The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6fed83957f21eff11c8496e9f24253b03d2bc1dc Mon Sep 17 00:00:00 2001

From: Jeffle Xu jefflexu@linux.alibaba.com Date: Mon, 23 Aug 2021 14:13:58 +0800 Subject: [PATCH] ext4: fix reserved space counter leakage

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/<dev>/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: stable@kernel.org Suggested-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Jeffle Xu jefflexu@linux.alibaba.com Reviewed-by: Eric Whitney enwlinux@gmail.com Signed-off-by: Theodore Ts'o tytso@mit.edu Link: https://lore.kernel.org/r/20210823061358.84473-1-jefflexu@linux.alibaba.com

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 2a076d236ba1..9df1ab070fa5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1628,6 +1628,7 @@ 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, @@ -1644,6 +1645,7 @@ 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, @@ -1656,6 +1658,7 @@ 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; } @@ -1666,6 +1669,8 @@ 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 feca816b6bf3..a52f1572daa5 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1352,6 +1352,12 @@ 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)