Messages in this thread Patch in this message | | | From | Chao Yu <> | Subject | [patch v2 2/2] f2fs: fix to avoid data update racing between GC and DIO | Date | Sun, 3 Jul 2016 22:00:32 +0800 |
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From: Chao Yu <yuchao0@huawei.com>
Datas in file can be operated by GC and DIO simultaneously, so we will face race case as below:
For write case: Thread A Thread B - generic_file_direct_write - invalidate_inode_pages2_range - f2fs_direct_IO - do_blockdev_direct_IO - do_direct_IO - get_more_blocks - f2fs_gc - do_garbage_collect - gc_data_segment - move_data_page - do_write_data_page migrate data block to new block address - dio_bio_submit update user data to old block address
For read case: Thread A Thread B - generic_file_direct_write - invalidate_inode_pages2_range - f2fs_direct_IO - do_blockdev_direct_IO - do_direct_IO - get_more_blocks - f2fs_balance_fs - f2fs_gc - do_garbage_collect - gc_data_segment - move_data_page - do_write_data_page migrate data block to new block address - write_checkpoint - do_checkpoint - clear_prefree_segments - f2fs_issue_discard discard old block adress - dio_bio_submit update user buffer from obsolete block address
In order to fix this, for one file, we should let DIO and GC getting exclusion against with each other.
Signed-off-by: Chao Yu <yuchao0@huawei.com> --- fs/f2fs/data.c | 11 +++++++++++ fs/f2fs/f2fs.h | 2 ++ fs/f2fs/gc.c | 19 +++++++++++++++++++ fs/f2fs/super.c | 2 ++ 4 files changed, 34 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index ba4963f..3a03285 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -1701,8 +1701,10 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) { struct address_space *mapping = iocb->ki_filp->f_mapping; struct inode *inode = mapping->host; + struct f2fs_inode_info *fi = F2FS_I(inode); size_t count = iov_iter_count(iter); loff_t offset = iocb->ki_pos; + bool is_write = (iov_iter_rw(iter) == WRITE); int err; err = check_direct_IO(inode, iter, offset); @@ -1716,7 +1718,16 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter) trace_f2fs_direct_IO_enter(inode, offset, count, iov_iter_rw(iter)); + if (is_write) + mutex_lock(&fi->dio_mutex); + else + down_read(&fi->dio_rwsem); err = blockdev_direct_IO(iocb, inode, iter, get_data_block_dio); + if (is_write) + mutex_unlock(&fi->dio_mutex); + else + up_read(&fi->dio_rwsem); + if (iov_iter_rw(iter) == WRITE) { if (err > 0) set_inode_flag(inode, FI_UPDATE_WRITE); diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index bd82b6d..ac3410a 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -474,6 +474,8 @@ struct f2fs_inode_info { struct list_head inmem_pages; /* inmemory pages managed by f2fs */ struct mutex inmem_lock; /* lock for inmemory pages */ struct extent_tree *extent_tree; /* cached extent_tree entry */ + struct mutex dio_mutex; /* avoid racing between write dio and gc */ + struct rw_semaphore dio_rwsem; /* avoid racing between read dio and gc */ }; static inline void get_extent_info(struct extent_info *ext, diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index c2c4ac3..a15ae8a 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -744,12 +744,31 @@ next_step: /* phase 3 */ inode = find_gc_inode(gc_list, dni.ino); if (inode) { + struct f2fs_inode_info *fi = F2FS_I(inode); + bool locked = false; + + if (S_ISREG(inode->i_mode)) { + if (!mutex_trylock(&fi->dio_mutex)) + continue; + if (!down_write_trylock(&fi->dio_rwsem)) { + mutex_unlock(&fi->dio_mutex); + continue; + } + locked = true; + } + start_bidx = start_bidx_of_node(nofs, inode) + ofs_in_node; if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) move_encrypted_block(inode, start_bidx); else move_data_page(inode, start_bidx, gc_type); + + if (locked) { + mutex_unlock(&fi->dio_mutex); + up_write(&fi->dio_rwsem); + } + stat_inc_data_blk_count(sbi, 1, gc_type); } } diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 8c698e1..512bbb4 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -575,6 +575,8 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb) INIT_LIST_HEAD(&fi->gdirty_list); INIT_LIST_HEAD(&fi->inmem_pages); mutex_init(&fi->inmem_lock); + mutex_init(&fi->dio_mutex); + init_rwsem(&fi->dio_rwsem); /* Will be used by directory only */ fi->i_dir_level = F2FS_SB(sb)->dir_level; -- 2.7.2
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