On Tue, Jan 31, 2023 at 1:57 PM Daeho Jeong <daeh...@gmail.com> wrote: > > On Tue, Jan 31, 2023 at 1:38 PM Daeho Jeong <daeh...@gmail.com> wrote: > > > > On Tue, Jan 31, 2023 at 11:13 AM Daeho Jeong <daeh...@gmail.com> wrote: > > > > > > Hi Chao, > > > > > > On Tue, Jan 31, 2023 at 3:37 AM Chao Yu <c...@kernel.org> wrote: > > > > > > > > Hi Daeho, > > > > > > > > On 2023/1/31 0:34, Daeho Jeong wrote: > > > > > Hi Chao, > > > > > > > > > > I read your patch series now and I like it. > > > > > > > > Thank you for checking the patches. :) > > > > > > > > > However, how about a race condition between start_atomic_write and > > > > > abort_atomic_write? > > > > > > > > Yup, I noticed that issue, I guess we can avoid this race condition by > > > > covering these two flows w/ i_atomic_sem. > > > > > > > > > abort_atomic_write is called without inode_lock in closing filp > > > > > scenarios. > > > > > What do you think about this? > > > > > > > > I'm fine w/ your change as it's more clean, but it's better to drop > > > > cow_inode's > > > > page cache if atomic_write is committed or aborted to avoid caching > > > > obsolete page? > > > > > > It's better to put that part in f2fs_abort_atomic_write(). > > > On top of that, maybe, we should move > > > f2fs_do_truncate_blocks(fi->cow_inode, 0, true) part from > > > f2fs_ioc_start_atomic_write() to f2fs_abort_atomic_write(), too. > > > > Oh, we shouldn't touch the f2fs_do_truncate_blocks() part, since there > > might be some left writeback after aborting atomic write. > > Plz. review it related to the timing of calling > > truncate_inode_pages_final(). > > Looks like the scenario becomes too complicated if I think about more > than one writer's scenario. > How about we check writecount in commit_atomic_write ioctl and return > EBUSY when it's not only one writer? > In that case, we can make the scenario simple and effective, and we > can release all the resources in abort_atomic_write().
Oh, I totally forgot this. We don't use pages of COW inode. So, we don't need to clean them up. > > > > > > > > > Thanks, > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > On Fri, Jan 27, 2023 at 6:07 PM Chao Yu <c...@kernel.org> wrote: > > > > >> > > > > >> Hi Daeho, Jaegeuk, > > > > >> > > > > >> Please take a look at patchset in below link: > > > > >> > > > > >> https://lore.kernel.org/linux-f2fs-devel/20230109034453.490176-1-c...@kernel.org/T/#t > > > > >> > > > > >> In PATCH 4/5, I'm trying to fix the same issue w/ alternative way, > > > > >> let me > > > > >> know your preference. :) > > > > >> > > > > >> One comment as below. > > > > >> > > > > >> On 2023/1/13 8:49, Daeho Jeong wrote: > > > > >>> From: Daeho Jeong <daehoje...@google.com> > > > > >>> > > > > >>> To fix a race condition between atomic write aborts, I use the inode > > > > >>> lock and make COW inode to be re-usable thoroughout the whole > > > > >>> atomic file inode lifetime. > > > > >>> > > > > >>> Reported-by: syzbot+823000d23b3400619...@syzkaller.appspotmail.com > > > > >>> Fixes: 3db1de0e582c ("f2fs: change the current atomic write way") > > > > >>> Signed-off-by: Daeho Jeong <daehoje...