Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2] f2fs: fix out-of-free problem caused by atomic write | From | Yunlong Song <> | Date | Fri, 3 Nov 2017 22:40:42 +0800 |
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Test: Newest kernel source code from f2fs-dev 1G zram with f2fs 8 threads to atomic write one same file on zram there are four kinds of atomic write at the same time: 1 no atomic start, with atomic commit 2 no atomic start, no atomic commit 3 atomic start, with atomic commit 4 atomic start, no atomic commit
And I add dump_stack after the check as following, + if ((sbi->user_block_count - valid_user_blocks(sbi)) < + fi->inmem_blocks) { + dump_stack(); + err = -ENOSPC; + goto drop; + }
then we have:
[ 136.237247] F2FS-fs (zram1): Unexpected flush for atomic writes: ino=4, npages=8193 [ 136.952469] CPU: 1 PID: 1274 Comm: atomic_t2 Not tainted 4.14.0-rc4+ #109 [ 136.952947] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014 [ 136.953162] Call Trace: [ 136.953162] dump_stack+0x4d/0x6e [ 136.953162] commit_inmem_pages+0x258/0x270 [ 136.953162] ? __sb_start_write+0x48/0x80 [ 136.953162] ? __mnt_want_write_file+0x18/0x30 [ 136.953162] f2fs_ioctl+0x1025/0x1e30 [ 136.953162] ? up_write+0x25/0x30 [ 136.953162] ? f2fs_file_write_iter+0xf3/0x1e0 [ 136.953162] ? selinux_file_ioctl+0x114/0x1e0 [ 136.953162] do_vfs_ioctl+0x96/0x5a0 [ 136.953162] SyS_ioctl+0x79/0x90 [ 136.953162] ? SyS_lseek+0x87/0xb0 [ 136.953162] entry_SYSCALL_64_fastpath+0x13/0x94 [ 136.953162] RIP: 0033:0x434b97 [ 136.953162] RSP: 002b:00007ffc68859de8 EFLAGS: 00000202 ORIG_RAX: 0000000000000010 [ 136.953162] RAX: ffffffffffffffda RBX: 00000000006b78e0 RCX: 0000000000434b97 [ 136.953162] RDX: 00000000006b70e8 RSI: 000000000000f502 RDI: 0000000000000003 [ 136.953162] RBP: 0000000002000010 R08: 00000000006b70e8 R09: 00000000006b7160 [ 136.953162] R10: 0000000000000022 R11: 0000000000000202 R12: 00007f491a1c4010 [ 136.953162] R13: 0000000002001000 R14: 0000000002000000 R15: 00000000006b7938
So I think we should add the check code.
On 2017/11/3 12:48, Yunlong Song wrote: > Because I found that it will still lead to out-of-free problem with > out that check. > I trace and find that it is possible that the committing date pages of > the atomic > file is bigger than the sbi->user_block_count - > valid_user_blocks(sbi), so I add > this check. > > On 2017/11/3 11:46, Jaegeuk Kim wrote: >> On 10/30, Yunlong Song wrote: >>> f2fs_balance_fs only actives once in the commit_inmem_pages, but there >>> are more than one page to commit, so all the other pages will miss the >>> check. This will lead to out-of-free problem when commit a very large >>> file. However, we cannot do f2fs_balance_fs for each inmem page, since >>> this will break atomicity. As a result, we should collect prefree >>> segments if needed and stop atomic commit when there are not enough >>> available blocks to write atomic pages. >>> >>> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> >>> --- >>> fs/f2fs/f2fs.h | 1 + >>> fs/f2fs/segment.c | 29 ++++++++++++++++++++++++++++- >>> 2 files changed, 29 insertions(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h >>> index 13a96b8..04ce48f 100644 >>> --- a/fs/f2fs/f2fs.h >>> +++ b/fs/f2fs/f2fs.h >>> @@ -610,6 +610,7 @@ struct f2fs_inode_info { >>> struct list_head inmem_pages; /* inmemory pages managed by >>> f2fs */ >>> struct task_struct *inmem_task; /* store inmemory task */ >>> struct mutex inmem_lock; /* lock for inmemory pages */ >>> + unsigned long inmem_blocks; /* inmemory