From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Introduce a new ioctl that uses the reverse mapping btree to return
information about the physical layout of the filesystem.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
[sandeen: rework to have less autoconf magic]
Modified-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
v3: rework the whole mess to have less autoconf magic; now we only
track if the system headers actually define getfsmap.
v2: shorten the device field to u32 since that's all we need for
dev_t. Support reporting reverse mapping information for all the
devices that XFS supports (data, log).
---
configure.ac | 1
include/builddefs.in | 4 ++
include/linux.h | 103 +++++++++++++++++++++++++++++++++++++++++++++++++
m4/package_libcdev.m4 | 20 ++++++++++
4 files changed, 128 insertions(+)
diff --git a/configure.ac b/configure.ac
index aa102e4..9534986 100644
--- a/configure.ac
+++ b/configure.ac
@@ -142,6 +142,7 @@ AC_HAVE_READDIR
AC_HAVE_FSETXATTR
AC_HAVE_MREMAP
AC_NEED_INTERNAL_FSXATTR
+AC_HAVE_GETFSMAP
if test "$enable_blkid" = yes; then
AC_HAVE_BLKID_TOPO
diff --git a/include/builddefs.in b/include/builddefs.in
index 4d6bb2d..ec630bd 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -112,6 +112,7 @@ HAVE_FLS = @have_fls@
HAVE_FSETXATTR = @have_fsetxattr@
HAVE_MREMAP = @have_mremap@
NEED_INTERNAL_FSXATTR = @need_internal_fsxattr@
+HAVE_GETFSMAP = @have_getfsmap@
GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall
# -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-decl
@@ -150,6 +151,9 @@ endif
ifeq ($(NEED_INTERNAL_FSXATTR),yes)
PCFLAGS+= -DOVERRIDE_SYSTEM_FSXATTR
endif
+ifeq ($(HAVE_GETFSMAP),yes)
+PCFLAGS+= -DHAVE_GETFSMAP
+endif
GCFLAGS = $(DEBUG) \
diff --git a/include/linux.h b/include/linux.h
index 6a676ca..38969d1 100644
--- a/include/linux.h
+++ b/include/linux.h
@@ -222,4 +222,107 @@ struct fsxattr {
#define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator hint */
#endif
+#ifndef HAVE_GETFSMAP
+/*
+ * 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 XFS_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)
+
+#define HAVE_GETFSMAP
+#endif /* HAVE_GETFSMAP */
+
#endif /* __XFS_LINUX_H__ */
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
index bc3b4ce..fa5b639 100644
--- a/m4/package_libcdev.m4
+++ b/m4/package_libcdev.m4
@@ -277,3 +277,23 @@ AC_DEFUN([AC_NEED_INTERNAL_FSXATTR],
)
AC_SUBST(need_internal_fsxattr)
])
+
+#
+# Check if we have a FS_IOC_GETFSMAP ioctl (Linux)
+#
+AC_DEFUN([AC_HAVE_GETFSMAP],
+ [ AC_MSG_CHECKING([for GETFSMAP])
+ AC_TRY_LINK([
+#define _GNU_SOURCE
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <linux/fs.h>
+#include <linux/fsmap.h>
+ ], [
+ unsigned long x = FS_IOC_GETFSMAP;
+ struct fsmap_head fh;
+ ], have_getfsmap=yes
+ AC_MSG_RESULT(yes),
+ AC_MSG_RESULT(no))
+ AC_SUBST(have_getfsmap)
+ ])
--
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