[PATCH v2] f2fs: reject setattr size changes on large folio files

[PATCH v2] f2fs: reject setattr size changes on large folio files

[Wenjie Qi]

F2FS large folios are only enabled for immutable non-compressed files.
Writable open and writable mmap reject such mappings, but truncate(2)
through f2fs_setattr() misses the same guard.

If FS_IMMUTABLE_FL is cleared while the inode is still cached, the mapping
can keep large-folio support and ATTR_SIZE can change i_size. Reject size
changes in that state.

Fixes: 05e65c14ea59 ("f2fs: support large folio for immutable non-compressed case")
Signed-off-by: Wenjie Qi <qiwenjie@xiaomi.com>
---
Changes in v2:
- Drop the obsolete user.fadvise/chmod part and keep only the ATTR_SIZE fix.

Tested with QEMU by clearing immutable on a cached large-folio file and
checking that truncate(2) now fails with EOPNOTSUPP.

 fs/f2fs/file.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 6edf0105dbc8..80a64f0ff9d6 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1098,6 +1098,8 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		return -EPERM;
 
 	if ((attr->ia_valid & ATTR_SIZE)) {
+		if (mapping_large_folio_support(inode->i_mapping))
+			return -EOPNOTSUPP;
 		if (!f2fs_is_compress_backend_ready(inode) ||
 				IS_DEVICE_ALIASING(inode))
 			return -EOPNOTSUPP;
-- 
2.43.0

Re: [PATCH v2] f2fs: reject setattr size changes on large folio files

[Chao Yu]

On 6/10/26 22:37, Wenjie Qi wrote:
> F2FS large folios are only enabled for immutable non-compressed files.
> Writable open and writable mmap reject such mappings, but truncate(2)
> through f2fs_setattr() misses the same guard.
> 
> If FS_IMMUTABLE_FL is cleared while the inode is still cached, the mapping
> can keep large-folio support and ATTR_SIZE can change i_size. Reject size
> changes in that state.
> 

Cc: stable@kernel.org

> Fixes: 05e65c14ea59 ("f2fs: support large folio for immutable non-compressed case")
> Signed-off-by: Wenjie Qi <qiwenjie@xiaomi.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,

Re: [f2fs-dev] [PATCH v2] f2fs: reject setattr size changes on large folio files

[patchwork-bot+f2fs]

Hello:

This patch was applied to jaegeuk/f2fs.git (dev)
by Jaegeuk Kim <jaegeuk@kernel.org>:

On Wed, 10 Jun 2026 22:37:35 +0800 you wrote:
> F2FS large folios are only enabled for immutable non-compressed files.
> Writable open and writable mmap reject such mappings, but truncate(2)
> through f2fs_setattr() misses the same guard.
> 
> If FS_IMMUTABLE_FL is cleared while the inode is still cached, the mapping
> can keep large-folio support and ATTR_SIZE can change i_size. Reject size
> changes in that state.
> 
> [...]

Here is the summary with links:
  - [f2fs-dev,v2] f2fs: reject setattr size changes on large folio files
    https://git.kernel.org/jaegeuk/f2fs/c/831bece2d6e6

You are awesome, thank you!
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