@google.com> > > > > >>> --- > > > > >>> fs/f2fs/file.c | 43 > > > > >>> ++++++++++++++++++++++++++++--------------- > > > > >>> fs/f2fs/inode.c | 11 +++++++++-- > > > > >>> fs/f2fs/segment.c | 3 --- > > > > >>> fs/f2fs/super.c | 2 -- > > > > >>> 4 files changed, 37 insertions(+), 22 deletions(-) > > > > >>> > > > > >>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > > >>> index ecbc8c135b49..ff072a9ed258 100644 > > > > >>> --- a/fs/f2fs/file.c > > > > >>> +++ b/fs/f2fs/file.c > > > > >>> @@ -1866,7 +1866,10 @@ static int f2fs_release_file(struct inode > > > > >>> *inode, struct file *filp) > > > > >>> atomic_read(&inode->i_writecount) != 1) > > > > >>> return 0; > > > > >>> > > > > >>> + inode_lock(inode); > > > > >>> f2fs_abort_atomic_write(inode, true); > > > > >>> + inode_unlock(inode); > > > > >>> + > > > > >>> return 0; > > > > >>> } > > > > >>> > > > > >>> @@ -1880,8 +1883,11 @@ static int f2fs_file_flush(struct file > > > > >>> *file, fl_owner_t id) > > > > >>> * until all the writers close its file. Since this should > > > > >>> be done > > > > >>> * before dropping file lock, it needs to do in ->flush. > > > > >>> */ > > > > >>> - if (F2FS_I(inode)->atomic_write_task == current) > > > > >>> + if (F2FS_I(inode)->atomic_write_task == current) { > > > > >>> + inode_lock(inode); > > > > >>> f2fs_abort_atomic_write(inode, true); > > > > >>> + inode_unlock(inode); > > > > >>> + } > > > > >>> return 0; > > > > >>> } > > > > >>> > > > > >>> @@ -2087,19 +2093,28 @@ static int > > > > >>> f2fs_ioc_start_atomic_write(struct file *filp, bool truncate) > > > > >>> goto out; > > > > >>> } > > > > >>> > > > > >>> - /* Create a COW inode for atomic write */ > > > > >>> - pinode = f2fs_iget(inode->i_sb, fi->i_pino); > > > > >>> - if (IS_ERR(pinode)) { > > > > >>> - f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > > > >>> - ret = PTR_ERR(pinode); > > > > >>> - goto out; > > > > >>> - } > > > > >>> + /* Check if the inode already has a COW inode */ > > > > >>> + if (fi->cow_inode == NULL) { > > > > >>> + /* Create a COW inode for atomic write */ > > > > >>> + pinode = f2fs_iget(inode->i_sb, fi->i_pino); > > > > >>> + if (IS_ERR(pinode)) { > > > > >>> + f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > > > >>> + ret = PTR_ERR(pinode); > > > > >>> + goto out; > > > > >>> + } > > > > >>> > > > > >>> - ret = f2fs_get_tmpfile(mnt_userns, pinode, &fi->cow_inode); > > > > >>> - iput(pinode); > > > > >>> - if (ret) { > > > > >>> - f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > > > >>> - goto out; > > > > >>> + ret = f2fs_get_tmpfile(mnt_userns, pinode, > > > > >>> &fi->cow_inode); > > > > >>> + iput(pinode); > > > > >>> + if (ret) { > > > > >>> + f2fs_up_write(&fi->i_gc_rwsem[WRITE]); > > > > >>> + goto out; > > > > >>> + } > > > > >>> + > > > > >>> + set_inode_flag(fi->cow_inode, FI_COW_FILE); > > > > >>> + clear_inode_flag(fi->cow_inode, FI_INLINE_DATA); > > > > >>> + } else { > > > > >>> + /* Reuse the already created COW inode */ > > > > >>> + f2fs_do_truncate_blocks(fi->cow_inode, 0, true); > > > > >>> } > > > > >>> > > > > >>> f2fs_write_inode(inode, NULL); > > > > >>> @@ -2107,8 +2122,6 @@ static int f2fs_ioc_start_atomic_write(struct > > > > >>> file *filp, bool