blocks */ >>> struct extent_tree *extent_tree; /* cached extent_tree >>> entry */ >>> struct rw_semaphore dio_rwsem[2];/* avoid racing between dio >>> and gc */ >>> struct rw_semaphore i_mmap_sem; >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c >>> index 46dfbca..813c110 100644 >>> --- a/fs/f2fs/segment.c >>> +++ b/fs/f2fs/segment.c >>> @@ -210,6 +210,7 @@ void register_inmem_page(struct inode *inode, >>> struct page *page) >>> list_add_tail(&fi->inmem_ilist, >>> &sbi->inode_list[ATOMIC_FILE]); >>> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); >>> inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES); >>> + fi->inmem_blocks++; >>> mutex_unlock(&fi->inmem_lock); >>> trace_f2fs_register_inmem_page(page, INMEM); >>> @@ -221,6 +222,7 @@ static int __revoke_inmem_pages(struct inode >>> *inode, >>> struct f2fs_sb_info *sbi = F2FS_I_SB(inode); >>> struct inmem_pages *cur, *tmp; >>> int err = 0; >>> + struct f2fs_inode_info *fi = F2FS_I(inode); >>> list_for_each_entry_safe(cur, tmp, head, list) { >>> struct page *page = cur->page; >>> @@ -263,6 +265,7 @@ static int __revoke_inmem_pages(struct inode >>> *inode, >>> list_del(&cur->list); >>> kmem_cache_free(inmem_entry_slab, cur); >>> dec_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES); >>> + fi->inmem_blocks--; >>> } >>> return err; >>> } >>> @@ -302,6 +305,10 @@ void drop_inmem_pages(struct inode *inode) >>> if (!list_empty(&fi->inmem_ilist)) >>> list_del_init(&fi->inmem_ilist); >>> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); >>> + if (fi->inmem_blocks) { >>> + f2fs_bug_on(sbi, 1); >>> + fi->inmem_blocks = 0; >>> + } >>> mutex_unlock(&fi->inmem_lock); >>> clear_inode_flag(inode, FI_ATOMIC_FILE); >>> @@ -326,6 +333,7 @@ void drop_inmem_page(struct inode *inode, struct >>> page *page) >>> f2fs_bug_on(sbi, !cur || cur->page != page); >>> list_del(&cur->list); >>> + fi->inmem_blocks--; >>> mutex_unlock(&fi->inmem_lock); >>> dec_page_count(sbi, F2FS_INMEM_PAGES); >>> @@ -410,11 +418,26 @@ int commit_inmem_pages(struct inode *inode) >>> INIT_LIST_HEAD(&revoke_list); >>> f2fs_balance_fs(sbi, true); >>> + if (prefree_segments(sbi) >>> + && has_not_enough_free_secs(sbi, 0, >>> + fi->inmem_blocks / BLKS_PER_SEC(sbi))) { >>> + struct cp_control cpc; >>> + >>> + cpc.reason = __get_cp_reason(sbi); >>> + err = write_checkpoint(sbi, &cpc); >>> + if (err) >>> + goto drop; >>> + } >>> f2fs_lock_op(sbi); >>> set_inode_flag(inode, FI_ATOMIC_COMMIT); >>> mutex_lock(&fi->inmem_lock); >>> + if ((sbi->user_block_count - valid_user_blocks(sbi)) < >> What does this mean? We already allocated blocks successfully? >> >>> + fi->inmem_blocks) { >>> + err = -ENOSPC; >>> + goto drop; >>> + } >>> err = __commit_inmem_pages(inode, &revoke_list); >>> if (err) { >>> int ret; >>> @@ -429,7 +452,7 @@ int commit_inmem_pages(struct inode *inode) >>> ret = __revoke_inmem_pages(inode, &revoke_list, false, true); >>> if (ret) >>> err = ret; >>> - >>> +drop: >>> /* drop all uncommitted pages */ >>> __revoke_inmem_pages(inode, &fi->inmem_pages, true, false); >>> } >>> @@ -437,6 +460,10 @@ int commit_inmem_pages(struct inode *inode) >>> if (!list_empty(&fi->inmem_ilist)) >>> list_del_init(&fi->inmem_ilist); >>> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); >>> + if (fi->inmem_blocks) { >>> + f2fs_bug_on(sbi, 1); >>> + fi->inmem_blocks = 0; >>> + } >>> mutex_unlock(&fi->inmem_lock); >>> clear_inode_flag(inode, FI_ATOMIC_COMMIT); >>> -- >>> 1.8.5.2 >> . >> >
-- Thanks, Yunlong Song
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