Messages in this thread | | | Date | Fri, 3 Apr 2020 09:20:52 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH] f2fs: prevent meta updates while checkpoint is in progress |
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On 04/01, Chao Yu wrote: > On 2020/4/1 2:43, Jaegeuk Kim wrote: > > On 03/31, Sahitya Tummala wrote: > >> On Mon, Mar 30, 2020 at 08:54:19PM -0700, Jaegeuk Kim wrote: > >>> On 03/26, Sahitya Tummala wrote: > >>>> allocate_segment_for_resize() can cause metapage updates if > >>>> it requires to change the current node/data segments for resizing. > >>>> Stop these meta updates when there is a checkpoint already > >>>> in progress to prevent inconsistent CP data. > >>> > >>> I'd prefer to use f2fs_lock_op() in bigger coverage. > >> > >> Do you mean to cover the entire free_segment_range() function within > >> f2fs_lock_op()? Please clarify. > > > > I didn't test tho, something like this? > > > > --- > > fs/f2fs/checkpoint.c | 6 ++++-- > > fs/f2fs/f2fs.h | 2 +- > > fs/f2fs/gc.c | 28 ++++++++++++++-------------- > > fs/f2fs/super.c | 1 - > > include/trace/events/f2fs.h | 4 +++- > > 5 files changed, 22 insertions(+), 19 deletions(-) > > > > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c > > index 852890b72d6ac..531995192b714 100644 > > --- a/fs/f2fs/checkpoint.c > > +++ b/fs/f2fs/checkpoint.c > > @@ -1553,7 +1553,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc) > > return 0; > > f2fs_warn(sbi, "Start checkpoint disabled!"); > > } > > - mutex_lock(&sbi->cp_mutex); > > + if (cpc->reason != CP_RESIZE) > > + mutex_lock(&sbi->cp_mutex); > > > > if (!is_sbi_flag_set(sbi, SBI_IS_DIRTY) && > > ((cpc->reason & CP_FASTBOOT) || (cpc->reason & CP_SYNC) || > > @@ -1622,7 +1623,8 @@ int f2fs_write_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc) > > f2fs_update_time(sbi, CP_TIME); > > trace_f2fs_write_checkpoint(sbi->sb, cpc->reason, "finish checkpoint"); > > out: > > - mutex_unlock(&sbi->cp_mutex); > > + if (cpc->reason != CP_RESIZE) > > + mutex_unlock(&sbi->cp_mutex); > > return err; > > } > > > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index c84442eefc56d..7c98dca3ec1d6 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -193,6 +193,7 @@ enum { > > #define CP_DISCARD 0x00000010 > > #define CP_TRIMMED 0x00000020 > > #define CP_PAUSE 0x00000040 > > +#define CP_RESIZE 0x00000080 > > > > #define MAX_DISCARD_BLOCKS(sbi) BLKS_PER_SEC(sbi) > > #define DEF_MAX_DISCARD_REQUEST 8 /* issue 8 discards per round */ > > @@ -1417,7 +1418,6 @@ 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 */ > > - struct mutex resize_mutex; /* for resize exclusion */ > > 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 */ > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > index 26248c8936db0..1e5a06fda09d3 100644 > > --- a/fs/f2fs/gc.c > > +++ b/fs/f2fs/gc.c > > @@ -1402,8 +1402,9 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi) > > static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start, > > unsigned int end) > > { > > - int type; > > unsigned int segno, next_inuse; > > + struct cp_control cpc = { CP_RESIZE, 0, 0, 0 }; > > + int type; > > int err = 0; > > > > /* Move out cursegs from the target range */ > > @@ -1417,16 +1418,14 @@ static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start, > > .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS), > > }; > > > > - down_write(&sbi->gc_lock); > > do_garbage_collect(sbi, segno, &gc_list, FG_GC); > > - up_write(&sbi->gc_lock); > > put_gc_inode(&gc_list); > > > > if (get_valid_blocks(sbi, segno, true)) > > return -EAGAIN; > > } > > > > - err = f2fs_sync_fs(sbi->sb, 1); > > + err = f2fs_write_checkpoint(sbi, &cpc); > > if (err) > > return err; > > > > @@ -1502,6 +1501,7 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs) > > int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > { > > __u64 old_block_count, shrunk_blocks; > > + struct cp_control cpc = { CP_RESIZE, 0, 0, 0 }; > > unsigned int secs; > > int gc_mode, gc_type; > > int err = 0; > > @@ -1538,7 +1538,9 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > return -EINVAL; > > } > > > > - freeze_bdev(sbi->sb->s_bdev); > > + freeze_super(sbi->sb); > > Look at this again, I guess holding freeze lock here may cause potential > hang task issue, imaging that in a low-end storage, shrinking large size > address space, free_segment_range() needs very long time to migrate all > valid blocks in the tail of device, that's why previously we do block > migration with small gc_lock coverage.
