Messages in this thread | | | Date | Mon, 6 Apr 2020 19:58:18 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH] f2fs: prevent meta updates while checkpoint is in progress |
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On 04/07, Chao Yu wrote: > On 2020/4/4 1:27, Jaegeuk Kim wrote: > > On 04/03, Jaegeuk Kim wrote: > >> On 04/01, Sahitya Tummala wrote: > >>> Hi Jaegeuk, > >>> > >>> Got it. > >>> The diff below looks good to me. > >>> Would you like me to test it and put a patch for this? > >> > >> Sahitya, Chao, > >> > >> Could you please take a look at this patch and test intensively? > >> > >> Thanks, > > > > v2: > > > >>From 6bf7d5b227d466b0fe90d4957af29bd184fb646e Mon Sep 17 00:00:00 2001 > > From: Jaegeuk Kim <jaegeuk@kernel.org> > > Date: Tue, 31 Mar 2020 11:43:07 -0700 > > Subject: [PATCH] f2fs: refactor resize_fs to avoid meta updates in progress > > > > Sahitya raised an issue: > > - prevent meta updates while checkpoint is in progress > > > > 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. > > > > Signed-off-by: Sahitya Tummala <stummala@codeaurora.org> > > Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > > --- > > fs/f2fs/checkpoint.c | 6 +- > > fs/f2fs/f2fs.h | 2 +- > > fs/f2fs/file.c | 5 +- > > fs/f2fs/gc.c | 107 +++++++++++++++++++----------------- > > fs/f2fs/super.c | 1 - > > include/trace/events/f2fs.h | 4 +- > > 6 files changed, 67 insertions(+), 58 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 be02a5cadd944..f9b2caa2135bd 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 */ > > @@ -1421,7 +1422,6 @@ 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/file.c b/fs/f2fs/file.c > > index 257e61d0afffb..b4c12370bb3d6 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -3305,7 +3305,6 @@ 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; > > @@ -3317,9 +3316,7 @@ static int f2fs_ioc_resize_fs(struct file *filp, unsigned long arg) > > sizeof(block_count))) > > return -EFAULT; > > > > - ret = f2fs_resize_fs(sbi, block_count); > > - > > - return ret; > > + return f2fs_resize_fs(sbi, block_count); > > } > > > > static int f2fs_ioc_enable_verity(struct file *filp, unsigned long arg) > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > index 26248c8936db0..46c75ecb64a2e 100644 > > --- a/fs/f2fs/gc.c > > +++ b/fs/f2fs/gc.c > > @@ -1399,12 +1399,29 @@ void f2fs_build_gc_manager(struct f2fs_sb_info *sbi) > > GET_SEGNO(sbi, FDEV(0).end_blk) + 1; > > } > > > > -static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start, > > - unsigned int end) > > +static int free_segment_range(struct f2fs_sb_info *sbi, > > + unsigned int secs, bool gc_only) > > { > > - int type; > > - unsigned int segno, next_inuse; > > + unsigned int segno, next_inuse, start, end; > > + struct cp_control cpc = { CP_RESIZE, 0, 0, 0 }; > > + int gc_mode, gc_type; > > int err = 0; > > + int type; > > + > > + /* Force block allocation for GC */ > > + MAIN_SECS(sbi) -= secs; > > + start = MAIN_SECS(sbi) * sbi->segs_per_sec; > > + end = MAIN_SEGS(sbi) - 1; > > + > > + mutex_lock(&DIRTY_I(sbi)->seglist_lock); > > + for (gc_mode = 0; gc_mode < MAX_GC_POLICY; gc_mode++) > > + if (SIT_I(sbi)->last_victim[gc_mode] >= start) > > + 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] >= start) > > + sbi->next_victim_seg[gc_type] = NULL_SEGNO; > > + mutex_unlock(&DIRTY_I(sbi)->seglist_lock); > > > > /* Move out cursegs from the target range */ > > for (type = CURSEG_HOT_DATA; type < NR_CURSEG_TYPE; type++) > > @@ -1417,18 +1434,20 @@ 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; > > + if (!gc_only && get_valid_blocks(sbi, segno, true)) { > > + err = -EAGAIN; > > + goto out; > > + } > > } > > + if (gc_only) > > + goto out; > > > > - err = f2fs_sync_fs(sbi->sb, 1); > > + err = f2fs_write_checkpoint(sbi, &cpc); > > if (err) > > - return err; > > + goto out; > > > > next_inuse = find_next_inuse(FREE_I(sbi), end + 1, start); > > if (next_inuse <= end) { > > @@ -1436,6 +1455,8 @@ static int free_segment_range(struct f2fs_sb_info *sbi, unsigned int start, > > next_inuse); > > f2fs_bug_on(sbi, 1); > > } > > +out: > > + MAIN_SECS(sbi) -= secs; > > return err; > > } > > > > @@ -1481,6 +1502,7 @@ static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs) > > > > SM_I(sbi)->segment_count = (int)SM_I(sbi)->segment_count + segs; > > MAIN_SEGS(sbi) = (int)MAIN_SEGS(sbi) + segs; > > + MAIN_SECS(sbi) += secs; > > FREE_I(sbi)->free_sections = (int)FREE_I(sbi)->free_sections + secs; > > FREE_I(sbi)->free_segments = (int)FREE_I(sbi)->free_segments + segs; > > F2FS_CKPT(sbi)->user_block_count = cpu_to_le64(user_block_count + blks); > > @@ -1502,8 +1524,8 @@ 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; > > __u32 rem; > > > > @@ -1538,10 +1560,22 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > return -EINVAL; > > } > > > > - freeze_bdev(sbi->sb->s_bdev); > > - > > shrunk_blocks = old_block_count - block_count; > > secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi)); > > + > > + /* protect MAIN_SEC in free_segment_range */ > > + f2fs_lock_op(sbi); > > + err = free_segment_range(sbi, secs, true); > > For this path, we break the rule that we need hold gc_lock during > do_garbage_collect().
I don't get the point. In free_segment_range(), gc_lock is held before/after do_garbage_collect().
> > One other concern is that still the granularity of lock_op is too large, > to avoid potential hang if it triggers heavy gc migration, how about using > a timeout mechanism in free_segment_range() like we did in > f2fs_disable_checkpoint()?
We can do first round GC without f2fs_lock_op().
> > > + f2fs_unlock_op(sbi); > > + if (err) > > + return err; > > + > > + set_sbi_flag(sbi, SBI_IS_RESIZEFS); > > + > > + freeze_super(sbi->sb); > > + down_write(&sbi->gc_lock); > > + mutex_lock(&sbi->cp_mutex); > > + > > spin_lock(&sbi->stat_lock); > > if (shrunk_blocks + valid_user_blocks(sbi) + > > sbi->current_reserved_blocks + sbi->unusable_block_count + > > @@ -1550,69 +1584,44 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > else > > sbi->user_block_count -= shrunk_blocks; > > spin_unlock(&sbi->stat_lock); > > - if (err) { > > - thaw_bdev(sbi->sb->s_bdev, sbi->sb); > > - return err; > > - } > > - > > - mutex_lock(&sbi->resize_mutex); > > - set_sbi_flag(sbi, SBI_IS_RESIZEFS); > > - > > - mutex_lock(&DIRTY_I(sbi)->seglist_lock); > > - > > - MAIN_SECS(sbi) -= secs; > > - > > - for (gc_mode = 0; gc_mode < MAX_GC_POLICY; gc_mode++) > > - if (SIT_I(sbi)->last_victim[gc_mode] >= > > - 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] >= > > - MAIN_SECS(sbi) * sbi->segs_per_sec) > > - sbi->next_victim_seg[gc_type] = NULL_SEGNO; > > - > > - mutex_unlock(&DIRTY_I(sbi)->seglist_lock); > > + if (err) > > + goto out_err; > > > > - err = free_segment_range(sbi, MAIN_SECS(sbi) * sbi->segs_per_sec, > > - MAIN_SEGS(sbi) - 1); > > + err = free_segment_range(sbi, secs, false); > > Lock coverage is still large here, what about just checking the resize condition > with find_next_inuse(, end + 1, start), if the migration finished, then let's call > write_checkpoint(), otherwise, returning -EAGAIN.
We did GC above, so how much time do you expect to complete here? Basically I hesitate to return EAGAIN, since there's no context with respect to how many times user need to retry to get succeess. Disabling checkpoint has some ways to get a sense tho. Nevertheless, if we want to return EAGAIN, it'd be better to give # of bytes that it requires to migrate further?
> > > if (err) > > - goto out; > > + goto recover_out; > > > > update_sb_metadata(sbi, -secs); > > > > err = f2fs_commit_super(sbi, false); > > if (err) { > > update_sb_metadata(sbi, secs); > > - goto out; > > + goto recover_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); > > } > > -out: > > +recover_out: > > if (err) { > > set_sbi_flag(sbi, SBI_NEED_FSCK); > > f2fs_err(sbi, "resize_fs failed, should run fsck to repair!"); > > > > - MAIN_SECS(sbi) += secs; > > spin_lock(&sbi->stat_lock); > > sbi->user_block_count += shrunk_blocks; > > spin_unlock(&sbi->stat_lock); > > } > > +out_err: > > + mutex_unlock(&sbi->cp_mutex); > > + up_write(&sbi->gc_lock); > > + thaw_super(sbi->sb); > > clear_sbi_flag(sbi, SBI_IS_RESIZEFS); > > - mutex_unlock(&sbi->resize_mutex); > > - thaw_bdev(sbi->sb->s_bdev, 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 4d7d4c391879d..5d1a72001fdb4 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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