Messages in this thread Patch in this message | | | Date | Mon, 9 Sep 2019 15:34:19 +0100 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH 2/2] f2fs: avoid infinite GC loop due to stale atomic files |
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On 09/09, Chao Yu wrote: > On 2019/9/9 16:38, Jaegeuk Kim wrote: > > On 09/09, Chao Yu wrote: > >> On 2019/9/9 16:21, Jaegeuk Kim wrote: > >>> On 09/09, Chao Yu wrote: > >>>> On 2019/9/9 16:01, Jaegeuk Kim wrote: > >>>>> On 09/09, Chao Yu wrote: > >>>>>> On 2019/9/9 15:30, Jaegeuk Kim wrote: > >>>>>>> On 09/09, Chao Yu wrote: > >>>>>>>> On 2019/9/9 9:25, Jaegeuk Kim wrote: > >>>>>>>>> If committing atomic pages is failed when doing f2fs_do_sync_file(), we can > >>>>>>>>> get commited 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 > >>>>>>>>> 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) > >>>>>>>>> > >>>>>>>>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> > >>>>>>>>> --- > >>>>>>>>> fs/f2fs/file.c | 10 +++++----- > >>>>>>>>> 1 file changed, 5 insertions(+), 5 deletions(-) > >>>>>>>>> > >>>>>>>>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > >>>>>>>>> index 7ae2f3bd8c2f..68b6da734e5f 100644 > >>>>>>>>> --- a/fs/f2fs/file.c > >>>>>>>>> +++ b/fs/f2fs/file.c > >>>>>>>>> @@ -1997,11 +1997,11 @@ 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); > >>>>>>>>> - } > >>>>>>>>> + > >>>>>>>>> + /* doesn't need to check error */ > >>>>>>>>> + clear_inode_flag(inode, FI_ATOMIC_FILE); > >>>>>>>>> + F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0; > >>>>>>>>> + stat_dec_atomic_write(inode); > >>>>>>>> > >>>>>>>> If there are still valid atomic write pages linked in .inmem_pages, it may cause > >>>>>>>> memory leak when we just clear FI_ATOMIC_FILE flag. > >>>>>>> > >>>>>>> f2fs_commit_inmem_pages() should have flushed them. > >>>>>> > >>>>>> Oh, we failed to flush its nodes. > >>>>>> > >>>>>> However we won't clear such info if we failed to flush inmen pages, it looks > >>>>>> inconsistent. > >>>>>> > >>>>>> Any interface needed to drop inmem pages or clear ATOMIC_FILE flag in that two > >>>>>> error path? I'm not very clear how sqlite handle such error. > >>>>> > >>>>> f2fs_drop_inmem_pages() did that, but not in this case. > >>>> > >>>> What I mean is, for any error returned from atomic_commit() interface, should > >>>> userspace application handle it with consistent way, like trigger > >>>> f2fs_drop_inmem_pages(), so we don't need to handle it inside atomic_commit(). > >>> > >>> f2fs_ioc_abort_volatile_write() will be triggered. > >> > >> If userspace can do this, we can get rid of this patch, or am I missing sth? > > > > We don't know when that will come. And, other threads are waiting for GC here. > > Yes, however, even atomic_write won't be called sometimes... that's why we add > handling logic in f2fs_gc().
We need to clean this up like:
If committing atomic pages is failed when doing f2fs_do_sync_file(), we can get commited 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 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().
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org> --- fs/f2fs/file.c | 17 +++++++++++------ fs/f2fs/segment.c | 24 +++++------------------- 2 files changed, 16 insertions(+), 25 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 10927a0b8df3..1f499ac13d9a 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1830,6 +1830,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) { struct inode *inode = file_inode(filp); int ret; + struct f2fs_inode_info *fi = F2FS_I(inode); if (!inode_owner_or_capable(inode)) return -EACCES; @@ -1871,10 +1872,17 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) goto out; } - set_inode_flag(inode, FI_ATOMIC_FILE); clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST); up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]); + 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); + f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); F2FS_I(inode)->inmem_task = current; stat_inc_atomic_write(inode); @@ -1912,11 +1920,8 @@ 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 18584d4c078a..a36bc8bf04c3 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -186,7 +186,6 @@ 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 +199,9 @@ 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]); inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES); - mutex_unlock(&fi->inmem_lock); trace_f2fs_register_inmem_page(page, INMEM); } @@ -330,19 +323,17 @@ 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 +462,6 @@ 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); -- 2.19.0.605.g01d371f741-goog
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