[f2fs-dev] [PATCH v4 2/2] f2fs: don't allow unaligned truncation to smaller/equal size on pinned file

[wangzijie <wangzijie1@honor.com>]

To prevent scattered pin block generation, don't allow non-section aligned truncation
to smaller or equal size on pinned file. But for truncation to larger size, after
commit 3fdd89b452c2("f2fs: prevent writing without fallocate() for pinned files"),
we only support overwrite IO to pinned file, so we don't need to consider
attr->ia_size > i_size case.

Signed-off-by: wangzijie <wangzijie1@honor.com>
---
v4:
- convert sbi first and apply change
---
 fs/f2fs/file.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 209f43653..4809f0fd6 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1048,6 +1048,17 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 			!IS_ALIGNED(attr->ia_size,
 			F2FS_BLK_TO_BYTES(fi->i_cluster_size)))
 			return -EINVAL;
+		/*
+		 * To prevent scattered pin block generation, we don't allow
+		 * smaller/equal size unaligned truncation for pinned file.
+		 * We only support overwrite IO to pinned file, so don't
+		 * care about larger size truncation.
+		 */
+		if (f2fs_is_pinned_file(inode) &&
+			attr->ia_size <= i_size_read(inode) &&
+			!IS_ALIGNED(attr->ia_size,
+			F2FS_BLK_TO_BYTES(CAP_BLKS_PER_SEC(sbi))))
+			return -EINVAL;
 	}
 
 	err = setattr_prepare(idmap, dentry, attr);
-- 
2.25.1



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