Re: [PATCH 21/21] xfsprogs: implement the upper half of parent pointers

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Mon, May 07, 2018 at 09:41:19PM -0700, Allison Henderson wrote:
> From: "Darrick J. Wong" <darrick.wong@oracle.com>
> 
> Add ioctl definitions to libxfs, build the necessary helpers into
> libfrog and libhandle to iterate parents (and parent paths), then wire
> up xfs_scrub to be able to query parent pointers from userspace.  The
> goal of this patch is to exercise userspace, and is nowhere near a
> complete solution.  A basic xfs_io parent command implementation
> replaces ... whatever that is that's there now.
> 
> Totally missing: actual support in libxfs for working with parent ptrs
> straight off the disk (mkfs, xfs_db, xfs_repair).
> 
> [achender: Minor syntax adjustments to sew solution in actual support
> 	   in libxfs for working with parent ptrs]
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> ---
>  include/handle.h   |   2 +
>  include/parent.h   |  18 ++
>  include/path.h     |  19 +++
>  io/parent.c        | 471 ++++++++++++++---------------------------------------
>  libfrog/paths.c    | 136 ++++++++++++++++
>  libhandle/Makefile |   2 +-
>  libhandle/handle.c |   7 +-
>  libhandle/parent.c | 325 ++++++++++++++++++++++++++++++++++++
>  libxfs/xfs_fs.h    |   8 +
>  scrub/inodes.c     |  26 +++
>  scrub/inodes.h     |   2 +
>  scrub/phase5.c     |   9 +-
>  12 files changed, 661 insertions(+), 364 deletions(-)
> 
> diff --git a/include/handle.h b/include/handle.h
> index 49f1441..00aa43d 100644
> --- a/include/handle.h
> +++ b/include/handle.h
> @@ -52,6 +52,8 @@ extern int  fssetdm_by_handle (void *__hanp, size_t __hlen,
>  
>  void fshandle_destroy(void);
>  
> +int handle_to_fsfd(void *hanp, char **path);
> +
>  #ifdef __cplusplus
>  }
>  #endif
> diff --git a/include/parent.h b/include/parent.h
> index 85cef85..33f8d85 100644
> --- a/include/parent.h
> +++ b/include/parent.h
> @@ -28,4 +28,22 @@ typedef struct parent_cursor {
>  	__u32	opaque[4];      /* an opaque cookie */
>  } parent_cursor_t;
>  
> +struct path_list;
> +
> +typedef int (*walk_pptr_fn)(struct xfs_pptr_info *pi, struct xfs_parent_ptr *pptr,
> +		void *arg);
> +typedef int (*walk_ppath_fn)(const char *mntpt, struct path_list *path,
> +		void *arg);
> +
> +#define WALK_PPTRS_ABORT	1
> +int fd_walk_pptrs(int fd, walk_pptr_fn fn, void *arg);
> +int handle_walk_pptrs(void *hanp, size_t hanlen, walk_pptr_fn fn, void *arg);
> +
> +#define WALK_PPATHS_ABORT	1
> +int fd_walk_ppaths(int fd, walk_ppath_fn fn, void *arg);
> +int handle_walk_ppaths(void *hanp, size_t hanlen, walk_ppath_fn fn, void *arg);
> +
> +int fd_to_path(int fd, char *path, size_t pathlen);
> +int handle_to_path(void *hanp, size_t hlen, char *path, size_t pathlen);
> +
>  #endif
> diff --git a/include/path.h b/include/path.h
> index 88dc44b..cbe4e19 100644
> --- a/include/path.h
> +++ b/include/path.h
> @@ -70,4 +70,23 @@ typedef struct fs_cursor {
>  extern void fs_cursor_initialise(char *__dir, uint __flags, fs_cursor_t *__cp);
>  extern fs_path_t *fs_cursor_next_entry(fs_cursor_t *__cp);
>  
> +/* Path information. */
> +
> +struct path_list;
> +struct path_component;
> +
> +struct path_component *path_component_init(const char *name);
> +void path_component_free(struct path_component *pc);
> +int path_component_change(struct path_component *pc, void *name,
> +		size_t namelen);
> +
> +struct path_list *path_list_init(void);
> +void path_list_free(struct path_list *path);
> +void path_list_add_parent_component(struct path_list *path,
> +		struct path_component *pc);
> +void path_list_add_component(struct path_list *path, struct path_component *pc);
> +void path_list_del_component(struct path_list *path, struct path_component *pc);
> +
> +ssize_t path_list_to_string(struct path_list *path, char *buf, size_t buflen);
> +
>  #endif	/* __PATH_H__ */
> diff --git a/io/parent.c b/io/parent.c
> index 55b8b49..ad51fe6 100644
> --- a/io/parent.c
> +++ b/io/parent.c
> @@ -21,366 +21,105 @@
>  #include "path.h"
>  #include "parent.h"
>  #include "handle.h"
