On 4/11/17 12:22 PM, Bill O'Donnell wrote:
> xfs_growfs manpage clearly states that the filesystem must
> be mounted to be grown. Current behavior allows xfs_growfs
> to proceed if the filesystem /containing/ the path
> of the desired target is mounted. This is not the specified
> behavior. Instead, also check the targeted fs argument against
> the entry found in the fstable lookup. Unless the targeted
> fs is actually mounted, reject the command.
>
> In order to cover bind-mounts, create a new lookup function
> based on the mountpoints instead of just the device name.
>
> Signed-off-by: Bill O'Donnell <billodo@xxxxxxxxxx>
> ---
>
> v2: in order to properly handle relative pathnames, symlinks,
> and bind-mounts, use realpath to establish canonical path name.
> This also requires the introduction of a lookup function based
> on the target mountpoint.
>
> growfs/xfs_growfs.c | 10 +++++++++-
> include/path.h | 1 +
> libxcmd/paths.c | 21 +++++++++++++++++++++
> 3 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/growfs/xfs_growfs.c b/growfs/xfs_growfs.c
> index a294e14..a61e2f1 100644
> --- a/growfs/xfs_growfs.c
> +++ b/growfs/xfs_growfs.c
> @@ -133,6 +133,7 @@ main(int argc, char **argv)
> int spinodes;
> int rmapbt_enabled;
> int reflink_enabled;
> + char rpath[PATH_MAX];
>
> progname = basename(argv[0]);
> setlocale(LC_ALL, "");
> @@ -202,7 +203,14 @@ main(int argc, char **argv)
> aflag = 1;
>
> fs_table_initialise(0, NULL, 0, NULL);
> - fs = fs_table_lookup(argv[optind], FS_MOUNT_POINT);
> +
> + if (!realpath(argv[optind], rpath)) {
> + fprintf(stderr, _("%s: %s is not a mounted XFS filesystem\n"),
> + progname, argv[optind]);
> + return 1;
Probably not the clearest error message; if realpath failed, we
really don't know much at all about the path yet.
(_("Path resolution failed for %s: %s\n"), path, strerror(errno))
or something like that would be more informative if it fails..
Otherwise, I think this looks ok. I was a little unsure about
keeping the old fs_table_lookup behavior around, but given that
xfs_growfs is the only utility (I think) which /explicitly/ says
it requires a mount point (and can have irreversible consequences
if it's pointed at the wrong thing) that's probably ok.
One other suggestion would be to document the difference between
the 2 lookup functions a bit more, making it more clear that one
will find the fs table entry for the fs hosting the file at *path,
and the other will find it only if it /is/ the mount point.
I had a concern that while you're passing a realpath'd path to
the new function, the mount points in the table aren't realpath'd.
But I /think/ that still works; if I mount onto a symlinked dir,
it's the realpath (symlink target) that ends up in /proc/mounts.
Still, it might be safest to realpath the path found in the
fs table as well prior to the comparison - if it's iterating
over /etc/mtab instead of /proc/mounts on an older machine, I'm
not sure what the paths end up looking like in that file.
-Eric
> + }
> +
> + fs = fs_table_lookup_mount(rpath);
> if (!fs) {
> fprintf(stderr, _("%s: %s is not a mounted XFS filesystem\n"),
> progname, argv[optind]);
> diff --git a/include/path.h b/include/path.h
> index d077bac..1d3a902 100644
> --- a/include/path.h
> +++ b/include/path.h
> @@ -56,6 +56,7 @@ extern void fs_table_insert_project_path(char *__dir, uint __projid);
>
>
> extern fs_path_t *fs_table_lookup(const char *__dir, uint __flags);
> +extern fs_path_t *fs_table_lookup_mount(const char *__dir);
>
> typedef struct fs_cursor {
> uint count; /* total count of mount entries */
> diff --git a/libxcmd/paths.c b/libxcmd/paths.c
> index 816acc2..10927c6 100644
> --- a/libxcmd/paths.c
> +++ b/libxcmd/paths.c
> @@ -86,6 +86,27 @@ fs_table_lookup(
> return NULL;
> }
>
> +/*
> + * Find the FS table entry for the given path. Compare
> + * the path to mountpoint entries in the table.
> + */
> +struct fs_path *
> +fs_table_lookup_mount(
> + const char *dir)
> +{
> + uint i;
> + dev_t dev = 0;
> +
> + if (fs_device_number(dir, &dev))
> + return NULL;
> +
> + for (i = 0; i < fs_count; i++) {
> + if (strcmp(fs_table[i].fs_dir, dir) == 0)
> + return &fs_table[i];
> + }
> + return NULL;
> +}
> +
> static int
> fs_table_insert(
> char *dir,
>
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