Add support for extra rename flags that can be passed to
vfs_rename() from kernel code.
Define a new internal vfs flag RENAME_VFS_DTYPE.
This flag indicates that caller would like fs to set the dtype
of the target entry to a specified value. The dtype value to use
is specified on the S_IFMT mask bits (12..15) of the rename flags.
For example, code can call vfs_rename(..., RENAME_DT_WHT) to set
the target dir entry type to DT_WHT, regardless of the value
of inode->i_mode.
File systems that supports the new RENAME_VFS_DTYPE flag would
check for (flags & RENAME_VFS_DTYPE) and use RENAME_DT_MODE(flags)
instead of inode->i_mode to determine the value of dtype to store
in the directory entry.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
include/linux/fs.h | 30 ++++++++++++++++++++++++++++++
include/uapi/linux/fs.h | 4 ++++
2 files changed, 34 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 8f1580d..82ce8ca 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1559,6 +1559,36 @@ extern int vfs_symlink(struct inode *, struct dentry *, const char *);
extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
extern int vfs_rmdir(struct inode *, struct dentry *);
extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
+
+/* vfs_rename() extra flags */
+#define RENAME_VFS_FLAG(i) (1 << (RENAME_UAPI_BITS + (i)))
+#define RENAME_VFS_DTYPE RENAME_VFS_FLAG(0) /* Set dest dtype */
+
+#define RENAME_VFS_FLAG_BITS 1
+
+#define RENAME_FLAGS_BITS (RENAME_UAPI_BITS + RENAME_VFS_FLAG_BITS)
+#define RENAME_FLAGS_MASK ((1 << RENAME_FLAGS_BITS) - 1)
+
+/*
+ * S_IFMT bits (12..15) carry the dtype value to set for RENAME_VFS_DTYPE.
+ *
+ * For example, code can call vfs_rename(..., RENAME_DT_WHT) to set the
+ * target dir entry type to DT_WHT, regardless of inode->i_mode.
+ * file systems that supports the new RENAME_VFS_DTYPE flag, would check
+ * for (flags & RENAME_VFS_DTYPE) and use RENAME_DT_MODE(flags) instead
+ * of inode->i_mode to determine the dtype to store in the directory entry.
+ */
+#define RENAME_DT_BITS 4
+#define RENAME_DT_SHIFT 12
+#define RENAME_DT_MASK S_IFMT
+#define RENAME_DT(dt) (((dt) << RENAME_DT_SHIFT) | RENAME_VFS_DTYPE)
+#define RENAME_DT_UNKNOWN RENAME_DT(DT_UNKNOWN)
+#define RENAME_DT_WHT RENAME_DT(DT_WHT)
+/* mode to use instead of i_mode when setting dtype */
+#define RENAME_DT_MODE(f) ((f) & RENAME_DT_MASK)
+
+#define RENAME_VFS_MASK (RENAME_FLAGS_MASK | RENAME_DT_MASK)
+
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
extern int vfs_whiteout(struct inode *, struct dentry *);
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 36da93f..11f0c6b 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -38,10 +38,14 @@
#define SEEK_HOLE 4 /* seek to the next hole */
#define SEEK_MAX SEEK_HOLE
+/* renameat2(2) user api flags */
#define RENAME_NOREPLACE (1 << 0) /* Don't overwrite target */
#define RENAME_EXCHANGE (1 << 1) /* Exchange source and dest */
#define RENAME_WHITEOUT (1 << 2) /* Whiteout source */
+#define RENAME_UAPI_BITS 3
+#define RENAME_UAPI_MASK ((1 << RENAME_UAPI_BITS) - 1)
+
struct file_clone_range {
__s64 src_fd;
__u64 src_offset;
--
2.7.4
--
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