Re: [PATCH 1/2] xfs_db: add a directory path lookup command

Chandan Babu R
2021-02-04T09:40:29Z

On 04 Feb 2021 at 01:13, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> Add a command to xfs_db so that we can navigate to inodes by path.

Looks good to me.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

>
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
> db/Makefile | 3 -
> db/command.c | 1
> db/command.h | 1
> db/namei.c | 220 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> man/man8/xfs_db.8 | 4 +
> 5 files changed, 228 insertions(+), 1 deletion(-)
> create mode 100644 db/namei.c
>
>
> diff --git a/db/Makefile b/db/Makefile
> index 9d502bf0..beafb105 100644
> --- a/db/Makefile
> +++ b/db/Makefile
> @@ -14,7 +14,8 @@ HFILES = addr.h agf.h agfl.h agi.h attr.h attrshort.h bit.h block.h bmap.h \
> io.h logformat.h malloc.h metadump.h output.h print.h quit.h sb.h \
> sig.h strvec.h text.h type.h write.h attrset.h symlink.h fsmap.h \
> fuzz.h
> -CFILES = $(HFILES:.h=.c) btdump.c btheight.c convert.c info.c timelimit.c
> +CFILES = $(HFILES:.h=.c) btdump.c btheight.c convert.c info.c namei.c \
> + timelimit.c
> LSRCFILES = xfs_admin.sh xfs_ncheck.sh xfs_metadump.sh
>
> LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBFROG) $(LIBUUID) $(LIBRT) $(LIBPTHREAD)
> diff --git a/db/command.c b/db/command.c
> index 43828369..02f778b9 100644
> --- a/db/command.c
> +++ b/db/command.c
> @@ -131,6 +131,7 @@ init_commands(void)
> logformat_init();
> io_init();
> metadump_init();
> + namei_init();
> output_init();
> print_init();
> quit_init();
> diff --git a/db/command.h b/db/command.h
> index 6913c817..498983ff 100644
> --- a/db/command.h
> +++ b/db/command.h
> @@ -33,3 +33,4 @@ extern void btdump_init(void);
> extern void info_init(void);
> extern void btheight_init(void);
> extern void timelimit_init(void);
> +extern void namei_init(void);
> diff --git a/db/namei.c b/db/namei.c
> new file mode 100644
> index 00000000..6fddbc4a
> --- /dev/null
> +++ b/db/namei.c
> @@ -0,0 +1,220 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2021 Oracle. All Rights Reserved.
> + * Author: Darrick J. Wong <djwong@kernel.org>
> + */
> +#include "libxfs.h"
> +#include "command.h"
> +#include "output.h"
> +#include "init.h"
> +#include "io.h"
> +#include "type.h"
> +#include "input.h"
> +#include "faddr.h"
> +#include "fprint.h"
> +#include "field.h"
> +#include "inode.h"
> +
> +/* Path lookup */
> +
> +/* Key for looking up metadata inodes. */
> +struct dirpath {
> + /* Array of string pointers. */
> + char **path;
> +
> + /* Number of strings in path. */
> + unsigned int depth;
> +};
> +
> +static void
> +path_free(
> + struct dirpath *dirpath)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < dirpath->depth; i++)
> + free(dirpath->path[i]);
> + free(dirpath->path);
> + free(dirpath);
> +}
> +
> +/* Chop a freeform string path into a structured path. */
> +static struct dirpath *
> +path_parse(
> + const char *path)
> +{
> + struct dirpath *dirpath;
> + const char *p = path;
> + const char *endp = path + strlen(path);
> +
> + dirpath = calloc(sizeof(*dirpath), 1);
> + if (!dirpath)
> + return NULL;
> +
> + while (p < endp) {
> + char **new_path;
> + const char *next_slash;
> +
> + next_slash = strchr(p, '/');
> + if (next_slash == p) {
> + p++;
> + continue;
> + }
> + if (!next_slash)
> + next_slash = endp;
> +
