[PATCH] 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>
---
 fs/f2fs/file.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index f92a9fba9991..7ae5a5af5ed9 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1036,7 +1036,7 @@ 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,
@@ -1117,6 +1117,9 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		if (err)
 			return err;
 
+		if (IS_DEVICE_ALIASING(inode))
+			f2fs_destroy_extent_tree(inode);
+
 		spin_lock(&fi->i_size_lock);
 		inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
 		fi->last_disk_size = i_size_read(inode);
-- 
2.49.0.rc1.451.g8f38331e32-goog