Re: [PATCH] f2fs: compress: do sanity check on cluster

Chao Yu
2021-08-04T02:39:26Z

On 2021/8/4 10:03, Jaegeuk Kim wrote:
> On 08/04, Chao Yu wrote:
>> On 2021/8/4 2:26, Jaegeuk Kim wrote:
>>> On 08/03, Chao Yu wrote:
>>>> This patch adds f2fs_sanity_check_cluster() to support doing
>>>> sanity check on cluster of compressed file, it will be triggered
>>>> from below two paths:
>>>>
>>>> - __f2fs_cluster_blocks()
>>>> - f2fs_map_blocks(F2FS_GET_BLOCK_FIEMAP)
>>>>
>>>> And it can detect below three kind of cluster insanity status.
>>>>
>>>> C: COMPRESS_ADDR
>>>> N: NULL_ADDR or NEW_ADDR
>>>> V: valid blkaddr
>>>> *: any value
>>>>
>>>> 1. [*|C|*|*]
>>>> 2. [C|*|C|*]
>>>> 3. [C|N|N|V]
>>>>
>>>> Signed-off-by: Chao Yu <chao@kernel.org>
>>>> ---
>>>> fs/f2fs/compress.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++
>>>> fs/f2fs/data.c | 21 ++++++++++++------
>>>> fs/f2fs/f2fs.h | 1 +
>>>> 3 files changed, 68 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>>>> index 455561826c7d..4aa166d3d9bf 100644
>>>> --- a/fs/f2fs/compress.c
>>>> +++ b/fs/f2fs/compress.c
>>>> @@ -898,6 +898,54 @@ static bool cluster_has_invalid_data(struct compress_ctx *cc)
>>>> return false;
>>>> }
>>>> +bool f2fs_sanity_check_cluster(struct dnode_of_data *dn)
>>>> +{
>>>> + struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
>>>> + unsigned int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
>>>> + bool compressed = dn->data_blkaddr == COMPRESS_ADDR;
>>>> + int cluster_end = 0;
>>>> + int i;
>>>> + char *reason = "";
>>>> +
>>>> + if (!compressed)
>>>> + return false;
>>>> +
>>>> + /* [..., COMPR_ADDR, ...] */
>>>> + if (dn->ofs_in_node % cluster_size) {
>>>> + reason = "[*|C|*|*]";
>>>> + goto out;
>>>> + }
>>>> +
>>>> + for (i = 1; i < cluster_size; i++) {
>>>> + block_t blkaddr = data_blkaddr(dn->inode, dn->node_page,
>>>> + dn->ofs_in_node + i);
>>>> +
>>>> + /* [COMPR_ADDR, ..., COMPR_ADDR] */
>>>> + if (blkaddr == COMPRESS_ADDR) {
>>>> + reason = "[C|*|C|*]";
>>>> + goto out;
>>>> + }
>>>> + if (compressed) {
>>>> + if (!__is_valid_data_blkaddr(blkaddr)) {
>>>> + if (!cluster_end)
>>>> + cluster_end = i;
>>>> + continue;
>>>> + }
>>>> + /* [COMPR_ADDR, NULL_ADDR or NEW_ADDR, valid_blkaddr] */
>>>> + if (cluster_end) {
>>>> + reason = "[C|N|N|V]";
>>>> + goto out;
>>>> + }
>>>> + }
>>>> + }
>>>> + return false;
>>>> +out:
>>>> + f2fs_warn(sbi, "access invalid cluster, ino:%lu, nid:%u, ofs_in_node:%u, reason:%s",
>>>> + dn->inode->i_ino, dn->nid, dn->ofs_in_node, reason);
>>>> + set_sbi_flag(sbi, SBI_NEED_FSCK);
>>>> + return true;
>>>> +}
>>>> +
>>>> static int __f2fs_cluster_blocks(struct inode *inode,
>>>> unsigned int cluster_idx, bool compr)
>>>> {
>>>> @@ -915,6 +963,11 @@ static int __f2fs_cluster_blocks(struct inode *inode,
>>>> goto fail;
>>>> }
>>>> + if (f2fs_sanity_check_cluster(&dn)) {
>>>> + ret = -EFSCORRUPTED;
>>>> + goto fail;
>>>> + }
>>>> +
>>>> if (dn.data_blkaddr == COMPRESS_ADDR) {
>>>> int i;
>>>> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
>>>> index 948083c88d17..75dda2035f68 100644
>>>> --- a/fs/f2fs/data.c
>>>> +++ b/fs/f2fs/data.c
>>>> @@ -1558,13 +1558,20 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
>>>> }
>>>> if (flag == F2FS_GET_BLOCK_PRECACHE)
>>>> goto sync_out;
>>>> - if (flag == F2FS_GET_BLOCK_FIEMAP &&
>>>> - blkaddr == NULL_ADDR) {
>>>> - if (map->m_next_pgofs)
>>>> - *map->m_next_pgofs = pgofs + 1;
>>>> - goto sync_out;
>>>> - }
>>>> - if (flag != F2FS_GET_BLOCK_FIEMAP) {
>>>> + if (flag == ) {
>>>> + if (blkaddr == NULL_ADDR) {
>>>> + if (map->m_next_pgofs)
>>>> + *map->m_next_pgofs = pgofs + 1;
>>>> + goto sync_out;
>>>> + }
>>>> +#ifdef CONFIG_F2FS_FS_COMPRESSION
>>>> + if (f2fs_compressed_file(inode) &&
>>>> + f2fs_sanity_check_cluster(&dn)) {
>>>> + err = -EFSCORRUPTED;
>>>
>>> I prefer to give the block map as is instead of giving an error, since this\
>>
>> It looks the policy is not consistent with the one we did in
>> f2fs_is_valid_blkaddr().
>
> Why FIEMAP only? Do we need to check in other cases likewise
> f2fs_is_valid_blkaddr()?

Agreed, let me cover all missing pieces.

>
>>
>>> takes away to debug the problem from user-land.
>>
>> We can debug through "dump.f2fs -i" command? also once f2fs_sanity_check_cluster()
>> fails, it will print kernel message for further debuging.
>
> My concern here is how to debug and get out of this endless fiemap error before
> recovered.

Got your concern.

For debug purpose, maybe we can add a new ioctl under CONFIG_F2FS_CHECK_FS to dump
original mapping? or support dump.f2fs -f to dump all blkaddrs of target file?

Thanks

>
>>
>> Thanks,
>>
>>>
>>>> + goto sync_out;
>>>> + }
>>>> +#endif
>>>> + } else {
>>>> /* for defragment case */
>>>> if (map->m_next_pgofs)
>>>> *map->m_next_pgofs = pgofs + 1;
>>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>>> index 20389b9b3eac..86d416ffad61 100644
>>>> --- a/fs/f2fs/f2fs.h
>>>> +++ b/fs/f2fs/f2fs.h
>>>> @@ -4060,6 +4060,7 @@ void f2fs_end_read_compressed_page(struct page *page, bool failed,
>>>> block_t blkaddr);
>>>> bool f2fs_cluster_is_empty(struct compress_ctx *cc);
>>>> bool f2fs_cluster_can_merge_page(struct compress_ctx *cc, pgoff_t index);
>>>> +bool f2fs_sanity_check_cluster(struct dnode_of_data *dn);
>>>> void f2fs_compress_ctx_add_page(struct compress_ctx *cc, struct page *page);
>>>> int f2fs_write_multi_pages(struct compress_ctx *cc,
>>>> int *submitted,
>>>> --
>>>> 2.22.1