> + new_path = realloc(dirpath->path,
> + (dirpath->depth + 1) * sizeof(char *));
> + if (!new_path) {
> + path_free(dirpath);
> + return NULL;
> + }
> +
> + dirpath->path = new_path;
> + dirpath->path[dirpath->depth] = strndup(p, next_slash - p);
> + dirpath->depth++;
> +
> + p = next_slash + 1;
> + }
> +
> + return dirpath;
> +}
> +
> +/* Given a directory and a structured path, walk the path and set the cursor. */
> +static int
> +path_navigate(
> + struct xfs_mount *mp,
> + xfs_ino_t rootino,
> + struct dirpath *dirpath)
> +{
> + struct xfs_inode *dp;
> + xfs_ino_t ino = rootino;
> + unsigned int i;
> + int error;
> +
> + error = -libxfs_iget(mp, NULL, ino, 0, &dp);
> + if (error)
> + return error;
> +
> + for (i = 0; i < dirpath->depth; i++) {
> + struct xfs_name xname = {
> + .name = dirpath->path[i],
> + .len = strlen(dirpath->path[i]),
> + };
> +
> + if (!S_ISDIR(VFS_I(dp)->i_mode)) {
> + error = ENOTDIR;
> + goto rele;
> + }
> +
> + error = -libxfs_dir_lookup(NULL, dp, &xname, &ino, NULL);
> + if (error)
> + goto rele;
> + if (!xfs_verify_ino(mp, ino)) {
> + error = EFSCORRUPTED;
> + goto rele;
> + }
> +
> + libxfs_irele(dp);
> + dp = NULL;
> +
> + error = -libxfs_iget(mp, NULL, ino, 0, &dp);
> + switch (error) {
> + case EFSCORRUPTED:
> + case EFSBADCRC:
> + case 0:
> + break;
> + default:
> + return error;
> + }
> + }
> +
> + set_cur_inode(ino);
> +rele:
> + if (dp)
> + libxfs_irele(dp);
> + return error;
> +}
> +
> +/* Walk a directory path to an inode and set the io cursor to that inode. */
> +static int
> +path_walk(
> + char *path)
> +{
> + struct dirpath *dirpath;
> + char *p = path;
> + xfs_ino_t rootino = mp->m_sb.sb_rootino;
> + int error = 0;
> +
> + if (*p == '/') {
> + /* Absolute path, start from the root inode. */
> + p++;
> + } else {
> + /* Relative path, start from current dir. */
> + if (iocur_top->typ != &typtab[TYP_INODE] ||
> + !S_ISDIR(iocur_top->mode))
> + return ENOTDIR;
> +
> + rootino = iocur_top->ino;
> + }
> +
> + dirpath = path_parse(p);
> + if (!dirpath)
> + return ENOMEM;
> +
> + error = path_navigate(mp, rootino, dirpath);
> + path_free(dirpath);
> + return error;
> +}
> +
> +static void
> +path_help(void)
> +{
> + dbprintf(_(
> +"\n"
> +" Navigate to an inode via directory path.\n"
> + ));
> +}
> +
> +static int
> +path_f(
> + int argc,
> + char **argv)
> +{
> + int c;
> + int error;
> +
> + while ((c = getopt(argc, argv, "")) != -1) {
> + switch (c) {
> + default:
> + path_help();
> + return 0;
> + }
> + }
> +
> + error = path_walk(argv[optind]);
> + if (error) {
> + dbprintf("%s: %s\n", argv[optind], strerror(error));
> + exitcode = 1;
> + }
> +
> + return 0;
> +}
> +
> +static struct cmdinfo path_cmd = {
> + .name = "path",
> + .altname = NULL,
> + .cfunc = path_f,
> + .argmin = 1,
> + .argmax = 1,
> + .canpush = 0,
> + .args = "",
> + .help = path_help,
> +};
> +
> +void
> +namei_init(void)
> +{
> + path_cmd.oneline = _("navigate to an inode by path");
> + add_command(&path_cmd);
> +}
> diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
> index 55388be6..4df265ec 100644
> --- a/man/man8/xfs_db.8
> +++ b/man/man8/xfs_db.8
> @@ -831,6 +831,10 @@ See the
> .B print
> command.
> .TP
> +.BI "path " dir_path
> +Walk the directory tree to an inode using the supplied path.
> +Absolute and relative paths are supported.
> +.TP
> .B pop
> Pop location from the stack.
> .TP

--
chandan