From: Allison Henderson <allison.henderson@xxxxxxxxxx>
This patch adds a new file ioctl to retrieve the parent pointer of a
given inode
Signed-off-by: Allison Henderson <allison.henderson@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
[djwong: move new ioctl to xfs_fs_staging.h, adjust to new ondisk format]
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
libxfs/xfs_fs.h | 1
libxfs/xfs_fs_staging.h | 66 +++++++++++
libxfs/xfs_ondisk.h | 4 +
libxfs/xfs_parent.c | 62 +++++++++++
libxfs/xfs_parent.h | 25 ++++
man/man2/ioctl_xfs_getparents.2 | 227 +++++++++++++++++++++++++++++++++++++++
6 files changed, 385 insertions(+)
create mode 100644 man/man2/ioctl_xfs_getparents.2
diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h
index 63a145e5035..e92b6a9612a 100644
--- a/libxfs/xfs_fs.h
+++ b/libxfs/xfs_fs.h
@@ -811,6 +811,7 @@ struct xfs_scrub_metadata {
/* XFS_IOC_GETFSMAP ------ hoisted 59 */
#define XFS_IOC_SCRUB_METADATA _IOWR('X', 60, struct xfs_scrub_metadata)
#define XFS_IOC_AG_GEOMETRY _IOWR('X', 61, struct xfs_ag_geometry)
+/* XFS_IOC_GETPARENTS ---- staging 62 */
/*
* ioctl commands that replace IRIX syssgi()'s
diff --git a/libxfs/xfs_fs_staging.h b/libxfs/xfs_fs_staging.h
index e3d9f3b32b0..e0650af0558 100644
--- a/libxfs/xfs_fs_staging.h
+++ b/libxfs/xfs_fs_staging.h
@@ -104,4 +104,70 @@ struct xfs_exch_range {
#define XFS_IOC_EXCHANGE_RANGE _IOWR('X', 129, struct xfs_exch_range)
+/* Iterating parent pointers of files. */
+
+/* return parents of the handle, not the open fd */
+#define XFS_GETPARENTS_IFLAG_HANDLE (1U << 0)
+
+/* target was the root directory */
+#define XFS_GETPARENTS_OFLAG_ROOT (1U << 1)
+
+/* Cursor is done iterating pptrs */
+#define XFS_GETPARENTS_OFLAG_DONE (1U << 2)
+
+#define XFS_GETPARENTS_FLAG_ALL (XFS_GETPARENTS_IFLAG_HANDLE | \
+ XFS_GETPARENTS_OFLAG_ROOT | \
+ XFS_GETPARENTS_OFLAG_DONE)
+
+/* Get an inode parent pointer through ioctl */
+struct xfs_getparents_rec {
+ __u64 gpr_ino; /* Inode number */
+ __u32 gpr_gen; /* Inode generation */
+ __u32 gpr_pad; /* Reserved */
+ __u64 gpr_rsvd; /* Reserved */
+ __u8 gpr_name[]; /* File name and null terminator */
+};
+
+/* Iterate through an inodes parent pointers */
+struct xfs_getparents {
+ /* File handle, if XFS_GETPARENTS_IFLAG_HANDLE is set */
+ struct xfs_handle gp_handle;
+
+ /*
+ * Structure to track progress in iterating the parent pointers.
+ * Must be initialized to zeroes before the first ioctl call, and
+ * not touched by callers after that.
