_opt(sbi, DISABLE_CHECKPOINT))) {
> __locate_dirty_segment(sbi, segno, PRE);
> __remove_dirty_segment(sbi, segno, DIRTY);
> } else if (valid_blocks < sbi->blocks_per_seg) {
> @@ -1980,7 +1991,8 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
> sbi->discard_blks--;
>
> /* don't overwrite by SSR to keep node chain */
> - if (IS_NODESEG(se->type)) {
> + if (IS_NODESEG(se->type) &&
> + !test_opt(sbi, DISABLE_CHECKPOINT)) {
> if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map))
> se->ckpt_valid_blocks++;
> }
> @@ -2002,6 +2014,25 @@ static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
> f2fs_bug_on(sbi, 1);
> se->valid_blocks++;
> del = 0;
> + } else {
> + /* If checkpoints are off, we must not reuse data that
> + * was used in the previous checkpoint. If it was used
> + * before, we must track that to know how much space we
> + * really have
> + */
> + if (f2fs_test_bit(offset, se->ckpt_valid_map)) {
> + spin_lock(&sbi->stat_lock);
> + sbi->unusable_block_count++;
> + spin_unlock(&sbi->stat_lock);
> + } else {
> + spin_lock(&sbi->stat_lock);
> + if (IS_DATASEG(se->type))
> + sbi->free_ssr_data_block++;
> + else
> + sbi->free_ssr_node_block++;
> + spin_unlock(&sbi->stat_lock);
> + }
> +
> }
>
> if (f2fs_discard_en(sbi) &&
> @@ -2291,7 +2322,8 @@ static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)
> return SIT_I(sbi)->last_victim[ALLOC_NEXT];
>
> /* find segments from 0 to reuse freed segments */
> - if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_REUSE)
> + if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_REUSE
> + || test_opt(sbi, DISABLE_CHECKPOINT))
> return 0;
>
> return CURSEG_I(sbi, type)->segno;
> @@ -2443,7 +2475,8 @@ static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
> else if (!is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_FLAG) &&
> type == CURSEG_WARM_NODE)
> new_curseg(sbi, type, false);
> - else if (curseg->alloc_type == LFS && is_next_segment_free(sbi, type))
> + else if (curseg->alloc_type == LFS && is_next_segment_free(sbi, type) &&
> + !test_opt(sbi, DISABLE_CHECKPOINT))
> new_curseg(sbi, type, false);
> else if (f2fs_need_SSR(sbi) && get_ssr_segment(sbi, type))
> change_curseg(sbi, type);
> @@ -3628,6 +3661,9 @@ void f2fs_flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> sit_i->dirty_sentries--;
> ses->entry_cnt--;
> }
> + spin_lock(&sbi->stat_lock);
> + sbi->unusable_block_count = 0;
> + spin_unlock(&sbi->stat_lock);
>
> if (to_journal)
> up_write(&curseg->journal_rwsem);
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index b3d9e317ff0c1..422b0ceb1eaaf 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -342,6 +342,12 @@ static inline unsigned int get_valid_blocks(struct f2fs_sb_info *sbi,
> return get_seg_entry(sbi, segno)->valid_blocks;
> }
>
> +static inline unsigned int get_ckpt_valid_blocks(struct f2fs_sb_info *sbi,
> + unsigned int segno)
> +{
> + return get_seg_entry(sbi, segno)->ckpt_valid_blocks;
> +}
> +
> static inline void seg_info_from_raw_sit(struct seg_entry *se,
> struct f2fs_sit_entry *rs)
> {
> @@ -524,6 +530,26 @@ static inline unsigned int dirty_segments(struct f2fs_sb_info *sbi)
> DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_NODE];
> }
>
> +void __locate_dirty_segment(struct f2fs_sb_info *sbi,
> + unsigned int segno, enum dirty_type dirty_type);
> +
> +void __remove_dirty_segment(struct f2fs_sb_info *sbi,
> + unsigned int segno, enum dirty_type dirty_type);
> +
> +/* This moves currently empty dirty blocks to prefree. Must hold seglist_lock */
> +static inline void dirty_to_prefree(struct f2fs_sb_info *sbi)
> +{
> + struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> + unsigned int segno;
> +
> + for_each_set_bit(segno, dirty_i->dirty_segmap[DIRTY], MAIN_SEGS(sbi)) {
> + if (!get_valid_blocks(sbi, segno, false)) {
> + __locate_dirty_segment(sbi, segno, PRE);
> + __remove_dirty_segment(sbi, segno, DIRTY);
> + }
> + }
> +}
> +
> static inline int overprovision_segments(struct f2fs_sb_info *sbi)
> {
> return SM_I(sbi)->ovp_segments;
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index bd57be470e23b..d7a35b390432b 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -132,6 +132,7 @@ enum {
