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[73.60.226.25]) by smtp.gmail.com with ESMTPSA id q192sm2616390qka.93.2021.08.23.13.30.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Aug 2021 13:30:11 -0700 (PDT) Date: Mon, 23 Aug 2021 16:30:09 -0400 From: Eric Whitney To: Jeffle Xu Cc: tytso@mit.edu, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, joseph.qi@linux.alibaba.com, enwlinux@gmail.com, hsiangkao@linux.alibaba.com Subject: Re: [PATCH v2] ext4: fix reserved space counter leakage Message-ID: <20210823203009.GA10429@localhost.localdomain> References: <20210823061358.84473-1-jefflexu@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210823061358.84473-1-jefflexu@linux.alibaba.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org * Jeffle Xu : > When ext4_insert_delayed block receives and recovers from an error from > ext4_es_insert_delayed_block(), e.g., ENOMEM, it does not release the > space it has reserved for that block insertion as it should. One effect > of this bug is that s_dirtyclusters_counter is not decremented and > remains incorrectly elevated until the file system has been unmounted. > This can result in premature ENOSPC returns and apparent loss of free > space. > > Another effect of this bug is that > /sys/fs/ext4//delayed_allocation_blocks can remain non-zero even > after syncfs has been executed on the filesystem. > > Besides, add check for s_dirtyclusters_counter when inode is going to be > evicted and freed. s_dirtyclusters_counter can still keep non-zero until > inode is written back in .evict_inode(), and thus the check is delayed > to .destroy_inode(). > > Fixes: 51865fda28e5 ("ext4: let ext4 maintain extent status tree") > Cc: > Suggested-by: Gao Xiang > Signed-off-by: Jeffle Xu > --- > changes since v1: > - improve commit log suggested by Eric Whitney > - update "Suggested-by" title for Gao Xian, who actually found this bug > code > - add check for s_dirtyclusters_counter in .destroy_inode() > --- > fs/ext4/inode.c | 5 +++++ > fs/ext4/super.c | 6 ++++++ > 2 files changed, 11 insertions(+) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index d8de607849df..73daf9443e5e 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -1640,6 +1640,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk) > struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); > int ret; > bool allocated = false; > + bool reserved = false; > > /* > * If the cluster containing lblk is shared with a delayed, > @@ -1656,6 +1657,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk) > ret = ext4_da_reserve_space(inode); > if (ret != 0) /* ENOSPC */ > goto errout; > + reserved = true; > } else { /* bigalloc */ > if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) { > if (!ext4_es_scan_clu(inode, > @@ -1668,6 +1670,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk) > ret = ext4_da_reserve_space(inode); > if (ret != 0) /* ENOSPC */ > goto errout; > + reserved = true; > } else { > allocated = true; > } > @@ -1678,6 +1681,8 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk) > } > > ret = ext4_es_insert_delayed_block(inode, lblk, allocated); > + if (ret && reserved) > + ext4_da_release_space(inode, 1); > > errout: > return ret; > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index dfa09a277b56..61bf52b58fca 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -1351,6 +1351,12 @@ static void ext4_destroy_inode(struct inode *inode) > true); > dump_stack(); > } > + > + if (EXT4_I(inode)->i_reserved_data_blocks) > + ext4_msg(inode->i_sb, KERN_ERR, > + "Inode %lu (%p): i_reserved_data_blocks (%u) not cleared!", > + inode->i_ino, EXT4_I(inode), > + EXT4_I(inode)->i_reserved_data_blocks); > } > > static void init_once(void *foo) > -- > 2.27.0 > Looks good, passed 4k xfstests-bld regression. Feel free to add: Reviewed-by: Eric Whitney Eric