> -#include "jdm.h"
>  #include "init.h"
>  #include "io.h"
>  
> -#define PARENTBUF_SZ		16384
> -#define BSTATBUF_SZ		16384
> -
>  static cmdinfo_t parent_cmd;
> -static int verbose_flag;
> -static int err_status;
> -static __u64 inodes_checked;
>  static char *mntpt;
>  
> -/*
> - * check out a parent entry to see if the values seem valid
> - */
> -static void
> -check_parent_entry(xfs_bstat_t *bstatp, parent_t *parent)
> -{
> -	int sts;
> -	char fullpath[PATH_MAX];
> -	struct stat statbuf;
> -	char *str;
> -
> -	snprintf(fullpath, parent->p_reclen, _("%s%s"), mntpt,
> -				((char*)parent)+sizeof(struct parent));
> -
> -	sts = lstat(fullpath, &statbuf);
> -	if (sts != 0) {
> -		fprintf(stderr,
> -			_("inode-path for inode: %llu is incorrect - path \"%s\" non-existent\n"),
> -			(unsigned long long) bstatp->bs_ino, fullpath);
> -		if (verbose_flag) {
> -			fprintf(stderr,
> -				_("path \"%s\" does not stat for inode: %llu; err = %s\n"),
> -				fullpath,
> -			       (unsigned long long) bstatp->bs_ino,
> -				strerror(errno));
> -		}
> -		err_status++;
> -		return;
> -	} else {
> -		if (verbose_flag > 1) {
> -			printf(_("path \"%s\" found\n"), fullpath);
> -		}
> -	}
> -
> -	if (statbuf.st_ino != bstatp->bs_ino) {
> -		fprintf(stderr,
> -			_("inode-path for inode: %llu is incorrect - wrong inode#\n"),
> -		       (unsigned long long) bstatp->bs_ino);
> -		if (verbose_flag) {
> -			fprintf(stderr,
> -				_("ino mismatch for path \"%s\" %llu vs %llu\n"),
> -				fullpath,
> -				(unsigned long long)statbuf.st_ino,
> -				(unsigned long long)bstatp->bs_ino);
> -		}
> -		err_status++;
> -		return;
> -	} else if (verbose_flag > 1) {
> -		printf(_("inode number match: %llu\n"),
> -			(unsigned long long)statbuf.st_ino);
> -	}
> -
> -	/* get parent path */
> -	str = strrchr(fullpath, '/');
> -	*str = '\0';
> -	sts = stat(fullpath, &statbuf);
> -	if (sts != 0) {
> -		fprintf(stderr,
> -			_("parent path \"%s\" does not stat: %s\n"),
> -			fullpath,
> -			strerror(errno));
> -		err_status++;
> -		return;
> -	} else {
> -		if (parent->p_ino != statbuf.st_ino) {
> -			fprintf(stderr,
> -				_("inode-path for inode: %llu is incorrect - wrong parent inode#\n"),
> -			       (unsigned long long) bstatp->bs_ino);
> -			if (verbose_flag) {
> -				fprintf(stderr,
> -					_("ino mismatch for path \"%s\" %llu vs %llu\n"),
> -					fullpath,
> -					(unsigned long long)parent->p_ino,
> -					(unsigned long long)statbuf.st_ino);
> -			}
> -			err_status++;
> -			return;
> -		} else {
> -			if (verbose_flag > 1) {
> -			       printf(_("parent ino match for %llu\n"),
> -				       (unsigned long long) parent->p_ino);
> -			}
> -		}
> -	}
> -}
> -
> -static void
> -check_parents(parent_t *parentbuf, size_t *parentbuf_size,
> -	     jdm_fshandle_t *fshandlep, xfs_bstat_t *statp)
> -{
> -	int error, i;
> -	__u32 count;
> -	parent_t *entryp;
> -
> -	do {
> -		error = jdm_parentpaths(fshandlep, statp, parentbuf, *parentbuf_size, &count);
> -
> -		if (error == ERANGE) {
> -			*parentbuf_size *= 2;
> -			parentbuf = (parent_t *)realloc(parentbuf, *parentbuf_size);
> -		} else if (error) {
> -			fprintf(stderr, _("parentpaths failed for ino %llu: %s\n"),
> -			       (unsigned long long) statp->bs_ino,
> -				strerror(errno));
> -			err_status++;
> -			break;
> -		}
> -	} while (error == ERANGE);
> -
> -
> -	if (count == 0) {
> -		/* no links for inode - something wrong here */
> -	       fprintf(stderr, _("inode-path for inode: %llu is missing\n"),
> -			       (unsigned long long) statp->bs_ino);
> -		err_status++;
> -	}
> -
> -	entryp = parentbuf;
> -	for (i = 0; i < count; i++) {
> -		check_parent_entry(statp, entryp);
> -		entryp = (parent_t*) (((char*)entryp) + entryp->p_reclen);
> -	}
> -}
> -
>  static int
> -do_bulkstat(parent_t *parentbuf, size_t *parentbuf_size, xfs_bstat_t *bstatbuf,
> -	    int fsfd, jdm_fshandle_t *fshandlep)
> +pptr_print(
> +	struct xfs_pptr_info	*pi,
> +	struct xfs_parent_ptr	*pptr,
> +	void			*arg)
>  {
> -	__s32 buflenout;
> -	__u64 lastino = 0;
> -	xfs_bstat_t *p;
> -	xfs_bstat_t *endp;
> -	xfs_fsop_bulkreq_t bulkreq;
