From 4156f580b23ab7419322533bd335926faa05a349 Mon Sep 17 00:00:00 2001 From: Sayali Lokhande Date: Thu, 12 Sep 2019 10:41:20 +0530 Subject: [PATCH] f2fs: avoid infinite GC loop due to stale atomic files If committing atomic pages is failed when doing f2fs_do_sync_file(), we can get committed pages but atomic_file being still set like: - inmem: 0, atomic IO: 4 (Max. 10), volatile IO: 0 (Max. 0) If GC selects this block, we can get an infinite loop like this: f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8, oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA, sector = 18533696, size = 4096 f2fs_get_victim: dev = (253,7), type = No TYPE, policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1, ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234 f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0, i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c In that moment, we can observe: [Before] Try to move 5084219 blocks (BG: 384508) - data blocks : 4962373 (274483) - node blocks : 121846 (110025) Skipped : atomic write 4534686 (10) [After] Try to move 5088973 blocks (BG: 384508) - data blocks : 4967127 (274483) - node blocks : 121846 (110025) Skipped : atomic write 4539440 (10) So, refactor atomic_write flow like this: 1. start_atomic_write - add inmem_list and set atomic_file 2. write() - register it in inmem_pages 3. commit_atomic_write - if no error, f2fs_drop_inmem_pages() - f2fs_commit_inmme_pages() failed : __revoked_inmem_pages() was done - f2fs_do_sync_file failed : abort_atomic_write later 4. abort_atomic_write - f2fs_drop_inmem_pages 5. f2fs_drop_inmem_pages - clear atomic_file - remove inmem_list Based on this change, when GC fails to move block in atomic_file, f2fs_drop_inmem_pages_all() can call f2fs_drop_inmem_pages(). Change-Id: I876038ae8ab980a9d7ab30f3a4416a9a7b9c9998 Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Git-commit: 743b620cb0516f6b6cbc45b48df00fe6d14d00ba Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux.git/ Signed-off-by: Sayali Lokhande --- fs/f2fs/file.c | 15 ++++++++++----- fs/f2fs/segment.c | 29 ++++++++--------------------- 2 files changed, 18 insertions(+), 26 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index c51d0c531213..a714f430675c 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1820,6 +1820,8 @@ static int f2fs_ioc_getversion(struct file *filp, unsigned long arg) static int f2fs_ioc_start_atomic_write(struct file *filp) { struct inode *inode = file_inode(filp); + struct f2fs_inode_info *fi = F2FS_I(inode); + struct f2fs_sb_info *sbi = F2FS_I_SB(inode); int ret; if (!inode_owner_or_capable(inode)) @@ -1859,6 +1861,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) goto out; } + spin_lock(&sbi->inode_lock[ATOMIC_FILE]); + if (list_empty(&fi->inmem_ilist)) + list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]); + spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); + + /* add inode in inmem_list first and set atomic_file */ set_inode_flag(inode, FI_ATOMIC_FILE); clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); @@ -1900,11 +1908,8 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp) goto err_out; ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true); - if (!ret) { - clear_inode_flag(inode, FI_ATOMIC_FILE); - F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; - stat_dec_atomic_write(inode); - } + if (!ret) + f2fs_drop_inmem_pages(inode); } else { ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false); } diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 553a16e985aa..3b608c4ec0b0 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -185,8 +185,6 @@ bool f2fs_need_SSR(struct f2fs_sb_info *sbi) void f2fs_register_inmem_page(struct inode *inode, struct page *page) { - struct f2fs_sb_info *sbi = F2FS_I_SB(inode); - struct f2fs_inode_info *fi = F2FS_I(inode); struct inmem_pages *new; f2fs_trace_pid(page); @@ -200,15 +198,11 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page) INIT_LIST_HEAD(&new->list); /* increase reference count with clean state */ - mutex_lock(&fi->inmem_lock); get_page(page); - list_add_tail(&new->list, &fi->inmem_pages); - spin_lock(&sbi->inode_lock[ATOMIC_FILE]); - if (list_empty(&fi->inmem_ilist)) - list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]); - spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); + mutex_lock(&F2FS_I(inode)->inmem_lock); + list_add_tail(&new->list, &F2FS_I(inode)->inmem_pages); inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES); - mutex_unlock(&fi->inmem_lock); + mutex_unlock(&F2FS_I(inode)->inmem_lock); trace_f2fs_register_inmem_page(page, INMEM); } @@ -330,19 +324,17 @@ void f2fs_drop_inmem_pages(struct inode *inode) mutex_lock(&fi->inmem_lock); __revoke_inmem_pages(inode, &fi->inmem_pages, true, false, true); - - if (list_empty(&fi->inmem_pages)) { - spin_lock(&sbi->inode_lock[ATOMIC_FILE]); - if (!list_empty(&fi->inmem_ilist)) - list_del_init(&fi->inmem_ilist); - spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); - } mutex_unlock(&fi->inmem_lock); } clear_inode_flag(inode, FI_ATOMIC_FILE); fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; stat_dec_atomic_write(inode); + + spin_lock(&sbi->inode_lock[ATOMIC_FILE]); + if (!list_empty(&fi->inmem_ilist)) + list_del_init(&fi->inmem_ilist); + spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); } void f2fs_drop_inmem_page(struct inode *inode, struct page *page) @@ -471,11 +463,6 @@ int f2fs_commit_inmem_pages(struct inode *inode) mutex_lock(&fi->inmem_lock); err = __f2fs_commit_inmem_pages(inode); - - spin_lock(&sbi->inode_lock[ATOMIC_FILE]); - if (!list_empty(&fi->inmem_ilist)) - list_del_init(&fi->inmem_ilist); - spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); mutex_unlock(&fi->inmem_lock); clear_inode_flag(inode, FI_ATOMIC_COMMIT); -- 2.11.0