> Opt_alloc,
> Opt_fsync,
> Opt_test_dummy_encryption,
> + Opt_checkpoint,
> Opt_err,
> };
>
> @@ -189,6 +190,7 @@ static match_table_t f2fs_tokens = {
> {Opt_alloc, "alloc_mode=%s"},
> {Opt_fsync, "fsync_mode=%s"},
> {Opt_test_dummy_encryption, "test_dummy_encryption"},
> + {Opt_checkpoint, "checkpoint=%s"},
> {Opt_err, NULL},
> };
>
> @@ -758,6 +760,23 @@ static int parse_options(struct super_block *sb, char *options)
> "Test dummy encryption mount option ignored");
> #endif
> break;
> + case Opt_checkpoint:
> + name = match_strdup(&args[0]);
> + if (!name)
> + return -ENOMEM;
> +
> + if (strlen(name) == 6 &&
> + !strncmp(name, "enable", 6)) {
> + clear_opt(sbi, DISABLE_CHECKPOINT);
> + } else if (strlen(name) == 7 &&
> + !strncmp(name, "disable", 7)) {
> + set_opt(sbi, DISABLE_CHECKPOINT);
> + } else {
> + kfree(name);
> + return -EINVAL;
> + }
> + kfree(name);
> + break;
> default:
> f2fs_msg(sb, KERN_ERR,
> "Unrecognized mount option \"%s\" or missing value",
> @@ -816,6 +835,12 @@ static int parse_options(struct super_block *sb, char *options)
> }
> }
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT) && test_opt(sbi, LFS)) {
> + f2fs_msg(sb, KERN_ERR,
> + "LFS not compatible with checkpoint=disable\n");
> + return -EINVAL;
> + }
> +
> /* Not pass down write hints if the number of active logs is lesser
> * than NR_CURSEG_TYPE.
> */
> @@ -1003,8 +1028,9 @@ static void f2fs_put_super(struct super_block *sb)
> * But, the previous checkpoint was not done by umount, it needs to do
> * clean checkpoint again.
> */
> - if (is_sbi_flag_set(sbi, SBI_IS_DIRTY) ||
> - !is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) {
> + if ((is_sbi_flag_set(sbi, SBI_IS_DIRTY) ||
> + !is_set_ckpt_flags(sbi, CP_UMOUNT_FLAG)) &&
> + !test_opt(sbi, DISABLE_CHECKPOINT)) {
> struct cp_control cpc = {
> .reason = CP_UMOUNT,
> };
> @@ -1014,7 +1040,8 @@ static void f2fs_put_super(struct super_block *sb)
> /* be sure to wait for any on-going discard commands */
> dropped = f2fs_wait_discard_bios(sbi);
>
> - if (f2fs_discard_en(sbi) && !sbi->discard_blks && !dropped) {
> + if (f2fs_discard_en(sbi) && !sbi->discard_blks && !dropped &&
> + !test_opt(sbi, DISABLE_CHECKPOINT)) {
> struct cp_control cpc = {
> .reason = CP_UMOUNT | CP_TRIMMED,
> };
> @@ -1075,6 +1102,8 @@ int f2fs_sync_fs(struct super_block *sb, int sync)
>
> if (unlikely(f2fs_cp_error(sbi)))
> return 0;
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + return 0;
>
> trace_f2fs_sync_fs(sb, sync);
>
> @@ -1173,7 +1202,8 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
>
> buf->f_blocks = total_count - start_count;
> buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
> - sbi->current_reserved_blocks;
> + sbi->current_reserved_blocks -
> + sbi->unusable_block_count;
> if (buf->f_bfree > F2FS_OPTION(sbi).root_reserved_blocks)
> buf->f_bavail = buf->f_bfree -
> F2FS_OPTION(sbi).root_reserved_blocks;
> @@ -1349,6 +1379,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
> else if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_REUSE)
> seq_printf(seq, ",alloc_mode=%s", "reuse");
>
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + seq_puts(seq, ",checkpoint=disable");
> +
> if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_POSIX)
> seq_printf(seq, ",fsync_mode=%s", "posix");
> else if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT)
> @@ -1376,6 +1409,7 @@ static void default_options(struct f2fs_sb_info *sbi)
> set_opt(sbi, INLINE_DENTRY);
> set_opt(sbi, EXTENT_CACHE);
> set_opt(sbi, NOHEAP);
> + clear_opt(sbi, DISABLE_CHECKPOINT);
> sbi->sb->s_flags |= SB_LAZYTIME;
> set_opt(sbi, FLUSH_MERGE);
> if (blk_queue_discard(bdev_get_queue(sbi->sb->s_bdev)))
> @@ -1398,6 +1432,60 @@ static void default_options(struct f2fs_sb_info *sbi)
> #ifdef CONFIG_QUOTA
> static int f2fs_enable_quotas(struct super_block *sb);
> #endif
> +
> +static void f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
> +{
> + struct cp_control cpc;
> + struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> + unsigned int segno;
> + int type;
> +
> + set_sbi_flag(sbi, SBI_CP_DISABLED);

