Eric reported a ioctl bug in below link:

https://lore.kernel.org/linux-f2fs-devel/20201103032234.GB2875@sol.localdomain/

That said, on some 32-bit architectures, u64 has only 32-bit alignment,
notably i386 and x86_32, so that size of struct f2fs_gc_range compiled
in x86_32 is 20 bytes, however the size in x86_64 is 24 bytes, binary
compiled in x86_32 can not call F2FS_IOC_GARBAGE_COLLECT_RANGE successfully
due to mismatched value of ioctl command in betweeen binary and f2fs
module, similarly, F2FS_IOC_MOVE_RANGE will fail too.

In this patch we introduce two ioctls for compatibility of above special
32-bit binary:
- F2FS_IOC32_GARBAGE_COLLECT_RANGE
- F2FS_IOC32_MOVE_RANGE

Signed-off-by: Chao Yu <yuch...@huawei.com>
---

Jaegeuk, Eric,

I have no 32-bit machine now, so I don't run any test on this patch,
please take a look at this RFC patch first.

 fs/f2fs/file.c            | 45 +++++++++++++++++++++++++++++++++++++--
 include/uapi/linux/f2fs.h | 25 ++++++++++++++++++++++
 2 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 52417a2e3f4f..2e0a5469745a 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -4236,6 +4236,45 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, 
struct iov_iter *from)
 }
 
 #ifdef CONFIG_COMPAT
+static int f2fs_compat_ioc_gc_range(struct file *file, unsigned long arg)
+{
+       struct compat_f2fs_gc_range __user *urange;
+       struct f2fs_gc_range range;
+       int err;
+
+       urange = compat_ptr(arg);
+       err = get_user(range.sync, &urange->sync);
+       err |= get_user(range.start, &urange->start);
+       err |= get_user(range.len, &urange->len);
+       if (err)
+               return -EFAULT;
+       if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(file)))))
+               return -EIO;
+       if (!f2fs_is_checkpoint_ready(F2FS_I_SB(file_inode(file))))
+               return -ENOSPC;
+       return f2fs_ioc_gc_range(file, (unsigned long)&range);
+}
+
+static int f2fs_compat_ioc_move_range(struct file *file, unsigned long arg)
+{
+       struct compat_f2fs_move_range __user *urange;
+       struct f2fs_move_range range;
+       int err;
+
+       urange = compat_ptr(arg);
+       err = get_user(range.dst_fd, &urange->dst_fd);
+       err |= get_user(range.pos_in, &urange->pos_in);
+       err |= get_user(range.pos_out, &urange->pos_out);
+       err |= get_user(range.len, &urange->len);
+       if (err)
+               return -EFAULT;
+       if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(file)))))
+               return -EIO;
+       if (!f2fs_is_checkpoint_ready(F2FS_I_SB(file_inode(file))))
+               return -ENOSPC;
+       return f2fs_ioc_move_range(file, (unsigned long)&range);
+}
+
 long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
        switch (cmd) {
@@ -4248,6 +4287,10 @@ long f2fs_compat_ioctl(struct file *file, unsigned int 
cmd, unsigned long arg)
        case FS_IOC32_GETVERSION:
                cmd = FS_IOC_GETVERSION;
                break;
+       case F2FS_IOC32_GARBAGE_COLLECT_RANGE:
+               return f2fs_compat_ioc_gc_range(file, arg);
+       case F2FS_IOC32_MOVE_RANGE:
+               return f2fs_compat_ioc_move_range(file, arg);
        case F2FS_IOC_START_ATOMIC_WRITE:
        case F2FS_IOC_COMMIT_ATOMIC_WRITE:
        case F2FS_IOC_START_VOLATILE_WRITE:
@@ -4265,10 +4308,8 @@ long f2fs_compat_ioctl(struct file *file, unsigned int 
cmd, unsigned long arg)
        case FS_IOC_GET_ENCRYPTION_KEY_STATUS:
        case FS_IOC_GET_ENCRYPTION_NONCE:
        case F2FS_IOC_GARBAGE_COLLECT:
-       case F2FS_IOC_GARBAGE_COLLECT_RANGE:
        case F2FS_IOC_WRITE_CHECKPOINT:
        case F2FS_IOC_DEFRAGMENT:
-       case F2FS_IOC_MOVE_RANGE:
        case F2FS_IOC_FLUSH_DEVICE:
        case F2FS_IOC_GET_FEATURES:
        case FS_IOC_FSGETXATTR:
diff --git a/include/uapi/linux/f2fs.h b/include/uapi/linux/f2fs.h
index f00199a2e38b..8c14e88a9645 100644
--- a/include/uapi/linux/f2fs.h
+++ b/include/uapi/linux/f2fs.h
@@ -5,6 +5,10 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 
+#ifdef __KERNEL__
+#include <linux/compat.h>
+#endif
+
 /*
  * f2fs-specific ioctl commands
  */
@@ -65,6 +69,16 @@ struct f2fs_gc_range {
        __u64 len;
 };
 
+#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
+struct compat_f2fs_gc_range {
+       u32 sync;
+       compat_u64 start;
+       compat_u64 len;
+};
+#define F2FS_IOC32_GARBAGE_COLLECT_RANGE       _IOW(F2FS_IOCTL_MAGIC, 11,\
+                                               struct compat_f2fs_gc_range)
+#endif
+
 struct f2fs_defragment {
        __u64 start;
        __u64 len;
@@ -77,6 +91,17 @@ struct f2fs_move_range {
        __u64 len;              /* size to move */
 };
 
+#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
+struct compat_f2fs_move_range {
+       u32 dst_fd;
+       compat_u64 pos_in;
+       compat_u64 pos_out;
+       compat_u64 len;
+};
+#define F2FS_IOC32_MOVE_RANGE          _IOWR(F2FS_IOCTL_MAGIC, 9,      \
+                                       struct compat_f2fs_move_range)
+#endif
+
 struct f2fs_flush_device {
        __u32 dev_num;          /* device number to flush */
        __u32 segments;         /* # of segments to flush */
-- 
2.26.2

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