> -	struct stat mntstat;
> +	char			buf[XFS_PPTR_MAXNAMELEN + 1];
>  
> -	if (stat(mntpt, &mntstat)) {
> -		fprintf(stderr, _("can't stat mount point \"%s\": %s\n"),
> -			mntpt, strerror(errno));
> -		return 1;
> +	if (pi->pi_flags & XFS_PPTR_OFLAG_ROOT) {
> +		printf(_("Root directory.\n"));
> +		return 0;
>  	}
>  
> -	bulkreq.lastip  = &lastino;
> -	bulkreq.icount  = BSTATBUF_SZ;
> -	bulkreq.ubuffer = (void *)bstatbuf;
> -	bulkreq.ocount  = &buflenout;
> -
> -	while (xfsctl(mntpt, fsfd, XFS_IOC_FSBULKSTAT, &bulkreq) == 0) {
> -		if (*(bulkreq.ocount) == 0) {
> -			return 0;
> -		}
> -		for (p = bstatbuf, endp = bstatbuf + *bulkreq.ocount; p < endp; p++) {
> -
> -			/* inode being modified, get synced data with iget */
> -			if ( (!p->bs_nlink || !p->bs_mode) && p->bs_ino != 0 ) {
> -
> -				if (xfsctl(mntpt, fsfd, XFS_IOC_FSBULKSTAT_SINGLE, &bulkreq) < 0) {
> -				    fprintf(stderr,
> -					  _("failed to get bulkstat information for inode %llu\n"),
> -					 (unsigned long long) p->bs_ino);
> -				    continue;
> -				}
> -				if (!p->bs_nlink || !p->bs_mode || !p->bs_ino) {
> -				    fprintf(stderr,
> -					  _("failed to get valid bulkstat information for inode %llu\n"),
> -					 (unsigned long long) p->bs_ino);
> -				    continue;
> -				}
> -			}
> -
> -			/* skip root */
> -			if (p->bs_ino == mntstat.st_ino) {
> -				continue;
> -			}
> -
> -			if (verbose_flag > 1) {
> -			       printf(_("checking inode %llu\n"),
> -				       (unsigned long long) p->bs_ino);
> -			}
> -
> -			/* print dotted progress */
> -			if ((inodes_checked % 100) == 0 && verbose_flag == 1) {
> -				printf("."); fflush(stdout);
> -			}
> -			inodes_checked++;
> -
> -			check_parents(parentbuf, parentbuf_size, fshandlep, p);
> -		}
> -
> -	}/*while*/
> -
> -	fprintf(stderr, _("syssgi bulkstat failed: %s\n"), strerror(errno));
> -	return 1;
> +	memcpy(buf, pptr->xpp_name, pptr->xpp_namelen);
> +	buf[pptr->xpp_namelen] = 0;
> +	printf(_("p_ino    = %llu\n"), (unsigned long long)pptr->xpp_ino);
> +	printf(_("p_gen    = %u\n"), (unsigned int)pptr->xpp_gen);
> +	printf(_("p_reclen = %u\n"), (unsigned int)pptr->xpp_namelen);
> +	printf(_("p_name   = \"%s\"\n\n"), buf);
> +	return 0;
>  }
>  
> -static int
> -parent_check(void)
> +int
> +print_parents(
> +	struct xfs_handle	*handle)
>  {
> -	int fsfd;
> -	jdm_fshandle_t *fshandlep;
> -	parent_t *parentbuf;
> -	size_t parentbuf_size = PARENTBUF_SZ;
> -	xfs_bstat_t *bstatbuf;
> -
> -	err_status = 0;
> -	inodes_checked = 0;
> -
> -	sync();
> -
> -        fsfd = file->fd;
> -
> -	fshandlep = jdm_getfshandle(mntpt);
> -	if (fshandlep == NULL) {
> -		fprintf(stderr, _("unable to open \"%s\" for jdm: %s\n"),
> -		      mntpt,
> -		      strerror(errno));
> -		return 1;
> -	}
> -
> -	/* allocate buffers */
> -        bstatbuf = (xfs_bstat_t *)calloc(BSTATBUF_SZ, sizeof(xfs_bstat_t));
> -	parentbuf = (parent_t *)malloc(parentbuf_size);
> -	if (!bstatbuf || !parentbuf) {
> -		fprintf(stderr, _("unable to allocate buffers: %s\n"),
> -			strerror(errno));
> -		err_status = 1;
> -		goto out;
> -	}
> +	int			ret;
>  
> -	if (do_bulkstat(parentbuf, &parentbuf_size, bstatbuf, fsfd, fshandlep) != 0)
> -		err_status++;
> -
> -	if (err_status > 0)
> -		fprintf(stderr, _("num errors: %d\n"), err_status);
> +	if (handle)
> +		ret = handle_walk_pptrs(handle, sizeof(*handle), pptr_print,
> +				NULL);
>  	else
> -		printf(_("succeeded checking %llu inodes\n"),
> -			(unsigned long long) inodes_checked);
> -
> -out:
> -	free(bstatbuf);
> -	free(parentbuf);
> -	free(fshandlep);
> -	return err_status;
> -}
> +		ret = fd_walk_pptrs(file->fd, pptr_print, NULL);
> +	if (ret)
> +		perror(file->name);
>  
> -static void
> -print_parent_entry(parent_t *parent, int fullpath)
> -{
> -       printf(_("p_ino    = %llu\n"),  (unsigned long long) parent->p_ino);
> -	printf(_("p_gen    = %u\n"),	parent->p_gen);
> -	printf(_("p_reclen = %u\n"),	parent->p_reclen);
> -	if (fullpath)
> -		printf(_("p_name   = \"%s%s\"\n"), mntpt,
> -					((char*)parent)+sizeof(struct parent));
> -	else
> -		printf(_("p_name   = \"%s\"\n"),
