F2FS_IOC_RELEASE_COMPRESS_BLOCKS sets FI_COMPRESS_RELEASED before walking
data nodes. If release_compress_blocks() fails before freeing any reserved
block, the inode keeps the flag while i_compr_blocks is still non-zero.

Then F2FS_IOC_RESERVE_COMPRESS_BLOCKS returns success with zero reserved
blocks, and regular writes keep failing with -EPERM.

Set the flag only after the ioctl succeeds, or after it has actually
released some blocks. This preserves the existing partial-release error
handling and leaves a failed zero-release attempt unchanged.

Fixes: ef8d563f184e ("f2fs: introduce F2FS_IOC_RELEASE_COMPRESS_BLOCKS")
Cc: stable@kernel.org
Signed-off-by: Wenjie Qi <qiwenjie@xiaomi.com>
---
QEMU fault-injection test with FAULT_BLKADDR_VALIDITY:
- before: release failed with -EFSCORRUPTED, reserve returned 0 blocks,
  and pwrite kept failing with -EPERM after remount.
- after: release still failed, reserve returned -EINVAL, and pwrite succeeded.
- normal release/reserve still released and reserved 192 blocks.

 fs/f2fs/file.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index c54897a25981..dca1722f92b3 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3916,10 +3916,6 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
 		goto out;
 	}
 
-	set_inode_flag(inode, FI_COMPRESS_RELEASED);
-	inode_set_ctime_current(inode);
-	f2fs_mark_inode_dirty_sync(inode, true);
-
 	f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
 	filemap_invalidate_lock(inode->i_mapping);
 
@@ -3963,6 +3959,12 @@ static int f2fs_release_compress_blocks(struct file *filp, unsigned long arg)
 
 	filemap_invalidate_unlock(inode->i_mapping);
 	f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
+
+	if (ret >= 0 || released_blocks) {
+		set_inode_flag(inode, FI_COMPRESS_RELEASED);
+		inode_set_ctime_current(inode);
+		f2fs_mark_inode_dirty_sync(inode, true);
+	}
 out:
 	if (released_blocks)
 		f2fs_update_time(sbi, REQ_TIME);
-- 
2.43.0