vfs: add common GETFSMAP ioctl definitions

Add the GETFSMAP headers to the VFS kernel headers

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/include/uapi/linux/fsmap.h b/include/uapi/linux/fsmap.h
new file mode 100644 (file)
index 0000000..7e8e5f0
--- /dev/null
+++ b/include/uapi/linux/fsmap.h
@@ -0,0 +1,112 @@
+/*
+ * FS_IOC_GETFSMAP ioctl infrastructure.
+ *
+ * Copyright (C) 2017 Oracle.  All Rights Reserved.
+ *
+ * Author: Darrick J. Wong <darrick.wong@oracle.com>
+ */
+#ifndef _LINUX_FSMAP_H
+#define _LINUX_FSMAP_H
+
+#include <linux/types.h>
+
+/*
+ *     Structure for FS_IOC_GETFSMAP.
+ *
+ *     The memory layout for this call are the scalar values defined in
+ *     struct fsmap_head, followed by two struct fsmap that describe
+ *     the lower and upper bound of mappings to return, followed by an
+ *     array of struct fsmap mappings.
+ *
+ *     fmh_iflags control the output of the call, whereas fmh_oflags report
+ *     on the overall record output.  fmh_count should be set to the
+ *     length of the fmh_recs array, and fmh_entries will be set to the
+ *     number of entries filled out during each call.  If fmh_count is
+ *     zero, the number of reverse mappings will be returned in
+ *     fmh_entries, though no mappings will be returned.  fmh_reserved
+ *     must be set to zero.
+ *
+ *     The two elements in the fmh_keys array are used to constrain the
+ *     output.  The first element in the array should represent the
+ *     lowest disk mapping ("low key") that the user wants to learn
+ *     about.  If this value is all zeroes, the filesystem will return
+ *     the first entry it knows about.  For a subsequent call, the
+ *     contents of fsmap_head.fmh_recs[fsmap_head.fmh_count - 1] should be
+ *     copied into fmh_keys[0] to have the kernel start where it left off.
+ *
+ *     The second element in the fmh_keys array should represent the
+ *     highest disk mapping ("high key") that the user wants to learn
+ *     about.  If this value is all ones, the filesystem will not stop
+ *     until it runs out of mapping to return or runs out of space in
+ *     fmh_recs.
+ *
+ *     fmr_device can be either a 32-bit cookie representing a device, or
+ *     a 32-bit dev_t if the FMH_OF_DEV_T flag is set.  fmr_physical,
+ *     fmr_offset, and fmr_length are expressed in units of bytes.
+ *     fmr_owner is either an inode number, or a special value if
+ *     FMR_OF_SPECIAL_OWNER is set in fmr_flags.
+ */
+struct fsmap {
+       __u32           fmr_device;     /* device id */
+       __u32           fmr_flags;      /* mapping flags */
+       __u64           fmr_physical;   /* device offset of segment */
+       __u64           fmr_owner;      /* owner id */
+       __u64           fmr_offset;     /* file offset of segment */
+       __u64           fmr_length;     /* length of segment */
+       __u64           fmr_reserved[3];        /* must be zero */
+};
+
+struct fsmap_head {
+       __u32           fmh_iflags;     /* control flags */
+       __u32           fmh_oflags;     /* output flags */
+       __u32           fmh_count;      /* # of entries in array incl. input */
+       __u32           fmh_entries;    /* # of entries filled in (output). */
+       __u64           fmh_reserved[6];        /* must be zero */
+
+       struct fsmap    fmh_keys[2];    /* low and high keys for the mapping search */
+       struct fsmap    fmh_recs[];     /* returned records */
+};
+
+/* Size of an fsmap_head with room for nr records. */
+static inline size_t
+fsmap_sizeof(
+       unsigned int    nr)
+{
+       return sizeof(struct fsmap_head) + nr * sizeof(struct fsmap);
+}
+
+/* Start the next fsmap query at the end of the current query results. */
+static inline void
+fsmap_advance(
+       struct fsmap_head       *head)
+{
+       head->fmh_keys[0] = head->fmh_recs[head->fmh_entries - 1];
+}
+
+/*     fmh_iflags values - set by FS_IOC_GETFSMAP caller in the header. */
+/* no flags defined yet */
+#define FMH_IF_VALID           0
+
+/*     fmh_oflags values - returned in the header segment only. */
+#define FMH_OF_DEV_T           0x1     /* fmr_device values will be dev_t */
+
+/*     fmr_flags values - returned for each non-header segment */
+#define FMR_OF_PREALLOC                0x1     /* segment = unwritten pre-allocation */
+#define FMR_OF_ATTR_FORK       0x2     /* segment = attribute fork */
+#define FMR_OF_EXTENT_MAP      0x4     /* segment = extent map */
+#define FMR_OF_SHARED          0x8     /* segment = shared with another file */
+#define FMR_OF_SPECIAL_OWNER   0x10    /* owner is a special value */
+#define FMR_OF_LAST            0x20    /* segment is the last in the FS */
+
+/* Each FS gets to define its own special owner codes. */
+#define FMR_OWNER(type, code)  (((__u64)type << 32) | \
+                                ((__u64)code & 0xFFFFFFFFULL))
+#define FMR_OWNER_TYPE(owner)  ((__u32)((__u64)owner >> 32))
+#define FMR_OWNER_CODE(owner)  ((__u32)(((__u64)owner & 0xFFFFFFFFULL)))
+#define FMR_OWN_FREE           FMR_OWNER(0, 1) /* free space */
+#define FMR_OWN_UNKNOWN                FMR_OWNER(0, 2) /* unknown owner */
+#define FMR_OWN_METADATA       FMR_OWNER(0, 3) /* metadata */
+
+#define FS_IOC_GETFSMAP                _IOWR('X', 59, struct fsmap_head)
+
+#endif /* _LINUX_FSMAP_H */