> -					((char*)parent)+sizeof(struct parent));
> +	return 0;
>  }
>  
>  static int
> -parent_list(int fullpath)
> -{
> -	void *handlep = NULL;
> -	size_t handlen;
> -	int error, i;
> -	int retval = 1;
> -	__u32 count;
> -	parent_t *entryp;
> -	parent_t *parentbuf = NULL;
> -	char *path = file->name;
> -	int pb_size = PARENTBUF_SZ;
> -
> -	/* XXXX for linux libhandle version - to set libhandle fsfd cache */
> -	{
> -		void *fshandle;
> -		size_t fshlen;
> -
> -		if (path_to_fshandle(mntpt, &fshandle, &fshlen) != 0) {
> -			fprintf(stderr, _("%s: failed path_to_fshandle \"%s\": %s\n"),
> -				progname, path, strerror(errno));
> -			goto error;
> -		}
> -		free_handle(fshandle, fshlen);
> -	}
> -
> -	if (path_to_handle(path, &handlep, &handlen) != 0) {
> -		fprintf(stderr, _("%s: path_to_handle failed for \"%s\"\n"), progname, path);
> -		goto error;
> -	}
> -
> -	do {
> -		parentbuf = (parent_t *)realloc(parentbuf, pb_size);
> -		if (!parentbuf) {
> -			fprintf(stderr, _("%s: unable to allocate parent buffer: %s\n"),
> -				progname, strerror(errno));
> -			goto error;
> -		}
> +path_print(
> +	const char		*mntpt,
> +	struct path_list	*path,
> +	void			*arg) {
>  
> -		if (fullpath) {
> -			error = parentpaths_by_handle(handlep,
> -						       handlen,
> -						       parentbuf,
> -						       pb_size,
> -						       &count);
> -		} else {
> -			error = parents_by_handle(handlep,
> -						   handlen,
> -						   parentbuf,
> -						   pb_size,
> -						   &count);
> -		}
> -		if (error == ERANGE) {
> -			pb_size *= 2;
> -		} else if (error) {
> -			fprintf(stderr, _("%s: %s call failed for \"%s\": %s\n"),
> -				progname, fullpath ? "parentpaths" : "parents",
> -				path, strerror(errno));
> -			goto error;
> -		}
> -	} while (error == ERANGE);
> +	char			buf[PATH_MAX];
> +	size_t			len = PATH_MAX;
> +	int			ret;
>  
> -	if (count == 0) {
> -		/* no links for inode - something wrong here */
> -		fprintf(stderr, _("%s: inode-path is missing\n"), progname);
> -		goto error;
> +	ret = snprintf(buf, len, "%s", mntpt);
> +	if (ret != strlen(mntpt)) {
> +		errno = ENOMEM;
> +		return -1;
>  	}
>  
> -	entryp = parentbuf;
> -	for (i = 0; i < count; i++) {
> -		print_parent_entry(entryp, fullpath);
> -		entryp = (parent_t*) (((char*)entryp) + entryp->p_reclen);
> -	}
> +	ret = path_list_to_string(path, buf + ret, len - ret);
> +	if (ret < 0)
> +		return ret;
> +	return 0;
> +}
>  
> -	retval = 0;
> -error:
> -	free(handlep);
> -	free(parentbuf);
> -	return retval;
> +int
> +print_paths(
> +	struct xfs_handle	*handle)
> +{
> +	int			ret;
> +
> +	if (handle)
> +		ret = handle_walk_ppaths(handle, sizeof(*handle), path_print,
> +				NULL);
> + 	else
> +		ret = fd_walk_ppaths(file->fd, path_print, NULL);
> +	if (ret)
> +		perror(file->name);
> +	return 0;
>  }
>  
>  int
> -parent_f(int argc, char **argv)
> +parent_f(
> +	int			argc,
> +	char			**argv)
>  {
> -	int c;
> -	int listpath_flag = 0;
> -	int check_flag = 0;
> -	fs_path_t *fs;
> -	static int tab_init;
> +	struct xfs_handle	handle;
> +	void			*hanp = NULL;
> +	size_t			hlen;
> +	struct fs_path		*fs;
> +	char			*p;
> +	uint64_t		ino = 0;
> +	uint32_t		gen = 0;
> +	int			c;
> +	int			listpath_flag = 0;
> +	int			ret;
> +	static int		tab_init;
>  
>  	if (!tab_init) {
>  		tab_init = 1;
> @@ -394,46 +133,72 @@ parent_f(int argc, char **argv)
>  	}
>  	mntpt = fs->fs_dir;
>  
> -	verbose_flag = 0;
> -
> -	while ((c = getopt(argc, argv, "cpv")) != EOF) {
> +	while ((c = getopt(argc, argv, "p")) != EOF) {
>  		switch (c) {
> -		case 'c':
> -			check_flag = 1;
> -			break;
>  		case 'p':
>  			listpath_flag = 1;
>  			break;
> -		case 'v':
> -			verbose_flag++;
> -			break;
>  		default:
>  			return command_usage(&parent_cmd);
>  		}
>  	}
>  
> -	if (!check_flag && !listpath_flag) /* default case */
> -		exitcode = parent_list(listpath_flag);
> -	else {
> -		if (listpath_flag)
> -			exitcode = parent_list(listpath_flag);
> -		if (check_flag)
> -			exitcode = parent_check();
> +	/*
> +	 * Always initialize the fshandle table because we need it for
> +	 * the ppaths functions to work.
