Re: [PATCH v3 1/1] f2fs: ioctl for removing a range from F2FS

From: Chao Yu
Date: Mon May 20 2019 - 23:18:53 EST

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In reply to: sunqiuyang: "[PATCH v3 1/1] f2fs: ioctl for removing a range from F2FS"
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On 2019/5/21 10:34, sunqiuyang wrote:
> From: Qiuyang Sun <sunqiuyang@xxxxxxxxxx>
>
> This ioctl shrinks a given length (aligned to sections) from end of the
> main area. Any cursegs and valid blocks will be moved out before
> invalidating the range.
>
> This feature can be used for adjusting partition sizes online.
>
> Changlog v1 ==> v2:
>
> Sahitya Tummala:
> - Add this ioctl for f2fs_compat_ioctl() as well.
> - Fix debugfs status to reflect the online resize changes.
> - Fix potential race between online resize path and allocate new data
> block path or gc path.
>
> Others:
> - Rename some identifiers.
> - Add some error handling branches.
> - Clear sbi->next_victim_seg[BG_GC/FG_GC] in shrinking range.
>
> Changelog v2 ==> v3:
> Implement this interface as ext4's, and change the parameter from shrunk
> bytes to new block count of F2FS.
>
> Signed-off-by: Qiuyang Sun <sunqiuyang@xxxxxxxxxx>
> Signed-off-by: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>
> ---
> fs/f2fs/debug.c | 7 ++++
> fs/f2fs/f2fs.h | 4 ++
> fs/f2fs/file.c | 28 ++++++++++++++
> fs/f2fs/gc.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
> fs/f2fs/segment.c | 49 +++++++++++++++++------
> fs/f2fs/segment.h | 1 +
> fs/f2fs/super.c | 1 +
> 7 files changed, 190 insertions(+), 13 deletions(-)
>
> diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
> index 99e9a5c..7706049 100644
> --- a/fs/f2fs/debug.c
> +++ b/fs/f2fs/debug.c
> @@ -27,8 +27,15 @@
> static void update_general_status(struct f2fs_sb_info *sbi)
> {
> struct f2fs_stat_info *si = F2FS_STAT(sbi);
> + struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
> int i;
>
> + /* these will be changed if online resize is done */
> + si->main_area_segs = le32_to_cpu(raw_super->segment_count_main);
> + si->main_area_sections = le32_to_cpu(raw_super->section_count);
> + si->main_area_zones = si->main_area_sections /
> + le32_to_cpu(raw_super->secs_per_zone);
> +
> /* validation check of the segment numbers */
> si->hit_largest = atomic64_read(&sbi->read_hit_largest);
> si->hit_cached = atomic64_read(&sbi->read_hit_cached);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index a205d4d..065f917 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -423,6 +423,7 @@ static inline bool __has_cursum_space(struct f2fs_journal *journal,
> #define F2FS_IOC_SET_PIN_FILE _IOW(F2FS_IOCTL_MAGIC, 13, __u32)
> #define F2FS_IOC_GET_PIN_FILE _IOR(F2FS_IOCTL_MAGIC, 14, __u32)
> #define F2FS_IOC_PRECACHE_EXTENTS _IO(F2FS_IOCTL_MAGIC, 15)
> +#define F2FS_IOC_RESIZE_FS _IOW(F2FS_IOCTL_MAGIC, 16, __u64)
>
> #define F2FS_IOC_SET_ENCRYPTION_POLICY FS_IOC_SET_ENCRYPTION_POLICY
> #define F2FS_IOC_GET_ENCRYPTION_POLICY FS_IOC_GET_ENCRYPTION_POLICY
> @@ -1309,6 +1310,7 @@ struct f2fs_sb_info {
> unsigned int segs_per_sec; /* segments per section */
> unsigned int secs_per_zone; /* sections per zone */
> unsigned int total_sections; /* total section count */
> + unsigned int current_total_sections; /* for shrink resize */
> unsigned int total_node_count; /* total node block count */
> unsigned int total_valid_node_count; /* valid node block count */
> loff_t max_file_blocks; /* max block index of file */
> @@ -3175,6 +3177,7 @@ void f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
> int f2fs_disable_cp_again(struct f2fs_sb_info *sbi, block_t unusable);
> void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi);
> int f2fs_npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra);
> +void allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type);
> void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi);
> int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range);
> bool f2fs_exist_trim_candidates(struct f2fs_sb_info *sbi,
> @@ -3318,6 +3321,7 @@ int f2fs_migrate_page(struct address_space *mapping, struct page *newpage,
> int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, bool background,
> unsigned int segno);
> void f2fs_build_gc_manager(struct f2fs_sb_info *sbi);
> +int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count);
>
> /*
> * recovery.c
