The patch titled Subject: nilfs2: prevent WARNING in nilfs_sufile_set_segment_usage() has been added to the -mm mm-hotfixes-unstable branch. Its filename is nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Ryusuke Konishi konishi.ryusuke@gmail.com Subject: nilfs2: prevent WARNING in nilfs_sufile_set_segment_usage() Date: Tue, 5 Dec 2023 17:59:47 +0900

If nilfs2 reads a disk image with corrupted segment usage metadata, and its segment usage information is marked as an error for the segment at the write location, nilfs_sufile_set_segment_usage() can trigger WARN_ONs during log writing.

Segments newly allocated for writing with nilfs_sufile_alloc() will not have this error flag set, but this unexpected situation will occur if the segment indexed by either nilfs->ns_segnum or nilfs->ns_nextnum (active segment) was marked in error.

Fix this issue by inserting a sanity check to treat it as a file system corruption.

Since error returns are not allowed during the execution phase where nilfs_sufile_set_segment_usage() is used, this inserts the sanity check into nilfs_sufile_mark_dirty() which pre-reads the buffer containing the segment usage record to be updated and sets it up in a dirty state for writing.

In addition, nilfs_sufile_set_segment_usage() is also called when canceling log writing and undoing segment usage update, so in order to avoid issuing the same kernel warning in that case, in case of cancellation, avoid checking the error flag in nilfs_sufile_set_segment_usage().

Link: https://lkml.kernel.org/r/20231205085947.4431-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+14e9f834f6ddecece094@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=14e9f834f6ddecece094 Tested-by: Ryusuke Konishi konishi.ryusuke@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/nilfs2/sufile.c | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-)

--- a/fs/nilfs2/sufile.c~nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage +++ a/fs/nilfs2/sufile.c @@ -501,15 +501,38 @@ int nilfs_sufile_mark_dirty(struct inode

down_write(&NILFS_MDT(sufile)->mi_sem); ret = nilfs_sufile_get_segment_usage_block(sufile, segnum, 0, &bh); - if (!ret) { - mark_buffer_dirty(bh); - nilfs_mdt_mark_dirty(sufile); - kaddr = kmap_atomic(bh->b_page); - su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr); + if (ret) + goto out_sem; + + kaddr = kmap_atomic(bh->b_page); + su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr); + if (unlikely(nilfs_segment_usage_error(su))) { + struct the_nilfs *nilfs = sufile->i_sb->s_fs_info; + + kunmap_atomic(kaddr); + brelse(bh); + if (nilfs_segment_is_active(nilfs, segnum)) { + nilfs_error(sufile->i_sb, + "active segment %llu is erroneous", + (unsigned long long)segnum); + } else { + /* + * Segments marked erroneous are never allocated by + * nilfs_sufile_alloc(); only active segments, ie, + * the segments indexed by ns_segnum or ns_nextnum, + * can be erroneous here. + */ + WARN_ON_ONCE(1); + } + ret = -EIO; + } else { nilfs_segment_usage_set_dirty(su); kunmap_atomic(kaddr); + mark_buffer_dirty(bh); + nilfs_mdt_mark_dirty(sufile); brelse(bh); } +out_sem: up_write(&NILFS_MDT(sufile)->mi_sem); return ret; } @@ -536,9 +559,14 @@ int nilfs_sufile_set_segment_usage(struc

kaddr = kmap_atomic(bh->b_page); su = nilfs_sufile_block_get_segment_usage(sufile, segnum, bh, kaddr); - WARN_ON(nilfs_segment_usage_error(su)); - if (modtime) + if (modtime) { + /* + * Check segusage error and set su_lastmod only when updating + * this entry with a valid timestamp, not for cancellation. + */ + WARN_ON_ONCE(nilfs_segment_usage_error(su)); su->su_lastmod = cpu_to_le64(modtime); + } su->su_nblocks = cpu_to_le32(nblocks); kunmap_atomic(kaddr);

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Patches currently in -mm which might be from konishi.ryusuke@gmail.com are

nilfs2-fix-missing-error-check-for-sb_set_blocksize-call.patch nilfs2-prevent-warning-in-nilfs_sufile_set_segment_usage.patch nilfs2-move-page-release-outside-of-nilfs_delete_entry-and-nilfs_set_link.patch nilfs2-eliminate-staggered-calls-to-kunmap-in-nilfs_rename.patch