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Subject[PATCH RFC] f2fs: fix compat F2FS_IOC_{MOVE,GARBAGE_COLLECT}_RANGE
Date
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 <yuchao0@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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