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Message-ID: <20220428165725.mvjh6mx7gr5vekqe@quack3.lan> Date: Thu, 28 Apr 2022 18:57:25 +0200 From: Jan Kara <jack@...e.cz> To: Baokun Li <libaokun1@...wei.com> Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, linux-kernel@...r.kernel.org, yi.zhang@...wei.com, yebin10@...wei.com, yukuai3@...wei.com, stable@...r.kernel.org, Hulk Robot <hulkci@...wei.com> Subject: Re: [PATCH v3] ext4: fix race condition between ext4_write and ext4_convert_inline_data On Thu 28-04-22 21:40:31, Baokun Li wrote: > Hulk Robot reported a BUG_ON: > ================================================================== > EXT4-fs error (device loop3): ext4_mb_generate_buddy:805: group 0, > block bitmap and bg descriptor inconsistent: 25 vs 31513 free clusters > kernel BUG at fs/ext4/ext4_jbd2.c:53! > invalid opcode: 0000 [#1] SMP KASAN PTI > CPU: 0 PID: 25371 Comm: syz-executor.3 Not tainted 5.10.0+ #1 > RIP: 0010:ext4_put_nojournal fs/ext4/ext4_jbd2.c:53 [inline] > RIP: 0010:__ext4_journal_stop+0x10e/0x110 fs/ext4/ext4_jbd2.c:116 > [...] > Call Trace: > ext4_write_inline_data_end+0x59a/0x730 fs/ext4/inline.c:795 > generic_perform_write+0x279/0x3c0 mm/filemap.c:3344 > ext4_buffered_write_iter+0x2e3/0x3d0 fs/ext4/file.c:270 > ext4_file_write_iter+0x30a/0x11c0 fs/ext4/file.c:520 > do_iter_readv_writev+0x339/0x3c0 fs/read_write.c:732 > do_iter_write+0x107/0x430 fs/read_write.c:861 > vfs_writev fs/read_write.c:934 [inline] > do_pwritev+0x1e5/0x380 fs/read_write.c:1031 > [...] > ================================================================== > > Above issue may happen as follows: > cpu1 cpu2 > __________________________|__________________________ > do_pwritev > vfs_writev > do_iter_write > ext4_file_write_iter > ext4_buffered_write_iter > generic_perform_write > ext4_da_write_begin > vfs_fallocate > ext4_fallocate > ext4_convert_inline_data > ext4_convert_inline_data_nolock > ext4_destroy_inline_data_nolock > clear EXT4_STATE_MAY_INLINE_DATA > ext4_map_blocks > ext4_ext_map_blocks > ext4_mb_new_blocks > ext4_mb_regular_allocator > ext4_mb_good_group_nolock > ext4_mb_init_group > ext4_mb_init_cache > ext4_mb_generate_buddy --> error > ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) > ext4_restore_inline_data > set EXT4_STATE_MAY_INLINE_DATA > ext4_block_write_begin > ext4_da_write_end > ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) > ext4_write_inline_data_end > handle=NULL > ext4_journal_stop(handle) > __ext4_journal_stop > ext4_put_nojournal(handle) > ref_cnt = (unsigned long)handle > BUG_ON(ref_cnt == 0) ---> BUG_ON > > The lock held by ext4_convert_inline_data is xattr_sem, but the lock > held by generic_perform_write is i_rwsem. Therefore, the two locks can > be concurrent. > > To solve above issue, we add inode_lock() for ext4_convert_inline_data(). > At the same time, move ext4_convert_inline_data() in front of > ext4_punch_hole(), remove similar handling from ext4_punch_hole(). > > Fixes: 0c8d414f163f ("ext4: let fallocate handle inline data correctly") > Cc: stable@...r.kernel.org > Reported-by: Hulk Robot <hulkci@...wei.com> > Signed-off-by: Baokun Li <libaokun1@...wei.com> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@...e.cz> Honza > --- > V1->V2: > Increase the range of the inode_lock. > V2->V3: > Move the lock outside the ext4_convert_inline_data(). > And reorganize ext4_fallocate(). > > fs/ext4/extents.c | 10 ++++++---- > fs/ext4/inode.c | 9 --------- > 2 files changed, 6 insertions(+), 13 deletions(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index e473fde6b64b..474479ce76e0 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -4693,15 +4693,17 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) > FALLOC_FL_INSERT_RANGE)) > return -EOPNOTSUPP; > > + inode_lock(inode); > + ret = ext4_convert_inline_data(inode); > + inode_unlock(inode); > + if (ret) > + goto exit; > + > if (mode & FALLOC_FL_PUNCH_HOLE) { > ret = ext4_punch_hole(file, offset, len); > goto exit; > } > > - ret = ext4_convert_inline_data(inode); > - if (ret) > - goto exit; > - > if (mode & FALLOC_FL_COLLAPSE_RANGE) { > ret = ext4_collapse_range(file, offset, len); > goto exit; > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 646ece9b3455..4779673d733e 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -3967,15 +3967,6 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length) > > trace_ext4_punch_hole(inode, offset, length, 0); > > - ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); > - if (ext4_has_inline_data(inode)) { > - filemap_invalidate_lock(mapping); > - ret = ext4_convert_inline_data(inode); > - filemap_invalidate_unlock(mapping); > - if (ret) > - return ret; > - } > - > /* > * Write out all dirty pages to avoid race conditions > * Then release them. > -- > 2.31.1 > -- Jan Kara <jack@...e.com> SUSE Labs, CR
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