> +	 */
> +	ret = path_to_fshandle((char *)mntpt, &hanp, &hlen);
> +	if (ret) {
> +		perror(mntpt);
> +		return 0;
> + 	}
> + 
> +	if (optind + 2 == argc) {
> +		ino = strtoull(argv[optind], &p, 0);
> +		if (*p != '\0' || ino == 0) {
> +			fprintf(stderr,
> +				_("Bad inode number '%s'.\n"),
> +				argv[optind]);
> +			return 0;
> +		}
> +		gen = strtoul(argv[optind + 1], &p, 0);
> +		if (*p != '\0') {
> +			fprintf(stderr,
> +				_("Bad generation number '%s'.\n"),
> +				argv[optind + 1]);
> +			return 0;
> +		}
> +
> +		memcpy(&handle, hanp, sizeof(handle));
> +		handle.ha_fid.fid_len = sizeof(xfs_fid_t) -
> +				sizeof(handle.ha_fid.fid_len);
> +		handle.ha_fid.fid_pad = 0;
> +		handle.ha_fid.fid_ino = ino;
> +		handle.ha_fid.fid_gen = gen;
> +
>  	}
>  
> +	if (listpath_flag)
> +		exitcode = print_paths(ino ? &handle : NULL);
> +	else
> +		exitcode = print_parents(ino ? &handle : NULL);
> +
> +	if (hanp)
> +		free_handle(hanp, hlen);
> +
>  	return 0;
>  }
>  
>  static void
>  parent_help(void)
>  {
> -	printf(_(
> +printf(_(
>  "\n"
>  " list the current file's parents and their filenames\n"
>  "\n"
> -" -c -- check the current file's file system for parent consistency\n"
> -" -p -- list the current file's parents and their full paths\n"
> -" -v -- verbose mode\n"
> +" -p -- list the current file's paths up to the root\n"
> +"\n"
> +"If ino and gen are supplied, use them instead.\n"
>  "\n"));
>  }
>  
> @@ -444,9 +209,9 @@ parent_init(void)
>  	parent_cmd.cfunc = parent_f;
>  	parent_cmd.argmin = 0;
>  	parent_cmd.argmax = -1;
> -	parent_cmd.args = _("[-cpv]");
> +	parent_cmd.args = _("[-p] [ino gen]");
>  	parent_cmd.flags = CMD_NOMAP_OK;
> -	parent_cmd.oneline = _("print or check parent inodes");
> +	parent_cmd.oneline = _("print parent inodes");
>  	parent_cmd.help = parent_help;
>  
>  	if (expert)
> diff --git a/libfrog/paths.c b/libfrog/paths.c
> index c7895e9..9fb0140 100644
> --- a/libfrog/paths.c
> +++ b/libfrog/paths.c
> @@ -27,6 +27,7 @@
>  #include "path.h"
>  #include "input.h"
>  #include "project.h"
> +#include "list.h"
>  #include <limits.h>
>  
>  extern char *progname;
> @@ -632,3 +633,138 @@ fs_table_insert_project_path(
>  		exit(1);
>  	}
>  }
> +
> +
> +/* Structured path components. */
> +
> +struct path_list {
> +	struct list_head	p_head;
> +};
> +
> +struct path_component {
> +	struct list_head	pc_list;
> +	char			*pc_fname;
> +};
> +
> +/* Initialize a path component with a given name. */
> +struct path_component *
> +path_component_init(
> +	const char		*name)
> +{
> +	struct path_component	*pc;
> +
> +	pc = malloc(sizeof(struct path_component));
> +	if (!pc)
> +		return NULL;
> +	INIT_LIST_HEAD(&pc->pc_list);
> +	pc->pc_fname = strdup(name);
> +	if (!pc->pc_fname) {
> +		free(pc);
> +		return NULL;
> +	}
> +	return pc;
> +}
> +
> +/* Free a path component. */
> +void
> +path_component_free(
> +	struct path_component	*pc)
> +{
> +	free(pc->pc_fname);
> +	free(pc);
> +}
> +
> +/* Change a path component's filename. */
> +int
> +path_component_change(
> +	struct path_component	*pc,
> +	void			*name,
> +	size_t			namelen)
> +{
> +	void			*p;
> +
> +	p = realloc(pc->pc_fname, namelen + 1);
> +	if (!p)
> +		return -1;
> +	pc->pc_fname = p;
> +	memcpy(pc->pc_fname, name, namelen);
> +	pc->pc_fname[namelen] = 0;
> +	return 0;
> +}
> +
> +/* Initialize a pathname. */
> +struct path_list *
> +path_list_init(void)
> +{
> +	struct path_list	*path;
> +
> +	path = malloc(sizeof(struct path_list));
> +	if (!path)
> +		return NULL;
> +	INIT_LIST_HEAD(&path->p_head);
> +	return path;
> +}
> +
> +/* Empty out a pathname. */
> +void
> +path_list_free(
> +	struct path_list	*path)
> +{
> +	struct path_component	*pos;
> +	struct path_component	*n;
> +
> +	list_for_each_entry_safe(pos, n, &path->p_head, pc_list) {
> +		path_list_del_component(path, pos);