truncate) > > > > >>> stat_inc_atomic_inode(inode); > > > > >>> > > > > >>> set_inode_flag(inode, FI_ATOMIC_FILE); > > > > >>> - set_inode_flag(fi->cow_inode, FI_COW_FILE); > > > > >>> - clear_inode_flag(fi->cow_inode, FI_INLINE_DATA); > > > > >>> > > > > >>> isize = i_size_read(inode); > > > > >>> fi->original_i_size = isize; > > > > >>> diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c > > > > >>> index ff6cf66ed46b..4921f7209e28 100644 > > > > >>> --- a/fs/f2fs/inode.c > > > > >>> +++ b/fs/f2fs/inode.c > > > > >>> @@ -766,11 +766,18 @@ int f2fs_write_inode(struct inode *inode, > > > > >>> struct writeback_control *wbc) > > > > >>> void f2fs_evict_inode(struct inode *inode) > > > > >>> { > > > > >>> struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > > > > >>> - nid_t xnid = F2FS_I(inode)->i_xattr_nid; > > > > >>> + struct f2fs_inode_info *fi = F2FS_I(inode); > > > > >>> + nid_t xnid = fi->i_xattr_nid; > > > > >>> int err = 0; > > > > >>> > > > > >>> f2fs_abort_atomic_write(inode, true); > > > > >>> > > > > >>> + if (fi->cow_inode) { > > > > >>> + clear_inode_flag(fi->cow_inode, FI_COW_FILE); > > > > >>> + iput(fi->cow_inode); > > > > >>> + fi->cow_inode = NULL; > > > > >>> + } > > > > >>> + > > > > >>> trace_f2fs_evict_inode(inode); > > > > >>> truncate_inode_pages_final(&inode->i_data); > > > > >>> > > > > >>> @@ -857,7 +864,7 @@ void f2fs_evict_inode(struct inode *inode) > > > > >>> stat_dec_inline_inode(inode); > > > > >>> stat_dec_compr_inode(inode); > > > > >>> stat_sub_compr_blocks(inode, > > > > >>> - atomic_read(&F2FS_I(inode)->i_compr_blocks)); > > > > >>> + atomic_read(&fi->i_compr_blocks)); > > > > >>> > > > > >>> if (likely(!f2fs_cp_error(sbi) && > > > > >>> !is_sbi_flag_set(sbi, > > > > >>> SBI_CP_DISABLED))) > > > > >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > > > > >>> index ae3c4e5474ef..536d7c674b04 100644 > > > > >>> --- a/fs/f2fs/segment.c > > > > >>> +++ b/fs/f2fs/segment.c > > > > >>> @@ -192,9 +192,6 @@ void f2fs_abort_atomic_write(struct inode > > > > >>> *inode, bool clean) > > > > >>> if (!f2fs_is_atomic_file(inode)) > > > > >>> return; > > > > >>> > > > > >>> - clear_inode_flag(fi->cow_inode, FI_COW_FILE); > > > > >>> - iput(fi->cow_inode); > > > > >>> - fi->cow_inode = NULL; > > > > >>> release_atomic_write_cnt(inode); > > > > >>> clear_inode_flag(inode, FI_ATOMIC_COMMITTED); > > > > >>> clear_inode_flag(inode, FI_ATOMIC_REPLACE); > > > > >>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > > > > >>> index 1f812b9ce985..10463f084d30 100644 > > > > >>> --- a/fs/f2fs/super.c > > > > >>> +++ b/fs/f2fs/super.c > > > > >>> @@ -1430,8 +1430,6 @@ static int f2fs_drop_inode(struct inode > > > > >>> *inode) > > > > >>> atomic_inc(&inode->i_count); > > > > >>> spin_unlock(&inode->i_lock); > > > > >>> > > > > >>> - f2fs_abort_atomic_write(inode, true); > > > > >> > > > > >> In order to avoid caching obsolete page of cow_inode, how about > > > > >> truncating > > > > >> them here? > > > > >> > > > > >> if (f2fs_is_atomic_file() && cow_inode) > > > > >> truncate_inode_pages_final(&cow_inode->i_data); > > > > >> > > > > >> Thanks, > > > > >> > > > > >>> - > > > > >>> /* should remain fi->extent_tree for > > > > >>> writepage */ > > > > >>> f2fs_destroy_extent_node(inode); > > > > >>> _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
