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Message-ID: <YQsZv1dqP6XMe1C2@google.com>
Date: Wed, 4 Aug 2021 15:50:39 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Chao Yu <chao.yu@...ux.dev>
Subject: Re: [PATCH] f2fs: compress: do sanity check on cluster
On 08/04, Chao Yu wrote:
> 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@...nel.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?
How about giving EFSCORRUPTED if CONFIG_F2FS_CHECK_FS is enabled? Sometimes it's
useful to ask fiemap to users.
>
> 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
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