> +		path_component_free(pos);
> +	}
> +	free(path);
> +}
> +
> +/* Add a parent component to a pathname. */
> +void
> +path_list_add_parent_component(
> +	struct path_list	*path,
> +	struct path_component	*pc)
> +{
> +	list_add(&pc->pc_list, &path->p_head);
> +}
> +
> +/* Add a component to a pathname. */
> +void
> +path_list_add_component(
> +	struct path_list	*path,
> +	struct path_component	*pc)
> +{
> +	list_add_tail(&pc->pc_list, &path->p_head);
> +}
> +
> +/* Remove a component from a pathname. */
> +void
> +path_list_del_component(
> +	struct path_list	*path,
> +	struct path_component	*pc)
> +{
> +	list_del_init(&pc->pc_list);
> +}
> +
> +/* Convert a pathname into a string. */
> +ssize_t
> +path_list_to_string(
> +	struct path_list	*path,
> +	char			*buf,
> +	size_t			buflen)
> +{
> +	struct path_component	*pos;
> +	ssize_t			bytes = 0;
> +	int			ret;
> +
> +	list_for_each_entry(pos, &path->p_head, pc_list) {
> +		ret = snprintf(buf, buflen, "/%s", pos->pc_fname);
> +		if (ret != 1 + strlen(pos->pc_fname))
> +			return -1;
> +		bytes += ret;
> +		buf += ret;
> +		buflen -= ret;
> +	}
> +	return bytes;
> +}
> diff --git a/libhandle/Makefile b/libhandle/Makefile
> index fe1a2af..d3cea41 100644
> --- a/libhandle/Makefile
> +++ b/libhandle/Makefile
> @@ -16,7 +16,7 @@ else
>  LTLDFLAGS += -Wl,--version-script,libhandle.sym
>  endif
>  
> -CFILES = handle.c jdm.c
> +CFILES = handle.c jdm.c parent.c
>  LSRCFILES = libhandle.sym
>  
>  default: ltdepend $(LTLIBRARY)
> diff --git a/libhandle/handle.c b/libhandle/handle.c
> index 878d14d..a70fa32 100644
> --- a/libhandle/handle.c
> +++ b/libhandle/handle.c
> @@ -41,7 +41,6 @@ typedef union {
>  } comarg_t;
>  
>  static int obj_to_handle(char *, int, unsigned int, comarg_t, void**, size_t*);
> -static int handle_to_fsfd(void *, char **);
>  static char *path_to_fspath(char *path);
>  
>  
> @@ -214,8 +213,10 @@ handle_to_fshandle(
>  	return 0;
>  }
>  
> -static int
> -handle_to_fsfd(void *hanp, char **path)
> +int
> +handle_to_fsfd(
> +	void		*hanp,
> +	char		**path)
>  {
>  	struct fdhash	*fdhp;
>  
> diff --git a/libhandle/parent.c b/libhandle/parent.c
> new file mode 100644
> index 0000000..f6be3bd
> --- /dev/null
> +++ b/libhandle/parent.c
> @@ -0,0 +1,325 @@
> +/*
> + * Copyright (C) 2017 Oracle.  All Rights Reserved.
> + *
> + * Author: Darrick J. Wong <darrick.wong@oracle.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version 2
> + * of the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation,
> + * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
> + */
> +#include "platform_defs.h"
> +#include "xfs.h"
> +#include "xfs_arch.h"
> +#include "list.h"
> +#include "path.h"
> +#include "handle.h"
> +#include "parent.h"
> +
> +/* Allocate a buffer large enough for some parent pointer records. */
> +static inline struct xfs_pptr_info *
> +xfs_pptr_alloc(
> +      size_t                  nr_ptrs)
> +{
> +      struct xfs_pptr_info    *pi;
> +
> +      pi = malloc(XFS_PPTR_INFO_SIZEOF(nr_ptrs));
> +      if (!pi)
> +              return NULL;
> +      memset(pi, 0, sizeof(struct xfs_pptr_info));
> +      pi->pi_ptrs_size = nr_ptrs;
> +      return pi;
> +}
> +
> +/* Walk all parents of the given file handle. */
> +static int
> +handle_walk_parents(
> +	int			fd,
> +	struct xfs_handle	*handle,
> +	walk_pptr_fn		fn,
> +	void			*arg)
> +{
> +	struct xfs_pptr_info	*pi;
> +	struct xfs_parent_ptr	*p;
> +	unsigned int		i;
> +	ssize_t			ret = -1;
> +
> +	pi = xfs_pptr_alloc(4);
> +	if (!pi)
> +		return -1;
> +
> +	if (handle) {
> +		memcpy(&pi->pi_handle, handle, sizeof(struct xfs_handle));
> +		pi->pi_flags = XFS_PPTR_IFLAG_HANDLE;
> +	}
> +
> +	ret = ioctl(fd, XFS_IOC_GETPPOINTER, pi);
> +	while (!ret) {
> +		if (pi->pi_flags & XFS_PPTR_OFLAG_ROOT) {
> +			ret = fn(pi, NULL, arg);
