On 6/15/17 3:36 PM, Darrick J. Wong wrote:
> 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>
Reviewed-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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