We'd better to do GC as much as possible before disabling checkpoint?

> +
> + cpc.reason = CP_PAUSE;
> +
> + mutex_lock(&sbi->gc_mutex);
> + f2fs_write_checkpoint(sbi, &cpc);
> +
> + mutex_lock(&dirty_i->seglist_lock);
> + for (type = 0; type < NR_CURSEG_TYPE; type++) {
> + for_each_set_bit(segno, dirty_i->dirty_segmap[type],
> + MAIN_SEGS(sbi)) {
> + if (IS_DATASEG(type))
> + sbi->free_ssr_data_block +=
> + get_valid_blocks(sbi, segno, false);

The # of free blocks for ssr would be like 512 - get_valid_blocks().

> + else
> + sbi->free_ssr_node_block +=
> + get_valid_blocks(sbi, segno, false);

We can add sbi->free_ssr_blocks[2], and use
sbi->free_ssr_blocks[IS_DATASEG(type) ? DATA : NODE]

> + }
> + }
> + sbi->free_segments = FREE_I(sbi)->free_segments;

sbi->cp_free_segments ?

> + mutex_unlock(&dirty_i->seglist_lock);
> + mutex_unlock(&sbi->gc_mutex);
> +}
> +
> +static void f2fs_enable_checkpoint(struct f2fs_sb_info *sbi)
> +{
> + struct super_block *sb = sbi->sb;
> + struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> +
> + clear_sbi_flag(sbi, SBI_CP_DISABLED);
> + writeback_inodes_sb(sb, WB_REASON_SYNC);
> + sync_inodes_sb(sb);
> +
> + mutex_lock(&dirty_i->seglist_lock);
> + dirty_to_prefree(sbi);
> + sbi->free_segments = 0;
> + sbi->free_ssr_data_block = 0;
> + sbi->free_ssr_node_block = 0;
> + mutex_unlock(&dirty_i->seglist_lock);
> +
> + set_sbi_flag(sbi, SBI_IS_DIRTY);
> + set_sbi_flag(sbi, SBI_IS_CLOSE);
> + f2fs_sync_fs(sb, 1);
> + clear_sbi_flag(sbi, SBI_IS_CLOSE);
> +}
> +
> static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> {
> struct f2fs_sb_info *sbi = F2FS_SB(sb);
> @@ -1407,6 +1495,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> bool need_restart_gc = false;
> bool need_stop_gc = false;
> bool no_extent_cache = !test_opt(sbi, EXTENT_CACHE);
> + bool disable_checkpoint = test_opt(sbi, DISABLE_CHECKPOINT);
> + bool checkpoint_changed;
> #ifdef CONFIG_QUOTA
> int i, j;
> #endif
> @@ -1451,6 +1541,8 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> err = parse_options(sb, data);
> if (err)
> goto restore_opts;
> + checkpoint_changed =
> + disable_checkpoint != test_opt(sbi, DISABLE_CHECKPOINT);
>
> /*
> * Previous and new state of filesystem is RO,
> @@ -1512,6 +1604,13 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
> clear_sbi_flag(sbi, SBI_IS_CLOSE);
> }
>
> + if (checkpoint_changed) {
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + f2fs_disable_checkpoint(sbi);
> + else
> + f2fs_enable_checkpoint(sbi);
> + }
> +
> /*
> * We stop issue flush thread if FS is mounted as RO
> * or if flush_merge is not passed in mount option.
> @@ -2997,7 +3096,8 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> goto free_meta;
>
> /* recover fsynced data */
> - if (!test_opt(sbi, DISABLE_ROLL_FORWARD)) {
> + if (!test_opt(sbi, DISABLE_ROLL_FORWARD) &&
> + !is_sbi_flag_set(sbi, SBI_CP_DISABLED)) {
> /*
> * mount should be failed, when device has readonly mode, and
> * previous checkpoint was not done by clean system shutdown.
> @@ -3063,6 +3163,12 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> cur_cp_version(F2FS_CKPT(sbi)));
> f2fs_update_time(sbi, CP_TIME);
> f2fs_update_time(sbi, REQ_TIME);
> +
> + if (test_opt(sbi, DISABLE_CHECKPOINT))
> + f2fs_disable_checkpoint(sbi);
> + else if (is_sbi_flag_set(sbi, SBI_CP_DISABLED))
> + f2fs_enable_checkpoint(sbi);
> +
> return 0;
>
> free_meta:
> --
> 2.18.0.597.ga71716f1ad-goog

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