diff options
author | Shida Zhang | 2024-08-30 13:37:38 +0800 |
---|---|---|
committer | Theodore Ts'o | 2024-09-03 22:14:17 -0400 |
commit | cb3de5fc876ee9ef2b830c9e6cdafac5c90903ef (patch) | |
tree | 09ce95a8a43a93b37459e97030f54259055ff7dd /fs/ext4 | |
parent | 6b730a405037501a260d6efd24782d2737e65d07 (diff) |
ext4: fix a potential assertion failure due to improperly dirtied buffer
On an old kernel version(4.19, ext3, data=journal, pagesize=64k),
an assertion failure will occasionally be triggered by the line below:
-----------
jbd2_journal_commit_transaction
{
...
J_ASSERT_BH(bh, !buffer_dirty(bh));
/*
* The buffer on BJ_Forget list and not jbddirty means
...
}
-----------
The same condition may also be applied to the lattest kernel version.
When blocksize < pagesize and we truncate a file, there can be buffers in
the mapping tail page beyond i_size. These buffers will be filed to
transaction's BJ_Forget list by ext4_journalled_invalidatepage() during
truncation. When the transaction doing truncate starts committing, we can
grow the file again. This calls __block_write_begin() which allocates new
blocks under these buffers in the tail page we go through the branch:
if (buffer_new(bh)) {
clean_bdev_bh_alias(bh);
if (folio_test_uptodate(folio)) {
clear_buffer_new(bh);
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
continue;
}
...
}
Hence buffers on BJ_Forget list of the committing transaction get marked
dirty and this triggers the jbd2 assertion.
Teach ext4_block_write_begin() to properly handle files with data
journalling by avoiding dirtying them directly. Instead of
folio_zero_new_buffers() we use ext4_journalled_zero_new_buffers() which
takes care of handling journalling. We also don't need to mark new uptodate
buffers as dirty in ext4_block_write_begin(). That will be either done
either by block_commit_write() in case of success or by
folio_zero_new_buffers() in case of failure.
Reported-by: Baolin Liu <liubaolin@kylinos.cn>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240830053739.3588573-4-zhangshida@kylinos.cn
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r-- | fs/ext4/ext4.h | 3 | ||||
-rw-r--r-- | fs/ext4/inline.c | 7 | ||||
-rw-r--r-- | fs/ext4/inode.c | 42 |
3 files changed, 40 insertions, 12 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 8bd08637fe14..8cc15d00e5c8 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3853,7 +3853,8 @@ static inline int ext4_buffer_uptodate(struct buffer_head *bh) return buffer_uptodate(bh); } -extern int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, +extern int ext4_block_write_begin(handle_t *handle, struct folio *folio, + loff_t pos, unsigned len, get_block_t *get_block); #endif /* __KERNEL__ */ diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index b018a80fec7a..7ca4aca53162 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -601,10 +601,11 @@ retry: goto out; if (ext4_should_dioread_nolock(inode)) { - ret = ext4_block_write_begin(folio, from, to, + ret = ext4_block_write_begin(handle, folio, from, to, ext4_get_block_unwritten); } else - ret = ext4_block_write_begin(folio, from, to, ext4_get_block); + ret = ext4_block_write_begin(handle, folio, from, to, + ext4_get_block); if (!ret && ext4_should_journal_data(inode)) { ret = ext4_walk_page_buffers(handle, inode, @@ -856,7 +857,7 @@ static int ext4_da_convert_inline_data_to_extent(struct address_space *mapping, goto out; } - ret = ext4_block_write_begin(folio, 0, inline_size, + ret = ext4_block_write_begin(NULL, folio, 0, inline_size, ext4_da_get_block_prep); if (ret) { up_read(&EXT4_I(inode)->xattr_sem); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 0010f7004688..a11e2626b5f6 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -49,6 +49,11 @@ #include <trace/events/ext4.h> +static void ext4_journalled_zero_new_buffers(handle_t *handle, + struct inode *inode, + struct folio *folio, + unsigned from, unsigned to); + static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw, struct ext4_inode_info *ei) { @@ -1023,7 +1028,8 @@ int do_journal_get_write_access(handle_t *handle, struct inode *inode, return ret; } -int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, +int ext4_block_write_begin(handle_t *handle, struct folio *folio, + loff_t pos, unsigned len, get_block_t *get_block) { unsigned from = pos & (PAGE_SIZE - 1); @@ -1037,6 +1043,7 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, struct buffer_head *bh, *head, *wait[2]; int nr_wait = 0; int i; + bool should_journal_data = ext4_should_journal_data(inode); BUG_ON(!folio_test_locked(folio)); BUG_ON(from > PAGE_SIZE); @@ -1066,10 +1073,22 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, if (err) break; if (buffer_new(bh)) { + /* + * We may be zeroing partial buffers or all new + * buffers in case of failure. Prepare JBD2 for + * that. + */ + if (should_journal_data) + do_journal_get_write_access(handle, + inode, bh); if (folio_test_uptodate(folio)) { - clear_buffer_new(bh); + /* + * Unlike __block_write_begin() we leave + * dirtying of new uptodate buffers to + * ->write_end() time or + * folio_zero_new_buffers(). + */ set_buffer_uptodate(bh); - mark_buffer_dirty(bh); continue; } if (block_end > to || block_start < from) @@ -1099,7 +1118,11 @@ int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, err = -EIO; } if (unlikely(err)) { - folio_zero_new_buffers(folio, from, to); + if (should_journal_data) + ext4_journalled_zero_new_buffers(handle, inode, folio, + from, to); + else + folio_zero_new_buffers(folio, from, to); } else if (fscrypt_inode_uses_fs_layer_crypto(inode)) { for (i = 0; i < nr_wait; i++) { int err2; @@ -1197,10 +1220,11 @@ retry_journal: folio_wait_stable(folio); if (ext4_should_dioread_nolock(inode)) - ret = ext4_block_write_begin(folio, pos, len, + ret = ext4_block_write_begin(handle, folio, pos, len, ext4_get_block_unwritten); else - ret = ext4_block_write_begin(folio, pos, len, ext4_get_block); + ret = ext4_block_write_begin(handle, folio, pos, len, + ext4_get_block); if (!ret && ext4_should_journal_data(inode)) { ret = ext4_walk_page_buffers(handle, inode, folio_buffers(folio), from, to, @@ -2926,7 +2950,8 @@ retry: if (IS_ERR(folio)) return PTR_ERR(folio); - ret = ext4_block_write_begin(folio, pos, len, ext4_da_get_block_prep); + ret = ext4_block_write_begin(NULL, folio, pos, len, + ext4_da_get_block_prep); if (ret < 0) { folio_unlock(folio); folio_put(folio); @@ -6183,7 +6208,8 @@ retry_alloc: if (folio_pos(folio) + len > size) len = size - folio_pos(folio); - err = __block_write_begin(&folio->page, 0, len, ext4_get_block); + err = ext4_block_write_begin(handle, folio, 0, len, + ext4_get_block); if (!err) { ret = VM_FAULT_SIGBUS; if (ext4_journal_folio_buffers(handle, folio, len)) |