Hmm, it seems we had to do like: 1) do GC 2) freeze everything 3) check it's okay to go new metadata 4) do resize 5) thaw
> > Quoted: > > Changelog v5 ==> v6: > - In free_segment_range(), reduce granularity of gc_mutex. > > Thanks, > > > + down_write(&sbi->gc_lock); > > + mutex_lock(&sbi->cp_mutex); > > > > shrunk_blocks = old_block_count - block_count; > > secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi)); > > @@ -1551,11 +1553,12 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > sbi->user_block_count -= shrunk_blocks; > > spin_unlock(&sbi->stat_lock); > > if (err) { > > - thaw_bdev(sbi->sb->s_bdev, sbi->sb); > > + mutex_unlock(&sbi->cp_mutex); > > + up_write(&sbi->gc_lock); > > + thaw_super(sbi->sb); > > return err; > > } > > > > - mutex_lock(&sbi->resize_mutex); > > set_sbi_flag(sbi, SBI_IS_RESIZEFS); > > > > mutex_lock(&DIRTY_I(sbi)->seglist_lock); > > @@ -1587,17 +1590,13 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > goto out; > > } > > > > - mutex_lock(&sbi->cp_mutex); > > update_fs_metadata(sbi, -secs); > > clear_sbi_flag(sbi, SBI_IS_RESIZEFS); > > set_sbi_flag(sbi, SBI_IS_DIRTY); > > - mutex_unlock(&sbi->cp_mutex); > > > > - err = f2fs_sync_fs(sbi->sb, 1); > > + err = f2fs_write_checkpoint(sbi, &cpc); > > if (err) { > > - mutex_lock(&sbi->cp_mutex); > > update_fs_metadata(sbi, secs); > > - mutex_unlock(&sbi->cp_mutex); > > update_sb_metadata(sbi, secs); > > f2fs_commit_super(sbi, false); > > } > > @@ -1612,7 +1611,8 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > spin_unlock(&sbi->stat_lock); > > } > > clear_sbi_flag(sbi, SBI_IS_RESIZEFS); > > - mutex_unlock(&sbi->resize_mutex); > > - thaw_bdev(sbi->sb->s_bdev, sbi->sb); > > + mutex_unlock(&sbi->cp_mutex); > > + up_write(&sbi->gc_lock); > > + thaw_super(sbi->sb); > > return err; > > } > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > index b83b17b54a0a6..1e7b1d21d0177 100644 > > --- a/fs/f2fs/super.c > > +++ b/fs/f2fs/super.c > > @@ -3412,7 +3412,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) > > init_rwsem(&sbi->gc_lock); > > mutex_init(&sbi->writepages); > > mutex_init(&sbi->cp_mutex); > > - mutex_init(&sbi->resize_mutex); > > init_rwsem(&sbi->node_write); > > init_rwsem(&sbi->node_change); > > > > diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h > > index d97adfc327f03..f5eb03c54e96f 100644 > > --- a/include/trace/events/f2fs.h > > +++ b/include/trace/events/f2fs.h > > @@ -50,6 +50,7 @@ TRACE_DEFINE_ENUM(CP_RECOVERY); > > TRACE_DEFINE_ENUM(CP_DISCARD); > > TRACE_DEFINE_ENUM(CP_TRIMMED); > > TRACE_DEFINE_ENUM(CP_PAUSE); > > +TRACE_DEFINE_ENUM(CP_RESIZE); > > > > #define show_block_type(type) \ > > __print_symbolic(type, \ > > @@ -126,7 +127,8 @@ TRACE_DEFINE_ENUM(CP_PAUSE); > > { CP_RECOVERY, "Recovery" }, \ > > { CP_DISCARD, "Discard" }, \ > > { CP_PAUSE, "Pause" }, \ > > - { CP_TRIMMED, "Trimmed" }) > > + { CP_TRIMMED, "Trimmed" }, \ > > + { CP_RESIZE, "Resize" }) > > > > #define show_fsync_cpreason(type) \ > > __print_symbolic(type, \ > >
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