mount: prevent second mount -a from mounting everything again

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/coreutils/df.c b/coreutils/df.c
index 11a739816f1cff86f8c2e88319eeb61f99e842f1..83794ad8824be9a52b60772ef9b136a72d6058d5 100644 (file)
--- a/coreutils/df.c
+++ b/coreutils/df.c
@@ -167,10 +167,9 @@ int df_main(int argc UNUSED_PARAM, char **argv)
                                continue;
 
 #ifdef WHY_WE_DO_IT_FOR_DEV_ROOT_ONLY
-/* ... and also this is the only user of find_block_device */
                        if (strcmp(device, "/dev/root") == 0) {
                                /* Adjusts device to be the real root device,
-                               * or leaves device alone if it can't find it */
+                                * or leaves device alone if it can't find it */
                                device = find_block_device("/");
                                if (!device) {
                                        goto set_error;

diff --git a/util-linux/mount.c b/util-linux/mount.c
index d7ca7da37a4c65dc1815938c755883714a018a09..c2b508e5b43011cea007a8271de7e7a6d06c1e04 100644 (file)
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -1829,7 +1829,8 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
        llist_t *lst_o = NULL;
        const char *fstabname;
        FILE *fstab;
-       int i, j, rc = 0;
+       int i, j;
+       int rc = EXIT_SUCCESS;
        unsigned opt;
        struct mntent mtpair[2], *mtcur = mtpair;
        IF_NOT_DESKTOP(const int nonroot = 0;)
@@ -1893,7 +1894,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                        mtpair->mnt_type = fstype;
                        mtpair->mnt_opts = cmdopts;
                        resolve_mount_spec(&mtpair->mnt_fsname);
-                       rc = singlemount(mtpair, 0);
+                       rc = singlemount(mtpair, /*ignore_busy:*/ 0);
                        return rc;
                }
                storage_path = bb_simplify_path(argv[0]); // malloced
@@ -1949,10 +1950,13 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                if (argv[0]) {
 
                        // Is this what we're looking for?
-                       if (strcmp(argv[0], mtcur->mnt_fsname) &&
-                          strcmp(storage_path, mtcur->mnt_fsname) &&
-                          strcmp(argv[0], mtcur->mnt_dir) &&
-                          strcmp(storage_path, mtcur->mnt_dir)) continue;
+                       if (strcmp(argv[0], mtcur->mnt_fsname) != 0
+                        && strcmp(storage_path, mtcur->mnt_fsname) != 0
+                        && strcmp(argv[0], mtcur->mnt_dir) != 0
+                        && strcmp(storage_path, mtcur->mnt_dir) != 0
+                       ) {
+                               continue; // no
+                       }
 
                        // Remember this entry.  Something later may have
                        // overmounted it, and we want the _last_ match.
@@ -1960,6 +1964,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
 
                // If we're mounting all
                } else {
+                       struct mntent *mp;
                        // No, mount -a won't mount anything,
                        // even user mounts, for mere humans
                        if (nonroot)
@@ -1969,7 +1974,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                        if (!match_fstype(mtcur, fstype))
                                continue;
 
-                       // Skip noauto and swap anyway.
+                       // Skip noauto and swap anyway
                        if ((parse_mount_options(mtcur->mnt_opts, NULL) & (MOUNT_NOAUTO | MOUNT_SWAP))
                        // swap is bogus "fstype", parse_mount_options can't check fstypes
                         || strcasecmp(mtcur->mnt_type, "swap") == 0
@@ -1987,10 +1992,23 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                        // NFS mounts want this to be xrealloc-able
                        mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
 
-                       // Mount this thing
-                       if (singlemount(mtcur, 1)) {
-                               // Count number of failed mounts
-                               rc++;
+                       // If nothing is mounted on this directory...
+                       // (otherwise repeated "mount -a" mounts everything again)
+                       mp = find_mount_point(mtcur->mnt_dir, /*subdir_too:*/ 0);
+                       // We do not check fsname match of found mount point -
+                       // "/" may have fsname of "/dev/root" while fstab
+                       // says "/dev/something_else".
+                       if (mp) {
+                               bb_error_msg("according to %s, "
+                                       "%s is already mounted on %s",
+                                       bb_path_mtab_file,
+                                       mp->mnt_fsname, mp->mnt_dir);
+                       } else {
+                               // ...mount this thing
+                               if (singlemount(mtcur, /*ignore_busy:*/ 1)) {
+                                       // Count number of failed mounts
+                                       rc++;
+                               }
                        }
                        free(mtcur->mnt_opts);
                }
@@ -1998,7 +2016,7 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
 
        // End of fstab/mtab is reached.
        // Were we looking for something specific?
-       if (argv[0]) {
+       if (argv[0]) { // yes
                long l;
 
                // If we didn't find anything, complain
@@ -2031,13 +2049,24 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                                bb_error_msg_and_die(bb_msg_you_must_be_root);
                }
 
-               // Mount the last thing we found
-               mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
-               append_mount_options(&(mtcur->mnt_opts), cmdopts);
-               resolve_mount_spec(&mtpair->mnt_fsname);
-               rc = singlemount(mtcur, 0);
-               if (ENABLE_FEATURE_CLEAN_UP)
-                       free(mtcur->mnt_opts);
+               //util-linux-2.12 does not do this check.
+               //// If nothing is mounted on this directory...
+               //// (otherwise repeated "mount FOO" mounts FOO again)
+               //mp = find_mount_point(mtcur->mnt_dir, /*subdir_too:*/ 0);
+               //if (mp) {
+               //      bb_error_msg("according to %s, "
+               //              "%s is already mounted on %s",
+               //              bb_path_mtab_file,
+               //              mp->mnt_fsname, mp->mnt_dir);
+               //} else {
+                       // ...mount the last thing we found
+                       mtcur->mnt_opts = xstrdup(mtcur->mnt_opts);
+                       append_mount_options(&(mtcur->mnt_opts), cmdopts);
+                       resolve_mount_spec(&mtpair->mnt_fsname);
+                       rc = singlemount(mtcur, /*ignore_busy:*/ 0);
+                       if (ENABLE_FEATURE_CLEAN_UP)
+                               free(mtcur->mnt_opts);
+               //}
        }
 
  //ret:
@@ -2047,5 +2076,15 @@ int mount_main(int argc UNUSED_PARAM, char **argv)
                free(storage_path);
                free(cmdopts);
        }
+
+//TODO: exitcode should be ORed mask of (from "man mount"):
+// 0 success
+// 1 incorrect invocation or permissions
+// 2 system error (out of memory, cannot fork, no more loop devices)
+// 4 internal mount bug or missing nfs support in mount
+// 8 user interrupt
+//16 problems writing or locking /etc/mtab
+//32 mount failure
+//64 some mount succeeded
        return rc;
 }