> +			break;
> +		}
> +		if (pi->pi_ptrs_used == 0)
> +			break;
> +		for (i = 0; i < pi->pi_ptrs_used; i++) {
> +			p = XFS_PPINFO_TO_PP(pi, i);
> +			ret = fn(pi, p, arg);
> +			if (ret)
> +				goto out_pi;
> +		}
> +		ret = ioctl(fd, XFS_IOC_GETPPOINTER, pi);
> +	}
> +
> +out_pi:
> +	free(pi);
> +	return ret;
> +}
> +
> +/* Walk all parent pointers of this handle. */
> +int
> +handle_walk_pptrs(
> +	void			*hanp,
> +	size_t			hlen,
> +	walk_pptr_fn		fn,
> +	void			*arg)
> +{
> +	char			*mntpt;
> +	int			fd;
> +
> +	if (hlen != sizeof(struct xfs_handle)) {
> +		errno = EINVAL;
> +		return -1;
> +	}
> +
> +	fd = handle_to_fsfd(hanp, &mntpt);
> +	if (fd < 0)
> +		return -1;
> +
> +	return handle_walk_parents(fd, hanp, fn, arg);
> +}
> +
> +/* Walk all parent pointers of this fd. */
> +int
> +fd_walk_pptrs(
> +	int			fd,
> +	walk_pptr_fn		fn,
> +	void			*arg)
> +{
> +	return handle_walk_parents(fd, NULL, fn, arg);
> +}
> +
> +struct walk_ppaths_info {
> +	walk_ppath_fn			fn;
> +	void				*arg;
> +	char				*mntpt;
> +	struct path_list		*path;
> +	int				fd;
> +};
> +
> +struct walk_ppath_level_info {
> +	struct xfs_handle		newhandle;
> +	struct path_component		*pc;
> +	struct walk_ppaths_info		*wpi;
> +};
> +
> +static int handle_walk_parent_paths(struct walk_ppaths_info *wpi,
> +		struct xfs_handle *handle);
> +
> +static int
> +handle_walk_parent_path_ptr(
> +	struct xfs_pptr_info		*pi,
> +	struct xfs_parent_ptr		*p,
> +	void				*arg)
> +{
> +	struct walk_ppath_level_info	*wpli = arg;
> +	struct walk_ppaths_info		*wpi = wpli->wpi;
> +	unsigned int			i;
> +	int				ret = 0;
> +
> +	if (pi->pi_flags & XFS_PPTR_OFLAG_ROOT)
> +		return wpi->fn(wpi->mntpt, wpi->path, wpi->arg);
> +
> +	for (i = 0; i < pi->pi_ptrs_used; i++) {
> +		p = XFS_PPINFO_TO_PP(pi, i);
> +		ret = path_component_change(wpli->pc, p->xpp_name,
> +				p->xpp_namelen);
> +		if (ret)
> +			break;
> +		wpli->newhandle.ha_fid.fid_ino = p->xpp_ino;
> +		wpli->newhandle.ha_fid.fid_gen = p->xpp_gen;
> +		path_list_add_parent_component(wpi->path, wpli->pc);
> +		ret = handle_walk_parent_paths(wpi, &wpli->newhandle);
> +		path_list_del_component(wpi->path, wpli->pc);
> +		if (ret)
> +			break;
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * Recursively walk all parents of the given file handle; if we hit the
> + * fs root then we call the associated function with the constructed path.
> + */
> +static int
> +handle_walk_parent_paths(
> +	struct walk_ppaths_info		*wpi,
> +	struct xfs_handle		*handle)
> +{
> +	struct walk_ppath_level_info	*wpli;
> +	int				ret;
> +
> +	wpli = malloc(sizeof(struct walk_ppath_level_info));
> +	if (!wpli)
> +		return -1;
> +	wpli->pc = path_component_init("");
> +	if (!wpli->pc) {
> +		free(wpli);
> +		return -1;
> +	}
> +	wpli->wpi = wpi;
> +	memcpy(&wpli->newhandle, handle, sizeof(struct xfs_handle));
> +
> +	ret = handle_walk_parents(wpi->fd, handle, handle_walk_parent_path_ptr,
> +			wpli);
> +
> +	path_component_free(wpli->pc);
> +	free(wpli);
> +	return ret;
> +}
> +
> +/*
> + * Call the given function on all known paths from the vfs root to the inode
> + * described in the handle.
> + */
> +int
> +handle_walk_ppaths(
> +	void			*hanp,
> +	size_t			hlen,
> +	walk_ppath_fn		fn,
> +	void			*arg)
> +{
> +	struct walk_ppaths_info	wpi;
> +	ssize_t			ret;
> +
> +	if (hlen != sizeof(struct xfs_handle)) {
> +		errno = EINVAL;
> +		return -1;
> +	}
> +
> +	wpi.fd = handle_to_fsfd(hanp, &wpi.mntpt);
> +	if (wpi.fd < 0)
> +		return -1;
> +	wpi.path = path_list_init();
> +	if (!wpi.path)
> +		return -1;
> +	wpi.fn = fn;
> +	wpi.arg = arg;
> +
> +	ret = handle_walk_parent_paths(&wpi, hanp);
> +	path_list_free(wpi.path);
> +
> +	return ret;
> +}
> +
> +/*
> + * Call the given function on all known paths from the vfs root to the inode
> + * referred to by the file description.
