[PATCH 2/6] ext4: skip truncate when verity in progress in ->write_begin()

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

When an error (e.g. ENOSPC) occurs during ext4_write_begin() when called
from ext4_write_merkle_tree_block(), skip truncating the file.  i_size
is not meaningful in this case, and the truncation is handled by
ext4_end_enable_verity() instead.  Also, this was triggering the
WARN_ON(!inode_is_locked(inode)) in ext4_truncate().

Fixes: ea54d7e4c0f8 ("ext4: add basic fs-verity support")
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/inode.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index b2c8d09acf652..cf0fce1173a4c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1340,6 +1340,9 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 	}
 
 	if (ret) {
+		bool extended = (pos + len > inode->i_size) &&
+				!ext4_verity_in_progress(inode);
+
 		unlock_page(page);
 		/*
 		 * __block_write_begin may have instantiated a few blocks
@@ -1349,11 +1352,11 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 		 * Add inode to orphan list in case we crash before
 		 * truncate finishes
 		 */
-		if (pos + len > inode->i_size && ext4_can_truncate(inode))
+		if (extended && ext4_can_truncate(inode))
 			ext4_orphan_add(handle, inode);
 
 		ext4_journal_stop(handle);
-		if (pos + len > inode->i_size) {
+		if (extended) {
 			ext4_truncate_failed_write(inode);
 			/*
 			 * If truncate failed early the inode might
-- 
2.22.0