+ */
+ struct xfs_attrlist_cursor gp_cursor;
+
+ /* Operational flags: XFS_GETPARENTS_*FLAG* */
+ __u32 gp_flags;
+
+ /* Must be set to zero */
+ __u32 gp_reserved;
+
+ /* Size of the buffer in bytes, including this header */
+ __u32 gp_bufsize;
+
+ /* # of entries filled in (output) */
+ __u32 gp_count;
+
+ /* Must be set to zero */
+ __u64 gp_reserved2[5];
+
+ /* Byte offset of each record within the buffer */
+ __u32 gp_offsets[];
+};
+
+static inline struct xfs_getparents_rec*
+xfs_getparents_rec(
+ struct xfs_getparents *info,
+ unsigned int idx)
+{
+ return (struct xfs_getparents_rec *)((char *)info +
+ info->gp_offsets[idx]);
+}
+
+#define XFS_IOC_GETPARENTS _IOWR('X', 62, struct xfs_getparents)
+
#endif /* __XFS_FS_STAGING_H__ */
diff --git a/libxfs/xfs_ondisk.h b/libxfs/xfs_ondisk.h
index d9c988c5ad6..bffd39242d4 100644
--- a/libxfs/xfs_ondisk.h
+++ b/libxfs/xfs_ondisk.h
@@ -155,6 +155,10 @@ xfs_check_ondisk_structs(void)
XFS_CHECK_OFFSET(struct xfs_efi_log_format_32, efi_extents, 16);
XFS_CHECK_OFFSET(struct xfs_efi_log_format_64, efi_extents, 16);
+ /* parent pointer ioctls */
+ XFS_CHECK_STRUCT_SIZE(struct xfs_getparents_rec, 24);
+ XFS_CHECK_STRUCT_SIZE(struct xfs_getparents, 96);
+
/*
* The v5 superblock format extended several v4 header structures with
* additional data. While new fields are only accessible on v5
diff --git a/libxfs/xfs_parent.c b/libxfs/xfs_parent.c
index 6c98f95f274..92b541737cb 100644
--- a/libxfs/xfs_parent.c
+++ b/libxfs/xfs_parent.c
@@ -305,3 +305,65 @@ xfs_parent_args_free(
{
kmem_cache_free(xfs_parent_args_cache, ppargs);
}
+
+/* Convert an ondisk parent pointer to the incore format. */
+void
+xfs_parent_irec_from_disk(
+ struct xfs_parent_name_irec *irec,
+ const struct xfs_parent_name_rec *rec,
+ const void *value,
+ unsigned int valuelen)
+{
+ irec->p_ino = be64_to_cpu(rec->p_ino);
+ irec->p_gen = be32_to_cpu(rec->p_gen);
+ irec->p_namehash = be32_to_cpu(rec->p_namehash);
+ irec->p_namelen = valuelen;
+ memcpy(irec->p_name, value, valuelen);
+}
+
+/* Convert an incore parent pointer to the ondisk attr name format. */
+void
+xfs_parent_irec_to_disk(
+ struct xfs_parent_name_rec *rec,
+ const struct xfs_parent_name_irec *irec)
+{
+ rec->p_ino = cpu_to_be64(irec->p_ino);
+ rec->p_gen = cpu_to_be32(irec->p_gen);
+ rec->p_namehash = cpu_to_be32(irec->p_namehash);
+}
+
+/* Is this a valid incore parent pointer? */
+bool
+xfs_parent_verify_irec(
+ struct xfs_mount *mp,
+ const struct xfs_parent_name_irec *irec)
+{
+ struct xfs_name dname = {
+ .name = irec->p_name,
+ .len = irec->p_namelen,
+ };
+
+ if (!xfs_verify_dir_ino(mp, irec->p_ino))
+ return false;
+ if (!xfs_parent_valuecheck(mp, irec->p_name, irec->p_namelen))
+ return false;
+ if (!xfs_dir2_namecheck(irec->p_name, irec->p_namelen))
+ return false;
+ if (irec->p_namehash != xfs_dir2_hashname(mp, &dname))
+ return false;
+ return true;
+}
+
+/* Compute p_namehash for the this parent pointer. */
+void
+xfs_parent_irec_hashname(
+ struct xfs_mount *mp,
+ struct xfs_parent_name_irec *irec)
+{
+ struct xfs_name dname = {
+ .name = irec->p_name,
+ .len = irec->p_namelen,
+ };
+
+ irec->p_namehash = xfs_dir2_hashname(mp, &dname);
+}
diff --git a/libxfs/xfs_parent.h b/libxfs/xfs_parent.h
index c68c501388e..e43ae5a7df8 100644
--- a/libxfs/xfs_parent.h
+++ b/libxfs/xfs_parent.h
@@ -127,4 +127,29 @@ xfs_parent_finish(
