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, 49 insertions, 35 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2c33c795c4a7..d47a57f3d8de 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -139,7 +139,6 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
 static void ext4_invalidatepage(struct page *page, unsigned int offset,
 				unsigned int length);
 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
-static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
 				  int pextents);
 
@@ -869,7 +868,8 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
 		 */
 		lock_buffer(bh);
 		BUFFER_TRACE(bh, "call get_create_access");
-		err = ext4_journal_get_create_access(handle, bh);
+		err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
+						     EXT4_JTR_NONE);
 		if (unlikely(err)) {
 			unlock_buffer(bh);
 			goto errout;
@@ -954,12 +954,12 @@ out_brelse:
 	return err;
 }
 
-int ext4_walk_page_buffers(handle_t *handle,
+int ext4_walk_page_buffers(handle_t *handle, struct inode *inode,
 			   struct buffer_head *head,
 			   unsigned from,
 			   unsigned to,
 			   int *partial,
-			   int (*fn)(handle_t *handle,
+			   int (*fn)(handle_t *handle, struct inode *inode,
 				     struct buffer_head *bh))
 {
 	struct buffer_head *bh;
@@ -978,7 +978,7 @@ int ext4_walk_page_buffers(handle_t *handle,
 				*partial = 1;
 			continue;
 		}
-		err = (*fn)(handle, bh);
+		err = (*fn)(handle, inode, bh);
 		if (!ret)
 			ret = err;
 	}
@@ -1009,7 +1009,7 @@ int ext4_walk_page_buffers(handle_t *handle,
  * is elevated.  We'll still have enough credits for the tiny quotafile
  * write.
  */
-int do_journal_get_write_access(handle_t *handle,
+int do_journal_get_write_access(handle_t *handle, struct inode *inode,
 				struct buffer_head *bh)
 {
 	int dirty = buffer_dirty(bh);
@@ -1028,7 +1028,8 @@ int do_journal_get_write_access(handle_t *handle,
 	if (dirty)
 		clear_buffer_dirty(bh);
 	BUFFER_TRACE(bh, "get write access");
-	ret = ext4_journal_get_write_access(handle, bh);
+	ret = ext4_journal_get_write_access(handle, inode->i_sb, bh,
+					    EXT4_JTR_NONE);
 	if (!ret && dirty)
 		ret = ext4_handle_dirty_metadata(handle, NULL, bh);
 	return ret;
@@ -1208,8 +1209,8 @@ retry_journal:
 		ret = __block_write_begin(page, pos, len, ext4_get_block);
 #endif
 	if (!ret && ext4_should_journal_data(inode)) {
-		ret = ext4_walk_page_buffers(handle, page_buffers(page),
-					     from, to, NULL,
+		ret = ext4_walk_page_buffers(handle, inode,
+					     page_buffers(page), from, to, NULL,
 					     do_journal_get_write_access);
 	}
 
@@ -1253,7 +1254,8 @@ retry_journal:
 }
 
 /* For write_end() in data=journal mode */
-static int write_end_fn(handle_t *handle, struct buffer_head *bh)
+static int write_end_fn(handle_t *handle, struct inode *inode,
+			struct buffer_head *bh)
 {
 	int ret;
 	if (!buffer_mapped(bh) || buffer_freed(bh))
@@ -1352,6 +1354,7 @@ errout:
  * to call ext4_handle_dirty_metadata() instead.
  */
 static void ext4_journalled_zero_new_buffers(handle_t *handle,
+					    struct inode *inode,
 					    struct page *page,
 					    unsigned from, unsigned to)
 {
@@ -1370,7 +1373,7 @@ static void ext4_journalled_zero_new_buffers(handle_t *handle,
 					size = min(to, block_end) - start;
 
 					zero_user(page, start, size);
-					write_end_fn(handle, bh);
+					write_end_fn(handle, inode, bh);
 				}
 				clear_buffer_new(bh);
 			}
@@ -1412,13 +1415,13 @@ static int ext4_journalled_write_end(struct file *file,
 		copied = ret;
 	} else if (unlikely(copied < len) && !PageUptodate(page)) {
 		copied = 0;
-		ext4_journalled_zero_new_buffers(handle, page, from, to);
+		ext4_journalled_zero_new_buffers(handle, inode, page, from, to);
 	} else {
 		if (unlikely(copied < len))
-			ext4_journalled_zero_new_buffers(handle, page,
+			ext4_journalled_zero_new_buffers(handle, inode, page,
 							 from + copied, to);
-		ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
-					     from + copied, &partial,
+		ret = ext4_walk_page_buffers(handle, inode, page_buffers(page),
+					     from, from + copied, &partial,
 					     write_end_fn);
 		if (!partial)
 			SetPageUptodate(page);
@@ -1619,7 +1622,8 @@ static void ext4_print_free_blocks(struct inode *inode)
 	return;
 }
 
-static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
+static int ext4_bh_delay_or_unwritten(handle_t *handle, struct inode *inode,
+				      struct buffer_head *bh)
 {
 	return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
 }
@@ -1851,13 +1855,15 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
 	return 0;
 }
 
-static int bget_one(handle_t *handle, struct buffer_head *bh)
+static int bget_one(handle_t *handle, struct inode *inode,
+		    struct buffer_head *bh)
 {
 	get_bh(bh);
 	return 0;
 }
 
