On 07/30, Chao Yu wrote: > On 2018/7/30 9:32, Jaegeuk Kim wrote: > > The f2fs_gc() called by f2fs_balance_fs() requires to be called outside of > > fi->i_gc_rwsem[WRITE], since f2fs_gc() can try to grab it in a loop. > > > > If it hits the miximum retrials in GC, let's give a chance to release > > gc_mutex for a short time in order not to go into live lock in the worst > > case. > > > > Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org> > > --- > > fs/f2fs/f2fs.h | 1 + > > fs/f2fs/file.c | 62 ++++++++++++++++++++++------------------------- > > fs/f2fs/gc.c | 22 ++++++++++++----- > > fs/f2fs/segment.c | 5 +++- > > fs/f2fs/segment.h | 2 +- > > 5 files changed, 51 insertions(+), 41 deletions(-) > > > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > > index a9447c7d6570..50349780001b 100644 > > --- a/fs/f2fs/f2fs.h > > +++ b/fs/f2fs/f2fs.h > > @@ -1223,6 +1223,7 @@ struct f2fs_sb_info { > > unsigned int gc_mode; /* current GC state */ > > /* for skip statistic */ > > unsigned long long skipped_atomic_files[2]; /* FG_GC and BG_GC */ > > + unsigned long long skipped_gc_rwsem; /* FG_GC only */ > > > > /* threshold for gc trials on pinned files */ > > u64 gc_pin_file_threshold; > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > index 78c1bd6b8497..2b7d26ebb294 100644 > > --- a/fs/f2fs/file.c > > +++ b/fs/f2fs/file.c > > @@ -1179,10 +1179,12 @@ static int __exchange_data_block(struct inode > > *src_inode, > > return ret; > > } > > > > -static int f2fs_do_collapse(struct inode *inode, pgoff_t start, pgoff_t > > end) > > +static int f2fs_do_collapse(struct inode *inode, loff_t offset, loff_t len) > > { > > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > pgoff_t nrpages = (i_size_read(inode) + PAGE_SIZE - 1) / PAGE_SIZE; > > + pgoff_t start = offset >> PAGE_SHIFT; > > + pgoff_t end = (offset + len) >> PAGE_SHIFT; > > int ret; > > > > f2fs_balance_fs(sbi, true); > > @@ -1190,14 +1192,18 @@ static int f2fs_do_collapse(struct inode *inode, > > pgoff_t start, pgoff_t end) > > > > f2fs_drop_extent_tree(inode); > > > > + /* avoid gc operation during block exchange */ > > + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > + truncate_pagecache(inode, offset); > > ret = __exchange_data_block(inode, inode, end, start, nrpages - end, > > true); > > + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > + > > f2fs_unlock_op(sbi); > > return ret; > > } > > > > static int f2fs_collapse_range(struct inode *inode, loff_t offset, loff_t > > len) > > { > > - pgoff_t pg_start, pg_end; > > loff_t new_size; > > int ret; > > > > @@ -1212,21 +1218,13 @@ static int f2fs_collapse_range(struct inode *inode, > > loff_t offset, loff_t len) > > if (ret) > > return ret; > > > > - pg_start = offset >> PAGE_SHIFT; > > - pg_end = (offset + len) >> PAGE_SHIFT; > > - > > - /* avoid gc operation during block exchange */ > > - down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > - > > down_write(&F2FS_I(inode)->i_mmap_sem); > > /* write out all dirty pages from offset */ > > ret = filemap_write_and_wait_range(inode->i_mapping, offset, LLONG_MAX); > > if (ret) > > goto out_unlock; > > > > - truncate_pagecache(inode, offset); > > - > > - ret = f2fs_do_collapse(inode, pg_start, pg_end); > > + ret = f2fs_do_collapse(inode, offset, len); > > if (ret) > > goto out_unlock; > > > > @@ -1242,7 +1240,6 @@ static int f2fs_collapse_range(struct inode *inode, > > loff_t offset, loff_t len) > > f2fs_i_size_write(inode, new_size); > > out_unlock: > > up_write(&F2FS_I(inode)->i_mmap_sem); > > - up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > return ret; > > } > > > > @@ -1417,9 +1414,6 @@ static int f2fs_insert_range(struct inode *inode, > > loff_t offset, loff_t len) > > > > f2fs_balance_fs(sbi, true); > > > > - /* avoid gc operation during block exchange */ > > - down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > - > > down_write(&F2FS_I(inode)->i_mmap_sem); > > ret = f2fs_truncate_blocks(inode, i_size_read(inode), true); > > if (ret) > > @@ -1430,13 +1424,15 @@ static int f2fs_insert_range(struct inode *inode, > > loff_t offset, loff_t len) > > if (ret) > > goto