[PATCH v2] f2fs: support zero sized file truncate for device aliasing files

[Daeho Jeong <daeho43@gmail.com>]

From: Daeho Jeong <daehojeong@google.com>

support a file truncation to zero size for device aliasing files.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
---
v2: make the extent length zero
---
 fs/f2fs/file.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index f92a9fba9991..69952f208086 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -775,6 +775,11 @@ int f2fs_do_truncate_blocks(struct inode *inode, u64 from, bool lock)
 		f2fs_update_time(sbi, REQ_TIME);
 
 		f2fs_put_page(ipage, 1);
+
+		write_lock(&et->lock);
+		et->largest.len = 0;
+		write_unlock(&et->lock);
+
 		goto out;
 	}
 
@@ -1036,7 +1041,7 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 
 	if ((attr->ia_valid & ATTR_SIZE)) {
 		if (!f2fs_is_compress_backend_ready(inode) ||
-				IS_DEVICE_ALIASING(inode))
+				(IS_DEVICE_ALIASING(inode) && attr->ia_size))
 			return -EOPNOTSUPP;
 		if (is_inode_flag_set(inode, FI_COMPRESS_RELEASED) &&
 			!IS_ALIGNED(attr->ia_size,
-- 
2.49.0.395.g12beb8f557-goog