-static int bput_one(handle_t *handle, struct buffer_head *bh)
+static int bput_one(handle_t *handle, struct inode *inode,
+		    struct buffer_head *bh)
 {
 	put_bh(bh);
 	return 0;
@@ -1888,7 +1894,7 @@ static int __ext4_journalled_writepage(struct page *page,
 			BUG();
 			goto out;
 		}
-		ext4_walk_page_buffers(handle, page_bufs, 0, len,
+		ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
 				       NULL, bget_one);
 	}
 	/*
@@ -1920,11 +1926,11 @@ static int __ext4_journalled_writepage(struct page *page,
 	if (inline_data) {
 		ret = ext4_mark_inode_dirty(handle, inode);
 	} else {
-		ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
-					     do_journal_get_write_access);
+		ret = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
+					     NULL, do_journal_get_write_access);
 
-		err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
-					     write_end_fn);
+		err = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
+					     NULL, write_end_fn);
 	}
 	if (ret == 0)
 		ret = err;
@@ -1941,7 +1947,7 @@ out:
 	unlock_page(page);
 out_no_pagelock:
 	if (!inline_data && page_bufs)
-		ext4_walk_page_buffers(NULL, page_bufs, 0, len,
+		ext4_walk_page_buffers(NULL, inode, page_bufs, 0, len,
 				       NULL, bput_one);
 	brelse(inode_bh);
 	return ret;
@@ -2031,7 +2037,7 @@ static int ext4_writepage(struct page *page,
 	 * for the extremely common case, this is an optimization that
 	 * skips a useless round trip through ext4_bio_write_page().
 	 */
-	if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+	if (ext4_walk_page_buffers(NULL, inode, page_bufs, 0, len, NULL,
 				   ext4_bh_delay_or_unwritten)) {
 		redirty_page_for_writepage(wbc, page);
 		if ((current->flags & PF_MEMALLOC) ||
@@ -3794,7 +3800,8 @@ static int __ext4_block_zero_page_range(handle_t *handle,
 	}
 	if (ext4_should_journal_data(inode)) {
 		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)
 			goto unlock;
 	}
@@ -5146,7 +5153,9 @@ static int ext4_do_update_inode(handle_t *handle,
 	ext4_clear_inode_state(inode, EXT4_STATE_NEW);
 	if (set_large_file) {
 		BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
-		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
+		err = ext4_journal_get_write_access(handle, sb,
+						    EXT4_SB(sb)->s_sbh,
+						    EXT4_JTR_NONE);
 		if (err)
 			goto out_brelse;
 		lock_buffer(EXT4_SB(sb)->s_sbh);
@@ -5747,7 +5756,8 @@ ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
 	err = ext4_get_inode_loc(inode, iloc);
 	if (!err) {
 		BUFFER_TRACE(iloc->bh, "get_write_access");
-		err = ext4_journal_get_write_access(handle, iloc->bh);
+		err = ext4_journal_get_write_access(handle, inode->i_sb,
+						    iloc->bh, EXT4_JTR_NONE);
 		if (err) {
 			brelse(iloc->bh);
 			iloc->bh = NULL;
@@ -5870,7 +5880,8 @@ int ext4_expand_extra_isize(struct inode *inode,
 	ext4_write_lock_xattr(inode, &no_expand);
 
 	BUFFER_TRACE(iloc->bh, "get_write_access");
-	error = ext4_journal_get_write_access(handle, iloc->bh);
+	error = ext4_journal_get_write_access(handle, inode->i_sb, iloc->bh,
+					      EXT4_JTR_NONE);
 	if (error) {
 		brelse(iloc->bh);
 		goto out_unlock;
@@ -6041,7 +6052,8 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
 	return err;
 }
 
-static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
+static int ext4_bh_unmapped(handle_t *handle, struct inode *inode,
+			    struct buffer_head *bh)
 {
 	return !buffer_mapped(bh);
 }
@@ -6114,7 +6126,7 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
 	 * inode to the transaction's list to writeprotect pages on commit.
 	 */
 	if (page_has_buffers(page)) {
-		if (!ext4_walk_page_buffers(NULL, page_buffers(page),
+		if (!ext4_walk_page_buffers(NULL, inode, page_buffers(page),
 					    0, len, NULL,
 					    ext4_bh_unmapped)) {
 			/* Wait so that we don't change page under IO */
@@ -6160,11 +6172,13 @@ retry_alloc:
 		err = __block_write_begin(page, 0, len, ext4_get_block);
 		if (!err) {
 			ret = VM_FAULT_SIGBUS;
-			if (ext4_walk_page_buffers(handle, page_buffers(page),
-					0, len, NULL, do_journal_get_write_access))
+			if (ext4_walk_page_buffers(handle, inode,
+					page_buffers(page), 0, len, NULL,
+					do_journal_get_write_access))
 				goto out_error;
-			if (ext4_walk_page_buffers(handle, page_buffers(page),
-					0, len, NULL, write_end_fn))
+			if (ext4_walk_page_buffers(handle, inode,
+					page_buffers(page), 0, len, NULL,
+					write_end_fn))
 				goto out_error;
 			if (ext4_jbd2_inode_add_write(handle, inode,
 						      page_offset(page), len))