On 3/28/17 10:29 AM, David Howells wrote:
> xfs_io: Allow "open -P" to specify O_PATH
>
> Allow "open -P" to specify O_PATH so that paths which would otherwise be
> unopenable might be opened for stat()'ing. Such things include files that
> would incur an access error or device files for which no corresponding
> driver is available.
Given all the trouble you ran into with this (and I guess I'm not too surprised),
it might make more sense to change stat_f() and statx_f() to be able
to take a pathname separate from the target pathname on the xfs_io
commandline, i.e. something like:
xfs_io -c "stat foo"
instead of
xfs_io -P -c "stat" foo
-Eric
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> ---
> io/io.h | 1 +
> io/open.c | 13 ++++++++++++-
> man/man8/xfs_io.8 | 6 +++++-
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/io/io.h b/io/io.h
> index 952bdb8..b49a133 100644
> --- a/io/io.h
> +++ b/io/io.h
> @@ -38,6 +38,7 @@
> #define IO_FOREIGN (1<<7)
> #define IO_NONBLOCK (1<<8)
> #define IO_TMPFILE (1<<9)
> +#define IO_PATH (1<<10)
>
> /*
> * Regular file I/O control
> diff --git a/io/open.c b/io/open.c
> index 2ed55cf..9eba8ae 100644
> --- a/io/open.c
> +++ b/io/open.c
> @@ -72,6 +72,8 @@ openfile(
> oflags |= O_NONBLOCK;
> if (flags & IO_TMPFILE)
> oflags |= O_TMPFILE;
> + if (flags & IO_PATH)
> + oflags |= O_PATH;
>
> fd = open(path, oflags, mode);
> if (fd < 0) {
> @@ -179,6 +181,7 @@ open_help(void)
> " -t -- open with O_TRUNC (truncate the file to zero length if it exists)\n"
> " -R -- mark the file as a realtime XFS file immediately after opening it\n"
> " -T -- open with O_TMPFILE (create a file not visible in the namespace)\n"
> +" -P -- open with O_PATH (create an fd that is merely a location reference)\n"
> " Note1: usually read/write direct IO requests must be blocksize aligned;\n"
> " some kernels, however, allow sectorsize alignment for direct IO.\n"
> " Note2: the bmap for non-regular files can be obtained provided the file\n"
> @@ -203,7 +206,7 @@ open_f(
> return 0;
> }
>
> - while ((c = getopt(argc, argv, "FRTacdfm:nrstx")) != EOF) {
> + while ((c = getopt(argc, argv, "FPRTacdfm:nrstx")) != EOF) {
> switch (c) {
> case 'F':
> /* Ignored / deprecated now, handled automatically */
> @@ -244,6 +247,9 @@ open_f(
> case 'T':
> flags |= IO_TMPFILE;
> break;
> + case 'P':
> + flags |= IO_PATH;
> + break;
> default:
> return command_usage(&open_cmd);
> }
> @@ -257,6 +263,11 @@ open_f(
> return -1;
> }
>
> + if ((flags & IO_PATH) && (flags & ~IO_PATH)) {
> + fprintf(stderr, _("-P is incompatible with other options\n"));
> + return -1;
> + }
> +
> fd = openfile(argv[optind], &geometry, flags, mode);
> if (fd < 0)
> return 0;
> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> index 022f0ea..77ba760 100644
> --- a/man/man8/xfs_io.8
> +++ b/man/man8/xfs_io.8
> @@ -122,7 +122,7 @@ command for more details on any command.
> Display a list of all open files and (optionally) switch to an alternate
> current open file.
> .TP
> -.BI "open [[ \-acdfrstRT ] " path " ]"
> +.BI "open [[ \-acdfrstRTP ] " path " ]"
> Closes the current file, and opens the file specified by
> .I path
> instead. Without any arguments, displays statistics about the current
> @@ -164,6 +164,10 @@ option.
> .B \-R
> marks the file as a realtime XFS file after
> opening it, if it is not already marked as such.
> +.TP
> +.B \-P
> +opens the path as a referent only (O_PATH). This is incompatible with other
> +flags specifying other O_xxx flags.
> .PD
> .RE
> .TP
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
