Partially revert "xfs: let writable tracepoint enable to clear flag of f_mode"

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4H3JT
CVE: NA

---------------------------

There are two issues with the current solution:
1) tracepoint xfs_read_file is visible in tracefs
It forms an ABI for userspace. It is bad because new field may be added
into xfs_writable_file to export more information to userspace.

2) tracepoint xfs_read_file is specific to xfs
HDFS can be stacked on ext4.

This reverts commit b1e9dddb, but keep
the definitions of FMODE_WILLNEED & FMODE_SPC_READAHEAD.
Signed-off-by: NHou Tao <houtao1@huawei.com>
Reviewed-by: NKuohai Xu <xukuohai@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

fs/xfs/xfs_file.c

@@ -35,8 +35,6 @@
 #include <linux/mman.h>
 #include <linux/fadvise.h>
 
-#define FMODE_MASK     (FMODE_RANDOM | FMODE_WILLNEED | FMODE_SPC_READAHEAD)
-
 static const struct vm_operations_struct xfs_file_vm_ops;
 
 int
@@ -240,17 +238,15 @@ xfs_file_buffered_aio_read(
 	struct xfs_writable_file file;
 
 	file.name = file_dentry(filp)->d_name.name;
-	file.clear_f_mode = 0;
 	file.f_mode = 0;
 	file.i_size = file_inode(filp)->i_size;
-	file.prev_pos = filp->f_ra.prev_pos >> PAGE_SHIFT;
-	file.pos = iocb->ki_pos >> PAGE_SHIFT;
+	file.prev_pos = filp->f_ra.prev_pos;
 
 	trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
 	trace_xfs_file_read(&file, ip, iov_iter_count(to), iocb->ki_pos);
 
-	filp->f_mode |= file.f_mode & FMODE_MASK;
-	filp->f_mode &= ~(file.clear_f_mode & FMODE_MASK);
+	if (file.f_mode)
+		filp->f_mode |= file.f_mode;
 
 	if (iocb->ki_flags & IOCB_NOWAIT) {
 		if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))

include/uapi/linux/xfs.h

@@ -7,11 +7,9 @@
 
 struct xfs_writable_file {
 	const unsigned char *name;
-	unsigned int clear_f_mode; /* can be cleared from file->f_mode */
 	unsigned int f_mode; /* can be set into file->f_mode */
 	long long i_size; /* file size */
-	long long prev_pos;  /* ra->prev_pos page index */
-	long long pos;  /* iocb->ki_pos page index */
+	long long prev_pos;  /* ra->prev_pos */
 };
 
 #endif /* _UAPI_LINUX_XFS_H */

tools/include/uapi/linux/xfs.h

@@ -5,7 +5,7 @@
 #include <linux/types.h>
 
 #define FMODE_RANDOM	(0x1000)
-#define FMODE_WILLNEED	(0x400000)
+#define FMODE_WILLNEED	(0x40000000)
 
 struct xfs_writable_file {
 	const unsigned char *name;