xfs_parent_args_free(mp, ppargs);
}
+/*
+ * Incore version of a parent pointer, also contains dirent name so callers
+ * can pass/obtain all the parent pointer information in a single structure
+ */
+struct xfs_parent_name_irec {
+ /* Parent pointer attribute name fields */
+ xfs_ino_t p_ino;
+ uint32_t p_gen;
+ xfs_dahash_t p_namehash;
+
+ /* Parent pointer attribute value fields */
+ uint8_t p_namelen;
+ unsigned char p_name[MAXNAMELEN];
+};
+
+void xfs_parent_irec_from_disk(struct xfs_parent_name_irec *irec,
+ const struct xfs_parent_name_rec *rec, const void *value,
+ unsigned int valuelen);
+void xfs_parent_irec_to_disk(struct xfs_parent_name_rec *rec,
+ const struct xfs_parent_name_irec *irec);
+void xfs_parent_irec_hashname(struct xfs_mount *mp,
+ struct xfs_parent_name_irec *irec);
+bool xfs_parent_verify_irec(struct xfs_mount *mp,
+ const struct xfs_parent_name_irec *irec);
+
#endif /* __XFS_PARENT_H__ */
diff --git a/man/man2/ioctl_xfs_getparents.2 b/man/man2/ioctl_xfs_getparents.2
new file mode 100644
index 00000000000..d6987979e85
--- /dev/null
+++ b/man/man2/ioctl_xfs_getparents.2
@@ -0,0 +1,227 @@
+.\" Copyright (c) 2019-2024 Oracle. All rights reserved.
+.\"
+.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
+.\" SPDX-License-Identifier: GPL-2.0-or-later
+.\" %%%LICENSE_END
+.TH IOCTL-XFS-GETPARENTS 2 2023-08-18 "XFS"
+.SH NAME
+ioctl_xfs_getparents \- query XFS directory parent information
+.SH SYNOPSIS
+.br
+.B #include <xfs/xfs_fs.h>
+.br
+.B #include <xfs/xfs_fs_staging.h>
+.PP
+.BI "int ioctl(int " fd ", XFS_IOC_GETPARENTS, struct xfs_getparents *" arg );
+.SH DESCRIPTION
+This command is used to get a file's parent pointers.
+Parent pointers point upwards in the directory tree from a child file towards a
+parent directories.
+Each entry in a parent directory must have a corresponding parent pointer in
+the child.
+
+Calling programs should allocate a large memory buffer and initialize the
+beginning of the buffer to a header of the following form:
+.PP
+.in +4n
+.nf
+struct xfs_getparents {
+ struct xfs_handle gp_handle;
+ struct xfs_attrlist_cursor gp_cursor;
+ __u32 gp_flags;
+ __u32 gp_reserved;
+ __u32 gp_bufsize;
+ __u32 gp_count;
+ __u64 gp_reserved2[5];
+ __u32 gp_offsets[];
+};
+.fi
+.in
+
+.PP
+If the flag
+.B XFS_GETPARENTS_IFLAG_HANDLE
+is set,
+the field
+.I gp_handle
+will be interpreted as if it contains file handle information.
+If the file handle is not stale, the file represented by the handle will be the
+target of the query.
+If the flag is not set, the file represented by
+.I fd
+will be queried instead.
+
+.PP
+The field
+.I gp_cursor
+tracks the progress of iterating through the parent pointers.
+Calling programs must initialize this to zero before the first system call
+and must not touch it after that.
+
+.PP
+The field
+.I gp_flags
+control the behavior of the query operation and provide more information
+about the outcome of the operation.
+.RS 0.4i
+.TP
+.B XFS_GETPARENTS_IFLAG_HANDLE
+If the caller sets this flag, the kernel driver will interpret the
+.I gp_handle
+field as if it were a file handle.
+If the handle maps to an allocated file, that file will be queried for
+parents instead of the open file descriptor.
+.TP
+.B XFS_GETPARENTS_OFLAG_ROOT
+The file queried was the root directory.
+.TP
+.B XFS_GETPARENTS_OFLAG_DONE
+There are no more parent pointers to query.