out; > > > > - truncate_pagecache(inode, offset); > > - > > pg_start = offset >> PAGE_SHIFT; > > pg_end = (offset + len) >> PAGE_SHIFT; > > delta = pg_end - pg_start; > > idx = (i_size_read(inode) + PAGE_SIZE - 1) / PAGE_SIZE; > > > > + /* avoid gc operation during block exchange */ > > + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > + truncate_pagecache(inode, offset); > > + > > while (!ret && idx > pg_start) { > > nr = idx - pg_start; > > if (nr > delta) > > @@ -1450,6 +1446,7 @@ static int f2fs_insert_range(struct inode *inode, > > loff_t offset, loff_t len) > > idx + delta, nr, false); > > f2fs_unlock_op(sbi); > > } > > + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > > > /* write out all moved pages, if possible */ > > filemap_write_and_wait_range(inode->i_mapping, offset, LLONG_MAX); > > @@ -1459,7 +1456,6 @@ static int f2fs_insert_range(struct inode *inode, > > loff_t offset, loff_t len) > > f2fs_i_size_write(inode, new_size); > > out: > > up_write(&F2FS_I(inode)->i_mmap_sem); > > - up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > return ret; > > } > > > > @@ -1706,8 +1702,6 @@ static int f2fs_ioc_start_atomic_write(struct file > > *filp) > > > > inode_lock(inode); > > > > - down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > After removing lock here, how can we handle below condition: > > commit 27319ba4044c0c67d62ae39e53c0118c89f0a029 > Author: Chao Yu <yuch...@huawei.com> > Date: Tue Apr 17 17:51:28 2018 +0800 > > f2fs: fix race in between GC and atomic open > > Thread GC thread > - f2fs_ioc_start_atomic_write > - get_dirty_pages > - filemap_write_and_wait_range > - f2fs_gc > - do_garbage_collect > - gc_data_segment > - move_data_page > - f2fs_is_atomic_file > - set_page_dirty > - set_inode_flag(, FI_ATOMIC_FILE) > > Dirty data page can still be generated by GC in race condition as > above call stack. > > This patch adds fi->dio_rwsem[WRITE] in f2fs_ioc_start_atomic_write > to avoid such race.
"f2fs: don't allow any writes on aborted atomic writes" disallows any writes on atomic file which has the revoking flag. So, this won't happen. In GC, f2fs_is_atomic_file won't make the page dirty. WDYT? Thanks, > > Thanks, > > > - > > if (f2fs_is_atomic_file(inode)) { > > if (is_inode_flag_set(inode, FI_ATOMIC_REVOKE_REQUEST)) > > ret = -EINVAL; > > @@ -1736,7 +1730,6 @@ static int f2fs_ioc_start_atomic_write(struct file > > *filp) > > stat_inc_atomic_write(inode); > > stat_update_max_atomic_write(inode); > > out: > > - up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > inode_unlock(inode); > > mnt_drop_write_file(filp); > > return ret; > > @@ -1754,9 +1747,9 @@ static int f2fs_ioc_commit_atomic_write(struct file > > *filp) > > if (ret) > > return ret; > > > > - inode_lock(inode); > > + f2fs_balance_fs(F2FS_I_SB(inode), true); > > > > - down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > + inode_lock(inode); > > > > if (f2fs_is_volatile_file(inode)) { > > ret = -EINVAL; > > @@ -1782,7 +1775,6 @@ static int f2fs_ioc_commit_atomic_write(struct file > > *filp) > > clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); > > ret = -EINVAL; > > } > > - up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > inode_unlock(inode); > > mnt_drop_write_file(filp); > > return ret; > > @@ -2378,15 +2370,10 @@ static int f2fs_move_file_range(struct file > > *file_in, loff_t pos_in, > > } > > > > inode_lock(src); > > - down_write(&F2FS_I(src)->i_gc_rwsem[WRITE]); > > if (src != dst) { > > ret = -EBUSY; > > if (!inode_trylock(dst)) > > goto out; > > - if (!down_write_trylock(&F2FS_I(dst)->i_gc_rwsem[WRITE])) { > > - inode_unlock(dst); > > - goto out; > > - } > > } > > > > ret = -EINVAL; > > @@ -2432,6 +2419,14 @@ static int f2fs_move_file_range(struct file > > *file_in, loff_t pos_in, > > > > f2fs_balance_fs(sbi, true); > > f2fs_lock_op(sbi); > > + > > + down_write(&F2FS_I(src)->i_gc_rwsem[WRITE]); > > + if (src != dst) { > > + ret = -EBUSY; > > + if (!down_write_trylock(&F2FS_I(dst)->i_gc_rwsem[WRITE])) > > + goto out_src; > > + } > > + > > ret = __exchange_data_block(src, dst, pos_in >> F2FS_BLKSIZE_BITS, > > pos_out >> F2FS_BLKSIZE_BITS, > > len >> F2FS_BLKSIZE_BITS, false); > > @@ -2442,14 +2437,15 @@ static int f2fs_move_file_range(struct file > > *file_in, loff_t pos_in, > > else if (dst_osize != dst->i_size) > > f2fs_i_size_write(dst, dst_osize); > > } > > + if (src != dst) > > + up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]); > > +out_src: > > + up_write(&F2FS_I(src)->i_gc_rwsem[WRITE]); > > f2fs_unlock_op(sbi); > > out_unlock: > > - if (src != dst) { > > - up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]); > > + if (src != dst) > > inode_unlock(dst); > > - } > > out: > > - up_write(&F2FS_I(src)->i_gc_rwsem[WRITE]); > > inode_unlock(src); > > return ret; > > } > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > index e352fbd33848..cac317e37306 100644 > > --- a/fs/f2fs/gc.c > > +++ b/fs/f2fs/gc.c > > @@ -884,6 +884,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, > > struct f2fs_summary *sum, > > if (!down_write_trylock( > > &F2FS_I(inode)->i_gc_rwsem[WRITE])) { > > iput(inode); > > + sbi->skipped_gc_rwsem++; > > continue; > > } > > > > @@ -913,6 +914,7 @@ static void gc_data_segment(struct f2fs_sb_info *sbi, > > struct f2fs_summary *sum, > > continue; > > if (!down_write_trylock( > > &fi->i_gc_rwsem[WRITE])) { > > + sbi->skipped_gc_rwsem++; > > up_write(&fi->i_gc_rwsem[READ]); > > continue; > > } > > @@ -1062,6 +1064,7 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, > > prefree_segments(sbi)); > > > > cpc.reason = __get_cp_reason(sbi); > > + sbi->skipped_gc_rwsem = 0; > > gc_more: > > if (unlikely(!(sbi->sb->s_flags & SB_ACTIVE))) { > > ret = -EINVAL; > > @@ -1103,7 +1106,8 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, > > total_freed += seg_freed; > > > > if (gc_type == FG_GC) { > > - if (sbi->skipped_atomic_files[FG_GC] > last_skipped) > > + if (sbi->skipped_atomic_files[FG_GC] > last_skipped || > > + sbi->skipped_gc_rwsem) > > skipped_round++; > > last_skipped = sbi->skipped_atomic_files[FG_GC]; > > round++; > > @@ -1112,15 +1116,21 @@ int f2fs_gc(struct f2fs_sb_info *sbi, bool sync, > > if (gc_type == FG_GC) > > sbi->cur_victim_sec = NULL_SEGNO; > > > > - if (!sync) { > > - if (has_not_enough_free_secs(sbi, sec_freed, 0)) { > > - if (skipped_round > MAX_SKIP_ATOMIC_COUNT && > > - skipped_round * 2 >= round) > > - f2fs_drop_inmem_pages_all(sbi, true); > > + if (sync) > > + goto stop; > > + > > + if (has_not_enough_free_secs(sbi, sec_freed, 0)) { > > + if (skipped_round <= MAX_SKIP_GC_COUNT || > > + skipped_round * 2 < round) { > > segno = NULL_SEGNO; > > goto gc_more; > > } > > > > + if (sbi->skipped_atomic_files[FG_GC] == last_skipped) { > > + f2fs_drop_inmem_pages_all(sbi, true); > > + segno = NULL_SEGNO; > > + goto gc_more; > > + } > > if (gc_type == FG_GC) > > ret = f2fs_write_checkpoint(sbi, &cpc); > > } > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > index 3662e1f429b4..15b3b095fd58 100644 > > --- a/fs/f2fs/segment.c > > +++ b/fs/f2fs/segment.c > > @@ -444,10 +444,12 @@ int f2fs_commit_inmem_pages(struct inode *inode) > > struct f2fs_inode_info *fi = F2FS_I(inode); > > int err; > > > > - f2fs_balance_fs(sbi, true); > > + f2fs_balance_fs(F2FS_I_SB(inode), true); > > + > > f2fs_lock_op(sbi); > > > > set_inode_flag(inode, FI_ATOMIC_COMMIT); > > + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > > > mutex_lock(&fi->inmem_lock); > > err = __f2fs_commit_inmem_pages(inode); > > @@ -458,6 +460,7 @@ int f2fs_commit_inmem_pages(struct inode *inode) > > spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); > > mutex_unlock(&fi->inmem_lock); > > > > + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); > > clear_inode_flag(inode, FI_ATOMIC_COMMIT); > > > > f2fs_unlock_op(sbi); > > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h > > index 50495515f0a0..b3d9e317ff0c 100644 > > --- a/fs/f2fs/segment.h > > +++ b/fs/f2fs/segment.h > > @@ -215,7 +215,7 @@ struct segment_allocation { > > #define IS_DUMMY_WRITTEN_PAGE(page) \ > > (page_private(page) == (unsigned long)DUMMY_WRITTEN_PAGE) > > > > -#define MAX_SKIP_ATOMIC_COUNT 16 > > +#define MAX_SKIP_GC_COUNT 16 > > > > struct inmem_pages { > > struct list_head list; > > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel