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Tue, 7 Apr 2020 10:34:19 +0800 Subject: Re: [f2fs-dev] [PATCH] f2fs: prevent meta updates while checkpoint is in progress To: Jaegeuk Kim , Sahitya Tummala CC: , References: <1585219019-24831-1-git-send-email-stummala@codeaurora.org> <20200331035419.GB79749@google.com> <20200331090608.GZ20234@codeaurora.org> <20200331184307.GA198665@google.com> <20200401050801.GA20234@codeaurora.org> <20200403171727.GB68460@google.com> <20200403172750.GD68460@google.com> From: Chao Yu Message-ID: <8ab6c209-8fbf-eadb-17cb-d96cc10f868d@huawei.com> Date: Tue, 7 Apr 2020 10:34:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200403172750.GD68460@google.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > 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 > Signed-off-by: Jaegeuk Kim > --- > 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(). 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()? > + 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. > 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, \ >