+.RE
+
+.PP
+The fields
+.I gp_reserved
+and
+.I gp_reserved2
+must be zero.
+
+.PP
+The field
+.I gp_bufsize
+should be set to the size of the buffer, in bytes.
+
+.PP
+The field
+.I gp_count
+will be set to the number of parent pointer records returned.
+
+.PP
+Each element of the array
+.I gp_offsets
+will be set to the byte offset within the buffer of each parent record.
+
+Parent pointer records are returned in the following form:
+.PP
+.in +4n
+.nf
+
+struct xfs_getparents_rec {
+ __u64 gpr_ino;
+ __u32 gpr_gen;
+ __u32 gpr_pad;
+ __u64 gpr_rsvd;
+ __u8 gpr_name[];
+};
+.fi
+.in
+
+.PP
+The field
+.I gpr_ino
+and
+.I gpr_gen
+will be set to the inode number and generation number of the parent.
+
+.PP
+The fields
+.I gpr_pad
+and
+.I gpr_rsvd
+will be set to zero.
+
+.PP
+The array
+.I gpr_name
+will be set to a NULL-terminated byte sequence representing the filename
+stored in the parent pointer.
+
+.SH SAMPLE PROGRAM
+Calling programs should allocate a large memory buffer, initialize the head
+structure to zeroes, set gp_bufsize to the size of the buffer, and call the
+ioctl.
+The kernel will fill out the gp_offsets array with integer offsets to
+struct xfs_getparents_rec objects that are written within the provided memory
+buffer.
+The size of the gp_offsets array is given by gp_count.
+The XFS_GETPARENTS_OFLAG_DONE flag will be set in gp_flags when there are no
+more parent pointers to be read.
+The below code is an example of XFS_IOC_GETPARENTS usage:
+
+.nf
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <xfs/linux.h>
+#include <xfs/xfs.h>
+#include <xfs/xfs_types.h>
+#include <xfs/xfs_fs.h>
+#include <xfs/xfs_fs_staging.h>
+
+int main() {
+ struct xfs_getparents *pi;
+ struct xfs_getparents_rec *p;
+ int i, error, fd, nr_ptrs = 4;
+
+ error = malloc(65536);
+ if (!error) {
+ perror("malloc");
+ return 1;
+ }
+
+ memset(pi, 0, sizeof(*pi));
+ pi->gp_bufsize = 65536;
+
+ fd = open("/mnt/test/foo.txt", O_RDONLY | O_CREAT);
+ if (fd == -1)
+ return errno;
+
+ do {
+ error = ioctl(fd, XFS_IOC_GETPARENTS, pi);
+ if (error)
+ return error;
+
+ for (i = 0; i < pi->gp_count; i++) {
+ p = xfs_getparents_rec(pi, i);
+ printf("inode = %llu\\n", (unsigned long long)p->gpr_ino);
+ printf("generation = %u\\n", (unsigned int)p->gpr_gen);
+ printf("name = \\"%s\\"\\n\\n", (char *)p->gpr_name);
+ }
+ } while (!(pi->gp_flags & XFS_GETPARENTS_OFLAG_DONE));
+
+ return 0;
+}
+.fi
+
+.SH RETURN VALUE
+On error, \-1 is returned, and
+.I errno
+is set to indicate the error.
+.PP
+.SH ERRORS
+Error codes can be one of, but are not limited to, the following:
+.TP
+.B EFSBADCRC
+Metadata checksum validation failed while performing the query.
+.TP
+.B EFSCORRUPTED
+Metadata corruption was encountered while performing the query.
+.TP
+.B EINVAL
+One or more of the arguments specified is invalid.
+.TP
+.B EOPNOTSUPP
+Repairs of the requested metadata object are not supported.
+.TP
+.B EROFS
+Filesystem is read-only and a repair was requested.
+.TP
+.B ESHUTDOWN
+Filesystem is shut down due to previous errors.
+.TP
+.B EIO
+An I/O error was encountered while performing the query.
+.SH CONFORMING TO
+This API is specific to XFS filesystem on the Linux kernel.
+.SH SEE ALSO
+.BR ioctl (2)
