Messages in this thread Patch in this message | | | Date | Sun, 5 Aug 2018 09:34:50 -0700 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH v3] f2fs: avoid fi->i_gc_rwsem[WRITE] lock in f2fs_gc |
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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 <jaegeuk@kernel.org> --- v3 - don't revoke atomic_writes all the time due to gc_rwsem - keep lock order in f2fs_commit_inmem_pages
fs/f2fs/f2fs.h | 1 + fs/f2fs/file.c | 76 ++++++++++++++++++++++++----------------------- fs/f2fs/gc.c | 24 +++++++++++---- fs/f2fs/segment.c | 6 +++- fs/f2fs/segment.h | 2 +- 5 files changed, 64 insertions(+), 45 deletions(-)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 1647a13be7f9..0c65c3146ead 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1234,6 +1234,7 @@ 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 67c9c2d4e2d9..4e2e3938f474 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1180,25 +1180,31 @@ 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); - f2fs_lock_op(sbi); - f2fs_drop_extent_tree(inode); + /* avoid gc operation during block exchange */ + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + f2fs_lock_op(sbi); + f2fs_drop_extent_tree(inode); + truncate_pagecache(inode, offset); ret = __exchange_data_block(inode, inode, end, start, nrpages - end, true); f2fs_unlock_op(sbi); + + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); 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; @@ -1213,21 +1219,13 @@ 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; @@ -1243,7 +1241,6 @@ 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; } @@ -1418,9 +1415,6 @@ 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) @@ -1431,13 +1425,15 @@ 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) @@ -1451,6 +1447,7 @@ 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); @@ -1460,7 +1457,6 @@ 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; } @@ -1707,8 +1703,6 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) inode_lock(inode); - down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); - if (f2fs_is_atomic_file(inode)) { if (is_inode_flag_set(inode, FI_ATOMIC_REVOKE_REQUEST)) ret = -EINVAL; @@ -1719,6 +1713,8 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) if (ret) goto out; + down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + if (!get_dirty_pages(inode)) goto skip_flush; @@ -1726,18 +1722,20 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) "Unexpected flush for atomic writes: ino=%lu, npages=%u", inode->i_ino, get_dirty_pages(inode)); ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX); - if (ret) + if (ret) { + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); goto out; + } skip_flush: set_inode_flag(inode, FI_ATOMIC_FILE); clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); - f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); + up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); F2FS_I(inode)->inmem_task = current; 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; @@ -1755,9 +1753,9 @@ 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; @@ -1783,7 +1781,6 @@ 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; @@ -2379,15 +2376,10 @@ 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 +2424,14 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in, goto out_unlock; f2fs_balance_fs(sbi, true); + + 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; + } + f2fs_lock_op(sbi); ret = __exchange_data_block(src, dst, pos_in >> F2FS_BLKSIZE_BITS, pos_out >> F2FS_BLKSIZE_BITS, @@ -2444,13 +2444,15 @@ static int f2fs_move_file_range(struct file *file_in, loff_t pos_in, f2fs_i_size_write(dst, dst_osize); } f2fs_unlock_op(sbi); -out_unlock: - if (src != dst) { + + if (src != dst) up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]); +out_src: + up_write(&F2FS_I(src)->i_gc_rwsem[WRITE]); +out_unlock: + 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..d816c328f02b 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 +1116,23 @@ 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 && + sbi->skipped_atomic_files[FG_GC] > + sbi->skipped_gc_rwsem) { + 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..f4ac006dac43 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -445,8 +445,10 @@ int f2fs_commit_inmem_pages(struct inode *inode) int err; f2fs_balance_fs(sbi, true); - f2fs_lock_op(sbi); + down_write(&fi->i_gc_rwsem[WRITE]); + + f2fs_lock_op(sbi); set_inode_flag(inode, FI_ATOMIC_COMMIT); mutex_lock(&fi->inmem_lock); @@ -461,6 +463,8 @@ int f2fs_commit_inmem_pages(struct inode *inode) clear_inode_flag(inode, FI_ATOMIC_COMMIT); f2fs_unlock_op(sbi); + up_write(&fi->i_gc_rwsem[WRITE]); + return err; } 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; -- 2.17.0.441.gb46fe60e1d-goog
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