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index d05ac21..a37a0d4 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3013,6 +3013,31 @@ static int f2fs_ioc_precache_extents(struct file *filp, unsigned long arg)
> return f2fs_precache_extents(file_inode(filp));
> }
>
> +static int f2fs_ioc_resize_fs(struct file *filp, unsigned long arg)
> +{
> + struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(filp));
> + __u64 block_count;
> + int ret;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + if (f2fs_readonly(sbi->sb))
> + return -EROFS;
> +
> + if (copy_from_user(&block_count, (__u64 __user *)arg, sizeof(__u64)))
> + return -EFAULT;
> +
> + ret = mnt_want_write_file(filp);
> + if (ret)
> + return ret;
> +
> + ret = f2fs_resize_fs(sbi, block_count);
> + mnt_drop_write_file(filp);
> +
> + return ret;
> +}
> +
> long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> {
> if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp)))))
> @@ -3069,6 +3094,8 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> return f2fs_ioc_set_pin_file(filp, arg);
> case F2FS_IOC_PRECACHE_EXTENTS:
> return f2fs_ioc_precache_extents(filp, arg);
> + case F2FS_IOC_RESIZE_FS:
> + return f2fs_ioc_resize_fs(filp, arg);
> default:
> return -ENOTTY;
> }
> @@ -3182,6 +3209,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> case F2FS_IOC_GET_PIN_FILE:
> case F2FS_IOC_SET_PIN_FILE:
> case F2FS_IOC_PRECACHE_EXTENTS:
> + case F2FS_IOC_RESIZE_FS:
> break;
> default:
> return -ENOIOCTLCMD;
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 963fb45..2dc7ce2 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -311,10 +311,11 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> struct sit_info *sm = SIT_I(sbi);
> struct victim_sel_policy p;
> unsigned int secno, last_victim;
> - unsigned int last_segment = MAIN_SEGS(sbi);
> + unsigned int last_segment;
> unsigned int nsearched = 0;
>
> mutex_lock(&dirty_i->seglist_lock);
> + last_segment = CUR_MAIN_SECS(sbi) * sbi->segs_per_sec;
>
> p.alloc_mode = alloc_mode;
> select_policy(sbi, gc_type, type, &p);
> @@ -404,7 +405,8 @@ static int get_victim_by_default(struct f2fs_sb_info *sbi,
> sm->last_victim[p.gc_mode] = last_victim + 1;
> else
> sm->last_victim[p.gc_mode] = segno + 1;
> - sm->last_victim[p.gc_mode] %= MAIN_SEGS(sbi);
> + sm->last_victim[p.gc_mode] %=
> + (CUR_MAIN_SECS(sbi) * sbi->segs_per_sec);
> break;
> }
> }
> @@ -1360,3 +1362,110 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi)
> SIT_I(sbi)->last_victim[ALLOC_NEXT] =
> GET_SEGNO(sbi, FDEV(0).end_blk) + 1;
> }
> +
> +static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start,
> + unsigned int end)
> +{
> + int type;
> + unsigned int segno, next_inuse;
> + struct gc_inode_list gc_list = {
> + .ilist = LIST_HEAD_INIT(gc_list.ilist),
> + .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
> + };
> + int err = 0;
> +
> + /* Move out cursegs from the target range */
> + for (type = CURSEG_HOT_DATA; type < NR_CURSEG_TYPE; type++) {
> + segno = CURSEG_I(sbi, type)->segno;
> + if (segno >= start && segno <= end)
> + allocate_segment_for_resize(sbi, type);
> + }
> +
> + /* do GC to move out valid blocks in the range */
> + mutex_lock(&sbi->gc_mutex);
> + for (segno = start; segno <= end; segno += sbi->segs_per_sec) {
> + do_garbage_collect(sbi, segno, &gc_list, FG_GC);
> + if (get_valid_blocks(sbi, segno, true)) {
> + err = -EAGAIN;
> + break;
> + }
> + }
> +
> + mutex_unlock(&sbi->gc_mutex);
> + put_gc_inode(&gc_list);
> +
> + if (err)
> + return err;
> +
> + err = f2fs_sync_fs(sbi->sb, 1);
> + if (err)
> + return err;
> +
> + next_inuse = find_next_inuse(FREE_I(sbi), end + 1, start);
> + if (next_inuse <= end) {
> + f2fs_msg(sbi->sb, KERN_ERR,
> + "segno %u should be free but still inuse!", next_inuse);
> + f2fs_bug_on(sbi, 1);
> + }
> + return err;
> +}
> +
> +int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count)
> +{
> + __u64 old_block_count = F2FS_RAW_SUPER(sbi)->block_count;
> + unsigned int secs;
> + int gc_mode, gc_type;
> + int err = 0;
> +
> + if (block_count > old_block_count)
> + return -EINVAL;
> +
> + if (block_count == old_block_count)
> + return 0;
> +
> + secs = (old_block_count - block_count + BLKS_PER_SEC(sbi) - 1) /
> + BLKS_PER_SEC(sbi);

There is one case that secs may equal to old_secs when
old_block_count - block_count < BLKS_PER_SEC(sbi), in this case, we don't need
to resize fs.

So I suggest we can restrict inputted block_count to align section size, as you
describe in commit message:

/* new fs size should align to section size */
if (block_count % section_count)
return -EINVAL;

> + if (secs * BLKS_PER_SEC(sbi) + valid_user_blocks(sbi) +
> + sbi->current_reserved_blocks + sbi->unusable_block_count +
> + F2FS_OPTION(sbi).root_reserved_blocks > sbi->user_block_count)
> + return -ENOSPC;

After above check, more free space can be grabbed by creator/writer, can we
expect -EAGAIN will be returned from free_segment_range() if we can not relocate
out-of-range data due to ENOSPC, but I doubt do_garbage_collect(, FG_GC) may
panic in move_data_{page,block}->f2fs_allocate_data_block->allocate_segment path
if there is no more free segment.

One more concern is we need to keep reisze_fs operation as atomical one to avoid
resize vs resize case..

> +
> + mutex_lock(&DIRTY_I(sbi)->seglist_lock);
> + CUR_MAIN_SECS(sbi) = MAIN_SECS(sbi) - secs;
> + for (gc_mode = 0; gc_mode < MAX_GC_POLICY; gc_mode++)
> + if (SIT_I(sbi)->last_victim[gc_mode] >=
> + CUR_MAIN_SECS(sbi) * sbi->segs_per_sec)
> + SIT_I(sbi)->last_victim[gc_mode] = 0;
> + for (gc_type = BG_GC; gc_type <= FG_GC; gc_type++)
> + if (sbi->next_victim_seg[gc_type] >=
> + CUR_MAIN_SECS(sbi) * sbi->segs_per_sec)
> + sbi->next_victim_seg[gc_type] = NULL_SEGNO;
> + mutex_unlock(&DIRTY_I(sbi)->seglist_lock);
> +
> + err = free_segment_range(sbi, CUR_MAIN_SECS(sbi) * sbi->segs_per_sec,
> + MAIN_SEGS(sbi) - 1);
> + if (err) {
> + CUR_MAIN_SECS(sbi) = MAIN_SECS(sbi);
> + return err;
> + }
> +
> + /* Update FS metadata */
> + SM_I(sbi)->segment_count -= secs * sbi->segs_per_sec;
> + MAIN_SECS(sbi) = CUR_MAIN_SECS(sbi);
> + MAIN_SEGS(sbi) = MAIN_SECS(sbi) * sbi->segs_per_sec;
> + sbi->user_block_count -= secs * BLKS_PER_SEC(sbi);
> + sbi->ckpt->user_block_count = cpu_to_le64(sbi->user_block_count);

F2FS_CKPT(sbi)->user_block_count

> + FREE_I(sbi)->free_sections -= secs;
> + FREE_I(sbi)->free_segments -= secs * sbi->segs_per_sec;
> +
> + /* Update superblock */
> + F2FS_RAW_SUPER(sbi)->section_count = cpu_to_le32(MAIN_SECS(sbi));
> + F2FS_RAW_SUPER(sbi)->segment_count = cpu_to_le32(le32_to_cpu(
> + F2FS_RAW_SUPER(sbi)->segment_count) - secs * sbi->segs_per_sec);
> + F2FS_RAW_SUPER(sbi)->segment_count_main = cpu_to_le32(MAIN_SEGS(sbi));
> + F2FS_RAW_SUPER(sbi)->block_count = cpu_to_le32(le32_to_cpu(
> + F2FS_RAW_SUPER(sbi)->block_count) - secs * BLKS_PER_SEC(sbi));

le64_to_cpu(F2FS_RAW_SUPER(sbi)->block_count)

> + err = f2fs_commit_super(sbi, false);

I inject error into commit_super() and do umount and run fsck, it reports that
image is inconsistent:

[FSCK] free segment_count matched with CP [Fail] [0x1fe7f]
[FSCK] next block offset is free [Ok..]
[FSCK] fixing SIT types
[FSCK] other corrupted bugs [Fail]

