On Thu, 12 Jan 2012 09:51:30 -0200
Carlos Maiolino <cmaiolino@xxxxxxxxxx> wrote:
> During a remount of a cifs filesystem, the mtab file is not properly updated,
> which leads to a doubled entry of the same filesystem in the /etc/mtab file.
> This patch adds a new function del_mtab() which is called before the add_mtab()
> in case the fs is being remounted.
> The del_mtab() function will delete from the mtab, the old entry from the
> filesystem which is being remounted, and then, calls add_mtab() to add an
> updated entry to the mtab file.
>
> Signed-off-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> ---
> mount.cifs.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 99 insertions(+), 1 deletions(-)
>
> diff --git a/mount.cifs.c b/mount.cifs.c
> index 147f7fc..2f95d35 100644
> --- a/mount.cifs.c
> +++ b/mount.cifs.c
> @@ -42,6 +42,7 @@
> #include <fcntl.h>
> #include <limits.h>
> #include <paths.h>
> +#include <libgen.h>
> #include <sys/mman.h>
> #include <sys/wait.h>
> #ifdef HAVE_LIBCAP_NG
> @@ -161,6 +162,7 @@
> #define OPT_BKUPUID 30
> #define OPT_BKUPGID 31
>
> +#define MNT_TMP_FILE "/.mtab.cifs.XXXXXX"
>
> /* struct for holding parsed mount info for use by privleged process */
> struct parsed_mount_info {
> @@ -1624,6 +1626,95 @@ add_mtab_exit:
> return rc;
> }
>
> +static int
> +del_mtab(char *mountpoint)
> +{
> + int tmprc, rc = 0;
> + FILE *mnttmp, *mntmtab;
> + struct mntent *mountent;
> + char *mtabfile, *mtabdir, *mtabtmpfile;
> +
> + mtabfile = strdup(MOUNTED);
> + mtabdir = dirname(mtabfile);
> + mtabdir = realloc(mtabdir, strlen(mtabdir) + strlen(MNT_TMP_FILE) + 2);
> + if (!mtabdir) {
> + fprintf(stderr, "del_mtab: cannot determine current mtab path");
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + mtabtmpfile = strcat(mtabdir, MNT_TMP_FILE);
> + if (!mtabtmpfile) {
> + fprintf(stderr, "del_mtab: cannot allocate memory to tmp file");
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + atexit(unlock_mtab);
> + rc = lock_mtab();
> + if (rc) {
> + fprintf(stderr, "del_mtab: cannot lock mtab");
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + mtabtmpfile = mktemp(mtabtmpfile);
> + if (!mtabtmpfile) {
> + fprintf(stderr, "del_mtab: cannot setup tmp file destination");
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + mntmtab = setmntent(MOUNTED, "r");
> + if (!mntmtab) {
> + fprintf(stderr, "del_mtab: could not update mount table\n");
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + mnttmp = setmntent(mtabtmpfile, "w");
> + if (!mnttmp) {
> + fprintf(stderr, "del_mtab: could not update mount table\n");
> + endmntent(mntmtab);
> + rc = EX_FILEIO;
> + goto del_mtab_exit;
> + }
> +
> + while ((mountent = getmntent(mntmtab)) != NULL) {
> + if (!strcmp(mountent->mnt_dir,mountpoint))
> + continue;
> + rc = addmntent(mnttmp, mountent);
> + if (rc) {
> + fprintf(stderr, "del_mtab: unable to add mount entry to mtab\n");
> + rc = EX_FILEIO;
> + goto del_mtab_error;
> + }
> + }
> +
> + endmntent(mntmtab);
> +
> + tmprc = my_endmntent(mnttmp, 0);
> + if (tmprc) {
> + fprintf(stderr, "del_mtab: error %d detected on close of tmp file\n",
> + tmprc);
> + rc = EX_FILEIO;
> + goto del_mtab_error;
> + }
> +
> + rename(mtabtmpfile, MOUNTED);
> +
> +del_mtab_exit:
> + unlock_mtab();
> + free(mtabdir);
> + return rc;
> +
> +del_mtab_error:
> + if (unlink(mtabtmpfile))
> + fprintf(stderr, "del_mtab: failed to delete tmp file - %s\n",
> + strerror(errno));
> + goto del_mtab_exit;
> +}
> +
> /* have the child drop root privileges */
> static int
> drop_child_privs(void)
> @@ -2021,8 +2112,15 @@ mount_retry:
> }
>
> do_mtab:
> - if (!parsed_info->nomtab && !mtab_unusable())
> + if (!parsed_info->nomtab && !mtab_unusable()) {
> + if (parsed_info->flags & MS_REMOUNT) {
> + rc = del_mtab(mountpoint);
> + if (rc)
> + goto mount_exit;
> + }
> +
> rc = add_mtab(orig_dev, mountpoint, parsed_info->flags, fstype);
> + }
>
> mount_exit:
> if (parsed_info) {
Looks good. I'll wait a couple of days before merging it in case anyone
else wants to comment, but it should make the next release.
Thanks,
--
Jeff Layton <jlayton@xxxxxxxxx>
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