> + */
> +int
> +fd_walk_ppaths(
> +	int			fd,
> +	walk_ppath_fn		fn,
> +	void			*arg)
> +{
> +	struct walk_ppaths_info	wpi;
> +	void			*hanp;
> +	size_t			hlen;
> +	int			fsfd;
> +	int			ret;
> +
> +	ret = fd_to_handle(fd, &hanp, &hlen);
> +	if (ret)
> +		return ret;
> +
> +	fsfd = handle_to_fsfd(hanp, &wpi.mntpt);
> +	if (fsfd < 0)
> +		return -1;
> +	wpi.fd = fd;
> +	wpi.path = path_list_init();
> +	if (!wpi.path)
> +		return -1;
> +	wpi.fn = fn;
> +	wpi.arg = arg;
> +
> +	ret = handle_walk_parent_paths(&wpi, hanp);
> +	path_list_free(wpi.path);
> +
> +	return ret;
> +}
> +
> +struct path_walk_info {
> +	char			*buf;
> +	size_t			len;
> +};
> +
> +/* Helper that stringifies the first full path that we find. */
> +static int
> +handle_to_path_walk(
> +	const char		*mntpt,
> +	struct path_list	*path,
> +	void			*arg)
> +{
> +	struct path_walk_info	*pwi = arg;
> +	int			ret;
> +
> +	ret = snprintf(pwi->buf, pwi->len, "%s", mntpt);
> +	if (ret != strlen(mntpt)) {
> +		errno = ENOMEM;
> +		return -1;
> +	}
> +
> +	ret = path_list_to_string(path, pwi->buf + ret, pwi->len - ret);
> +	if (ret < 0)
> +		return ret;
> +
> +	return WALK_PPATHS_ABORT;
> +}
> +
> +/* Return any eligible path to this file handle. */
> +int
> +handle_to_path(
> +	void			*hanp,
> +	size_t			hlen,
> +	char			*path,
> +	size_t			pathlen)
> +{
> +	struct path_walk_info	pwi;
> +
> +	pwi.buf = path;
> +	pwi.len = pathlen;
> +	return handle_walk_ppaths(hanp, hlen, handle_to_path_walk, &pwi);
> +}
> +
> +/* Return any eligible path to this file description. */
> +int
> +fd_to_path(
> +	int			fd,
> +	char			*path,
> +	size_t			pathlen)
> +{
> +	struct path_walk_info	pwi;
> +
> +	pwi.buf = path;
> +	pwi.len = pathlen;
> +	return fd_walk_ppaths(fd, handle_to_path_walk, &pwi);
> +}
> diff --git a/libxfs/xfs_fs.h b/libxfs/xfs_fs.h
> index e3ce233..aa613f9 100644
> --- a/libxfs/xfs_fs.h
> +++ b/libxfs/xfs_fs.h
> @@ -610,6 +610,14 @@ struct xfs_pptr_info {
>  #define XFS_PPINFO_TO_PP(info, idx)    \
>  	(&(((struct xfs_parent_ptr *)((char *)(info) + sizeof(*(info))))[(idx)]))
>  
> +#define XFS_PPTR_ALL_IFLAGS    (XFS_PPTR_IFLAG_HANDLE)
> +
> +/* partial results only */
> +#define XFS_PPTR_OFLAG_PARTIAL (1U << 0)
> +
> +/* target was the root directory */
> +#define XFS_PPTR_OFLAG_ROOT    (1U << 1)

Uhoh, I forgot about this chunk, which should be in the kernel patches
somewhere I guess...

--D

> +
>  /*
>   * ioctl limits
>   */
> diff --git a/scrub/inodes.c b/scrub/inodes.c
> index ccfb9e0..3fbcd1a 100644
> --- a/scrub/inodes.c
> +++ b/scrub/inodes.c
> @@ -31,6 +31,7 @@
>  #include "xfs_scrub.h"
>  #include "common.h"
>  #include "inodes.h"
> +#include "parent.h"
>  
>  /*
>   * Iterate a range of inodes.
> @@ -293,3 +294,28 @@ xfs_open_handle(
>  	return open_by_fshandle(handle, sizeof(*handle),
>  			O_RDONLY | O_NOATIME | O_NOFOLLOW | O_NOCTTY);
>  }
> +
> +/* Construct a description for an inode. */
> +void
> +xfs_scrub_ino_descr(
> +	struct scrub_ctx	*ctx,
> +	struct xfs_handle	*handle,
> +	char			*buf,
> +	size_t			buflen)
> +{
> +	uint64_t		ino;
> +	xfs_agnumber_t		agno;
> +	xfs_agino_t		agino;
> +	int			ret;
> +
> +	ret = handle_to_path(handle, sizeof(struct xfs_handle), buf, buflen);
> +	if (ret >= 0)
> +		return;
> +
> +	ino = handle->ha_fid.fid_ino;
> +	agno = ino / (1ULL << (ctx->inopblog + ctx->agblklog));
> +	agino = ino % (1ULL << (ctx->inopblog + ctx->agblklog));
> +	snprintf(buf, buflen, _("inode %"PRIu64" (%u/%u)"), ino, agno,
> +			agino);
> +}
> +
> diff --git a/scrub/inodes.h b/scrub/inodes.h
> index 693cb05..e94de0a 100644
> --- a/scrub/inodes.h
> +++ b/scrub/inodes.h
> @@ -28,5 +28,7 @@ bool xfs_scan_all_inodes(struct scrub_ctx *ctx, xfs_inode_iter_fn fn,
>  		void *arg);
>  
>  int xfs_open_handle(struct xfs_handle *handle);
> +void xfs_scrub_ino_descr(struct scrub_ctx *ctx, struct xfs_handle *handle,
> +		char *buf, size_t buflen);
>  
>  #endif /* XFS_SCRUB_INODES_H_ */
> diff --git a/scrub/phase5.c b/scrub/phase5.c
> index 01038f7..ecaaaaa 100644
> --- a/scrub/phase5.c
> +++ b/scrub/phase5.c
> @@ -245,16 +245,11 @@ xfs_scrub_connections(
>  	void			*arg)
>  {
>  	bool			*pmoveon = arg;
> -	char			descr[DESCR_BUFSZ];
> +	char			descr[PATH_MAX];
>  	bool			moveon = true;
> -	xfs_agnumber_t		agno;
> -	xfs_agino_t		agino;
>  	int			fd = -1;
>  
> -	agno = bstat->bs_ino / (1ULL << (ctx->inopblog + ctx->agblklog));
> -	agino = bstat->bs_ino % (1ULL << (ctx->inopblog + ctx->agblklog));
> -	snprintf(descr, DESCR_BUFSZ, _("inode %"PRIu64" (%u/%u)"),
> -			(uint64_t)bstat->bs_ino, agno, agino);
> +	xfs_scrub_ino_descr(ctx, handle, descr, PATH_MAX);
>  	background_sleep();
>  
>  	/* Warn about naming problems in xattrs. */
> -- 
> 2.7.4
> 
> --
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