> +
> + return err;
> +}
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 07e9235..5a68fc0 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -2360,7 +2360,7 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> {
> struct free_segmap_info *free_i = FREE_I(sbi);
> unsigned int segno, secno, zoneno;
> - unsigned int total_zones = MAIN_SECS(sbi) / sbi->secs_per_zone;
> + unsigned int total_zones = CUR_MAIN_SECS(sbi) / sbi->secs_per_zone;
> unsigned int hint = GET_SEC_FROM_SEG(sbi, *newseg);
> unsigned int old_zoneno = GET_ZONE_FROM_SEG(sbi, *newseg);
> unsigned int left_start = hint;
> @@ -2377,12 +2377,13 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> goto got_it;
> }
> find_other_zone:
> - secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
> - if (secno >= MAIN_SECS(sbi)) {
> + secno = find_next_zero_bit(free_i->free_secmap, CUR_MAIN_SECS(sbi),
> + hint);
> + if (secno >= CUR_MAIN_SECS(sbi)) {
> if (dir == ALLOC_RIGHT) {
> secno = find_next_zero_bit(free_i->free_secmap,
> - MAIN_SECS(sbi), 0);
> - f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
> + CUR_MAIN_SECS(sbi), 0);
> + f2fs_bug_on(sbi, secno >= CUR_MAIN_SECS(sbi));
> } else {
> go_left = 1;
> left_start = hint - 1;
> @@ -2397,8 +2398,8 @@ static void get_new_segment(struct f2fs_sb_info *sbi,
> continue;
> }
> left_start = find_next_zero_bit(free_i->free_secmap,
> - MAIN_SECS(sbi), 0);
> - f2fs_bug_on(sbi, left_start >= MAIN_SECS(sbi));
> + CUR_MAIN_SECS(sbi), 0);
> + f2fs_bug_on(sbi, left_start >= CUR_MAIN_SECS(sbi));
> break;
> }
> secno = left_start;
> @@ -2651,6 +2652,27 @@ static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
> stat_inc_seg_type(sbi, curseg);
> }
>
> +void allocate_segment_for_resize(struct f2fs_sb_info *sbi, int type)
> +{
> + struct curseg_info *curseg = CURSEG_I(sbi, type);
> + unsigned int old_segno = curseg->segno;
> +

down_read(&SM_I(sbi)->curseg_lock);

> + mutex_lock(&curseg->curseg_mutex);
> + if (f2fs_need_SSR(sbi) && get_ssr_segment(sbi, type))
> + change_curseg(sbi, type);
> + else
> + new_curseg(sbi, type, true);
> +
> + stat_inc_seg_type(sbi, curseg);
> + mutex_unlock(&curseg->curseg_mutex);

up_read();

Thanks,

> +
> + if (get_valid_blocks(sbi, old_segno, false) == 0)
> + __set_test_and_free(sbi, old_segno);
> + f2fs_msg(sbi->sb, KERN_NOTICE,
> + "For resize: curseg of type %d: %u ==> %u",
> + type, old_segno, curseg->segno);
> +}
> +
> void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi)
> {
> struct curseg_info *curseg;
> @@ -3753,6 +3775,12 @@ static void remove_sits_in_journal(struct f2fs_sb_info *sbi)
> bool dirtied;
>
> segno = le32_to_cpu(segno_in_journal(journal, i));
> + if (segno >= MAIN_SEGS(sbi)) {
> + f2fs_msg(sbi->sb, KERN_NOTICE,
> + "Skip segno %u / %u in jnl!\n",
> + segno, MAIN_SEGS(sbi));
> + continue;
> + }
> dirtied = __mark_sit_entry_dirty(sbi, segno);
>
> if (!dirtied)
> @@ -4108,12 +4136,11 @@ static int build_sit_entries(struct f2fs_sb_info *sbi)
>
> start = le32_to_cpu(segno_in_journal(journal, i));
> if (start >= MAIN_SEGS(sbi)) {
> - f2fs_msg(sbi->sb, KERN_ERR,
> + /* This may happen if the FS was once resized. */
> + f2fs_msg(sbi->sb, KERN_NOTICE,
> "Wrong journal entry on segno %u",
> start);
> - set_sbi_flag(sbi, SBI_NEED_FSCK);
> - err = -EINVAL;
> - break;
> + continue;
> }
>
> se = &sit_i->sentries[start];
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 429007b..eaa9782 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -59,6 +59,7 @@
>
> #define MAIN_SEGS(sbi) (SM_I(sbi)->main_segments)
> #define MAIN_SECS(sbi) ((sbi)->total_sections)
> +#define CUR_MAIN_SECS(sbi) ((sbi)->current_total_sections)
>
> #define TOTAL_SEGS(sbi) \
> (SM_I(sbi) ? SM_I(sbi)->segment_count : \
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 1f581f0..6c0e9cc 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2843,6 +2843,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
> sbi->segs_per_sec = le32_to_cpu(raw_super->segs_per_sec);
> sbi->secs_per_zone = le32_to_cpu(raw_super->secs_per_zone);
> sbi->total_sections = le32_to_cpu(raw_super->section_count);
> + sbi->current_total_sections = sbi->total_sections;
> sbi->total_node_count =
> (le32_to_cpu(raw_super->segment_count_nat) / 2)
> * sbi->blocks_per_seg * NAT_ENTRY_PER_BLOCK;
>

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