From a569469e967022d9ceeaa4b73619f96614087d2d Mon Sep 17 00:00:00 2001 From: Jin Xu Date: Mon, 5 Aug 2013 20:02:04 +0800 Subject: [PATCH] f2fs: fix a deadlock in fsync This patch fixes a deadlock bug that occurs quite often when there are concurrent write and fsync on a same file. Following is the simplified call trace when tasks get hung. fsync thread: - f2fs_sync_file ... - f2fs_write_data_pages ... - update_extent_cache ... - update_inode - wait_on_page_writeback bdi writeback thread - __writeback_single_inode - f2fs_write_data_pages - mutex_lock(sbi->writepages) The deadlock happens when the fsync thread waits on a inode page that has been added to the f2fs' cached bio sbi->bio[NODE], and unfortunately, no one else could be able to submit the cached bio to block layer for writeback. This is because the fsync thread already hold a sbi->fs_lock and the sbi->writepages lock, causing the bdi thread being blocked when attempt to write data pages for the same inode. At the same time, f2fs_gc thread does not notice the situation and could not help. Even the sync syscall gets blocked. To fix it, we could submit the cached bio first before waiting on a inode page that is being written back. Signed-off-by: Jin Xu [Jaegeuk Kim: add more cases to use f2fs_wait_on_page_writeback] Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 2 +- fs/f2fs/f2fs.h | 3 ++- fs/f2fs/gc.c | 8 ++------ fs/f2fs/inode.c | 2 +- fs/f2fs/segment.c | 10 ++++++++++ 5 files changed, 16 insertions(+), 9 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index f458883..a7eb529 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -37,7 +37,7 @@ static void __set_data_blkaddr(struct dnode_of_data *dn, block_t new_addr) struct page *node_page = dn->node_page; unsigned int ofs_in_node = dn->ofs_in_node; - wait_on_page_writeback(node_page); + f2fs_wait_on_page_writeback(node_page, NODE, false); rn = F2FS_NODE(node_page); diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 63813be..13db10b 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1023,7 +1023,8 @@ int npages_for_summary_flush(struct f2fs_sb_info *); void allocate_new_segments(struct f2fs_sb_info *); struct page *get_sum_page(struct f2fs_sb_info *, unsigned int); struct bio *f2fs_bio_alloc(struct block_device *, int); -void f2fs_submit_bio(struct f2fs_sb_info *, enum page_type, bool sync); +void f2fs_submit_bio(struct f2fs_sb_info *, enum page_type, bool); +void f2fs_wait_on_page_writeback(struct page *, enum page_type, bool); void write_meta_page(struct f2fs_sb_info *, struct page *); void write_node_page(struct f2fs_sb_info *, struct page *, unsigned int, block_t, block_t *); diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index d286d8b..e6b3ffd 100644 --- a/fs/f2fs/gc.c +++ b/fs/f2fs/gc.c @@ -422,8 +422,7 @@ next_step: /* set page dirty and write it */ if (gc_type == FG_GC) { - f2fs_submit_bio(sbi, NODE, true); - wait_on_page_writeback(node_page); + f2fs_wait_on_page_writeback(node_page, NODE, true); set_page_dirty(node_page); } else { if (!PageWriteback(node_page)) @@ -523,10 +522,7 @@ static void move_data_page(struct inode *inode, struct page *page, int gc_type) } else { struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb); - if (PageWriteback(page)) { - f2fs_submit_bio(sbi, DATA, true); - wait_on_page_writeback(page); - } + f2fs_wait_on_page_writeback(page, DATA, true); if (clear_page_dirty_for_io(page) && S_ISDIR(inode->i_mode)) { diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index debf743..9ab81e7 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -151,7 +151,7 @@ void update_inode(struct inode *inode, struct page *node_page) struct f2fs_node *rn; struct f2fs_inode *ri; - wait_on_page_writeback(node_page); + f2fs_wait_on_page_writeback(node_page, NODE, false); rn = F2FS_NODE(node_page); ri = &(rn->i); diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 9b74ae2..68e344f 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -705,6 +705,16 @@ retry: trace_f2fs_submit_write_page(page, blk_addr, type); } +void f2fs_wait_on_page_writeback(struct page *page, + enum page_type type, bool sync) +{ + struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb); + if (PageWriteback(page)) { + f2fs_submit_bio(sbi, type, sync); + wait_on_page_writeback(page); + } +} + static bool __has_curseg_space(struct f2fs_sb_info *sbi, int type) { struct curseg_info *curseg = CURSEG_I(sbi, type); -- 2.7.4