ext4: Support for checksumming from journal triggers

JBD2 layer support triggers which are called when journaling layer moves
buffer to a certain state. We can use the frozen trigger, which gets
called when buffer data is frozen and about to be written out to the
journal, to compute block checksums for some buffer types (similarly as
does ocfs2). This avoids unnecessary repeated recomputation of the
checksum (at the cost of larger window where memory corruption won't be
caught by checksumming) and is even necessary when there are
unsynchronized updaters of the checksummed data.

So add superblock and journal trigger type arguments to
ext4_journal_get_write_access() and ext4_journal_get_create_access() so
that frozen triggers can be set accordingly. Also add inode argument to
ext4_walk_page_buffers() and all the callbacks used with that function
for the same purpose. This patch is mostly only a change of prototype of
the above mentioned functions and a few small helpers. Real checksumming
will come later.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210816095713.16537-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 26 insertions, 14 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index f3bbcd4efb56..dfb3ae61dfe8 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -70,7 +70,8 @@ static struct buffer_head *ext4_append(handle_t *handle,
 	inode->i_size += inode->i_sb->s_blocksize;
 	EXT4_I(inode)->i_disksize = inode->i_size;
 	BUFFER_TRACE(bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, bh);
+	err = ext4_journal_get_write_access(handle, inode->i_sb, bh,
+					    EXT4_JTR_NONE);
 	if (err) {
 		brelse(bh);
 		ext4_std_error(inode->i_sb, err);
@@ -1927,12 +1928,14 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 	}
 
 	BUFFER_TRACE(*bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, *bh);
+	err = ext4_journal_get_write_access(handle, dir->i_sb, *bh,
+					    EXT4_JTR_NONE);
 	if (err)
 		goto journal_error;
 
 	BUFFER_TRACE(frame->bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, frame->bh);
+	err = ext4_journal_get_write_access(handle, dir->i_sb, frame->bh,
+					    EXT4_JTR_NONE);
 	if (err)
 		goto journal_error;
 
@@ -2109,7 +2112,8 @@ static int add_dirent_to_buf(handle_t *handle, struct ext4_filename *fname,
 			return err;
 	}
 	BUFFER_TRACE(bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, bh);
+	err = ext4_journal_get_write_access(handle, dir->i_sb, bh,
+					    EXT4_JTR_NONE);
 	if (err) {
 		ext4_std_error(dir->i_sb, err);
 		return err;
@@ -2167,7 +2171,8 @@ static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 	blocksize =  dir->i_sb->s_blocksize;
 	dxtrace(printk(KERN_DEBUG "Creating index: inode %lu\n", dir->i_ino));
 	BUFFER_TRACE(bh, "get_write_access");
-	retval = ext4_journal_get_write_access(handle, bh);
+	retval = ext4_journal_get_write_access(handle, dir->i_sb, bh,
+					       EXT4_JTR_NONE);
 	if (retval) {
 		ext4_std_error(dir->i_sb, retval);
 		brelse(bh);
@@ -2419,7 +2424,7 @@ again:
 	}
 
 	BUFFER_TRACE(bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, bh);
+	err = ext4_journal_get_write_access(handle, sb, bh, EXT4_JTR_NONE);
 	if (err)
 		goto journal_error;
 
@@ -2476,7 +2481,8 @@ again:
 		node2->fake.rec_len = ext4_rec_len_to_disk(sb->s_blocksize,
 							   sb->s_blocksize);
 		BUFFER_TRACE(frame->bh, "get_write_access");
-		err = ext4_journal_get_write_access(handle, frame->bh);
+		err = ext4_journal_get_write_access(handle, sb, frame->bh,
+						    EXT4_JTR_NONE);
 		if (err)
 			goto journal_error;
 		if (!add_level) {
@@ -2486,8 +2492,9 @@ again:
 				       icount1, icount2));
 
 			BUFFER_TRACE(frame->bh, "get_write_access"); /* index root */
-			err = ext4_journal_get_write_access(handle,
-							     (frame - 1)->bh);
+			err = ext4_journal_get_write_access(handle, sb,
+							    (frame - 1)->bh,
+							    EXT4_JTR_NONE);
 			if (err)
 				goto journal_error;
 
@@ -2636,7 +2643,8 @@ static int ext4_delete_entry(handle_t *handle,
 		csum_size = sizeof(struct ext4_dir_entry_tail);
 
 	BUFFER_TRACE(bh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, bh);
+	err = ext4_journal_get_write_access(handle, dir->i_sb, bh,
+					    EXT4_JTR_NONE);
 	if (unlikely(err))
 		goto out;
 
@@ -3088,7 +3096,8 @@ int ext4_orphan_add(handle_t *handle, struct inode *inode)
 		  S_ISLNK(inode->i_mode)) || inode->i_nlink == 0);
 
 	BUFFER_TRACE(sbi->s_sbh, "get_write_access");
-	err = ext4_journal_get_write_access(handle, sbi->s_sbh);
+	err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
+					    EXT4_JTR_NONE);
 	if (err)
 		goto out;
 
@@ -3186,7 +3195,8 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode)
 	if (prev == &sbi->s_orphan) {
 		jbd_debug(4, "superblock will point to %u\n", ino_next);
 		BUFFER_TRACE(sbi->s_sbh, "get_write_access");
-		err = ext4_journal_get_write_access(handle, sbi->s_sbh);
+		err = ext4_journal_get_write_access(handle, inode->i_sb,
+						    sbi->s_sbh, EXT4_JTR_NONE);
 		if (err) {
 			mutex_unlock(&sbi->s_orphan_lock);
 			goto out_brelse;
@@ -3675,7 +3685,8 @@ static int ext4_rename_dir_prepare(handle_t *handle, struct ext4_renament *ent)
 	if (le32_to_cpu(ent->parent_de->inode) != ent->dir->i_ino)
 		return -EFSCORRUPTED;
 	BUFFER_TRACE(ent->dir_bh, "get_write_access");
-	return ext4_journal_get_write_access(handle, ent->dir_bh);
+	return ext4_journal_get_write_access(handle, ent->dir->i_sb,
+					     ent->dir_bh, EXT4_JTR_NONE);
 }
 
 static int ext4_rename_dir_finish(handle_t *handle, struct ext4_renament *ent,
@@ -3710,7 +3721,8 @@ static int ext4_setent(handle_t *handle, struct ext4_renament *ent,
 	int retval, retval2;
 
 	BUFFER_TRACE(ent->bh, "get write access");
-	retval = ext4_journal_get_write_access(handle, ent->bh);
+	retval = ext4_journal_get_write_access(handle, ent->dir->i_sb, ent->bh,
+					       EXT4_JTR_NONE);
 	if (retval)
 		return retval;
 	ent->de->inode = cpu_to_le32(ino);